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-rw-r--r--CHANGES.md27
-rw-r--r--changelog.d/6349.feature1
-rw-r--r--changelog.d/6377.bugfix1
-rw-r--r--changelog.d/6385.bugfix1
-rw-r--r--changelog.d/6394.feature1
-rw-r--r--changelog.d/6411.feature1
-rw-r--r--changelog.d/6497.bugfix1
-rw-r--r--changelog.d/6501.misc1
-rw-r--r--changelog.d/6502.removal1
-rw-r--r--changelog.d/6503.misc1
-rw-r--r--changelog.d/6504.misc1
-rw-r--r--changelog.d/6505.misc1
-rw-r--r--changelog.d/6506.misc1
-rw-r--r--changelog.d/6510.misc1
-rw-r--r--changelog.d/6512.misc1
-rw-r--r--changelog.d/6514.bugfix1
-rw-r--r--changelog.d/6515.misc1
-rw-r--r--changelog.d/6517.misc1
-rw-r--r--changelog.d/6521.misc1
-rw-r--r--docs/saml_mapping_providers.md77
-rw-r--r--docs/sample_config.yaml61
-rw-r--r--mypy.ini2
-rwxr-xr-xscripts-dev/make_full_schema.sh184
-rw-r--r--synapse/__init__.py2
-rw-r--r--synapse/app/homeserver.py6
-rw-r--r--synapse/app/pusher.py7
-rw-r--r--synapse/config/saml2_config.py186
-rw-r--r--synapse/event_auth.py8
-rw-r--r--synapse/federation/federation_client.py191
-rw-r--r--synapse/federation/federation_server.py15
-rw-r--r--synapse/federation/transport/client.py33
-rw-r--r--synapse/federation/transport/server.py32
-rw-r--r--synapse/handlers/account_data.py14
-rw-r--r--synapse/handlers/account_validity.py86
-rw-r--r--synapse/handlers/federation.py286
-rw-r--r--synapse/handlers/initial_sync.py19
-rw-r--r--synapse/handlers/message.py5
-rw-r--r--synapse/handlers/pagination.py27
-rw-r--r--synapse/handlers/saml_handler.py198
-rw-r--r--synapse/handlers/search.py34
-rw-r--r--synapse/logging/context.py11
-rw-r--r--synapse/rest/client/v1/profile.py12
-rw-r--r--synapse/state/__init__.py3
-rw-r--r--synapse/storage/data_stores/main/client_ips.py8
-rw-r--r--synapse/storage/data_stores/main/events.py23
-rw-r--r--synapse/storage/data_stores/main/events_bg_updates.py8
-rw-r--r--synapse/storage/data_stores/main/events_worker.py97
-rw-r--r--synapse/storage/data_stores/main/room.py5
-rw-r--r--synapse/storage/data_stores/main/schema/delta/56/redaction_censor.sql1
-rw-r--r--synapse/storage/data_stores/main/schema/delta/56/redaction_censor2.sql4
-rw-r--r--synapse/storage/data_stores/main/schema/delta/56/redaction_censor4.sql16
-rw-r--r--synapse/storage/data_stores/main/schema/full_schemas/README.md13
-rw-r--r--synapse/storage/data_stores/main/schema/full_schemas/README.txt19
-rw-r--r--synapse/storage/data_stores/main/search.py8
-rw-r--r--synapse/storage/data_stores/main/state.py18
-rw-r--r--synapse/util/caches/snapshot_cache.py94
-rw-r--r--tests/rest/client/v2_alpha/test_register.py3
-rw-r--r--tests/storage/test_client_ips.py49
-rw-r--r--tests/test_federation.py14
-rw-r--r--tests/util/test_logcontext.py24
-rw-r--r--tests/util/test_snapshot_cache.py63
61 files changed, 1304 insertions, 707 deletions
diff --git a/CHANGES.md b/CHANGES.md
index 0ef9794aac..c83a6afbcd 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,17 +1,28 @@
+Synapse 1.7.0rc2 (2019-12-11)
+=============================
+
+Bugfixes
+--------
+
+- Fix incorrect error message for invalid requests when setting user's avatar URL. ([\#6497](https://github.com/matrix-org/synapse/issues/6497))
+- Fix support for SQLite 3.7. ([\#6499](https://github.com/matrix-org/synapse/issues/6499))
+- Fix regression where sending email push would not work when using a pusher worker. ([\#6507](https://github.com/matrix-org/synapse/issues/6507), [\#6509](https://github.com/matrix-org/synapse/issues/6509))
+
+
 Synapse 1.7.0rc1 (2019-12-09)
 =============================
 
 Features
 --------
 
-- Implement per-room message retention policies. ([\#5815](https://github.com/matrix-org/synapse/issues/5815))
+- Implement per-room message retention policies. ([\#5815](https://github.com/matrix-org/synapse/issues/5815), [\#6436](https://github.com/matrix-org/synapse/issues/6436))
 - Add etag and count fields to key backup endpoints to help clients guess if there are new keys. ([\#5858](https://github.com/matrix-org/synapse/issues/5858))
-- Add admin/v2/users endpoint with pagination. Contributed by Awesome Technologies Innovationslabor GmbH. ([\#5925](https://github.com/matrix-org/synapse/issues/5925))
+- Add `/admin/v2/users` endpoint with pagination. Contributed by Awesome Technologies Innovationslabor GmbH. ([\#5925](https://github.com/matrix-org/synapse/issues/5925))
 - Require User-Interactive Authentication for `/account/3pid/add`, meaning the user's password will be required to add a third-party ID to their account. ([\#6119](https://github.com/matrix-org/synapse/issues/6119))
 - Implement the `/_matrix/federation/unstable/net.atleastfornow/state/<context>` API as drafted in MSC2314. ([\#6176](https://github.com/matrix-org/synapse/issues/6176))
-- Configure privacy preserving settings by default for the room directory. ([\#6354](https://github.com/matrix-org/synapse/issues/6354))
+- Configure privacy-preserving settings by default for the room directory. ([\#6355](https://github.com/matrix-org/synapse/issues/6355))
 - Add ephemeral messages support by partially implementing [MSC2228](https://github.com/matrix-org/matrix-doc/pull/2228). ([\#6409](https://github.com/matrix-org/synapse/issues/6409))
-- Add support for MSC 2367, which allows specifying a reason on all membership events. ([\#6434](https://github.com/matrix-org/synapse/issues/6434))
+- Add support for [MSC 2367](https://github.com/matrix-org/matrix-doc/pull/2367), which allows specifying a reason on all membership events. ([\#6434](https://github.com/matrix-org/synapse/issues/6434))
 
 
 Bugfixes
@@ -26,8 +37,6 @@ Bugfixes
 - Fix an intermittent exception when handling read-receipts. ([\#6408](https://github.com/matrix-org/synapse/issues/6408))
 - Fix broken guest registration when there are existing blocks of numeric user IDs. ([\#6420](https://github.com/matrix-org/synapse/issues/6420))
 - Fix startup error when http proxy is defined. ([\#6421](https://github.com/matrix-org/synapse/issues/6421))
-- Clean up local threepids from user on account deactivation. ([\#6426](https://github.com/matrix-org/synapse/issues/6426))
-- Fix a bug where a room could become unusable with a low retention policy and a low activity. ([\#6436](https://github.com/matrix-org/synapse/issues/6436))
 - Fix error when using synapse_port_db on a vanilla synapse db. ([\#6449](https://github.com/matrix-org/synapse/issues/6449))
 - Fix uploading multiple cross signing signatures for the same user. ([\#6451](https://github.com/matrix-org/synapse/issues/6451))
 - Fix bug which lead to exceptions being thrown in a loop when a cross-signed device is deleted. ([\#6462](https://github.com/matrix-org/synapse/issues/6462))
@@ -67,14 +76,10 @@ Internal Changes
 - Add a test scenario to make sure room history purges don't break `/messages` in the future. ([\#6392](https://github.com/matrix-org/synapse/issues/6392))
 - Clarifications for the email configuration settings. ([\#6423](https://github.com/matrix-org/synapse/issues/6423))
 - Add more tests to the blacklist when running in worker mode. ([\#6429](https://github.com/matrix-org/synapse/issues/6429))
-- Move data store specific code out of `SQLBaseStore`. ([\#6454](https://github.com/matrix-org/synapse/issues/6454))
-- Prepare SQLBaseStore functions being moved out of the stores. ([\#6464](https://github.com/matrix-org/synapse/issues/6464))
-- Move per database functionality out of the data stores and into a dedicated `Database` class. ([\#6469](https://github.com/matrix-org/synapse/issues/6469))
+- Refactor data store layer to support multiple databases in the future. ([\#6454](https://github.com/matrix-org/synapse/issues/6454), [\#6464](https://github.com/matrix-org/synapse/issues/6464), [\#6469](https://github.com/matrix-org/synapse/issues/6469), [\#6487](https://github.com/matrix-org/synapse/issues/6487)) 
 - Port synapse.rest.client.v1 to async/await. ([\#6482](https://github.com/matrix-org/synapse/issues/6482))
 - Port synapse.rest.client.v2_alpha to async/await. ([\#6483](https://github.com/matrix-org/synapse/issues/6483))
 - Port SyncHandler to async/await. ([\#6484](https://github.com/matrix-org/synapse/issues/6484))
-- Pass in `Database` object to data stores. ([\#6487](https://github.com/matrix-org/synapse/issues/6487))
-
 
 Synapse 1.6.1 (2019-11-28)
 ==========================
diff --git a/changelog.d/6349.feature b/changelog.d/6349.feature
new file mode 100644
index 0000000000..56c4fbf78e
--- /dev/null
+++ b/changelog.d/6349.feature
@@ -0,0 +1 @@
+Implement v2 APIs for the `send_join` and `send_leave` federation endpoints (as described in [MSC1802](https://github.com/matrix-org/matrix-doc/pull/1802)).
diff --git a/changelog.d/6377.bugfix b/changelog.d/6377.bugfix
new file mode 100644
index 0000000000..ccda96962f
--- /dev/null
+++ b/changelog.d/6377.bugfix
@@ -0,0 +1 @@
+Prevent redacted events from being returned during message search.
\ No newline at end of file
diff --git a/changelog.d/6385.bugfix b/changelog.d/6385.bugfix
new file mode 100644
index 0000000000..7a2bc02170
--- /dev/null
+++ b/changelog.d/6385.bugfix
@@ -0,0 +1 @@
+Prevent error on trying to search a upgraded room when the server is not in the predecessor room.
\ No newline at end of file
diff --git a/changelog.d/6394.feature b/changelog.d/6394.feature
new file mode 100644
index 0000000000..1a0e8845ad
--- /dev/null
+++ b/changelog.d/6394.feature
@@ -0,0 +1 @@
+Add a develop script to generate full SQL schemas.
\ No newline at end of file
diff --git a/changelog.d/6411.feature b/changelog.d/6411.feature
new file mode 100644
index 0000000000..ebea4a208d
--- /dev/null
+++ b/changelog.d/6411.feature
@@ -0,0 +1 @@
+Allow custom SAML username mapping functinality through an external provider plugin.
\ No newline at end of file
diff --git a/changelog.d/6497.bugfix b/changelog.d/6497.bugfix
deleted file mode 100644
index 92ed08fc40..0000000000
--- a/changelog.d/6497.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix error message when setting your profile's avatar URL mentioning displaynames, and prevent NoneType avatar_urls.
\ No newline at end of file
diff --git a/changelog.d/6501.misc b/changelog.d/6501.misc
new file mode 100644
index 0000000000..255f45a9c3
--- /dev/null
+++ b/changelog.d/6501.misc
@@ -0,0 +1 @@
+Refactor get_events_from_store_or_dest to return a dict.
diff --git a/changelog.d/6502.removal b/changelog.d/6502.removal
new file mode 100644
index 0000000000..0b72261d58
--- /dev/null
+++ b/changelog.d/6502.removal
@@ -0,0 +1 @@
+Remove redundant code from event authorisation implementation.
diff --git a/changelog.d/6503.misc b/changelog.d/6503.misc
new file mode 100644
index 0000000000..e4e9a5a3d4
--- /dev/null
+++ b/changelog.d/6503.misc
@@ -0,0 +1 @@
+Move get_state methods into FederationHandler.
diff --git a/changelog.d/6504.misc b/changelog.d/6504.misc
new file mode 100644
index 0000000000..7c873459af
--- /dev/null
+++ b/changelog.d/6504.misc
@@ -0,0 +1 @@
+Port handlers.account_data and handlers.account_validity to async/await.
diff --git a/changelog.d/6505.misc b/changelog.d/6505.misc
new file mode 100644
index 0000000000..3a75b2d9dd
--- /dev/null
+++ b/changelog.d/6505.misc
@@ -0,0 +1 @@
+Make `make_deferred_yieldable` to work with async/await.
diff --git a/changelog.d/6506.misc b/changelog.d/6506.misc
new file mode 100644
index 0000000000..99d7a70bcf
--- /dev/null
+++ b/changelog.d/6506.misc
@@ -0,0 +1 @@
+Remove `SnapshotCache` in favour of `ResponseCache`.
diff --git a/changelog.d/6510.misc b/changelog.d/6510.misc
new file mode 100644
index 0000000000..214f06539b
--- /dev/null
+++ b/changelog.d/6510.misc
@@ -0,0 +1 @@
+Change phone home stats to not assume there is a single database and report information about the database used by the main data store.
diff --git a/changelog.d/6512.misc b/changelog.d/6512.misc
new file mode 100644
index 0000000000..37a8099eec
--- /dev/null
+++ b/changelog.d/6512.misc
@@ -0,0 +1 @@
+Silence mypy errors for files outside those specified.
diff --git a/changelog.d/6514.bugfix b/changelog.d/6514.bugfix
new file mode 100644
index 0000000000..6dc1985c24
--- /dev/null
+++ b/changelog.d/6514.bugfix
@@ -0,0 +1 @@
+Fix race which occasionally caused deleted devices to reappear.
diff --git a/changelog.d/6515.misc b/changelog.d/6515.misc
new file mode 100644
index 0000000000..a9c303ed1c
--- /dev/null
+++ b/changelog.d/6515.misc
@@ -0,0 +1 @@
+Clean up some logging when handling incoming events over federation.
diff --git a/changelog.d/6517.misc b/changelog.d/6517.misc
new file mode 100644
index 0000000000..c6ffed9952
--- /dev/null
+++ b/changelog.d/6517.misc
@@ -0,0 +1 @@
+Port some of FederationHandler to async/await.
\ No newline at end of file
diff --git a/changelog.d/6521.misc b/changelog.d/6521.misc
new file mode 100644
index 0000000000..d9a44389b9
--- /dev/null
+++ b/changelog.d/6521.misc
@@ -0,0 +1 @@
+Refactor some code in the event authentication path for clarity.
diff --git a/docs/saml_mapping_providers.md b/docs/saml_mapping_providers.md
new file mode 100644
index 0000000000..92f2380488
--- /dev/null
+++ b/docs/saml_mapping_providers.md
@@ -0,0 +1,77 @@
+# SAML Mapping Providers
+
+A SAML mapping provider is a Python class (loaded via a Python module) that
+works out how to map attributes of a SAML response object to Matrix-specific
+user attributes. Details such as user ID localpart, displayname, and even avatar
+URLs are all things that can be mapped from talking to a SSO service.
+
+As an example, a SSO service may return the email address
+"john.smith@example.com" for a user, whereas Synapse will need to figure out how
+to turn that into a displayname when creating a Matrix user for this individual.
+It may choose `John Smith`, or `Smith, John [Example.com]` or any number of
+variations. As each Synapse configuration may want something different, this is
+where SAML mapping providers come into play.
+
+## Enabling Providers
+
+External mapping providers are provided to Synapse in the form of an external
+Python module. Retrieve this module from [PyPi](https://pypi.org) or elsewhere,
+then tell Synapse where to look for the handler class by editing the
+`saml2_config.user_mapping_provider.module` config option.
+
+`saml2_config.user_mapping_provider.config` allows you to provide custom
+configuration options to the module. Check with the module's documentation for
+what options it provides (if any). The options listed by default are for the
+user mapping provider built in to Synapse. If using a custom module, you should
+comment these options out and use those specified by the module instead.
+
+## Building a Custom Mapping Provider
+
+A custom mapping provider must specify the following methods:
+
+* `__init__(self, parsed_config)`
+   - Arguments:
+     - `parsed_config` - A configuration object that is the return value of the
+       `parse_config` method. You should set any configuration options needed by
+       the module here.
+* `saml_response_to_user_attributes(self, saml_response, failures)`
+    - Arguments:
+      - `saml_response` - A `saml2.response.AuthnResponse` object to extract user
+                          information from.
+      - `failures` - An `int` that represents the amount of times the returned
+                     mxid localpart mapping has failed.  This should be used
+                     to create a deduplicated mxid localpart which should be
+                     returned instead. For example, if this method returns
+                     `john.doe` as the value of `mxid_localpart` in the returned
+                     dict, and that is already taken on the homeserver, this
+                     method will be called again with the same parameters but
+                     with failures=1. The method should then return a different
+                     `mxid_localpart` value, such as `john.doe1`.
+    - This method must return a dictionary, which will then be used by Synapse
+      to build a new user. The following keys are allowed:
+       * `mxid_localpart` - Required. The mxid localpart of the new user.
+       * `displayname` - The displayname of the new user. If not provided, will default to
+                         the value of `mxid_localpart`.
+* `parse_config(config)`
+    - This method should have the `@staticmethod` decoration.
+    - Arguments:
+        - `config` - A `dict` representing the parsed content of the
+          `saml2_config.user_mapping_provider.config` homeserver config option.
+           Runs on homeserver startup. Providers should extract any option values
+           they need here.
+    - Whatever is returned will be passed back to the user mapping provider module's
+      `__init__` method during construction.
+* `get_saml_attributes(config)`
+    - This method should have the `@staticmethod` decoration.
+    - Arguments:
+        - `config` - A object resulting from a call to `parse_config`.
+    - Returns a tuple of two sets. The first set equates to the saml auth
+      response attributes that are required for the module to function, whereas
+      the second set consists of those attributes which can be used if available,
+      but are not necessary.
+
+## Synapse's Default Provider
+
+Synapse has a built-in SAML mapping provider if a custom provider isn't
+specified in the config. It is located at
+[`synapse.handlers.saml_handler.DefaultSamlMappingProvider`](../synapse/handlers/saml_handler.py).
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 10664ae8f7..4d44e631d1 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1250,33 +1250,58 @@ saml2_config:
   #
   #config_path: "CONFDIR/sp_conf.py"
 
-  # the lifetime of a SAML session. This defines how long a user has to
+  # The lifetime of a SAML session. This defines how long a user has to
   # complete the authentication process, if allow_unsolicited is unset.
   # The default is 5 minutes.
   #
   #saml_session_lifetime: 5m
 
-  # The SAML attribute (after mapping via the attribute maps) to use to derive
-  # the Matrix ID from. 'uid' by default.
+  # An external module can be provided here as a custom solution to
+  # mapping attributes returned from a saml provider onto a matrix user.
   #
-  #mxid_source_attribute: displayName
-
-  # The mapping system to use for mapping the saml attribute onto a matrix ID.
-  # Options include:
-  #  * 'hexencode' (which maps unpermitted characters to '=xx')
-  #  * 'dotreplace' (which replaces unpermitted characters with '.').
-  # The default is 'hexencode'.
-  #
-  #mxid_mapping: dotreplace
+  user_mapping_provider:
+    # The custom module's class. Uncomment to use a custom module.
+    #
+    #module: mapping_provider.SamlMappingProvider
 
-  # In previous versions of synapse, the mapping from SAML attribute to MXID was
-  # always calculated dynamically rather than stored in a table. For backwards-
-  # compatibility, we will look for user_ids matching such a pattern before
-  # creating a new account.
+    # Custom configuration values for the module. Below options are
+    # intended for the built-in provider, they should be changed if
+    # using a custom module. This section will be passed as a Python
+    # dictionary to the module's `parse_config` method.
+    #
+    config:
+      # The SAML attribute (after mapping via the attribute maps) to use
+      # to derive the Matrix ID from. 'uid' by default.
+      #
+      # Note: This used to be configured by the
+      # saml2_config.mxid_source_attribute option. If that is still
+      # defined, its value will be used instead.
+      #
+      #mxid_source_attribute: displayName
+
+      # The mapping system to use for mapping the saml attribute onto a
+      # matrix ID.
+      #
+      # Options include:
+      #  * 'hexencode' (which maps unpermitted characters to '=xx')
+      #  * 'dotreplace' (which replaces unpermitted characters with
+      #     '.').
+      # The default is 'hexencode'.
+      #
+      # Note: This used to be configured by the
+      # saml2_config.mxid_mapping option. If that is still defined, its
+      # value will be used instead.
+      #
+      #mxid_mapping: dotreplace
+
+  # In previous versions of synapse, the mapping from SAML attribute to
+  # MXID was always calculated dynamically rather than stored in a
+  # table. For backwards- compatibility, we will look for user_ids
+  # matching such a pattern before creating a new account.
   #
   # This setting controls the SAML attribute which will be used for this
-  # backwards-compatibility lookup. Typically it should be 'uid', but if the
-  # attribute maps are changed, it may be necessary to change it.
+  # backwards-compatibility lookup. Typically it should be 'uid', but if
+  # the attribute maps are changed, it may be necessary to change it.
   #
   # The default is 'uid'.
   #
diff --git a/mypy.ini b/mypy.ini
index 1d77c0ecc8..a66434b76b 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,7 +1,7 @@
 [mypy]
 namespace_packages = True
 plugins = mypy_zope:plugin
-follow_imports = normal
+follow_imports = silent
 check_untyped_defs = True
 show_error_codes = True
 show_traceback = True
diff --git a/scripts-dev/make_full_schema.sh b/scripts-dev/make_full_schema.sh
new file mode 100755
index 0000000000..60e8970a35
--- /dev/null
+++ b/scripts-dev/make_full_schema.sh
@@ -0,0 +1,184 @@
+#!/bin/bash
+#
+# This script generates SQL files for creating a brand new Synapse DB with the latest
+# schema, on both SQLite3 and Postgres.
+#
+# It does so by having Synapse generate an up-to-date SQLite DB, then running
+# synapse_port_db to convert it to Postgres. It then dumps the contents of both.
+
+POSTGRES_HOST="localhost"
+POSTGRES_DB_NAME="synapse_full_schema.$$"
+
+SQLITE_FULL_SCHEMA_OUTPUT_FILE="full.sql.sqlite"
+POSTGRES_FULL_SCHEMA_OUTPUT_FILE="full.sql.postgres"
+
+REQUIRED_DEPS=("matrix-synapse" "psycopg2")
+
+usage() {
+  echo
+  echo "Usage: $0 -p <postgres_username> -o <path> [-c] [-n] [-h]"
+  echo
+  echo "-p <postgres_username>"
+  echo "  Username to connect to local postgres instance. The password will be requested"
+  echo "  during script execution."
+  echo "-c"
+  echo "  CI mode. Enables coverage tracking and prints every command that the script runs."
+  echo "-o <path>"
+  echo "  Directory to output full schema files to."
+  echo "-h"
+  echo "  Display this help text."
+}
+
+while getopts "p:co:h" opt; do
+  case $opt in
+    p)
+      POSTGRES_USERNAME=$OPTARG
+      ;;
+    c)
+      # Print all commands that are being executed
+      set -x
+
+      # Modify required dependencies for coverage
+      REQUIRED_DEPS+=("coverage" "coverage-enable-subprocess")
+
+      COVERAGE=1
+      ;;
+    o)
+      command -v realpath > /dev/null || (echo "The -o flag requires the 'realpath' binary to be installed" && exit 1)
+      OUTPUT_DIR="$(realpath "$OPTARG")"
+      ;;
+    h)
+      usage
+      exit
+      ;;
+    \?)
+      echo "ERROR: Invalid option: -$OPTARG" >&2
+      usage
+      exit
+      ;;
+  esac
+done
+
+# Check that required dependencies are installed
+unsatisfied_requirements=()
+for dep in "${REQUIRED_DEPS[@]}"; do
+  pip show "$dep" --quiet || unsatisfied_requirements+=("$dep")
+done
+if [ ${#unsatisfied_requirements} -ne 0 ]; then
+  echo "Please install the following python packages: ${unsatisfied_requirements[*]}"
+  exit 1
+fi
+
+if [ -z "$POSTGRES_USERNAME" ]; then
+  echo "No postgres username supplied"
+  usage
+  exit 1
+fi
+
+if [ -z "$OUTPUT_DIR" ]; then
+  echo "No output directory supplied"
+  usage
+  exit 1
+fi
+
+# Create the output directory if it doesn't exist
+mkdir -p "$OUTPUT_DIR"
+
+read -rsp "Postgres password for '$POSTGRES_USERNAME': " POSTGRES_PASSWORD
+echo ""
+
+# Exit immediately if a command fails
+set -e
+
+# cd to root of the synapse directory
+cd "$(dirname "$0")/.."
+
+# Create temporary SQLite and Postgres homeserver db configs and key file
+TMPDIR=$(mktemp -d)
+KEY_FILE=$TMPDIR/test.signing.key # default Synapse signing key path
+SQLITE_CONFIG=$TMPDIR/sqlite.conf
+SQLITE_DB=$TMPDIR/homeserver.db
+POSTGRES_CONFIG=$TMPDIR/postgres.conf
+
+# Ensure these files are delete on script exit
+trap 'rm -rf $TMPDIR' EXIT
+
+cat > "$SQLITE_CONFIG" <<EOF
+server_name: "test"
+
+signing_key_path: "$KEY_FILE"
+macaroon_secret_key: "abcde"
+
+report_stats: false
+
+database:
+  name: "sqlite3"
+  args:
+    database: "$SQLITE_DB"
+
+# Suppress the key server warning.
+trusted_key_servers: []
+EOF
+
+cat > "$POSTGRES_CONFIG" <<EOF
+server_name: "test"
+
+signing_key_path: "$KEY_FILE"
+macaroon_secret_key: "abcde"
+
+report_stats: false
+
+database:
+  name: "psycopg2"
+  args:
+    user: "$POSTGRES_USERNAME"
+    host: "$POSTGRES_HOST"
+    password: "$POSTGRES_PASSWORD"
+    database: "$POSTGRES_DB_NAME"
+
+# Suppress the key server warning.
+trusted_key_servers: []
+EOF
+
+# Generate the server's signing key.
+echo "Generating SQLite3 db schema..."
+python -m synapse.app.homeserver --generate-keys -c "$SQLITE_CONFIG"
+
+# Make sure the SQLite3 database is using the latest schema and has no pending background update.
+echo "Running db background jobs..."
+scripts-dev/update_database --database-config "$SQLITE_CONFIG"
+
+# Create the PostgreSQL database.
+echo "Creating postgres database..."
+createdb $POSTGRES_DB_NAME
+
+echo "Copying data from SQLite3 to Postgres with synapse_port_db..."
+if [ -z "$COVERAGE" ]; then
+  # No coverage needed
+  scripts/synapse_port_db --sqlite-database "$SQLITE_DB" --postgres-config "$POSTGRES_CONFIG"
+else
+  # Coverage desired
+  coverage run scripts/synapse_port_db --sqlite-database "$SQLITE_DB" --postgres-config "$POSTGRES_CONFIG"
+fi
+
+# Delete schema_version, applied_schema_deltas and applied_module_schemas tables
+# This needs to be done after synapse_port_db is run
+echo "Dropping unwanted db tables..."
+SQL="
+DROP TABLE schema_version;
+DROP TABLE applied_schema_deltas;
+DROP TABLE applied_module_schemas;
+"
+sqlite3 "$SQLITE_DB" <<< "$SQL"
+psql $POSTGRES_DB_NAME -U "$POSTGRES_USERNAME" -w <<< "$SQL"
+
+echo "Dumping SQLite3 schema to '$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE'..."
+sqlite3 "$SQLITE_DB" ".dump" > "$OUTPUT_DIR/$SQLITE_FULL_SCHEMA_OUTPUT_FILE"
+
+echo "Dumping Postgres schema to '$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE'..."
+pg_dump --format=plain --no-tablespaces --no-acl --no-owner $POSTGRES_DB_NAME | sed -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > "$OUTPUT_DIR/$POSTGRES_FULL_SCHEMA_OUTPUT_FILE"
+
+echo "Cleaning up temporary Postgres database..."
+dropdb $POSTGRES_DB_NAME
+
+echo "Done! Files dumped to: $OUTPUT_DIR"
diff --git a/synapse/__init__.py b/synapse/__init__.py
index c67a51a8d5..fc2a6e4ee6 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -36,7 +36,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.7.0rc1"
+__version__ = "1.7.0rc2"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 79341784c5..b8661457e2 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -514,8 +514,10 @@ def phone_stats_home(hs, stats, stats_process=_stats_process):
     # Database version
     #
 
-    stats["database_engine"] = hs.database_engine.module.__name__
-    stats["database_server_version"] = hs.database_engine.server_version
+    # This only reports info about the *main* database.
+    stats["database_engine"] = hs.get_datastore().db.engine.module.__name__
+    stats["database_server_version"] = hs.get_datastore().db.engine.server_version
+
     logger.info("Reporting stats to %s: %s" % (hs.config.report_stats_endpoint, stats))
     try:
         yield hs.get_proxied_http_client().put_json(
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index e157cbf64b..09e639040a 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -33,6 +33,7 @@ from synapse.replication.slave.storage.account_data import SlavedAccountDataStor
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.pushers import SlavedPusherStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
+from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.storage import DataStore
@@ -44,7 +45,11 @@ logger = logging.getLogger("synapse.app.pusher")
 
 
 class PusherSlaveStore(
-    SlavedEventStore, SlavedPusherStore, SlavedReceiptsStore, SlavedAccountDataStore
+    SlavedEventStore,
+    SlavedPusherStore,
+    SlavedReceiptsStore,
+    SlavedAccountDataStore,
+    RoomStore,
 ):
     update_pusher_last_stream_ordering_and_success = __func__(
         DataStore.update_pusher_last_stream_ordering_and_success
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index c5ea2d43a1..b91414aa35 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -14,17 +14,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import re
+import logging
 
 from synapse.python_dependencies import DependencyException, check_requirements
-from synapse.types import (
-    map_username_to_mxid_localpart,
-    mxid_localpart_allowed_characters,
-)
-from synapse.util.module_loader import load_python_module
+from synapse.util.module_loader import load_module, load_python_module
 
 from ._base import Config, ConfigError
 
+logger = logging.getLogger(__name__)
+
+DEFAULT_USER_MAPPING_PROVIDER = (
+    "synapse.handlers.saml_handler.DefaultSamlMappingProvider"
+)
+
 
 def _dict_merge(merge_dict, into_dict):
     """Do a deep merge of two dicts
@@ -75,15 +77,69 @@ class SAML2Config(Config):
 
         self.saml2_enabled = True
 
-        self.saml2_mxid_source_attribute = saml2_config.get(
-            "mxid_source_attribute", "uid"
-        )
-
         self.saml2_grandfathered_mxid_source_attribute = saml2_config.get(
             "grandfathered_mxid_source_attribute", "uid"
         )
 
-        saml2_config_dict = self._default_saml_config_dict()
+        # user_mapping_provider may be None if the key is present but has no value
+        ump_dict = saml2_config.get("user_mapping_provider") or {}
+
+        # Use the default user mapping provider if not set
+        ump_dict.setdefault("module", DEFAULT_USER_MAPPING_PROVIDER)
+
+        # Ensure a config is present
+        ump_dict["config"] = ump_dict.get("config") or {}
+
+        if ump_dict["module"] == DEFAULT_USER_MAPPING_PROVIDER:
+            # Load deprecated options for use by the default module
+            old_mxid_source_attribute = saml2_config.get("mxid_source_attribute")
+            if old_mxid_source_attribute:
+                logger.warning(
+                    "The config option saml2_config.mxid_source_attribute is deprecated. "
+                    "Please use saml2_config.user_mapping_provider.config"
+                    ".mxid_source_attribute instead."
+                )
+                ump_dict["config"]["mxid_source_attribute"] = old_mxid_source_attribute
+
+            old_mxid_mapping = saml2_config.get("mxid_mapping")
+            if old_mxid_mapping:
+                logger.warning(
+                    "The config option saml2_config.mxid_mapping is deprecated. Please "
+                    "use saml2_config.user_mapping_provider.config.mxid_mapping instead."
+                )
+                ump_dict["config"]["mxid_mapping"] = old_mxid_mapping
+
+        # Retrieve an instance of the module's class
+        # Pass the config dictionary to the module for processing
+        (
+            self.saml2_user_mapping_provider_class,
+            self.saml2_user_mapping_provider_config,
+        ) = load_module(ump_dict)
+
+        # Ensure loaded user mapping module has defined all necessary methods
+        # Note parse_config() is already checked during the call to load_module
+        required_methods = [
+            "get_saml_attributes",
+            "saml_response_to_user_attributes",
+        ]
+        missing_methods = [
+            method
+            for method in required_methods
+            if not hasattr(self.saml2_user_mapping_provider_class, method)
+        ]
+        if missing_methods:
+            raise ConfigError(
+                "Class specified by saml2_config."
+                "user_mapping_provider.module is missing required "
+                "methods: %s" % (", ".join(missing_methods),)
+            )
+
+        # Get the desired saml auth response attributes from the module
+        saml2_config_dict = self._default_saml_config_dict(
+            *self.saml2_user_mapping_provider_class.get_saml_attributes(
+                self.saml2_user_mapping_provider_config
+            )
+        )
         _dict_merge(
             merge_dict=saml2_config.get("sp_config", {}), into_dict=saml2_config_dict
         )
@@ -103,22 +159,27 @@ class SAML2Config(Config):
             saml2_config.get("saml_session_lifetime", "5m")
         )
 
-        mapping = saml2_config.get("mxid_mapping", "hexencode")
-        try:
-            self.saml2_mxid_mapper = MXID_MAPPER_MAP[mapping]
-        except KeyError:
-            raise ConfigError("%s is not a known mxid_mapping" % (mapping,))
-
-    def _default_saml_config_dict(self):
+    def _default_saml_config_dict(
+        self, required_attributes: set, optional_attributes: set
+    ):
+        """Generate a configuration dictionary with required and optional attributes that
+        will be needed to process new user registration
+
+        Args:
+            required_attributes: SAML auth response attributes that are
+                necessary to function
+            optional_attributes: SAML auth response attributes that can be used to add
+                additional information to Synapse user accounts, but are not required
+
+        Returns:
+            dict: A SAML configuration dictionary
+        """
         import saml2
 
         public_baseurl = self.public_baseurl
         if public_baseurl is None:
             raise ConfigError("saml2_config requires a public_baseurl to be set")
 
-        required_attributes = {"uid", self.saml2_mxid_source_attribute}
-
-        optional_attributes = {"displayName"}
         if self.saml2_grandfathered_mxid_source_attribute:
             optional_attributes.add(self.saml2_grandfathered_mxid_source_attribute)
         optional_attributes -= required_attributes
@@ -207,33 +268,58 @@ class SAML2Config(Config):
           #
           #config_path: "%(config_dir_path)s/sp_conf.py"
 
-          # the lifetime of a SAML session. This defines how long a user has to
+          # The lifetime of a SAML session. This defines how long a user has to
           # complete the authentication process, if allow_unsolicited is unset.
           # The default is 5 minutes.
           #
           #saml_session_lifetime: 5m
 
-          # The SAML attribute (after mapping via the attribute maps) to use to derive
-          # the Matrix ID from. 'uid' by default.
+          # An external module can be provided here as a custom solution to
+          # mapping attributes returned from a saml provider onto a matrix user.
           #
-          #mxid_source_attribute: displayName
-
-          # The mapping system to use for mapping the saml attribute onto a matrix ID.
-          # Options include:
-          #  * 'hexencode' (which maps unpermitted characters to '=xx')
-          #  * 'dotreplace' (which replaces unpermitted characters with '.').
-          # The default is 'hexencode'.
-          #
-          #mxid_mapping: dotreplace
-
-          # In previous versions of synapse, the mapping from SAML attribute to MXID was
-          # always calculated dynamically rather than stored in a table. For backwards-
-          # compatibility, we will look for user_ids matching such a pattern before
-          # creating a new account.
+          user_mapping_provider:
+            # The custom module's class. Uncomment to use a custom module.
+            #
+            #module: mapping_provider.SamlMappingProvider
+
+            # Custom configuration values for the module. Below options are
+            # intended for the built-in provider, they should be changed if
+            # using a custom module. This section will be passed as a Python
+            # dictionary to the module's `parse_config` method.
+            #
+            config:
+              # The SAML attribute (after mapping via the attribute maps) to use
+              # to derive the Matrix ID from. 'uid' by default.
+              #
+              # Note: This used to be configured by the
+              # saml2_config.mxid_source_attribute option. If that is still
+              # defined, its value will be used instead.
+              #
+              #mxid_source_attribute: displayName
+
+              # The mapping system to use for mapping the saml attribute onto a
+              # matrix ID.
+              #
+              # Options include:
+              #  * 'hexencode' (which maps unpermitted characters to '=xx')
+              #  * 'dotreplace' (which replaces unpermitted characters with
+              #     '.').
+              # The default is 'hexencode'.
+              #
+              # Note: This used to be configured by the
+              # saml2_config.mxid_mapping option. If that is still defined, its
+              # value will be used instead.
+              #
+              #mxid_mapping: dotreplace
+
+          # In previous versions of synapse, the mapping from SAML attribute to
+          # MXID was always calculated dynamically rather than stored in a
+          # table. For backwards- compatibility, we will look for user_ids
+          # matching such a pattern before creating a new account.
           #
           # This setting controls the SAML attribute which will be used for this
-          # backwards-compatibility lookup. Typically it should be 'uid', but if the
-          # attribute maps are changed, it may be necessary to change it.
+          # backwards-compatibility lookup. Typically it should be 'uid', but if
+          # the attribute maps are changed, it may be necessary to change it.
           #
           # The default is 'uid'.
           #
@@ -241,23 +327,3 @@ class SAML2Config(Config):
         """ % {
             "config_dir_path": config_dir_path
         }
-
-
-DOT_REPLACE_PATTERN = re.compile(
-    ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
-)
-
-
-def dot_replace_for_mxid(username: str) -> str:
-    username = username.lower()
-    username = DOT_REPLACE_PATTERN.sub(".", username)
-
-    # regular mxids aren't allowed to start with an underscore either
-    username = re.sub("^_", "", username)
-    return username
-
-
-MXID_MAPPER_MAP = {
-    "hexencode": map_username_to_mxid_localpart,
-    "dotreplace": dot_replace_for_mxid,
-}
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index ec3243b27b..c940b84470 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -42,6 +42,8 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
     Returns:
          if the auth checks pass.
     """
+    assert isinstance(auth_events, dict)
+
     if do_size_check:
         _check_size_limits(event)
 
@@ -74,12 +76,6 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
             if not event.signatures.get(event_id_domain):
                 raise AuthError(403, "Event not signed by sending server")
 
-    if auth_events is None:
-        # Oh, we don't know what the state of the room was, so we
-        # are trusting that this is allowed (at least for now)
-        logger.warning("Trusting event: %s", event.event_id)
-        return
-
     if event.type == EventTypes.Create:
         sender_domain = get_domain_from_id(event.sender)
         room_id_domain = get_domain_from_id(event.room_id)
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 709449c9e3..af652a7659 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -18,8 +18,6 @@ import copy
 import itertools
 import logging
 
-from six.moves import range
-
 from prometheus_client import Counter
 
 from twisted.internet import defer
@@ -39,7 +37,7 @@ from synapse.api.room_versions import (
 )
 from synapse.events import builder, room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
-from synapse.logging.context import make_deferred_yieldable, run_in_background
+from synapse.logging.context import make_deferred_yieldable
 from synapse.logging.utils import log_function
 from synapse.util import unwrapFirstError
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -310,19 +308,12 @@ class FederationClient(FederationBase):
         return signed_pdu
 
     @defer.inlineCallbacks
-    @log_function
-    def get_state_for_room(self, destination, room_id, event_id):
-        """Requests all of the room state at a given event from a remote homeserver.
-
-        Args:
-            destination (str): The remote homeserver to query for the state.
-            room_id (str): The id of the room we're interested in.
-            event_id (str): The id of the event we want the state at.
+    def get_room_state_ids(self, destination: str, room_id: str, event_id: str):
+        """Calls the /state_ids endpoint to fetch the state at a particular point
+        in the room, and the auth events for the given event
 
         Returns:
-            Deferred[Tuple[List[EventBase], List[EventBase]]]:
-                A list of events in the state, and a list of events in the auth chain
-                for the given event.
+            Tuple[List[str], List[str]]:  a tuple of (state event_ids, auth event_ids)
         """
         result = yield self.transport_layer.get_room_state_ids(
             destination, room_id, event_id=event_id
@@ -331,86 +322,12 @@ class FederationClient(FederationBase):
         state_event_ids = result["pdu_ids"]
         auth_event_ids = result.get("auth_chain_ids", [])
 
-        fetched_events, failed_to_fetch = yield self.get_events_from_store_or_dest(
-            destination, room_id, set(state_event_ids + auth_event_ids)
-        )
-
-        if failed_to_fetch:
-            logger.warning(
-                "Failed to fetch missing state/auth events for %s: %s",
-                room_id,
-                failed_to_fetch,
-            )
-
-        event_map = {ev.event_id: ev for ev in fetched_events}
+        if not isinstance(state_event_ids, list) or not isinstance(
+            auth_event_ids, list
+        ):
+            raise Exception("invalid response from /state_ids")
 
-        pdus = [event_map[e_id] for e_id in state_event_ids if e_id in event_map]
-        auth_chain = [event_map[e_id] for e_id in auth_event_ids if e_id in event_map]
-
-        auth_chain.sort(key=lambda e: e.depth)
-
-        return pdus, auth_chain
-
-    @defer.inlineCallbacks
-    def get_events_from_store_or_dest(self, destination, room_id, event_ids):
-        """Fetch events from a remote destination, checking if we already have them.
-
-        Args:
-            destination (str)
-            room_id (str)
-            event_ids (list)
-
-        Returns:
-            Deferred: A deferred resolving to a 2-tuple where the first is a list of
-            events and the second is a list of event ids that we failed to fetch.
-        """
-        seen_events = yield self.store.get_events(event_ids, allow_rejected=True)
-        signed_events = list(seen_events.values())
-
-        failed_to_fetch = set()
-
-        missing_events = set(event_ids)
-        for k in seen_events:
-            missing_events.discard(k)
-
-        if not missing_events:
-            return signed_events, failed_to_fetch
-
-        logger.debug(
-            "Fetching unknown state/auth events %s for room %s",
-            missing_events,
-            event_ids,
-        )
-
-        room_version = yield self.store.get_room_version(room_id)
-
-        batch_size = 20
-        missing_events = list(missing_events)
-        for i in range(0, len(missing_events), batch_size):
-            batch = set(missing_events[i : i + batch_size])
-
-            deferreds = [
-                run_in_background(
-                    self.get_pdu,
-                    destinations=[destination],
-                    event_id=e_id,
-                    room_version=room_version,
-                )
-                for e_id in batch
-            ]
-
-            res = yield make_deferred_yieldable(
-                defer.DeferredList(deferreds, consumeErrors=True)
-            )
-            for success, result in res:
-                if success and result:
-                    signed_events.append(result)
-                    batch.discard(result.event_id)
-
-            # We removed all events we successfully fetched from `batch`
-            failed_to_fetch.update(batch)
-
-        return signed_events, failed_to_fetch
+        return state_event_ids, auth_event_ids
 
     @defer.inlineCallbacks
     @log_function
@@ -609,13 +526,7 @@ class FederationClient(FederationBase):
 
         @defer.inlineCallbacks
         def send_request(destination):
-            time_now = self._clock.time_msec()
-            _, content = yield self.transport_layer.send_join(
-                destination=destination,
-                room_id=pdu.room_id,
-                event_id=pdu.event_id,
-                content=pdu.get_pdu_json(time_now),
-            )
+            content = yield self._do_send_join(destination, pdu)
 
             logger.debug("Got content: %s", content)
 
@@ -683,6 +594,44 @@ class FederationClient(FederationBase):
         return self._try_destination_list("send_join", destinations, send_request)
 
     @defer.inlineCallbacks
+    def _do_send_join(self, destination, pdu):
+        time_now = self._clock.time_msec()
+
+        try:
+            content = yield self.transport_layer.send_join_v2(
+                destination=destination,
+                room_id=pdu.room_id,
+                event_id=pdu.event_id,
+                content=pdu.get_pdu_json(time_now),
+            )
+
+            return content
+        except HttpResponseException as e:
+            if e.code in [400, 404]:
+                err = e.to_synapse_error()
+
+                # If we receive an error response that isn't a generic error, or an
+                # unrecognised endpoint error, we  assume that the remote understands
+                # the v2 invite API and this is a legitimate error.
+                if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]:
+                    raise err
+            else:
+                raise e.to_synapse_error()
+
+        logger.debug("Couldn't send_join with the v2 API, falling back to the v1 API")
+
+        resp = yield self.transport_layer.send_join_v1(
+            destination=destination,
+            room_id=pdu.room_id,
+            event_id=pdu.event_id,
+            content=pdu.get_pdu_json(time_now),
+        )
+
+        # We expect the v1 API to respond with [200, content], so we only return the
+        # content.
+        return resp[1]
+
+    @defer.inlineCallbacks
     def send_invite(self, destination, room_id, event_id, pdu):
         room_version = yield self.store.get_room_version(room_id)
 
@@ -791,18 +740,50 @@ class FederationClient(FederationBase):
 
         @defer.inlineCallbacks
         def send_request(destination):
-            time_now = self._clock.time_msec()
-            _, content = yield self.transport_layer.send_leave(
+            content = yield self._do_send_leave(destination, pdu)
+
+            logger.debug("Got content: %s", content)
+            return None
+
+        return self._try_destination_list("send_leave", destinations, send_request)
+
+    @defer.inlineCallbacks
+    def _do_send_leave(self, destination, pdu):
+        time_now = self._clock.time_msec()
+
+        try:
+            content = yield self.transport_layer.send_leave_v2(
                 destination=destination,
                 room_id=pdu.room_id,
                 event_id=pdu.event_id,
                 content=pdu.get_pdu_json(time_now),
             )
 
-            logger.debug("Got content: %s", content)
-            return None
+            return content
+        except HttpResponseException as e:
+            if e.code in [400, 404]:
+                err = e.to_synapse_error()
 
-        return self._try_destination_list("send_leave", destinations, send_request)
+                # If we receive an error response that isn't a generic error, or an
+                # unrecognised endpoint error, we  assume that the remote understands
+                # the v2 invite API and this is a legitimate error.
+                if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]:
+                    raise err
+            else:
+                raise e.to_synapse_error()
+
+        logger.debug("Couldn't send_leave with the v2 API, falling back to the v1 API")
+
+        resp = yield self.transport_layer.send_leave_v1(
+            destination=destination,
+            room_id=pdu.room_id,
+            event_id=pdu.event_id,
+            content=pdu.get_pdu_json(time_now),
+        )
+
+        # We expect the v1 API to respond with [200, content], so we only return the
+        # content.
+        return resp[1]
 
     def get_public_rooms(
         self,
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 84d4eca041..d7ce333822 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -384,15 +384,10 @@ class FederationServer(FederationBase):
 
         res_pdus = await self.handler.on_send_join_request(origin, pdu)
         time_now = self._clock.time_msec()
-        return (
-            200,
-            {
-                "state": [p.get_pdu_json(time_now) for p in res_pdus["state"]],
-                "auth_chain": [
-                    p.get_pdu_json(time_now) for p in res_pdus["auth_chain"]
-                ],
-            },
-        )
+        return {
+            "state": [p.get_pdu_json(time_now) for p in res_pdus["state"]],
+            "auth_chain": [p.get_pdu_json(time_now) for p in res_pdus["auth_chain"]],
+        }
 
     async def on_make_leave_request(self, origin, room_id, user_id):
         origin_host, _ = parse_server_name(origin)
@@ -419,7 +414,7 @@ class FederationServer(FederationBase):
         pdu = await self._check_sigs_and_hash(room_version, pdu)
 
         await self.handler.on_send_leave_request(origin, pdu)
-        return 200, {}
+        return {}
 
     async def on_event_auth(self, origin, room_id, event_id):
         with (await self._server_linearizer.queue((origin, room_id))):
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 46dba84cac..198257414b 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -243,7 +243,7 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
-    def send_join(self, destination, room_id, event_id, content):
+    def send_join_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/send_join/%s/%s", room_id, event_id)
 
         response = yield self.client.put_json(
@@ -254,7 +254,18 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
-    def send_leave(self, destination, room_id, event_id, content):
+    def send_join_v2(self, destination, room_id, event_id, content):
+        path = _create_v2_path("/send_join/%s/%s", room_id, event_id)
+
+        response = yield self.client.put_json(
+            destination=destination, path=path, data=content
+        )
+
+        return response
+
+    @defer.inlineCallbacks
+    @log_function
+    def send_leave_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/send_leave/%s/%s", room_id, event_id)
 
         response = yield self.client.put_json(
@@ -272,6 +283,24 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
+    def send_leave_v2(self, destination, room_id, event_id, content):
+        path = _create_v2_path("/send_leave/%s/%s", room_id, event_id)
+
+        response = yield self.client.put_json(
+            destination=destination,
+            path=path,
+            data=content,
+            # we want to do our best to send this through. The problem is
+            # that if it fails, we won't retry it later, so if the remote
+            # server was just having a momentary blip, the room will be out of
+            # sync.
+            ignore_backoff=True,
+        )
+
+        return response
+
+    @defer.inlineCallbacks
+    @log_function
     def send_invite_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/invite/%s/%s", room_id, event_id)
 
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index fefc789c85..b4cbf23394 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -506,11 +506,21 @@ class FederationMakeLeaveServlet(BaseFederationServlet):
         return 200, content
 
 
-class FederationSendLeaveServlet(BaseFederationServlet):
+class FederationV1SendLeaveServlet(BaseFederationServlet):
     PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
     async def on_PUT(self, origin, content, query, room_id, event_id):
         content = await self.handler.on_send_leave_request(origin, content, room_id)
+        return 200, (200, content)
+
+
+class FederationV2SendLeaveServlet(BaseFederationServlet):
+    PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+
+    PREFIX = FEDERATION_V2_PREFIX
+
+    async def on_PUT(self, origin, content, query, room_id, event_id):
+        content = await self.handler.on_send_leave_request(origin, content, room_id)
         return 200, content
 
 
@@ -521,9 +531,21 @@ class FederationEventAuthServlet(BaseFederationServlet):
         return await self.handler.on_event_auth(origin, context, event_id)
 
 
-class FederationSendJoinServlet(BaseFederationServlet):
+class FederationV1SendJoinServlet(BaseFederationServlet):
+    PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+
+    async def on_PUT(self, origin, content, query, context, event_id):
+        # TODO(paul): assert that context/event_id parsed from path actually
+        #   match those given in content
+        content = await self.handler.on_send_join_request(origin, content, context)
+        return 200, (200, content)
+
+
+class FederationV2SendJoinServlet(BaseFederationServlet):
     PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
 
+    PREFIX = FEDERATION_V2_PREFIX
+
     async def on_PUT(self, origin, content, query, context, event_id):
         # TODO(paul): assert that context/event_id parsed from path actually
         #   match those given in content
@@ -1367,8 +1389,10 @@ FEDERATION_SERVLET_CLASSES = (
     FederationMakeJoinServlet,
     FederationMakeLeaveServlet,
     FederationEventServlet,
-    FederationSendJoinServlet,
-    FederationSendLeaveServlet,
+    FederationV1SendJoinServlet,
+    FederationV2SendJoinServlet,
+    FederationV1SendLeaveServlet,
+    FederationV2SendLeaveServlet,
     FederationV1InviteServlet,
     FederationV2InviteServlet,
     FederationQueryAuthServlet,
diff --git a/synapse/handlers/account_data.py b/synapse/handlers/account_data.py
index 2d7e6df6e4..20ec1ca01b 100644
--- a/synapse/handlers/account_data.py
+++ b/synapse/handlers/account_data.py
@@ -13,8 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 
 class AccountDataEventSource(object):
     def __init__(self, hs):
@@ -23,15 +21,14 @@ class AccountDataEventSource(object):
     def get_current_key(self, direction="f"):
         return self.store.get_max_account_data_stream_id()
 
-    @defer.inlineCallbacks
-    def get_new_events(self, user, from_key, **kwargs):
+    async def get_new_events(self, user, from_key, **kwargs):
         user_id = user.to_string()
         last_stream_id = from_key
 
-        current_stream_id = yield self.store.get_max_account_data_stream_id()
+        current_stream_id = self.store.get_max_account_data_stream_id()
 
         results = []
-        tags = yield self.store.get_updated_tags(user_id, last_stream_id)
+        tags = await self.store.get_updated_tags(user_id, last_stream_id)
 
         for room_id, room_tags in tags.items():
             results.append(
@@ -41,7 +38,7 @@ class AccountDataEventSource(object):
         (
             account_data,
             room_account_data,
-        ) = yield self.store.get_updated_account_data_for_user(user_id, last_stream_id)
+        ) = await self.store.get_updated_account_data_for_user(user_id, last_stream_id)
 
         for account_data_type, content in account_data.items():
             results.append({"type": account_data_type, "content": content})
@@ -54,6 +51,5 @@ class AccountDataEventSource(object):
 
         return results, current_stream_id
 
-    @defer.inlineCallbacks
-    def get_pagination_rows(self, user, config, key):
+    async def get_pagination_rows(self, user, config, key):
         return [], config.to_id
diff --git a/synapse/handlers/account_validity.py b/synapse/handlers/account_validity.py
index d04e0fe576..829f52eca1 100644
--- a/synapse/handlers/account_validity.py
+++ b/synapse/handlers/account_validity.py
@@ -18,8 +18,7 @@ import email.utils
 import logging
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
-
-from twisted.internet import defer
+from typing import List
 
 from synapse.api.errors import StoreError
 from synapse.logging.context import make_deferred_yieldable
@@ -78,42 +77,39 @@ class AccountValidityHandler(object):
                 # run as a background process to make sure that the database transactions
                 # have a logcontext to report to
                 return run_as_background_process(
-                    "send_renewals", self.send_renewal_emails
+                    "send_renewals", self._send_renewal_emails
                 )
 
             self.clock.looping_call(send_emails, 30 * 60 * 1000)
 
-    @defer.inlineCallbacks
-    def send_renewal_emails(self):
+    async def _send_renewal_emails(self):
         """Gets the list of users whose account is expiring in the amount of time
         configured in the ``renew_at`` parameter from the ``account_validity``
         configuration, and sends renewal emails to all of these users as long as they
         have an email 3PID attached to their account.
         """
-        expiring_users = yield self.store.get_users_expiring_soon()
+        expiring_users = await self.store.get_users_expiring_soon()
 
         if expiring_users:
             for user in expiring_users:
-                yield self._send_renewal_email(
+                await self._send_renewal_email(
                     user_id=user["user_id"], expiration_ts=user["expiration_ts_ms"]
                 )
 
-    @defer.inlineCallbacks
-    def send_renewal_email_to_user(self, user_id):
-        expiration_ts = yield self.store.get_expiration_ts_for_user(user_id)
-        yield self._send_renewal_email(user_id, expiration_ts)
+    async def send_renewal_email_to_user(self, user_id: str):
+        expiration_ts = await self.store.get_expiration_ts_for_user(user_id)
+        await self._send_renewal_email(user_id, expiration_ts)
 
-    @defer.inlineCallbacks
-    def _send_renewal_email(self, user_id, expiration_ts):
+    async def _send_renewal_email(self, user_id: str, expiration_ts: int):
         """Sends out a renewal email to every email address attached to the given user
         with a unique link allowing them to renew their account.
 
         Args:
-            user_id (str): ID of the user to send email(s) to.
-            expiration_ts (int): Timestamp in milliseconds for the expiration date of
+            user_id: ID of the user to send email(s) to.
+            expiration_ts: Timestamp in milliseconds for the expiration date of
                 this user's account (used in the email templates).
         """
-        addresses = yield self._get_email_addresses_for_user(user_id)
+        addresses = await self._get_email_addresses_for_user(user_id)
 
         # Stop right here if the user doesn't have at least one email address.
         # In this case, they will have to ask their server admin to renew their
@@ -125,7 +121,7 @@ class AccountValidityHandler(object):
             return
 
         try:
-            user_display_name = yield self.store.get_profile_displayname(
+            user_display_name = await self.store.get_profile_displayname(
                 UserID.from_string(user_id).localpart
             )
             if user_display_name is None:
@@ -133,7 +129,7 @@ class AccountValidityHandler(object):
         except StoreError:
             user_display_name = user_id
 
-        renewal_token = yield self._get_renewal_token(user_id)
+        renewal_token = await self._get_renewal_token(user_id)
         url = "%s_matrix/client/unstable/account_validity/renew?token=%s" % (
             self.hs.config.public_baseurl,
             renewal_token,
@@ -165,7 +161,7 @@ class AccountValidityHandler(object):
 
             logger.info("Sending renewal email to %s", address)
 
-            yield make_deferred_yieldable(
+            await make_deferred_yieldable(
                 self.sendmail(
                     self.hs.config.email_smtp_host,
                     self._raw_from,
@@ -180,19 +176,18 @@ class AccountValidityHandler(object):
                 )
             )
 
-        yield self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
+        await self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
 
-    @defer.inlineCallbacks
-    def _get_email_addresses_for_user(self, user_id):
+    async def _get_email_addresses_for_user(self, user_id: str) -> List[str]:
         """Retrieve the list of email addresses attached to a user's account.
 
         Args:
-            user_id (str): ID of the user to lookup email addresses for.
+            user_id: ID of the user to lookup email addresses for.
 
         Returns:
-            defer.Deferred[list[str]]: Email addresses for this account.
+            Email addresses for this account.
         """
-        threepids = yield self.store.user_get_threepids(user_id)
+        threepids = await self.store.user_get_threepids(user_id)
 
         addresses = []
         for threepid in threepids:
@@ -201,16 +196,15 @@ class AccountValidityHandler(object):
 
         return addresses
 
-    @defer.inlineCallbacks
-    def _get_renewal_token(self, user_id):
+    async def _get_renewal_token(self, user_id: str) -> str:
         """Generates a 32-byte long random string that will be inserted into the
         user's renewal email's unique link, then saves it into the database.
 
         Args:
-            user_id (str): ID of the user to generate a string for.
+            user_id: ID of the user to generate a string for.
 
         Returns:
-            defer.Deferred[str]: The generated string.
+            The generated string.
 
         Raises:
             StoreError(500): Couldn't generate a unique string after 5 attempts.
@@ -219,52 +213,52 @@ class AccountValidityHandler(object):
         while attempts < 5:
             try:
                 renewal_token = stringutils.random_string(32)
-                yield self.store.set_renewal_token_for_user(user_id, renewal_token)
+                await self.store.set_renewal_token_for_user(user_id, renewal_token)
                 return renewal_token
             except StoreError:
                 attempts += 1
         raise StoreError(500, "Couldn't generate a unique string as refresh string.")
 
-    @defer.inlineCallbacks
-    def renew_account(self, renewal_token):
+    async def renew_account(self, renewal_token: str) -> bool:
         """Renews the account attached to a given renewal token by pushing back the
         expiration date by the current validity period in the server's configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
+            renewal_token: Token sent with the renewal request.
         Returns:
-            bool: Whether the provided token is valid.
+            Whether the provided token is valid.
         """
         try:
-            user_id = yield self.store.get_user_from_renewal_token(renewal_token)
+            user_id = await self.store.get_user_from_renewal_token(renewal_token)
         except StoreError:
-            defer.returnValue(False)
+            return False
 
         logger.debug("Renewing an account for user %s", user_id)
-        yield self.renew_account_for_user(user_id)
+        await self.renew_account_for_user(user_id)
 
-        defer.returnValue(True)
+        return True
 
-    @defer.inlineCallbacks
-    def renew_account_for_user(self, user_id, expiration_ts=None, email_sent=False):
+    async def renew_account_for_user(
+        self, user_id: str, expiration_ts: int = None, email_sent: bool = False
+    ) -> int:
         """Renews the account attached to a given user by pushing back the
         expiration date by the current validity period in the server's
         configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
-            expiration_ts (int): New expiration date. Defaults to now + validity period.
-            email_sent (bool): Whether an email has been sent for this validity period.
+            renewal_token: Token sent with the renewal request.
+            expiration_ts: New expiration date. Defaults to now + validity period.
+            email_sen: Whether an email has been sent for this validity period.
                 Defaults to False.
 
         Returns:
-            defer.Deferred[int]: New expiration date for this account, as a timestamp
-                in milliseconds since epoch.
+            New expiration date for this account, as a timestamp in
+            milliseconds since epoch.
         """
         if expiration_ts is None:
             expiration_ts = self.clock.time_msec() + self._account_validity.period
 
-        yield self.store.set_account_validity_for_user(
+        await self.store.set_account_validity_for_user(
             user_id=user_id, expiration_ts=expiration_ts, email_sent=email_sent
         )
 
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index bc26921768..62985bab9f 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -19,7 +19,7 @@
 
 import itertools
 import logging
-from typing import Dict, Iterable, Optional, Sequence, Tuple
+from typing import Dict, Iterable, List, Optional, Sequence, Tuple
 
 import six
 from six import iteritems, itervalues
@@ -63,8 +63,9 @@ from synapse.replication.http.federation import (
 )
 from synapse.replication.http.membership import ReplicationUserJoinedLeftRoomRestServlet
 from synapse.state import StateResolutionStore, resolve_events_with_store
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.types import UserID, get_domain_from_id
-from synapse.util import unwrapFirstError
+from synapse.util import batch_iter, unwrapFirstError
 from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room
 from synapse.util.retryutils import NotRetryingDestination
@@ -164,8 +165,7 @@ class FederationHandler(BaseHandler):
 
         self._ephemeral_messages_enabled = hs.config.enable_ephemeral_messages
 
-    @defer.inlineCallbacks
-    def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
+    async def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False) -> None:
         """ Process a PDU received via a federation /send/ transaction, or
         via backfill of missing prev_events
 
@@ -175,17 +175,15 @@ class FederationHandler(BaseHandler):
             pdu (FrozenEvent): received PDU
             sent_to_us_directly (bool): True if this event was pushed to us; False if
                 we pulled it as the result of a missing prev_event.
-
-        Returns (Deferred): completes with None
         """
 
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        logger.info("[%s %s] handling received PDU: %s", room_id, event_id, pdu)
+        logger.info("handling received PDU: %s", pdu)
 
         # We reprocess pdus when we have seen them only as outliers
-        existing = yield self.store.get_event(
+        existing = await self.store.get_event(
             event_id, allow_none=True, allow_rejected=True
         )
 
@@ -229,7 +227,7 @@ class FederationHandler(BaseHandler):
         #
         # Note that if we were never in the room then we would have already
         # dropped the event, since we wouldn't know the room version.
-        is_in_room = yield self.auth.check_host_in_room(room_id, self.server_name)
+        is_in_room = await self.auth.check_host_in_room(room_id, self.server_name)
         if not is_in_room:
             logger.info(
                 "[%s %s] Ignoring PDU from %s as we're not in the room",
@@ -245,12 +243,12 @@ class FederationHandler(BaseHandler):
         # Get missing pdus if necessary.
         if not pdu.internal_metadata.is_outlier():
             # We only backfill backwards to the min depth.
-            min_depth = yield self.get_min_depth_for_context(pdu.room_id)
+            min_depth = await self.get_min_depth_for_context(pdu.room_id)
 
             logger.debug("[%s %s] min_depth: %d", room_id, event_id, min_depth)
 
             prevs = set(pdu.prev_event_ids())
-            seen = yield self.store.have_seen_events(prevs)
+            seen = await self.store.have_seen_events(prevs)
 
             if min_depth and pdu.depth < min_depth:
                 # This is so that we don't notify the user about this
@@ -270,7 +268,7 @@ class FederationHandler(BaseHandler):
                         len(missing_prevs),
                         shortstr(missing_prevs),
                     )
-                    with (yield self._room_pdu_linearizer.queue(pdu.room_id)):
+                    with (await self._room_pdu_linearizer.queue(pdu.room_id)):
                         logger.info(
                             "[%s %s] Acquired room lock to fetch %d missing prev_events",
                             room_id,
@@ -278,13 +276,19 @@ class FederationHandler(BaseHandler):
                             len(missing_prevs),
                         )
 
-                        yield self._get_missing_events_for_pdu(
-                            origin, pdu, prevs, min_depth
-                        )
+                        try:
+                            await self._get_missing_events_for_pdu(
+                                origin, pdu, prevs, min_depth
+                            )
+                        except Exception as e:
+                            raise Exception(
+                                "Error fetching missing prev_events for %s: %s"
+                                % (event_id, e)
+                            )
 
                         # Update the set of things we've seen after trying to
                         # fetch the missing stuff
-                        seen = yield self.store.have_seen_events(prevs)
+                        seen = await self.store.have_seen_events(prevs)
 
                         if not prevs - seen:
                             logger.info(
@@ -292,14 +296,6 @@ class FederationHandler(BaseHandler):
                                 room_id,
                                 event_id,
                             )
-                elif missing_prevs:
-                    logger.info(
-                        "[%s %s] Not recursively fetching %d missing prev_events: %s",
-                        room_id,
-                        event_id,
-                        len(missing_prevs),
-                        shortstr(missing_prevs),
-                    )
 
             if prevs - seen:
                 # We've still not been able to get all of the prev_events for this event.
@@ -344,13 +340,19 @@ class FederationHandler(BaseHandler):
                         affected=pdu.event_id,
                     )
 
+                logger.info(
+                    "Event %s is missing prev_events: calculating state for a "
+                    "backwards extremity",
+                    event_id,
+                )
+
                 # Calculate the state after each of the previous events, and
                 # resolve them to find the correct state at the current event.
                 auth_chains = set()
                 event_map = {event_id: pdu}
                 try:
                     # Get the state of the events we know about
-                    ours = yield self.state_store.get_state_groups_ids(room_id, seen)
+                    ours = await self.state_store.get_state_groups_ids(room_id, seen)
 
                     # state_maps is a list of mappings from (type, state_key) to event_id
                     state_maps = list(
@@ -364,13 +366,10 @@ class FederationHandler(BaseHandler):
                     # know about
                     for p in prevs - seen:
                         logger.info(
-                            "[%s %s] Requesting state at missing prev_event %s",
-                            room_id,
-                            event_id,
-                            p,
+                            "Requesting state at missing prev_event %s", event_id,
                         )
 
-                        room_version = yield self.store.get_room_version(room_id)
+                        room_version = await self.store.get_room_version(room_id)
 
                         with nested_logging_context(p):
                             # note that if any of the missing prevs share missing state or
@@ -379,24 +378,10 @@ class FederationHandler(BaseHandler):
                             (
                                 remote_state,
                                 got_auth_chain,
-                            ) = yield self.federation_client.get_state_for_room(
-                                origin, room_id, p
-                            )
-
-                            # we want the state *after* p; get_state_for_room returns the
-                            # state *before* p.
-                            remote_event = yield self.federation_client.get_pdu(
-                                [origin], p, room_version, outlier=True
+                            ) = await self._get_state_for_room(
+                                origin, room_id, p, include_event_in_state=True
                             )
 
-                            if remote_event is None:
-                                raise Exception(
-                                    "Unable to get missing prev_event %s" % (p,)
-                                )
-
-                            if remote_event.is_state():
-                                remote_state.append(remote_event)
-
                             # XXX hrm I'm not convinced that duplicate events will compare
                             # for equality, so I'm not sure this does what the author
                             # hoped.
@@ -410,7 +395,7 @@ class FederationHandler(BaseHandler):
                             for x in remote_state:
                                 event_map[x.event_id] = x
 
-                    state_map = yield resolve_events_with_store(
+                    state_map = await resolve_events_with_store(
                         room_version,
                         state_maps,
                         event_map,
@@ -422,10 +407,10 @@ class FederationHandler(BaseHandler):
 
                     # First though we need to fetch all the events that are in
                     # state_map, so we can build up the state below.
-                    evs = yield self.store.get_events(
+                    evs = await self.store.get_events(
                         list(state_map.values()),
                         get_prev_content=False,
-                        check_redacted=False,
+                        redact_behaviour=EventRedactBehaviour.AS_IS,
                     )
                     event_map.update(evs)
 
@@ -446,12 +431,11 @@ class FederationHandler(BaseHandler):
                         affected=event_id,
                     )
 
-        yield self._process_received_pdu(
+        await self._process_received_pdu(
             origin, pdu, state=state, auth_chain=auth_chain
         )
 
-    @defer.inlineCallbacks
-    def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
+    async def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
         """
         Args:
             origin (str): Origin of the pdu. Will be called to get the missing events
@@ -463,12 +447,12 @@ class FederationHandler(BaseHandler):
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        seen = yield self.store.have_seen_events(prevs)
+        seen = await self.store.have_seen_events(prevs)
 
         if not prevs - seen:
             return
 
-        latest = yield self.store.get_latest_event_ids_in_room(room_id)
+        latest = await self.store.get_latest_event_ids_in_room(room_id)
 
         # We add the prev events that we have seen to the latest
         # list to ensure the remote server doesn't give them to us
@@ -532,7 +516,7 @@ class FederationHandler(BaseHandler):
         # All that said: Let's try increasing the timout to 60s and see what happens.
 
         try:
-            missing_events = yield self.federation_client.get_missing_events(
+            missing_events = await self.federation_client.get_missing_events(
                 origin,
                 room_id,
                 earliest_events_ids=list(latest),
@@ -571,7 +555,7 @@ class FederationHandler(BaseHandler):
             )
             with nested_logging_context(ev.event_id):
                 try:
-                    yield self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
+                    await self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
                 except FederationError as e:
                     if e.code == 403:
                         logger.warning(
@@ -583,8 +567,116 @@ class FederationHandler(BaseHandler):
                     else:
                         raise
 
-    @defer.inlineCallbacks
-    def _process_received_pdu(self, origin, event, state, auth_chain):
+    async def _get_state_for_room(
+        self,
+        destination: str,
+        room_id: str,
+        event_id: str,
+        include_event_in_state: bool = False,
+    ) -> Tuple[List[EventBase], List[EventBase]]:
+        """Requests all of the room state at a given event from a remote homeserver.
+
+        Args:
+            destination: The remote homeserver to query for the state.
+            room_id: The id of the room we're interested in.
+            event_id: The id of the event we want the state at.
+            include_event_in_state: if true, the event itself will be included in the
+                returned state event list.
+
+        Returns:
+            A list of events in the state, possibly including the event itself, and
+            a list of events in the auth chain for the given event.
+        """
+        (
+            state_event_ids,
+            auth_event_ids,
+        ) = await self.federation_client.get_room_state_ids(
+            destination, room_id, event_id=event_id
+        )
+
+        desired_events = set(state_event_ids + auth_event_ids)
+
+        if include_event_in_state:
+            desired_events.add(event_id)
+
+        event_map = await self._get_events_from_store_or_dest(
+            destination, room_id, desired_events
+        )
+
+        failed_to_fetch = desired_events - event_map.keys()
+        if failed_to_fetch:
+            logger.warning(
+                "Failed to fetch missing state/auth events for %s %s",
+                event_id,
+                failed_to_fetch,
+            )
+
+        remote_state = [
+            event_map[e_id] for e_id in state_event_ids if e_id in event_map
+        ]
+
+        if include_event_in_state:
+            remote_event = event_map.get(event_id)
+            if not remote_event:
+                raise Exception("Unable to get missing prev_event %s" % (event_id,))
+            if remote_event.is_state():
+                remote_state.append(remote_event)
+
+        auth_chain = [event_map[e_id] for e_id in auth_event_ids if e_id in event_map]
+        auth_chain.sort(key=lambda e: e.depth)
+
+        return remote_state, auth_chain
+
+    async def _get_events_from_store_or_dest(
+        self, destination: str, room_id: str, event_ids: Iterable[str]
+    ) -> Dict[str, EventBase]:
+        """Fetch events from a remote destination, checking if we already have them.
+
+        Args:
+            destination
+            room_id
+            event_ids
+
+        Returns:
+            map from event_id to event
+        """
+        fetched_events = await self.store.get_events(event_ids, allow_rejected=True)
+
+        missing_events = set(event_ids) - fetched_events.keys()
+
+        if not missing_events:
+            return fetched_events
+
+        logger.debug(
+            "Fetching unknown state/auth events %s for room %s",
+            missing_events,
+            event_ids,
+        )
+
+        room_version = await self.store.get_room_version(room_id)
+
+        # XXX 20 requests at once? really?
+        for batch in batch_iter(missing_events, 20):
+            deferreds = [
+                run_in_background(
+                    self.federation_client.get_pdu,
+                    destinations=[destination],
+                    event_id=e_id,
+                    room_version=room_version,
+                )
+                for e_id in batch
+            ]
+
+            res = await make_deferred_yieldable(
+                defer.DeferredList(deferreds, consumeErrors=True)
+            )
+            for success, result in res:
+                if success and result:
+                    fetched_events[result.event_id] = result
+
+        return fetched_events
+
+    async def _process_received_pdu(self, origin, event, state, auth_chain):
         """ Called when we have a new pdu. We need to do auth checks and put it
         through the StateHandler.
         """
@@ -599,7 +691,7 @@ class FederationHandler(BaseHandler):
         if auth_chain:
             event_ids |= {e.event_id for e in auth_chain}
 
-        seen_ids = yield self.store.have_seen_events(event_ids)
+        seen_ids = await self.store.have_seen_events(event_ids)
 
         if state and auth_chain is not None:
             # If we have any state or auth_chain given to us by the replication
@@ -626,18 +718,18 @@ class FederationHandler(BaseHandler):
                 event_id,
                 [e.event.event_id for e in event_infos],
             )
-            yield self._handle_new_events(origin, event_infos)
+            await self._handle_new_events(origin, event_infos)
 
         try:
-            context = yield self._handle_new_event(origin, event, state=state)
+            context = await self._handle_new_event(origin, event, state=state)
         except AuthError as e:
             raise FederationError("ERROR", e.code, e.msg, affected=event.event_id)
 
-        room = yield self.store.get_room(room_id)
+        room = await self.store.get_room(room_id)
 
         if not room:
             try:
-                yield self.store.store_room(
+                await self.store.store_room(
                     room_id=room_id, room_creator_user_id="", is_public=False
                 )
             except StoreError:
@@ -650,11 +742,11 @@ class FederationHandler(BaseHandler):
                 # changing their profile info.
                 newly_joined = True
 
-                prev_state_ids = yield context.get_prev_state_ids(self.store)
+                prev_state_ids = await context.get_prev_state_ids(self.store)
 
                 prev_state_id = prev_state_ids.get((event.type, event.state_key))
                 if prev_state_id:
-                    prev_state = yield self.store.get_event(
+                    prev_state = await self.store.get_event(
                         prev_state_id, allow_none=True
                     )
                     if prev_state and prev_state.membership == Membership.JOIN:
@@ -662,11 +754,10 @@ class FederationHandler(BaseHandler):
 
                 if newly_joined:
                     user = UserID.from_string(event.state_key)
-                    yield self.user_joined_room(user, room_id)
+                    await self.user_joined_room(user, room_id)
 
     @log_function
-    @defer.inlineCallbacks
-    def backfill(self, dest, room_id, limit, extremities):
+    async def backfill(self, dest, room_id, limit, extremities):
         """ Trigger a backfill request to `dest` for the given `room_id`
 
         This will attempt to get more events from the remote. If the other side
@@ -683,9 +774,9 @@ class FederationHandler(BaseHandler):
         if dest == self.server_name:
             raise SynapseError(400, "Can't backfill from self.")
 
-        room_version = yield self.store.get_room_version(room_id)
+        room_version = await self.store.get_room_version(room_id)
 
-        events = yield self.federation_client.backfill(
+        events = await self.federation_client.backfill(
             dest, room_id, limit=limit, extremities=extremities
         )
 
@@ -700,7 +791,7 @@ class FederationHandler(BaseHandler):
         #     self._sanity_check_event(ev)
 
         # Don't bother processing events we already have.
-        seen_events = yield self.store.have_events_in_timeline(
+        seen_events = await self.store.have_events_in_timeline(
             set(e.event_id for e in events)
         )
 
@@ -723,7 +814,7 @@ class FederationHandler(BaseHandler):
         state_events = {}
         events_to_state = {}
         for e_id in edges:
-            state, auth = yield self.federation_client.get_state_for_room(
+            state, auth = await self._get_state_for_room(
                 destination=dest, room_id=room_id, event_id=e_id
             )
             auth_events.update({a.event_id: a for a in auth})
@@ -748,7 +839,7 @@ class FederationHandler(BaseHandler):
         # We repeatedly do this until we stop finding new auth events.
         while missing_auth - failed_to_fetch:
             logger.info("Missing auth for backfill: %r", missing_auth)
-            ret_events = yield self.store.get_events(missing_auth - failed_to_fetch)
+            ret_events = await self.store.get_events(missing_auth - failed_to_fetch)
             auth_events.update(ret_events)
 
             required_auth.update(
@@ -762,7 +853,7 @@ class FederationHandler(BaseHandler):
                     missing_auth - failed_to_fetch,
                 )
 
-                results = yield make_deferred_yieldable(
+                results = await make_deferred_yieldable(
                     defer.gatherResults(
                         [
                             run_in_background(
@@ -789,7 +880,7 @@ class FederationHandler(BaseHandler):
 
                 failed_to_fetch = missing_auth - set(auth_events)
 
-        seen_events = yield self.store.have_seen_events(
+        seen_events = await self.store.have_seen_events(
             set(auth_events.keys()) | set(state_events.keys())
         )
 
@@ -851,7 +942,7 @@ class FederationHandler(BaseHandler):
                 )
             )
 
-        yield self._handle_new_events(dest, ev_infos, backfilled=True)
+        await self._handle_new_events(dest, ev_infos, backfilled=True)
 
         # Step 2: Persist the rest of the events in the chunk one by one
         events.sort(key=lambda e: e.depth)
@@ -867,16 +958,15 @@ class FederationHandler(BaseHandler):
             # We store these one at a time since each event depends on the
             # previous to work out the state.
             # TODO: We can probably do something more clever here.
-            yield self._handle_new_event(dest, event, backfilled=True)
+            await self._handle_new_event(dest, event, backfilled=True)
 
         return events
 
-    @defer.inlineCallbacks
-    def maybe_backfill(self, room_id, current_depth):
+    async def maybe_backfill(self, room_id, current_depth):
         """Checks the database to see if we should backfill before paginating,
         and if so do.
         """
-        extremities = yield self.store.get_oldest_events_with_depth_in_room(room_id)
+        extremities = await self.store.get_oldest_events_with_depth_in_room(room_id)
 
         if not extremities:
             logger.debug("Not backfilling as no extremeties found.")
@@ -908,15 +998,17 @@ class FederationHandler(BaseHandler):
         #   state *before* the event, ignoring the special casing certain event
         #   types have.
 
-        forward_events = yield self.store.get_successor_events(list(extremities))
+        forward_events = await self.store.get_successor_events(list(extremities))
 
-        extremities_events = yield self.store.get_events(
-            forward_events, check_redacted=False, get_prev_content=False
+        extremities_events = await self.store.get_events(
+            forward_events,
+            redact_behaviour=EventRedactBehaviour.AS_IS,
+            get_prev_content=False,
         )
 
         # We set `check_history_visibility_only` as we might otherwise get false
         # positives from users having been erased.
-        filtered_extremities = yield filter_events_for_server(
+        filtered_extremities = await filter_events_for_server(
             self.storage,
             self.server_name,
             list(extremities_events.values()),
@@ -946,7 +1038,7 @@ class FederationHandler(BaseHandler):
         # First we try hosts that are already in the room
         # TODO: HEURISTIC ALERT.
 
-        curr_state = yield self.state_handler.get_current_state(room_id)
+        curr_state = await self.state_handler.get_current_state(room_id)
 
         def get_domains_from_state(state):
             """Get joined domains from state
@@ -985,12 +1077,11 @@ class FederationHandler(BaseHandler):
             domain for domain, depth in curr_domains if domain != self.server_name
         ]
 
-        @defer.inlineCallbacks
-        def try_backfill(domains):
+        async def try_backfill(domains):
             # TODO: Should we try multiple of these at a time?
             for dom in domains:
                 try:
-                    yield self.backfill(
+                    await self.backfill(
                         dom, room_id, limit=100, extremities=extremities
                     )
                     # If this succeeded then we probably already have the
@@ -1021,7 +1112,7 @@ class FederationHandler(BaseHandler):
 
             return False
 
-        success = yield try_backfill(likely_domains)
+        success = await try_backfill(likely_domains)
         if success:
             return True
 
@@ -1035,7 +1126,7 @@ class FederationHandler(BaseHandler):
 
         logger.debug("calling resolve_state_groups in _maybe_backfill")
         resolve = preserve_fn(self.state_handler.resolve_state_groups_for_events)
-        states = yield make_deferred_yieldable(
+        states = await make_deferred_yieldable(
             defer.gatherResults(
                 [resolve(room_id, [e]) for e in event_ids], consumeErrors=True
             )
@@ -1045,7 +1136,7 @@ class FederationHandler(BaseHandler):
         # event_ids.
         states = dict(zip(event_ids, [s.state for s in states]))
 
-        state_map = yield self.store.get_events(
+        state_map = await self.store.get_events(
             [e_id for ids in itervalues(states) for e_id in itervalues(ids)],
             get_prev_content=False,
         )
@@ -1061,7 +1152,7 @@ class FederationHandler(BaseHandler):
         for e_id, _ in sorted_extremeties_tuple:
             likely_domains = get_domains_from_state(states[e_id])
 
-            success = yield try_backfill(
+            success = await try_backfill(
                 [dom for dom, _ in likely_domains if dom not in tried_domains]
             )
             if success:
@@ -1210,7 +1301,7 @@ class FederationHandler(BaseHandler):
             # Check whether this room is the result of an upgrade of a room we already know
             # about. If so, migrate over user information
             predecessor = yield self.store.get_room_predecessor(room_id)
-            if not predecessor:
+            if not predecessor or not isinstance(predecessor.get("room_id"), str):
                 return
             old_room_id = predecessor["room_id"]
             logger.debug(
@@ -1238,8 +1329,7 @@ class FederationHandler(BaseHandler):
 
         return True
 
-    @defer.inlineCallbacks
-    def _handle_queued_pdus(self, room_queue):
+    async def _handle_queued_pdus(self, room_queue):
         """Process PDUs which got queued up while we were busy send_joining.
 
         Args:
@@ -1255,7 +1345,7 @@ class FederationHandler(BaseHandler):
                     p.room_id,
                 )
                 with nested_logging_context(p.event_id):
-                    yield self.on_receive_pdu(origin, p, sent_to_us_directly=True)
+                    await self.on_receive_pdu(origin, p, sent_to_us_directly=True)
             except Exception as e:
                 logger.warning(
                     "Error handling queued PDU %s from %s: %s", p.event_id, origin, e
@@ -1453,7 +1543,7 @@ class FederationHandler(BaseHandler):
     @defer.inlineCallbacks
     def do_remotely_reject_invite(self, target_hosts, room_id, user_id, content):
         origin, event, event_format_version = yield self._make_and_verify_event(
-            target_hosts, room_id, user_id, "leave", content=content,
+            target_hosts, room_id, user_id, "leave", content=content
         )
         # Mark as outlier as we don't have any state for this event; we're not
         # even in the room.
@@ -2814,7 +2904,7 @@ class FederationHandler(BaseHandler):
                 room_id=room_id, user_id=user.to_string(), change="joined"
             )
         else:
-            return user_joined_room(self.distributor, user, room_id)
+            return defer.succeed(user_joined_room(self.distributor, user, room_id))
 
     @defer.inlineCallbacks
     def get_room_complexity(self, remote_room_hosts, room_id):
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 81dce96f4b..73c110a92b 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -26,7 +26,7 @@ from synapse.streams.config import PaginationConfig
 from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
 from synapse.util.async_helpers import concurrently_execute
-from synapse.util.caches.snapshot_cache import SnapshotCache
+from synapse.util.caches.response_cache import ResponseCache
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -41,7 +41,7 @@ class InitialSyncHandler(BaseHandler):
         self.state = hs.get_state_handler()
         self.clock = hs.get_clock()
         self.validator = EventValidator()
-        self.snapshot_cache = SnapshotCache()
+        self.snapshot_cache = ResponseCache(hs, "initial_sync_cache")
         self._event_serializer = hs.get_event_client_serializer()
         self.storage = hs.get_storage()
         self.state_store = self.storage.state
@@ -79,17 +79,14 @@ class InitialSyncHandler(BaseHandler):
             as_client_event,
             include_archived,
         )
-        now_ms = self.clock.time_msec()
-        result = self.snapshot_cache.get(now_ms, key)
-        if result is not None:
-            return result
 
-        return self.snapshot_cache.set(
-            now_ms,
+        return self.snapshot_cache.wrap(
             key,
-            self._snapshot_all_rooms(
-                user_id, pagin_config, as_client_event, include_archived
-            ),
+            self._snapshot_all_rooms,
+            user_id,
+            pagin_config,
+            as_client_event,
+            include_archived,
         )
 
     @defer.inlineCallbacks
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 54fa216d83..bf9add7fe2 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -46,6 +46,7 @@ from synapse.events.validator import EventValidator
 from synapse.logging.context import run_in_background
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.storage.state import StateFilter
 from synapse.types import RoomAlias, UserID, create_requester
 from synapse.util.async_helpers import Linearizer
@@ -875,7 +876,7 @@ class EventCreationHandler(object):
             if event.type == EventTypes.Redaction:
                 original_event = yield self.store.get_event(
                     event.redacts,
-                    check_redacted=False,
+                    redact_behaviour=EventRedactBehaviour.AS_IS,
                     get_prev_content=False,
                     allow_rejected=False,
                     allow_none=True,
@@ -952,7 +953,7 @@ class EventCreationHandler(object):
         if event.type == EventTypes.Redaction:
             original_event = yield self.store.get_event(
                 event.redacts,
-                check_redacted=False,
+                redact_behaviour=EventRedactBehaviour.AS_IS,
                 get_prev_content=False,
                 allow_rejected=False,
                 allow_none=True,
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 8514ddc600..00a6afc963 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -280,8 +280,7 @@ class PaginationHandler(object):
 
             await self.storage.purge_events.purge_room(room_id)
 
-    @defer.inlineCallbacks
-    def get_messages(
+    async def get_messages(
         self,
         requester,
         room_id=None,
@@ -307,7 +306,7 @@ class PaginationHandler(object):
             room_token = pagin_config.from_token.room_key
         else:
             pagin_config.from_token = (
-                yield self.hs.get_event_sources().get_current_token_for_pagination()
+                await self.hs.get_event_sources().get_current_token_for_pagination()
             )
             room_token = pagin_config.from_token.room_key
 
@@ -319,11 +318,11 @@ class PaginationHandler(object):
 
         source_config = pagin_config.get_source_config("room")
 
-        with (yield self.pagination_lock.read(room_id)):
+        with (await self.pagination_lock.read(room_id)):
             (
                 membership,
                 member_event_id,
-            ) = yield self.auth.check_in_room_or_world_readable(room_id, user_id)
+            ) = await self.auth.check_in_room_or_world_readable(room_id, user_id)
 
             if source_config.direction == "b":
                 # if we're going backwards, we might need to backfill. This
@@ -331,7 +330,7 @@ class PaginationHandler(object):
                 if room_token.topological:
                     max_topo = room_token.topological
                 else:
-                    max_topo = yield self.store.get_max_topological_token(
+                    max_topo = await self.store.get_max_topological_token(
                         room_id, room_token.stream
                     )
 
@@ -339,18 +338,18 @@ class PaginationHandler(object):
                     # If they have left the room then clamp the token to be before
                     # they left the room, to save the effort of loading from the
                     # database.
-                    leave_token = yield self.store.get_topological_token_for_event(
+                    leave_token = await self.store.get_topological_token_for_event(
                         member_event_id
                     )
                     leave_token = RoomStreamToken.parse(leave_token)
                     if leave_token.topological < max_topo:
                         source_config.from_key = str(leave_token)
 
-                yield self.hs.get_handlers().federation_handler.maybe_backfill(
+                await self.hs.get_handlers().federation_handler.maybe_backfill(
                     room_id, max_topo
                 )
 
-            events, next_key = yield self.store.paginate_room_events(
+            events, next_key = await self.store.paginate_room_events(
                 room_id=room_id,
                 from_key=source_config.from_key,
                 to_key=source_config.to_key,
@@ -365,7 +364,7 @@ class PaginationHandler(object):
             if event_filter:
                 events = event_filter.filter(events)
 
-            events = yield filter_events_for_client(
+            events = await filter_events_for_client(
                 self.storage, user_id, events, is_peeking=(member_event_id is None)
             )
 
@@ -385,19 +384,19 @@ class PaginationHandler(object):
                 (EventTypes.Member, event.sender) for event in events
             )
 
-            state_ids = yield self.state_store.get_state_ids_for_event(
+            state_ids = await self.state_store.get_state_ids_for_event(
                 events[0].event_id, state_filter=state_filter
             )
 
             if state_ids:
-                state = yield self.store.get_events(list(state_ids.values()))
+                state = await self.store.get_events(list(state_ids.values()))
                 state = state.values()
 
         time_now = self.clock.time_msec()
 
         chunk = {
             "chunk": (
-                yield self._event_serializer.serialize_events(
+                await self._event_serializer.serialize_events(
                     events, time_now, as_client_event=as_client_event
                 )
             ),
@@ -406,7 +405,7 @@ class PaginationHandler(object):
         }
 
         if state:
-            chunk["state"] = yield self._event_serializer.serialize_events(
+            chunk["state"] = await self._event_serializer.serialize_events(
                 state, time_now, as_client_event=as_client_event
             )
 
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index cc9e6b9bd0..0082f85c26 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -13,20 +13,36 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import re
+from typing import Tuple
 
 import attr
 import saml2
+import saml2.response
 from saml2.client import Saml2Client
 
 from synapse.api.errors import SynapseError
+from synapse.config import ConfigError
 from synapse.http.servlet import parse_string
 from synapse.rest.client.v1.login import SSOAuthHandler
-from synapse.types import UserID, map_username_to_mxid_localpart
+from synapse.types import (
+    UserID,
+    map_username_to_mxid_localpart,
+    mxid_localpart_allowed_characters,
+)
 from synapse.util.async_helpers import Linearizer
 
 logger = logging.getLogger(__name__)
 
 
+@attr.s
+class Saml2SessionData:
+    """Data we track about SAML2 sessions"""
+
+    # time the session was created, in milliseconds
+    creation_time = attr.ib()
+
+
 class SamlHandler:
     def __init__(self, hs):
         self._saml_client = Saml2Client(hs.config.saml2_sp_config)
@@ -37,11 +53,14 @@ class SamlHandler:
         self._datastore = hs.get_datastore()
         self._hostname = hs.hostname
         self._saml2_session_lifetime = hs.config.saml2_session_lifetime
-        self._mxid_source_attribute = hs.config.saml2_mxid_source_attribute
         self._grandfathered_mxid_source_attribute = (
             hs.config.saml2_grandfathered_mxid_source_attribute
         )
-        self._mxid_mapper = hs.config.saml2_mxid_mapper
+
+        # plugin to do custom mapping from saml response to mxid
+        self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
+            hs.config.saml2_user_mapping_provider_config
+        )
 
         # identifier for the external_ids table
         self._auth_provider_id = "saml"
@@ -118,22 +137,10 @@ class SamlHandler:
             remote_user_id = saml2_auth.ava["uid"][0]
         except KeyError:
             logger.warning("SAML2 response lacks a 'uid' attestation")
-            raise SynapseError(400, "uid not in SAML2 response")
-
-        try:
-            mxid_source = saml2_auth.ava[self._mxid_source_attribute][0]
-        except KeyError:
-            logger.warning(
-                "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute
-            )
-            raise SynapseError(
-                400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
-            )
+            raise SynapseError(400, "'uid' not in SAML2 response")
 
         self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
 
-        displayName = saml2_auth.ava.get("displayName", [None])[0]
-
         with (await self._mapping_lock.queue(self._auth_provider_id)):
             # first of all, check if we already have a mapping for this user
             logger.info(
@@ -173,22 +180,46 @@ class SamlHandler:
                     )
                     return registered_user_id
 
-            # figure out a new mxid for this user
-            base_mxid_localpart = self._mxid_mapper(mxid_source)
+            # Map saml response to user attributes using the configured mapping provider
+            for i in range(1000):
+                attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
+                    saml2_auth, i
+                )
+
+                logger.debug(
+                    "Retrieved SAML attributes from user mapping provider: %s "
+                    "(attempt %d)",
+                    attribute_dict,
+                    i,
+                )
+
+                localpart = attribute_dict.get("mxid_localpart")
+                if not localpart:
+                    logger.error(
+                        "SAML mapping provider plugin did not return a "
+                        "mxid_localpart object"
+                    )
+                    raise SynapseError(500, "Error parsing SAML2 response")
 
-            suffix = 0
-            while True:
-                localpart = base_mxid_localpart + (str(suffix) if suffix else "")
+                displayname = attribute_dict.get("displayname")
+
+                # Check if this mxid already exists
                 if not await self._datastore.get_users_by_id_case_insensitive(
                     UserID(localpart, self._hostname).to_string()
                 ):
+                    # This mxid is free
                     break
-                suffix += 1
-            logger.info("Allocating mxid for new user with localpart %s", localpart)
+            else:
+                # Unable to generate a username in 1000 iterations
+                # Break and return error to the user
+                raise SynapseError(
+                    500, "Unable to generate a Matrix ID from the SAML response"
+                )
 
             registered_user_id = await self._registration_handler.register_user(
-                localpart=localpart, default_display_name=displayName
+                localpart=localpart, default_display_name=displayname
             )
+
             await self._datastore.record_user_external_id(
                 self._auth_provider_id, remote_user_id, registered_user_id
             )
@@ -205,9 +236,120 @@ class SamlHandler:
             del self._outstanding_requests_dict[reqid]
 
 
+DOT_REPLACE_PATTERN = re.compile(
+    ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
+)
+
+
+def dot_replace_for_mxid(username: str) -> str:
+    username = username.lower()
+    username = DOT_REPLACE_PATTERN.sub(".", username)
+
+    # regular mxids aren't allowed to start with an underscore either
+    username = re.sub("^_", "", username)
+    return username
+
+
+MXID_MAPPER_MAP = {
+    "hexencode": map_username_to_mxid_localpart,
+    "dotreplace": dot_replace_for_mxid,
+}
+
+
 @attr.s
-class Saml2SessionData:
-    """Data we track about SAML2 sessions"""
+class SamlConfig(object):
+    mxid_source_attribute = attr.ib()
+    mxid_mapper = attr.ib()
 
-    # time the session was created, in milliseconds
-    creation_time = attr.ib()
+
+class DefaultSamlMappingProvider(object):
+    __version__ = "0.0.1"
+
+    def __init__(self, parsed_config: SamlConfig):
+        """The default SAML user mapping provider
+
+        Args:
+            parsed_config: Module configuration
+        """
+        self._mxid_source_attribute = parsed_config.mxid_source_attribute
+        self._mxid_mapper = parsed_config.mxid_mapper
+
+    def saml_response_to_user_attributes(
+        self, saml_response: saml2.response.AuthnResponse, failures: int = 0,
+    ) -> dict:
+        """Maps some text from a SAML response to attributes of a new user
+
+        Args:
+            saml_response: A SAML auth response object
+
+            failures: How many times a call to this function with this
+                saml_response has resulted in a failure
+
+        Returns:
+            dict: A dict containing new user attributes. Possible keys:
+                * mxid_localpart (str): Required. The localpart of the user's mxid
+                * displayname (str): The displayname of the user
+        """
+        try:
+            mxid_source = saml_response.ava[self._mxid_source_attribute][0]
+        except KeyError:
+            logger.warning(
+                "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute,
+            )
+            raise SynapseError(
+                400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
+            )
+
+        # Use the configured mapper for this mxid_source
+        base_mxid_localpart = self._mxid_mapper(mxid_source)
+
+        # Append suffix integer if last call to this function failed to produce
+        # a usable mxid
+        localpart = base_mxid_localpart + (str(failures) if failures else "")
+
+        # Retrieve the display name from the saml response
+        # If displayname is None, the mxid_localpart will be used instead
+        displayname = saml_response.ava.get("displayName", [None])[0]
+
+        return {
+            "mxid_localpart": localpart,
+            "displayname": displayname,
+        }
+
+    @staticmethod
+    def parse_config(config: dict) -> SamlConfig:
+        """Parse the dict provided by the homeserver's config
+        Args:
+            config: A dictionary containing configuration options for this provider
+        Returns:
+            SamlConfig: A custom config object for this module
+        """
+        # Parse config options and use defaults where necessary
+        mxid_source_attribute = config.get("mxid_source_attribute", "uid")
+        mapping_type = config.get("mxid_mapping", "hexencode")
+
+        # Retrieve the associating mapping function
+        try:
+            mxid_mapper = MXID_MAPPER_MAP[mapping_type]
+        except KeyError:
+            raise ConfigError(
+                "saml2_config.user_mapping_provider.config: '%s' is not a valid "
+                "mxid_mapping value" % (mapping_type,)
+            )
+
+        return SamlConfig(mxid_source_attribute, mxid_mapper)
+
+    @staticmethod
+    def get_saml_attributes(config: SamlConfig) -> Tuple[set, set]:
+        """Returns the required attributes of a SAML
+
+        Args:
+            config: A SamlConfig object containing configuration params for this provider
+
+        Returns:
+            tuple[set,set]: The first set equates to the saml auth response
+                attributes that are required for the module to function, whereas the
+                second set consists of those attributes which can be used if
+                available, but are not necessary
+        """
+        return {"uid", config.mxid_source_attribute}, {"displayName"}
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index 56ed262a1f..ef750d1497 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -21,7 +21,7 @@ from unpaddedbase64 import decode_base64, encode_base64
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import SynapseError
+from synapse.api.errors import NotFoundError, SynapseError
 from synapse.api.filtering import Filter
 from synapse.storage.state import StateFilter
 from synapse.visibility import filter_events_for_client
@@ -37,6 +37,7 @@ class SearchHandler(BaseHandler):
         self._event_serializer = hs.get_event_client_serializer()
         self.storage = hs.get_storage()
         self.state_store = self.storage.state
+        self.auth = hs.get_auth()
 
     @defer.inlineCallbacks
     def get_old_rooms_from_upgraded_room(self, room_id):
@@ -53,23 +54,38 @@ class SearchHandler(BaseHandler):
             room_id (str): id of the room to search through.
 
         Returns:
-            Deferred[iterable[unicode]]: predecessor room ids
+            Deferred[iterable[str]]: predecessor room ids
         """
 
         historical_room_ids = []
 
-        while True:
-            predecessor = yield self.store.get_room_predecessor(room_id)
+        # The initial room must have been known for us to get this far
+        predecessor = yield self.store.get_room_predecessor(room_id)
 
-            # If no predecessor, assume we've hit a dead end
+        while True:
             if not predecessor:
+                # We have reached the end of the chain of predecessors
+                break
+
+            if not isinstance(predecessor.get("room_id"), str):
+                # This predecessor object is malformed. Exit here
+                break
+
+            predecessor_room_id = predecessor["room_id"]
+
+            # Don't add it to the list until we have checked that we are in the room
+            try:
+                next_predecessor_room = yield self.store.get_room_predecessor(
+                    predecessor_room_id
+                )
+            except NotFoundError:
+                # The predecessor is not a known room, so we are done here
                 break
 
-            # Add predecessor's room ID
-            historical_room_ids.append(predecessor["room_id"])
+            historical_room_ids.append(predecessor_room_id)
 
-            # Scan through the old room for further predecessors
-            room_id = predecessor["room_id"]
+            # And repeat
+            predecessor = next_predecessor_room
 
         return historical_room_ids
 
diff --git a/synapse/logging/context.py b/synapse/logging/context.py
index 2c1fb9ddac..6747f29e6a 100644
--- a/synapse/logging/context.py
+++ b/synapse/logging/context.py
@@ -23,6 +23,7 @@ them.
 See doc/log_contexts.rst for details on how this works.
 """
 
+import inspect
 import logging
 import threading
 import types
@@ -612,7 +613,8 @@ def run_in_background(f, *args, **kwargs):
 
 
 def make_deferred_yieldable(deferred):
-    """Given a deferred, make it follow the Synapse logcontext rules:
+    """Given a deferred (or coroutine), make it follow the Synapse logcontext
+    rules:
 
     If the deferred has completed (or is not actually a Deferred), essentially
     does nothing (just returns another completed deferred with the
@@ -624,6 +626,13 @@ def make_deferred_yieldable(deferred):
 
     (This is more-or-less the opposite operation to run_in_background.)
     """
+    if inspect.isawaitable(deferred):
+        # If we're given a coroutine we convert it to a deferred so that we
+        # run it and find out if it immediately finishes, it it does then we
+        # don't need to fiddle with log contexts at all and can return
+        # immediately.
+        deferred = defer.ensureDeferred(deferred)
+
     if not isinstance(deferred, defer.Deferred):
         return deferred
 
diff --git a/synapse/rest/client/v1/profile.py b/synapse/rest/client/v1/profile.py
index 4f47562c1b..e7fe50ed72 100644
--- a/synapse/rest/client/v1/profile.py
+++ b/synapse/rest/client/v1/profile.py
@@ -15,6 +15,7 @@
 
 """ This module contains REST servlets to do with profile: /profile/<paths> """
 
+from synapse.api.errors import Codes, SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.types import UserID
@@ -103,12 +104,11 @@ class ProfileAvatarURLRestServlet(RestServlet):
 
         content = parse_json_object_from_request(request)
         try:
-            new_avatar_url = content.get("avatar_url")
-        except Exception:
-            return 400, "Unable to parse avatar_url"
-
-        if new_avatar_url is None:
-            return 400, "Missing required key: avatar_url"
+            new_avatar_url = content["avatar_url"]
+        except KeyError:
+            raise SynapseError(
+                400, "Missing key 'avatar_url'", errcode=Codes.MISSING_PARAM
+            )
 
         await self.profile_handler.set_avatar_url(
             user, requester, new_avatar_url, is_admin
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index 139beef8ed..3e6d62eef1 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -32,6 +32,7 @@ from synapse.events import EventBase
 from synapse.events.snapshot import EventContext
 from synapse.logging.utils import log_function
 from synapse.state import v1, v2
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -645,7 +646,7 @@ class StateResolutionStore(object):
 
         return self.store.get_events(
             event_ids,
-            check_redacted=False,
+            redact_behaviour=EventRedactBehaviour.AS_IS,
             get_prev_content=False,
             allow_rejected=allow_rejected,
         )
diff --git a/synapse/storage/data_stores/main/client_ips.py b/synapse/storage/data_stores/main/client_ips.py
index 320c5b0f07..add3037b69 100644
--- a/synapse/storage/data_stores/main/client_ips.py
+++ b/synapse/storage/data_stores/main/client_ips.py
@@ -451,16 +451,18 @@ class ClientIpStore(ClientIpBackgroundUpdateStore):
                 # Technically an access token might not be associated with
                 # a device so we need to check.
                 if device_id:
-                    self.db.simple_upsert_txn(
+                    # this is always an update rather than an upsert: the row should
+                    # already exist, and if it doesn't, that may be because it has been
+                    # deleted, and we don't want to re-create it.
+                    self.db.simple_update_txn(
                         txn,
                         table="devices",
                         keyvalues={"user_id": user_id, "device_id": device_id},
-                        values={
+                        updatevalues={
                             "user_agent": user_agent,
                             "last_seen": last_seen,
                             "ip": ip,
                         },
-                        lock=False,
                     )
             except Exception as e:
                 # Failed to upsert, log and continue
diff --git a/synapse/storage/data_stores/main/events.py b/synapse/storage/data_stores/main/events.py
index da1529f6ea..998bba1aad 100644
--- a/synapse/storage/data_stores/main/events.py
+++ b/synapse/storage/data_stores/main/events.py
@@ -1039,20 +1039,25 @@ class EventsStore(
             },
         )
 
-    @defer.inlineCallbacks
-    def _censor_redactions(self):
+    async def _censor_redactions(self):
         """Censors all redactions older than the configured period that haven't
         been censored yet.
 
         By censor we mean update the event_json table with the redacted event.
-
-        Returns:
-            Deferred
         """
 
         if self.hs.config.redaction_retention_period is None:
             return
 
+        if not (
+            await self.db.updates.has_completed_background_update(
+                "redactions_have_censored_ts_idx"
+            )
+        ):
+            # We don't want to run this until the appropriate index has been
+            # created.
+            return
+
         before_ts = self._clock.time_msec() - self.hs.config.redaction_retention_period
 
         # We fetch all redactions that:
@@ -1074,15 +1079,15 @@ class EventsStore(
             LIMIT ?
         """
 
-        rows = yield self.db.execute(
+        rows = await self.db.execute(
             "_censor_redactions_fetch", None, sql, before_ts, 100
         )
 
         updates = []
 
         for redaction_id, event_id in rows:
-            redaction_event = yield self.get_event(redaction_id, allow_none=True)
-            original_event = yield self.get_event(
+            redaction_event = await self.get_event(redaction_id, allow_none=True)
+            original_event = await self.get_event(
                 event_id, allow_rejected=True, allow_none=True
             )
 
@@ -1115,7 +1120,7 @@ class EventsStore(
                     updatevalues={"have_censored": True},
                 )
 
-        yield self.db.runInteraction("_update_censor_txn", _update_censor_txn)
+        await self.db.runInteraction("_update_censor_txn", _update_censor_txn)
 
     def _censor_event_txn(self, txn, event_id, pruned_json):
         """Censor an event by replacing its JSON in the event_json table with the
diff --git a/synapse/storage/data_stores/main/events_bg_updates.py b/synapse/storage/data_stores/main/events_bg_updates.py
index efee17b929..5177b71016 100644
--- a/synapse/storage/data_stores/main/events_bg_updates.py
+++ b/synapse/storage/data_stores/main/events_bg_updates.py
@@ -90,6 +90,14 @@ class EventsBackgroundUpdatesStore(SQLBaseStore):
             "event_store_labels", self._event_store_labels
         )
 
+        self.db.updates.register_background_index_update(
+            "redactions_have_censored_ts_idx",
+            index_name="redactions_have_censored_ts",
+            table="redactions",
+            columns=["received_ts"],
+            where_clause="NOT have_censored",
+        )
+
     @defer.inlineCallbacks
     def _background_reindex_fields_sender(self, progress, batch_size):
         target_min_stream_id = progress["target_min_stream_id_inclusive"]
diff --git a/synapse/storage/data_stores/main/events_worker.py b/synapse/storage/data_stores/main/events_worker.py
index 9ee117ce0f..2c9142814c 100644
--- a/synapse/storage/data_stores/main/events_worker.py
+++ b/synapse/storage/data_stores/main/events_worker.py
@@ -19,8 +19,10 @@ import itertools
 import logging
 import threading
 from collections import namedtuple
+from typing import List, Optional
 
 from canonicaljson import json
+from constantly import NamedConstant, Names
 
 from twisted.internet import defer
 
@@ -55,6 +57,16 @@ EVENT_QUEUE_TIMEOUT_S = 0.1  # Timeout when waiting for requests for events
 _EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event"))
 
 
+class EventRedactBehaviour(Names):
+    """
+    What to do when retrieving a redacted event from the database.
+    """
+
+    AS_IS = NamedConstant()
+    REDACT = NamedConstant()
+    BLOCK = NamedConstant()
+
+
 class EventsWorkerStore(SQLBaseStore):
     def __init__(self, database: Database, db_conn, hs):
         super(EventsWorkerStore, self).__init__(database, db_conn, hs)
@@ -125,25 +137,27 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_event(
         self,
-        event_id,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
-        allow_none=False,
-        check_room_id=None,
+        event_id: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
+        allow_none: bool = False,
+        check_room_id: Optional[str] = None,
     ):
         """Get an event from the database by event_id.
 
         Args:
-            event_id (str): The event_id of the event to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_id: The event_id of the event to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
-            allow_none (bool): If True, return None if no event found, if
+            allow_rejected: If True return rejected events.
+            allow_none: If True, return None if no event found, if
                 False throw a NotFoundError
-            check_room_id (str|None): if not None, check the room of the found event.
+            check_room_id: if not None, check the room of the found event.
                 If there is a mismatch, behave as per allow_none.
 
         Returns:
@@ -154,7 +168,7 @@ class EventsWorkerStore(SQLBaseStore):
 
         events = yield self.get_events_as_list(
             [event_id],
-            check_redacted=check_redacted,
+            redact_behaviour=redact_behaviour,
             get_prev_content=get_prev_content,
             allow_rejected=allow_rejected,
         )
@@ -173,27 +187,30 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_events(
         self,
-        event_ids,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
+        event_ids: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
     ):
         """Get events from the database
 
         Args:
-            event_ids (list): The event_ids of the events to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_ids: The event_ids of the events to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible
+                values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
+            allow_rejected: If True return rejected events.
 
         Returns:
             Deferred : Dict from event_id to event.
         """
         events = yield self.get_events_as_list(
             event_ids,
-            check_redacted=check_redacted,
+            redact_behaviour=redact_behaviour,
             get_prev_content=get_prev_content,
             allow_rejected=allow_rejected,
         )
@@ -203,21 +220,23 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_events_as_list(
         self,
-        event_ids,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
+        event_ids: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
     ):
         """Get events from the database and return in a list in the same order
         as given by `event_ids` arg.
 
         Args:
-            event_ids (list): The event_ids of the events to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_ids: The event_ids of the events to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
+            allow_rejected: If True, return rejected events.
 
         Returns:
             Deferred[list[EventBase]]: List of events fetched from the database. The
@@ -319,10 +338,14 @@ class EventsWorkerStore(SQLBaseStore):
                     # Update the cache to save doing the checks again.
                     entry.event.internal_metadata.recheck_redaction = False
 
-            if check_redacted and entry.redacted_event:
-                event = entry.redacted_event
-            else:
-                event = entry.event
+            event = entry.event
+
+            if entry.redacted_event:
+                if redact_behaviour == EventRedactBehaviour.BLOCK:
+                    # Skip this event
+                    continue
+                elif redact_behaviour == EventRedactBehaviour.REDACT:
+                    event = entry.redacted_event
 
             events.append(event)
 
diff --git a/synapse/storage/data_stores/main/room.py b/synapse/storage/data_stores/main/room.py
index 0148be20d3..aa476d0fbf 100644
--- a/synapse/storage/data_stores/main/room.py
+++ b/synapse/storage/data_stores/main/room.py
@@ -46,6 +46,11 @@ RatelimitOverride = collections.namedtuple(
 
 
 class RoomWorkerStore(SQLBaseStore):
+    def __init__(self, database: Database, db_conn, hs):
+        super(RoomWorkerStore, self).__init__(database, db_conn, hs)
+
+        self.config = hs.config
+
     def get_room(self, room_id):
         """Retrieve a room.
 
diff --git a/synapse/storage/data_stores/main/schema/delta/56/redaction_censor.sql b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor.sql
index fe51b02309..ea95db0ed7 100644
--- a/synapse/storage/data_stores/main/schema/delta/56/redaction_censor.sql
+++ b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor.sql
@@ -14,4 +14,3 @@
  */
 
 ALTER TABLE redactions ADD COLUMN have_censored BOOL NOT NULL DEFAULT false;
-CREATE INDEX redactions_have_censored ON redactions(event_id) WHERE not have_censored;
diff --git a/synapse/storage/data_stores/main/schema/delta/56/redaction_censor2.sql b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor2.sql
index 77a5eca499..49ce35d794 100644
--- a/synapse/storage/data_stores/main/schema/delta/56/redaction_censor2.sql
+++ b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor2.sql
@@ -14,7 +14,9 @@
  */
 
 ALTER TABLE redactions ADD COLUMN received_ts BIGINT;
-CREATE INDEX redactions_have_censored_ts ON redactions(received_ts) WHERE not have_censored;
 
 INSERT INTO background_updates (update_name, progress_json) VALUES
   ('redactions_received_ts', '{}');
+
+INSERT INTO background_updates (update_name, progress_json) VALUES
+  ('redactions_have_censored_ts_idx', '{}');
diff --git a/synapse/storage/data_stores/main/schema/delta/56/redaction_censor4.sql b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor4.sql
new file mode 100644
index 0000000000..b7550f6f4e
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/delta/56/redaction_censor4.sql
@@ -0,0 +1,16 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+DROP INDEX IF EXISTS redactions_have_censored;
diff --git a/synapse/storage/data_stores/main/schema/full_schemas/README.md b/synapse/storage/data_stores/main/schema/full_schemas/README.md
new file mode 100644
index 0000000000..bbd3f18604
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/full_schemas/README.md
@@ -0,0 +1,13 @@
+# Building full schema dumps
+
+These schemas need to be made from a database that has had all background updates run.
+
+To do so, use `scripts-dev/make_full_schema.sh`. This will produce
+`full.sql.postgres ` and `full.sql.sqlite` files.
+
+Ensure postgres is installed and your user has the ability to run bash commands
+such as `createdb`.
+
+```
+./scripts-dev/make_full_schema.sh -p postgres_username -o output_dir/
+```
diff --git a/synapse/storage/data_stores/main/schema/full_schemas/README.txt b/synapse/storage/data_stores/main/schema/full_schemas/README.txt
deleted file mode 100644
index d3f6401344..0000000000
--- a/synapse/storage/data_stores/main/schema/full_schemas/README.txt
+++ /dev/null
@@ -1,19 +0,0 @@
-Building full schema dumps
-==========================
-
-These schemas need to be made from a database that has had all background updates run.
-
-Postgres
---------
-
-$ pg_dump --format=plain --schema-only --no-tablespaces --no-acl --no-owner $DATABASE_NAME| sed -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > full.sql.postgres
-
-SQLite
-------
-
-$ sqlite3 $DATABASE_FILE ".schema" > full.sql.sqlite
-
-After
------
-
-Delete the CREATE statements for "sqlite_stat1", "schema_version", "applied_schema_deltas", and "applied_module_schemas".
\ No newline at end of file
diff --git a/synapse/storage/data_stores/main/search.py b/synapse/storage/data_stores/main/search.py
index 4eec2fae5e..dfb46ee0f8 100644
--- a/synapse/storage/data_stores/main/search.py
+++ b/synapse/storage/data_stores/main/search.py
@@ -25,6 +25,7 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.storage._base import SQLBaseStore, make_in_list_sql_clause
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.storage.database import Database
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 
@@ -453,7 +454,12 @@ class SearchStore(SearchBackgroundUpdateStore):
 
         results = list(filter(lambda row: row["room_id"] in room_ids, results))
 
-        events = yield self.get_events_as_list([r["event_id"] for r in results])
+        # We set redact_behaviour to BLOCK here to prevent redacted events being returned in
+        # search results (which is a data leak)
+        events = yield self.get_events_as_list(
+            [r["event_id"] for r in results],
+            redact_behaviour=EventRedactBehaviour.BLOCK,
+        )
 
         event_map = {ev.event_id: ev for ev in events}
 
diff --git a/synapse/storage/data_stores/main/state.py b/synapse/storage/data_stores/main/state.py
index 9ef7b48c74..dcc6b43cdf 100644
--- a/synapse/storage/data_stores/main/state.py
+++ b/synapse/storage/data_stores/main/state.py
@@ -278,7 +278,7 @@ class StateGroupWorkerStore(
 
     @defer.inlineCallbacks
     def get_room_predecessor(self, room_id):
-        """Get the predecessor room of an upgraded room if one exists.
+        """Get the predecessor of an upgraded room if it exists.
         Otherwise return None.
 
         Args:
@@ -291,14 +291,22 @@ class StateGroupWorkerStore(
                     * room_id (str): The room ID of the predecessor room
                     * event_id (str): The ID of the tombstone event in the predecessor room
 
+                None if a predecessor key is not found, or is not a dictionary.
+
         Raises:
-            NotFoundError if the room is unknown
+            NotFoundError if the given room is unknown
         """
         # Retrieve the room's create event
         create_event = yield self.get_create_event_for_room(room_id)
 
-        # Return predecessor if present
-        return create_event.content.get("predecessor", None)
+        # Retrieve the predecessor key of the create event
+        predecessor = create_event.content.get("predecessor", None)
+
+        # Ensure the key is a dictionary
+        if not isinstance(predecessor, dict):
+            return None
+
+        return predecessor
 
     @defer.inlineCallbacks
     def get_create_event_for_room(self, room_id):
@@ -318,7 +326,7 @@ class StateGroupWorkerStore(
 
         # If we can't find the create event, assume we've hit a dead end
         if not create_id:
-            raise NotFoundError("Unknown room %s" % (room_id))
+            raise NotFoundError("Unknown room %s" % (room_id,))
 
         # Retrieve the room's create event and return
         create_event = yield self.get_event(create_id)
diff --git a/synapse/util/caches/snapshot_cache.py b/synapse/util/caches/snapshot_cache.py
deleted file mode 100644
index 8318db8d2c..0000000000
--- a/synapse/util/caches/snapshot_cache.py
+++ /dev/null
@@ -1,94 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015, 2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from synapse.util.async_helpers import ObservableDeferred
-
-
-class SnapshotCache(object):
-    """Cache for snapshots like the response of /initialSync.
-    The response of initialSync only has to be a recent snapshot of the
-    server state. It shouldn't matter to clients if it is a few minutes out
-    of date.
-
-    This caches a deferred response. Until the deferred completes it will be
-    returned from the cache. This means that if the client retries the request
-    while the response is still being computed, that original response will be
-    used rather than trying to compute a new response.
-
-    Once the deferred completes it will removed from the cache after 5 minutes.
-    We delay removing it from the cache because a client retrying its request
-    could race with us finishing computing the response.
-
-    Rather than tracking precisely how long something has been in the cache we
-    keep two generations of completed responses. Every 5 minutes discard the
-    old generation, move the new generation to the old generation, and set the
-    new generation to be empty. This means that a result will be in the cache
-    somewhere between 5 and 10 minutes.
-    """
-
-    DURATION_MS = 5 * 60 * 1000  # Cache results for 5 minutes.
-
-    def __init__(self):
-        self.pending_result_cache = {}  # Request that haven't finished yet.
-        self.prev_result_cache = {}  # The older requests that have finished.
-        self.next_result_cache = {}  # The newer requests that have finished.
-        self.time_last_rotated_ms = 0
-
-    def rotate(self, time_now_ms):
-        # Rotate once if the cache duration has passed since the last rotation.
-        if time_now_ms - self.time_last_rotated_ms >= self.DURATION_MS:
-            self.prev_result_cache = self.next_result_cache
-            self.next_result_cache = {}
-            self.time_last_rotated_ms += self.DURATION_MS
-
-        # Rotate again if the cache duration has passed twice since the last
-        # rotation.
-        if time_now_ms - self.time_last_rotated_ms >= self.DURATION_MS:
-            self.prev_result_cache = self.next_result_cache
-            self.next_result_cache = {}
-            self.time_last_rotated_ms = time_now_ms
-
-    def get(self, time_now_ms, key):
-        self.rotate(time_now_ms)
-        # This cache is intended to deduplicate requests, so we expect it to be
-        # missed most of the time. So we just lookup the key in all of the
-        # dictionaries rather than trying to short circuit the lookup if the
-        # key is found.
-        result = self.prev_result_cache.get(key)
-        result = self.next_result_cache.get(key, result)
-        result = self.pending_result_cache.get(key, result)
-        if result is not None:
-            return result.observe()
-        else:
-            return None
-
-    def set(self, time_now_ms, key, deferred):
-        self.rotate(time_now_ms)
-
-        result = ObservableDeferred(deferred)
-
-        self.pending_result_cache[key] = result
-
-        def shuffle_along(r):
-            # When the deferred completes we shuffle it along to the first
-            # generation of the result cache. So that it will eventually
-            # expire from the rotation of that cache.
-            self.next_result_cache[key] = result
-            self.pending_result_cache.pop(key, None)
-            return r
-
-        result.addBoth(shuffle_along)
-
-        return result.observe()
diff --git a/tests/rest/client/v2_alpha/test_register.py b/tests/rest/client/v2_alpha/test_register.py
index c0d0d2b44e..d0c997e385 100644
--- a/tests/rest/client/v2_alpha/test_register.py
+++ b/tests/rest/client/v2_alpha/test_register.py
@@ -391,9 +391,8 @@ class AccountValidityRenewalByEmailTestCase(unittest.HomeserverTestCase):
         # Email config.
         self.email_attempts = []
 
-        def sendmail(*args, **kwargs):
+        async def sendmail(*args, **kwargs):
             self.email_attempts.append((args, kwargs))
-            return
 
         config["email"] = {
             "enable_notifs": True,
diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py
index fc279340d4..bf674dd184 100644
--- a/tests/storage/test_client_ips.py
+++ b/tests/storage/test_client_ips.py
@@ -37,9 +37,13 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
         self.reactor.advance(12345678)
 
         user_id = "@user:id"
+        device_id = "MY_DEVICE"
+
+        # Insert a user IP
+        self.get_success(self.store.store_device(user_id, device_id, "display name",))
         self.get_success(
             self.store.insert_client_ip(
-                user_id, "access_token", "ip", "user_agent", "device_id"
+                user_id, "access_token", "ip", "user_agent", device_id
             )
         )
 
@@ -47,14 +51,14 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
         self.reactor.advance(10)
 
         result = self.get_success(
-            self.store.get_last_client_ip_by_device(user_id, "device_id")
+            self.store.get_last_client_ip_by_device(user_id, device_id)
         )
 
-        r = result[(user_id, "device_id")]
+        r = result[(user_id, device_id)]
         self.assertDictContainsSubset(
             {
                 "user_id": user_id,
-                "device_id": "device_id",
+                "device_id": device_id,
                 "ip": "ip",
                 "user_agent": "user_agent",
                 "last_seen": 12345678000,
@@ -209,14 +213,16 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
                 self.store.db.updates.do_next_background_update(100), by=0.1
             )
 
-        # Insert a user IP
         user_id = "@user:id"
+        device_id = "MY_DEVICE"
+
+        # Insert a user IP
+        self.get_success(self.store.store_device(user_id, device_id, "display name",))
         self.get_success(
             self.store.insert_client_ip(
-                user_id, "access_token", "ip", "user_agent", "device_id"
+                user_id, "access_token", "ip", "user_agent", device_id
             )
         )
-
         # Force persisting to disk
         self.reactor.advance(200)
 
@@ -224,7 +230,7 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
         self.get_success(
             self.store.db.simple_update(
                 table="devices",
-                keyvalues={"user_id": user_id, "device_id": "device_id"},
+                keyvalues={"user_id": user_id, "device_id": device_id},
                 updatevalues={"last_seen": None, "ip": None, "user_agent": None},
                 desc="test_devices_last_seen_bg_update",
             )
@@ -232,14 +238,14 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
 
         # We should now get nulls when querying
         result = self.get_success(
-            self.store.get_last_client_ip_by_device(user_id, "device_id")
+            self.store.get_last_client_ip_by_device(user_id, device_id)
         )
 
-        r = result[(user_id, "device_id")]
+        r = result[(user_id, device_id)]
         self.assertDictContainsSubset(
             {
                 "user_id": user_id,
-                "device_id": "device_id",
+                "device_id": device_id,
                 "ip": None,
                 "user_agent": None,
                 "last_seen": None,
@@ -272,14 +278,14 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
 
         # We should now get the correct result again
         result = self.get_success(
-            self.store.get_last_client_ip_by_device(user_id, "device_id")
+            self.store.get_last_client_ip_by_device(user_id, device_id)
         )
 
-        r = result[(user_id, "device_id")]
+        r = result[(user_id, device_id)]
         self.assertDictContainsSubset(
             {
                 "user_id": user_id,
-                "device_id": "device_id",
+                "device_id": device_id,
                 "ip": "ip",
                 "user_agent": "user_agent",
                 "last_seen": 0,
@@ -296,11 +302,14 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
                 self.store.db.updates.do_next_background_update(100), by=0.1
             )
 
-        # Insert a user IP
         user_id = "@user:id"
+        device_id = "MY_DEVICE"
+
+        # Insert a user IP
+        self.get_success(self.store.store_device(user_id, device_id, "display name",))
         self.get_success(
             self.store.insert_client_ip(
-                user_id, "access_token", "ip", "user_agent", "device_id"
+                user_id, "access_token", "ip", "user_agent", device_id
             )
         )
 
@@ -324,7 +333,7 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
                     "access_token": "access_token",
                     "ip": "ip",
                     "user_agent": "user_agent",
-                    "device_id": "device_id",
+                    "device_id": device_id,
                     "last_seen": 0,
                 }
             ],
@@ -347,14 +356,14 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase):
 
         # But we should still get the correct values for the device
         result = self.get_success(
-            self.store.get_last_client_ip_by_device(user_id, "device_id")
+            self.store.get_last_client_ip_by_device(user_id, device_id)
         )
 
-        r = result[(user_id, "device_id")]
+        r = result[(user_id, device_id)]
         self.assertDictContainsSubset(
             {
                 "user_id": user_id,
-                "device_id": "device_id",
+                "device_id": device_id,
                 "ip": "ip",
                 "user_agent": "user_agent",
                 "last_seen": 0,
diff --git a/tests/test_federation.py b/tests/test_federation.py
index ad165d7295..68684460c6 100644
--- a/tests/test_federation.py
+++ b/tests/test_federation.py
@@ -1,6 +1,6 @@
 from mock import Mock
 
-from twisted.internet.defer import maybeDeferred, succeed
+from twisted.internet.defer import ensureDeferred, maybeDeferred, succeed
 
 from synapse.events import FrozenEvent
 from synapse.logging.context import LoggingContext
@@ -70,8 +70,10 @@ class MessageAcceptTests(unittest.TestCase):
         )
 
         # Send the join, it should return None (which is not an error)
-        d = self.handler.on_receive_pdu(
-            "test.serv", join_event, sent_to_us_directly=True
+        d = ensureDeferred(
+            self.handler.on_receive_pdu(
+                "test.serv", join_event, sent_to_us_directly=True
+            )
         )
         self.reactor.advance(1)
         self.assertEqual(self.successResultOf(d), None)
@@ -119,8 +121,10 @@ class MessageAcceptTests(unittest.TestCase):
         )
 
         with LoggingContext(request="lying_event"):
-            d = self.handler.on_receive_pdu(
-                "test.serv", lying_event, sent_to_us_directly=True
+            d = ensureDeferred(
+                self.handler.on_receive_pdu(
+                    "test.serv", lying_event, sent_to_us_directly=True
+                )
             )
 
             # Step the reactor, so the database fetches come back
diff --git a/tests/util/test_logcontext.py b/tests/util/test_logcontext.py
index 8b8455c8b7..281b32c4b8 100644
--- a/tests/util/test_logcontext.py
+++ b/tests/util/test_logcontext.py
@@ -179,6 +179,30 @@ class LoggingContextTestCase(unittest.TestCase):
             nested_context = nested_logging_context(suffix="bar")
             self.assertEqual(nested_context.request, "foo-bar")
 
+    @defer.inlineCallbacks
+    def test_make_deferred_yieldable_with_await(self):
+        # an async function which retuns an incomplete coroutine, but doesn't
+        # follow the synapse rules.
+
+        async def blocking_function():
+            d = defer.Deferred()
+            reactor.callLater(0, d.callback, None)
+            await d
+
+        sentinel_context = LoggingContext.current_context()
+
+        with LoggingContext() as context_one:
+            context_one.request = "one"
+
+            d1 = make_deferred_yieldable(blocking_function())
+            # make sure that the context was reset by make_deferred_yieldable
+            self.assertIs(LoggingContext.current_context(), sentinel_context)
+
+            yield d1
+
+            # now it should be restored
+            self._check_test_key("one")
+
 
 # a function which returns a deferred which has been "called", but
 # which had a function which returned another incomplete deferred on
diff --git a/tests/util/test_snapshot_cache.py b/tests/util/test_snapshot_cache.py
deleted file mode 100644
index 1a44f72425..0000000000
--- a/tests/util/test_snapshot_cache.py
+++ /dev/null
@@ -1,63 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015, 2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-
-from twisted.internet.defer import Deferred
-
-from synapse.util.caches.snapshot_cache import SnapshotCache
-
-from .. import unittest
-
-
-class SnapshotCacheTestCase(unittest.TestCase):
-    def setUp(self):
-        self.cache = SnapshotCache()
-        self.cache.DURATION_MS = 1
-
-    def test_get_set(self):
-        # Check that getting a missing key returns None
-        self.assertEquals(self.cache.get(0, "key"), None)
-
-        # Check that setting a key with a deferred returns
-        # a deferred that resolves when the initial deferred does
-        d = Deferred()
-        set_result = self.cache.set(0, "key", d)
-        self.assertIsNotNone(set_result)
-        self.assertFalse(set_result.called)
-
-        # Check that getting the key before the deferred has resolved
-        # returns a deferred that resolves when the initial deferred does.
-        get_result_at_10 = self.cache.get(10, "key")
-        self.assertIsNotNone(get_result_at_10)
-        self.assertFalse(get_result_at_10.called)
-
-        # Check that the returned deferreds resolve when the initial deferred
-        # does.
-        d.callback("v")
-        self.assertTrue(set_result.called)
-        self.assertTrue(get_result_at_10.called)
-
-        # Check that getting the key after the deferred has resolved
-        # before the cache expires returns a resolved deferred.
-        get_result_at_11 = self.cache.get(11, "key")
-        self.assertIsNotNone(get_result_at_11)
-        if isinstance(get_result_at_11, Deferred):
-            # The cache may return the actual result rather than a deferred
-            self.assertTrue(get_result_at_11.called)
-
-        # Check that getting the key after the deferred has resolved
-        # after the cache expires returns None
-        get_result_at_12 = self.cache.get(12, "key")
-        self.assertIsNone(get_result_at_12)