Merge tag 'v1.4.0'

Synapse 1.4.0 (2019-10-03)
==========================

Bugfixes
--------

- Redact `client_secret` in server logs. ([\#6158](https://github.com/matrix-org/synapse/issues/6158))

Synapse 1.4.0rc2 (2019-10-02)
=============================

Bugfixes
--------

- Fix bug in background update that adds last seen information to the `devices` table, and improve its performance on Postgres. ([\#6135](https://github.com/matrix-org/synapse/issues/6135))
- Fix bad performance of censoring redactions background task. ([\#6141](https://github.com/matrix-org/synapse/issues/6141))
- Fix fetching censored redactions from DB, which caused APIs like initial sync to fail if it tried to include the censored redaction. ([\#6145](https://github.com/matrix-org/synapse/issues/6145))
- Fix exceptions when storing large retry intervals for down remote servers. ([\#6146](https://github.com/matrix-org/synapse/issues/6146))

Internal Changes
----------------

- Fix up sample config entry for `redaction_retention_period` option. ([\#6117](https://github.com/matrix-org/synapse/issues/6117))

Synapse 1.4.0rc1 (2019-09-26)
=============================

Note that this release includes significant changes around 3pid
verification. Administrators are reminded to review the [upgrade notes](UPGRADE.rst#upgrading-to-v140).

Features
--------

- Changes to 3pid verification:
  - Add the ability to send registration emails from the homeserver rather than delegating to an identity server. ([\#5835](https://github.com/matrix-org/synapse/issues/5835), [\#5940](https://github.com/matrix-org/synapse/issues/5940), [\#5993](https://github.com/matrix-org/synapse/issues/5993), [\#5994](https://github.com/matrix-org/synapse/issues/5994), [\#5868](https://github.com/matrix-org/synapse/issues/5868))
  - Replace `trust_identity_server_for_password_resets` config option with `account_threepid_delegates`, and make the `id_server` parameteter optional on `*/requestToken` endpoints, as per [MSC2263](https://github.com/matrix-org/matrix-doc/pull/2263). ([\#5876](https://github.com/matrix-org/synapse/issues/5876), [\#5969](https://github.com/matrix-org/synapse/issues/5969), [\#6028](https://github.com/matrix-org/synapse/issues/6028))
  - Switch to using the v2 Identity Service `/lookup` API where available, with fallback to v1. (Implements [MSC2134](https://github.com/matrix-org/matrix-doc/pull/2134) plus `id_access_token authentication` for v2 Identity Service APIs from [MSC2140](https://github.com/matrix-org/matrix-doc/pull/2140)). ([\#5897](https://github.com/matrix-org/synapse/issues/5897))
  - Remove `bind_email` and `bind_msisdn` parameters from `/register` ala [MSC2140](https://github.com/matrix-org/matrix-doc/pull/2140). ([\#5964](https://github.com/matrix-org/synapse/issues/5964))
  - Add `m.id_access_token` to `unstable_features` in `/versions` as per [MSC2264](https://github.com/matrix-org/matrix-doc/pull/2264). ([\#5974](https://github.com/matrix-org/synapse/issues/5974))
  - Use the v2 Identity Service API for 3PID invites. ([\#5979](https://github.com/matrix-org/synapse/issues/5979))
  - Add `POST /_matrix/client/unstable/account/3pid/unbind` endpoint from [MSC2140](https://github.com/matrix-org/matrix-doc/pull/2140) for unbinding a 3PID from an identity server without removing it from the homeserver user account. ([\#5980](https://github.com/matrix-org/synapse/issues/5980), [\#6062](https://github.com/matrix-org/synapse/issues/6062))
  - Use `account_threepid_delegate.email` and `account_threepid_delegate.msisdn` for validating threepid sessions. ([\#6011](https://github.com/matrix-org/synapse/issues/6011))
  - Allow homeserver to handle or delegate email validation when adding an email to a user's account. ([\#6042](https://github.com/matrix-org/synapse/issues/6042))
  - Implement new Client Server API endpoints `/account/3pid/add` and `/account/3pid/bind` as per [MSC2290](https://github.com/matrix-org/matrix-doc/pull/2290). ([\#6043](https://github.com/matrix-org/synapse/issues/6043))
  - Add an unstable feature flag for separate add/bind 3pid APIs. ([\#6044](https://github.com/matrix-org/synapse/issues/6044))
  - Remove `bind` parameter from Client Server POST `/account` endpoint as per [MSC2290](https://github.com/matrix-org/matrix-doc/pull/2290/). ([\#6067](https://github.com/matrix-org/synapse/issues/6067))
  - Add `POST /add_threepid/msisdn/submit_token` endpoint for proxying submitToken on an `account_threepid_handler`. ([\#6078](https://github.com/matrix-org/synapse/issues/6078))
  - Add `submit_url` response parameter to `*/msisdn/requestToken` endpoints. ([\#6079](https://github.com/matrix-org/synapse/issues/6079))
  - Add `m.require_identity_server` flag to /version's unstable_features. ([\#5972](https://github.com/matrix-org/synapse/issues/5972))
- Enhancements to OpenTracing support:
  - Make OpenTracing work in worker mode. ([\#5771](https://github.com/matrix-org/synapse/issues/5771))
  - Pass OpenTracing contexts between servers when transmitting EDUs. ([\#5852](https://github.com/matrix-org/synapse/issues/5852))
  - OpenTracing for device list updates. ([\#5853](https://github.com/matrix-org/synapse/issues/5853))
  - Add a tag recording a request's authenticated entity and corresponding servlet in OpenTracing. ([\#5856](https://github.com/matrix-org/synapse/issues/5856))
  - Add minimum OpenTracing for client servlets. ([\#5983](https://github.com/matrix-org/synapse/issues/5983))
  - Check at setup that OpenTracing is installed if it's enabled in the config. ([\#5985](https://github.com/matrix-org/synapse/issues/5985))
  - Trace replication send times. ([\#5986](https://github.com/matrix-org/synapse/issues/5986))
  - Include missing OpenTracing contexts in outbout replication requests. ([\#5982](https://github.com/matrix-org/synapse/issues/5982))
  - Fix sending of EDUs when OpenTracing is enabled with an empty whitelist. ([\#5984](https://github.com/matrix-org/synapse/issues/5984))
  - Fix invalid references to None while OpenTracing if the log context slips. ([\#5988](https://github.com/matrix-org/synapse/issues/5988), [\#5991](https://github.com/matrix-org/synapse/issues/5991))
  - OpenTracing for room and e2e keys. ([\#5855](https://github.com/matrix-org/synapse/issues/5855))
  - Add OpenTracing span over HTTP push processing. ([\#6003](https://github.com/matrix-org/synapse/issues/6003))
- Add an admin API to purge old rooms from the database. ([\#5845](https://github.com/matrix-org/synapse/issues/5845))
- Retry well-known lookups if we have recently seen a valid well-known record for the server. ([\#5850](https://github.com/matrix-org/synapse/issues/5850))
- Add support for filtered room-directory search requests over federation ([MSC2197](https://github.com/matrix-org/matrix-doc/pull/2197), in order to allow upcoming room directory query performance improvements. ([\#5859](https://github.com/matrix-org/synapse/issues/5859))
- Correctly retry all hosts returned from SRV when we fail to connect. ([\#5864](https://github.com/matrix-org/synapse/issues/5864))
- Add admin API endpoint for setting whether or not a user is a server administrator. ([\#5878](https://github.com/matrix-org/synapse/issues/5878))
- Enable cleaning up extremities with dummy events by default to prevent undue build up of forward extremities. ([\#5884](https://github.com/matrix-org/synapse/issues/5884))
- Add config option to sign remote key query responses with a separate key. ([\#5895](https://github.com/matrix-org/synapse/issues/5895))
- Add support for config templating. ([\#5900](https://github.com/matrix-org/synapse/issues/5900))
- Users with the type of "support" or "bot" are no longer required to consent. ([\#5902](https://github.com/matrix-org/synapse/issues/5902))
- Let synctl accept a directory of config files. ([\#5904](https://github.com/matrix-org/synapse/issues/5904))
- Increase max display name size to 256. ([\#5906](https://github.com/matrix-org/synapse/issues/5906))
- Add admin API endpoint for getting whether or not a user is a server administrator. ([\#5914](https://github.com/matrix-org/synapse/issues/5914))
- Redact events in the database that have been redacted for a week. ([\#5934](https://github.com/matrix-org/synapse/issues/5934))
- New prometheus metrics:
  - `synapse_federation_known_servers`: represents the total number of servers your server knows about (i.e. is in rooms with), including itself. Enable by setting `metrics_flags.known_servers` to True in the configuration.([\#5981](https://github.com/matrix-org/synapse/issues/5981))
  - `synapse_build_info`: exposes the Python version, OS version, and Synapse version of the running server. ([\#6005](https://github.com/matrix-org/synapse/issues/6005))
- Give appropriate exit codes when synctl fails. ([\#5992](https://github.com/matrix-org/synapse/issues/5992))
- Apply the federation blacklist to requests to identity servers. ([\#6000](https://github.com/matrix-org/synapse/issues/6000))
- Add `report_stats_endpoint` option to configure where stats are reported to, if enabled. Contributed by @Sorunome. ([\#6012](https://github.com/matrix-org/synapse/issues/6012))
- Add config option to increase ratelimits for room admins redacting messages. ([\#6015](https://github.com/matrix-org/synapse/issues/6015))
- Stop sending federation transactions to servers which have been down for a long time. ([\#6026](https://github.com/matrix-org/synapse/issues/6026))
- Make the process for mapping SAML2 users to matrix IDs more flexible. ([\#6037](https://github.com/matrix-org/synapse/issues/6037))
- Return a clearer error message when a timeout occurs when attempting to contact an identity server. ([\#6073](https://github.com/matrix-org/synapse/issues/6073))
- Prevent password reset's submit_token endpoint from accepting trailing slashes. ([\#6074](https://github.com/matrix-org/synapse/issues/6074))
- Return 403 on `/register/available` if registration has been disabled. ([\#6082](https://github.com/matrix-org/synapse/issues/6082))
- Explicitly log when a homeserver does not have the `trusted_key_servers` config field configured. ([\#6090](https://github.com/matrix-org/synapse/issues/6090))
- Add support for pruning old rows in `user_ips` table. ([\#6098](https://github.com/matrix-org/synapse/issues/6098))

Bugfixes
--------

- Don't create broken room when `power_level_content_override.users` does not contain `creator_id`. ([\#5633](https://github.com/matrix-org/synapse/issues/5633))
- Fix database index so that different backup versions can have the same sessions. ([\#5857](https://github.com/matrix-org/synapse/issues/5857))
- Fix Synapse looking for config options `password_reset_failure_template` and `password_reset_success_template`, when they are actually `password_reset_template_failure_html`, `password_reset_template_success_html`. ([\#5863](https://github.com/matrix-org/synapse/issues/5863))
- Fix stack overflow when recovering an appservice which had an outage. ([\#5885](https://github.com/matrix-org/synapse/issues/5885))
- Fix error message which referred to `public_base_url` instead of `public_baseurl`. Thanks to @aaronraimist for the fix! ([\#5909](https://github.com/matrix-org/synapse/issues/5909))
- Fix 404 for thumbnail download when `dynamic_thumbnails` is `false` and the thumbnail was dynamically generated. Fix reported by rkfg. ([\#5915](https://github.com/matrix-org/synapse/issues/5915))
- Fix a cache-invalidation bug for worker-based deployments. ([\#5920](https://github.com/matrix-org/synapse/issues/5920))
- Fix admin API for listing media in a room not being available with an external media repo. ([\#5966](https://github.com/matrix-org/synapse/issues/5966))
- Fix list media admin API always returning an error. ([\#5967](https://github.com/matrix-org/synapse/issues/5967))
- Fix room and user stats tracking. ([\#5971](https://github.com/matrix-org/synapse/issues/5971), [\#5998](https://github.com/matrix-org/synapse/issues/5998), [\#6029](https://github.com/matrix-org/synapse/issues/6029))
- Return a `M_MISSING_PARAM` if `sid` is not provided to `/account/3pid`. ([\#5995](https://github.com/matrix-org/synapse/issues/5995))
- `federation_certificate_verification_whitelist` now will not cause `TypeErrors` to be raised (a regression in 1.3). Additionally, it now supports internationalised domain names in their non-canonical representation. ([\#5996](https://github.com/matrix-org/synapse/issues/5996))
- Only count real users when checking for auto-creation of auto-join room. ([\#6004](https://github.com/matrix-org/synapse/issues/6004))
- Ensure support users can be registered even if MAU limit is reached. ([\#6020](https://github.com/matrix-org/synapse/issues/6020))
- Fix bug where login error was shown incorrectly on SSO fallback login. ([\#6024](https://github.com/matrix-org/synapse/issues/6024))
- Fix bug in calculating the federation retry backoff period. ([\#6025](https://github.com/matrix-org/synapse/issues/6025))
- Prevent exceptions being logged when extremity-cleanup events fail due to lack of user consent to the terms of service. ([\#6053](https://github.com/matrix-org/synapse/issues/6053))
- Remove POST method from password-reset `submit_token` endpoint until we implement `submit_url` functionality. ([\#6056](https://github.com/matrix-org/synapse/issues/6056))
- Fix logcontext spam on non-Linux platforms. ([\#6059](https://github.com/matrix-org/synapse/issues/6059))
- Ensure query parameters in email validation links are URL-encoded. ([\#6063](https://github.com/matrix-org/synapse/issues/6063))
- Fix a bug which caused SAML attribute maps to be overridden by defaults. ([\#6069](https://github.com/matrix-org/synapse/issues/6069))
- Fix the logged number of updated items for the `users_set_deactivated_flag` background update. ([\#6092](https://github.com/matrix-org/synapse/issues/6092))
- Add `sid` to `next_link` for email validation. ([\#6097](https://github.com/matrix-org/synapse/issues/6097))
- Threepid validity checks on msisdns should not be dependent on `threepid_behaviour_email`. ([\#6104](https://github.com/matrix-org/synapse/issues/6104))
- Ensure that servers which are not configured to support email address verification do not offer it in the registration flows. ([\#6107](https://github.com/matrix-org/synapse/issues/6107))

Updates to the Docker image
---------------------------

- Avoid changing `UID/GID` if they are already correct. ([\#5970](https://github.com/matrix-org/synapse/issues/5970))
- Provide `SYNAPSE_WORKER` envvar to specify python module. ([\#6058](https://github.com/matrix-org/synapse/issues/6058))

Improved Documentation
----------------------

- Convert documentation to markdown (from rst) ([\#5849](https://github.com/matrix-org/synapse/issues/5849))
- Update `INSTALL.md` to say that Python 2 is no longer supported. ([\#5953](https://github.com/matrix-org/synapse/issues/5953))
- Add developer documentation for using SAML2. ([\#6032](https://github.com/matrix-org/synapse/issues/6032))
- Add some notes on rolling back to v1.3.1. ([\#6049](https://github.com/matrix-org/synapse/issues/6049))
- Update the upgrade notes. ([\#6050](https://github.com/matrix-org/synapse/issues/6050))

Deprecations and Removals
-------------------------

- Remove shared-secret registration from `/_matrix/client/r0/register` endpoint. Contributed by Awesome Technologies Innovationslabor GmbH. ([\#5877](https://github.com/matrix-org/synapse/issues/5877))
- Deprecate the `trusted_third_party_id_servers` option. ([\#5875](https://github.com/matrix-org/synapse/issues/5875))

Internal Changes
----------------

- Lay the groundwork for structured logging output. ([\#5680](https://github.com/matrix-org/synapse/issues/5680))
- Retry well-known lookup before the cache expires, giving a grace period where the remote well-known can be down but we still use the old result. ([\#5844](https://github.com/matrix-org/synapse/issues/5844))
- Remove log line for debugging issue #5407. ([\#5860](https://github.com/matrix-org/synapse/issues/5860))
- Refactor the Appservice scheduler code. ([\#5886](https://github.com/matrix-org/synapse/issues/5886))
- Compatibility with v2 Identity Service APIs other than /lookup. ([\#5892](https://github.com/matrix-org/synapse/issues/5892), [\#6013](https://github.com/matrix-org/synapse/issues/6013))
- Stop populating some unused tables. ([\#5893](https://github.com/matrix-org/synapse/issues/5893), [\#6047](https://github.com/matrix-org/synapse/issues/6047))
- Add missing index on `users_in_public_rooms` to improve the performance of directory queries. ([\#5894](https://github.com/matrix-org/synapse/issues/5894))
- Improve the logging when we have an error when fetching signing keys. ([\#5896](https://github.com/matrix-org/synapse/issues/5896))
- Add support for database engine-specific schema deltas, based on file extension. ([\#5911](https://github.com/matrix-org/synapse/issues/5911))
- Update Buildkite pipeline to use plugins instead of buildkite-agent commands. ([\#5922](https://github.com/matrix-org/synapse/issues/5922))
- Add link in sample config to the logging config schema. ([\#5926](https://github.com/matrix-org/synapse/issues/5926))
- Remove unnecessary parentheses in return statements. ([\#5931](https://github.com/matrix-org/synapse/issues/5931))
- Remove unused `jenkins/prepare_sytest.sh` file. ([\#5938](https://github.com/matrix-org/synapse/issues/5938))
- Move Buildkite pipeline config to the pipelines repo. ([\#5943](https://github.com/matrix-org/synapse/issues/5943))
- Remove unnecessary return statements in the codebase which were the result of a regex run. ([\#5962](https://github.com/matrix-org/synapse/issues/5962))
- Remove left-over methods from v1 registration API. ([\#5963](https://github.com/matrix-org/synapse/issues/5963))
- Cleanup event auth type initialisation. ([\#5975](https://github.com/matrix-org/synapse/issues/5975))
- Clean up dependency checking at setup. ([\#5989](https://github.com/matrix-org/synapse/issues/5989))
- Update OpenTracing docs to use the unified `trace` method. ([\#5776](https://github.com/matrix-org/synapse/issues/5776))
- Small refactor of function arguments and docstrings in` RoomMemberHandler`. ([\#6009](https://github.com/matrix-org/synapse/issues/6009))
- Remove unused `origin` argument on `FederationHandler.add_display_name_to_third_party_invite`. ([\#6010](https://github.com/matrix-org/synapse/issues/6010))
- Add a `failure_ts` column to the `destinations` database table. ([\#6016](https://github.com/matrix-org/synapse/issues/6016), [\#6072](https://github.com/matrix-org/synapse/issues/6072))
- Clean up some code in the retry logic. ([\#6017](https://github.com/matrix-org/synapse/issues/6017))
- Fix the structured logging tests stomping on the global log configuration for subsequent tests. ([\#6023](https://github.com/matrix-org/synapse/issues/6023))
- Clean up the sample config for SAML authentication. ([\#6064](https://github.com/matrix-org/synapse/issues/6064))
- Change mailer logging to reflect Synapse doesn't just do chat notifications by email now. ([\#6075](https://github.com/matrix-org/synapse/issues/6075))
- Move last-seen info into devices table. ([\#6089](https://github.com/matrix-org/synapse/issues/6089))
- Remove unused parameter to `get_user_id_by_threepid`. ([\#6099](https://github.com/matrix-org/synapse/issues/6099))
- Refactor the user-interactive auth handling. ([\#6105](https://github.com/matrix-org/synapse/issues/6105))
- Refactor code for calculating registration flows. ([\#6106](https://github.com/matrix-org/synapse/issues/6106))

1 files changed, 261 insertions, 21 deletions

diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index ac876287fc..2e485c8644 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -23,7 +23,7 @@ from functools import wraps
 from six import iteritems, text_type
 from six.moves import range
 
-from canonicaljson import json
+from canonicaljson import encode_canonical_json, json
 from prometheus_client import Counter, Histogram
 
 from twisted.internet import defer
@@ -33,6 +33,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import SynapseError
 from synapse.events import EventBase  # noqa: F401
 from synapse.events.snapshot import EventContext  # noqa: F401
+from synapse.events.utils import prune_event_dict
 from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
 from synapse.logging.utils import log_function
 from synapse.metrics import BucketCollector
@@ -262,6 +263,14 @@ class EventsStore(
 
         hs.get_clock().looping_call(read_forward_extremities, 60 * 60 * 1000)
 
+        def _censor_redactions():
+            return run_as_background_process(
+                "_censor_redactions", self._censor_redactions
+            )
+
+        if self.hs.config.redaction_retention_period is not None:
+            hs.get_clock().looping_call(_censor_redactions, 5 * 60 * 1000)
+
     @defer.inlineCallbacks
     def _read_forward_extremities(self):
         def fetch(txn):
@@ -810,7 +819,7 @@ class EventsStore(
         # If they old and new groups are the same then we don't need to do
         # anything.
         if old_state_groups == new_state_groups:
-            return (None, None)
+            return None, None
 
         if len(new_state_groups) == 1 and len(old_state_groups) == 1:
             # If we're going from one state group to another, lets check if
@@ -827,7 +836,7 @@ class EventsStore(
                 # the current state in memory then lets also return that,
                 # but it doesn't matter if we don't.
                 new_state = state_groups_map.get(new_state_group)
-                return (new_state, delta_ids)
+                return new_state, delta_ids
 
         # Now that we have calculated new_state_groups we need to get
         # their state IDs so we can resolve to a single state set.
@@ -839,7 +848,7 @@ class EventsStore(
         if len(new_state_groups) == 1:
             # If there is only one state group, then we know what the current
             # state is.
-            return (state_groups_map[new_state_groups.pop()], None)
+            return state_groups_map[new_state_groups.pop()], None
 
         # Ok, we need to defer to the state handler to resolve our state sets.
 
@@ -868,7 +877,7 @@ class EventsStore(
             state_res_store=StateResolutionStore(self),
         )
 
-        return (res.state, None)
+        return res.state, None
 
     @defer.inlineCallbacks
     def _calculate_state_delta(self, room_id, current_state):
@@ -891,7 +900,7 @@ class EventsStore(
             if ev_id != existing_state.get(key)
         }
 
-        return (to_delete, to_insert)
+        return to_delete, to_insert
 
     @log_function
     def _persist_events_txn(
@@ -1302,15 +1311,11 @@ class EventsStore(
             "event_reference_hashes",
             "event_search",
             "event_to_state_groups",
-            "guest_access",
-            "history_visibility",
             "local_invites",
-            "room_names",
             "state_events",
             "rejections",
             "redactions",
             "room_memberships",
-            "topics",
         ):
             txn.executemany(
                 "DELETE FROM %s WHERE event_id = ?" % (table,),
@@ -1384,6 +1389,18 @@ class EventsStore(
             ],
         )
 
+        for event, _ in events_and_contexts:
+            if not event.internal_metadata.is_redacted():
+                # If we're persisting an unredacted event we go and ensure
+                # that we mark any redactions that reference this event as
+                # requiring censoring.
+                self._simple_update_txn(
+                    txn,
+                    table="redactions",
+                    keyvalues={"redacts": event.event_id},
+                    updatevalues={"have_censored": False},
+                )
+
     def _store_rejected_events_txn(self, txn, events_and_contexts):
         """Add rows to the 'rejections' table for received events which were
         rejected
@@ -1454,10 +1471,10 @@ class EventsStore(
 
         for event, _ in events_and_contexts:
             if event.type == EventTypes.Name:
-                # Insert into the room_names and event_search tables.
+                # Insert into the event_search table.
                 self._store_room_name_txn(txn, event)
             elif event.type == EventTypes.Topic:
-                # Insert into the topics table and event_search table.
+                # Insert into the event_search table.
                 self._store_room_topic_txn(txn, event)
             elif event.type == EventTypes.Message:
                 # Insert into the event_search table.
@@ -1465,12 +1482,6 @@ class EventsStore(
             elif event.type == EventTypes.Redaction:
                 # Insert into the redactions table.
                 self._store_redaction(txn, event)
-            elif event.type == EventTypes.RoomHistoryVisibility:
-                # Insert into the event_search table.
-                self._store_history_visibility_txn(txn, event)
-            elif event.type == EventTypes.GuestAccess:
-                # Insert into the event_search table.
-                self._store_guest_access_txn(txn, event)
 
             self._handle_event_relations(txn, event)
 
@@ -1553,11 +1564,102 @@ class EventsStore(
     def _store_redaction(self, txn, event):
         # invalidate the cache for the redacted event
         txn.call_after(self._invalidate_get_event_cache, event.redacts)
-        txn.execute(
-            "INSERT INTO redactions (event_id, redacts) VALUES (?,?)",
-            (event.event_id, event.redacts),
+
+        self._simple_insert_txn(
+            txn,
+            table="redactions",
+            values={
+                "event_id": event.event_id,
+                "redacts": event.redacts,
+                "received_ts": self._clock.time_msec(),
+            },
+        )
+
+    @defer.inlineCallbacks
+    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
+
+        before_ts = self._clock.time_msec() - self.hs.config.redaction_retention_period
+
+        # We fetch all redactions that:
+        #   1. point to an event we have,
+        #   2. has a received_ts from before the cut off, and
+        #   3. we haven't yet censored.
+        #
+        # This is limited to 100 events to ensure that we don't try and do too
+        # much at once. We'll get called again so this should eventually catch
+        # up.
+        sql = """
+            SELECT redactions.event_id, redacts FROM redactions
+            LEFT JOIN events AS original_event ON (
+                redacts = original_event.event_id
+            )
+            WHERE NOT have_censored
+            AND redactions.received_ts <= ?
+            ORDER BY redactions.received_ts ASC
+            LIMIT ?
+        """
+
+        rows = yield self._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(
+                event_id, allow_rejected=True, allow_none=True
+            )
+
+            # The SQL above ensures that we have both the redaction and
+            # original event, so if the `get_event` calls return None it
+            # means that the redaction wasn't allowed. Either way we know that
+            # the result won't change so we mark the fact that we've checked.
+            if (
+                redaction_event
+                and original_event
+                and original_event.internal_metadata.is_redacted()
+            ):
+                # Redaction was allowed
+                pruned_json = encode_canonical_json(
+                    prune_event_dict(original_event.get_dict())
+                )
+            else:
+                # Redaction wasn't allowed
+                pruned_json = None
+
+            updates.append((redaction_id, event_id, pruned_json))
+
+        def _update_censor_txn(txn):
+            for redaction_id, event_id, pruned_json in updates:
+                if pruned_json:
+                    self._simple_update_one_txn(
+                        txn,
+                        table="event_json",
+                        keyvalues={"event_id": event_id},
+                        updatevalues={"json": pruned_json},
+                    )
+
+                self._simple_update_one_txn(
+                    txn,
+                    table="redactions",
+                    keyvalues={"event_id": redaction_id},
+                    updatevalues={"have_censored": True},
+                )
+
+        yield self.runInteraction("_update_censor_txn", _update_censor_txn)
+
     @defer.inlineCallbacks
     def count_daily_messages(self):
         """
@@ -2191,6 +2293,144 @@ class EventsStore(
 
         return to_delete, to_dedelta
 
+    def purge_room(self, room_id):
+        """Deletes all record of a room
+
+        Args:
+            room_id (str):
+        """
+
+        return self.runInteraction("purge_room", self._purge_room_txn, room_id)
+
+    def _purge_room_txn(self, txn, room_id):
+        # first we have to delete the state groups states
+        logger.info("[purge] removing %s from state_groups_state", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_groups_state WHERE state_group IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # ... and the state group edges
+        logger.info("[purge] removing %s from state_group_edges", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_group_edges WHERE state_group IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # ... and the state groups
+        logger.info("[purge] removing %s from state_groups", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_groups WHERE id IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # and then tables which lack an index on room_id but have one on event_id
+        for table in (
+            "event_auth",
+            "event_edges",
+            "event_push_actions_staging",
+            "event_reference_hashes",
+            "event_relations",
+            "event_to_state_groups",
+            "redactions",
+            "rejections",
+            "state_events",
+        ):
+            logger.info("[purge] removing %s from %s", room_id, table)
+
+            txn.execute(
+                """
+                DELETE FROM %s WHERE event_id IN (
+                  SELECT event_id FROM events WHERE room_id=?
+                )
+                """
+                % (table,),
+                (room_id,),
+            )
+
+        # and finally, the tables with an index on room_id (or no useful index)
+        for table in (
+            "current_state_events",
+            "event_backward_extremities",
+            "event_forward_extremities",
+            "event_json",
+            "event_push_actions",
+            "event_search",
+            "events",
+            "group_rooms",
+            "public_room_list_stream",
+            "receipts_graph",
+            "receipts_linearized",
+            "room_aliases",
+            "room_depth",
+            "room_memberships",
+            "room_stats_state",
+            "room_stats_current",
+            "room_stats_historical",
+            "room_stats_earliest_token",
+            "rooms",
+            "stream_ordering_to_exterm",
+            "topics",
+            "users_in_public_rooms",
+            "users_who_share_private_rooms",
+            # no useful index, but let's clear them anyway
+            "appservice_room_list",
+            "e2e_room_keys",
+            "event_push_summary",
+            "pusher_throttle",
+            "group_summary_rooms",
+            "local_invites",
+            "room_account_data",
+            "room_tags",
+        ):
+            logger.info("[purge] removing %s from %s", room_id, table)
+            txn.execute("DELETE FROM %s WHERE room_id=?" % (table,), (room_id,))
+
+        # Other tables we do NOT need to clear out:
+        #
+        #  - blocked_rooms
+        #    This is important, to make sure that we don't accidentally rejoin a blocked
+        #    room after it was purged
+        #
+        #  - user_directory
+        #    This has a room_id column, but it is unused
+        #
+
+        # Other tables that we might want to consider clearing out include:
+        #
+        #  - event_reports
+        #       Given that these are intended for abuse management my initial
+        #       inclination is to leave them in place.
+        #
+        #  - current_state_delta_stream
+        #  - ex_outlier_stream
+        #  - room_tags_revisions
+        #       The problem with these is that they are largeish and there is no room_id
+        #       index on them. In any case we should be clearing out 'stream' tables
+        #       periodically anyway (#5888)
+
+        # TODO: we could probably usefully do a bunch of cache invalidation here
+
+        logger.info("[purge] done")
+
     @defer.inlineCallbacks
     def is_event_after(self, event_id1, event_id2):
         """Returns True if event_id1 is after event_id2 in the stream