Merge tag 'v0.33.3'

Features
--------

- Add support for the SNI extension to federation TLS connections. Thanks to @vojeroen! ([\#3439](https://github.com/matrix-org/synapse/issues/3439))
- Add /_media/r0/config ([\#3184](https://github.com/matrix-org/synapse/issues/3184))
- speed up /members API and add `at` and `membership` params as per MSC1227 ([\#3568](https://github.com/matrix-org/synapse/issues/3568))
- implement `summary` block in /sync response as per MSC688 ([\#3574](https://github.com/matrix-org/synapse/issues/3574))
- Add lazy-loading support to /messages as per MSC1227 ([\#3589](https://github.com/matrix-org/synapse/issues/3589))
- Add ability to limit number of monthly active users on the server ([\#3633](https://github.com/matrix-org/synapse/issues/3633))
- Support more federation endpoints on workers ([\#3653](https://github.com/matrix-org/synapse/issues/3653))
- Basic support for room versioning ([\#3654](https://github.com/matrix-org/synapse/issues/3654))
- Ability to disable client/server Synapse via conf toggle ([\#3655](https://github.com/matrix-org/synapse/issues/3655))
- Ability to whitelist specific threepids against monthly active user limiting ([\#3662](https://github.com/matrix-org/synapse/issues/3662))
- Add some metrics for the appservice and federation event sending loops ([\#3664](https://github.com/matrix-org/synapse/issues/3664))
- Where server is disabled, block ability for locked out users to read new messages ([\#3670](https://github.com/matrix-org/synapse/issues/3670))
- set admin uri via config, to be used in error messages where the user should contact the administrator ([\#3687](https://github.com/matrix-org/synapse/issues/3687))
- Synapse's presence functionality can now be disabled with the "use_presence" configuration option. ([\#3694](https://github.com/matrix-org/synapse/issues/3694))
- For resource limit blocked users, prevent writing into rooms ([\#3708](https://github.com/matrix-org/synapse/issues/3708))

Bugfixes
--------

- Fix occasional glitches in the synapse_event_persisted_position metric ([\#3658](https://github.com/matrix-org/synapse/issues/3658))
- Fix bug on deleting 3pid when using identity servers that don't support unbind API ([\#3661](https://github.com/matrix-org/synapse/issues/3661))
- Make the tests pass on Twisted < 18.7.0 ([\#3676](https://github.com/matrix-org/synapse/issues/3676))
- Don’t ship recaptcha_ajax.js, use it directly from Google ([\#3677](https://github.com/matrix-org/synapse/issues/3677))
- Fixes test_reap_monthly_active_users so it passes under postgres ([\#3681](https://github.com/matrix-org/synapse/issues/3681))
- Fix mau blocking calulation bug on login ([\#3689](https://github.com/matrix-org/synapse/issues/3689))
- Fix missing yield in synapse.storage.monthly_active_users.initialise_reserved_users ([\#3692](https://github.com/matrix-org/synapse/issues/3692))
- Improve HTTP request logging to include all requests ([\#3700](https://github.com/matrix-org/synapse/issues/3700))
- Avoid timing out requests while we are streaming back the response ([\#3701](https://github.com/matrix-org/synapse/issues/3701))
- Support more federation endpoints on workers ([\#3705](https://github.com/matrix-org/synapse/issues/3705), [\#3713](https://github.com/matrix-org/synapse/issues/3713))
- Fix "Starting db txn 'get_all_updated_receipts' from sentinel context" warning ([\#3710](https://github.com/matrix-org/synapse/issues/3710))
- Fix bug where `state_cache` cache factor ignored environment variables ([\#3719](https://github.com/matrix-org/synapse/issues/3719))
- Fix bug in v0.33.3rc1 which caused infinite loops and OOMs ([\#3723](https://github.com/matrix-org/synapse/issues/3723))
- Fix bug introduced in v0.33.3rc1 which made the ToS give a 500 error ([\#3732](https://github.com/matrix-org/synapse/issues/3732))

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

- The Shared-Secret registration method of the legacy v1/register REST endpoint has been removed. For a replacement, please see [the admin/register API documentation](https://github.com/matrix-org/synapse/blob/master/docs/admin_api/register_api.rst). ([\#3703](https://github.com/matrix-org/synapse/issues/3703))

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

- The test suite now can run under PostgreSQL. ([\#3423](https://github.com/matrix-org/synapse/issues/3423))
- Refactor HTTP replication endpoints to reduce code duplication ([\#3632](https://github.com/matrix-org/synapse/issues/3632))
- Tests now correctly execute on Python 3. ([\#3647](https://github.com/matrix-org/synapse/issues/3647))
- Sytests can now be run inside a Docker container. ([\#3660](https://github.com/matrix-org/synapse/issues/3660))
- Port over enough to Python 3 to allow the sytests to start. ([\#3668](https://github.com/matrix-org/synapse/issues/3668))
- Update docker base image from alpine 3.7 to 3.8. ([\#3669](https://github.com/matrix-org/synapse/issues/3669))
- Rename synapse.util.async to synapse.util.async_helpers to mitigate async becoming a keyword on Python 3.7. ([\#3678](https://github.com/matrix-org/synapse/issues/3678))
- Synapse's tests are now formatted with the black autoformatter. ([\#3679](https://github.com/matrix-org/synapse/issues/3679))
- Implemented a new testing base class to reduce test boilerplate. ([\#3684](https://github.com/matrix-org/synapse/issues/3684))
- Rename MAU prometheus metrics ([\#3690](https://github.com/matrix-org/synapse/issues/3690))
- add new error type ResourceLimit ([\#3707](https://github.com/matrix-org/synapse/issues/3707))
- Logcontexts for replication command handlers ([\#3709](https://github.com/matrix-org/synapse/issues/3709))
- Update admin register API documentation to reference a real user ID. ([\#3712](https://github.com/matrix-org/synapse/issues/3712))

8 files changed, 111 insertions, 57 deletions

diff --git a/synapse/util/async.py b/synapse/util/async_helpers.py
index a7094e2fb4..9b3f2f4b96 100644
--- a/synapse/util/async.py
+++ b/synapse/util/async_helpers.py
@@ -188,62 +188,30 @@ class Linearizer(object):
         # things blocked from executing.
         self.key_to_defer = {}
 
-    @defer.inlineCallbacks
     def queue(self, key):
+        # we avoid doing defer.inlineCallbacks here, so that cancellation works correctly.
+        # (https://twistedmatrix.com/trac/ticket/4632 meant that cancellations were not
+        # propagated inside inlineCallbacks until Twisted 18.7)
         entry = self.key_to_defer.setdefault(key, [0, collections.OrderedDict()])
 
         # If the number of things executing is greater than the maximum
         # then add a deferred to the list of blocked items
-        # When on of the things currently executing finishes it will callback
+        # When one of the things currently executing finishes it will callback
         # this item so that it can continue executing.
         if entry[0] >= self.max_count:
-            new_defer = defer.Deferred()
-            entry[1][new_defer] = 1
-
-            logger.info(
-                "Waiting to acquire linearizer lock %r for key %r", self.name, key,
-            )
-            try:
-                yield make_deferred_yieldable(new_defer)
-            except Exception as e:
-                if isinstance(e, CancelledError):
-                    logger.info(
-                        "Cancelling wait for linearizer lock %r for key %r",
-                        self.name, key,
-                    )
-                else:
-                    logger.warn(
-                        "Unexpected exception waiting for linearizer lock %r for key %r",
-                        self.name, key,
-                    )
-
-                # we just have to take ourselves back out of the queue.
-                del entry[1][new_defer]
-                raise
-
-            logger.info("Acquired linearizer lock %r for key %r", self.name, key)
-            entry[0] += 1
-
-            # if the code holding the lock completes synchronously, then it
-            # will recursively run the next claimant on the list. That can
-            # relatively rapidly lead to stack exhaustion. This is essentially
-            # the same problem as http://twistedmatrix.com/trac/ticket/9304.
-            #
-            # In order to break the cycle, we add a cheeky sleep(0) here to
-            # ensure that we fall back to the reactor between each iteration.
-            #
-            # (This needs to happen while we hold the lock, and the context manager's exit
-            # code must be synchronous, so this is the only sensible place.)
-            yield self._clock.sleep(0)
-
+            res = self._await_lock(key)
         else:
             logger.info(
                 "Acquired uncontended linearizer lock %r for key %r", self.name, key,
             )
             entry[0] += 1
+            res = defer.succeed(None)
+
+        # once we successfully get the lock, we need to return a context manager which
+        # will release the lock.
 
         @contextmanager
-        def _ctx_manager():
+        def _ctx_manager(_):
             try:
                 yield
             finally:
@@ -264,7 +232,64 @@ class Linearizer(object):
                     # map.
                     del self.key_to_defer[key]
 
-        defer.returnValue(_ctx_manager())
+        res.addCallback(_ctx_manager)
+        return res
+
+    def _await_lock(self, key):
+        """Helper for queue: adds a deferred to the queue
+
+        Assumes that we've already checked that we've reached the limit of the number
+        of lock-holders we allow. Creates a new deferred which is added to the list, and
+        adds some management around cancellations.
+
+        Returns the deferred, which will callback once we have secured the lock.
+
+        """
+        entry = self.key_to_defer[key]
+
+        logger.info(
+            "Waiting to acquire linearizer lock %r for key %r", self.name, key,
+        )
+
+        new_defer = make_deferred_yieldable(defer.Deferred())
+        entry[1][new_defer] = 1
+
+        def cb(_r):
+            logger.info("Acquired linearizer lock %r for key %r", self.name, key)
+            entry[0] += 1
+
+            # if the code holding the lock completes synchronously, then it
+            # will recursively run the next claimant on the list. That can
+            # relatively rapidly lead to stack exhaustion. This is essentially
+            # the same problem as http://twistedmatrix.com/trac/ticket/9304.
+            #
+            # In order to break the cycle, we add a cheeky sleep(0) here to
+            # ensure that we fall back to the reactor between each iteration.
+            #
+            # (This needs to happen while we hold the lock, and the context manager's exit
+            # code must be synchronous, so this is the only sensible place.)
+            return self._clock.sleep(0)
+
+        def eb(e):
+            logger.info("defer %r got err %r", new_defer, e)
+            if isinstance(e, CancelledError):
+                logger.info(
+                    "Cancelling wait for linearizer lock %r for key %r",
+                    self.name, key,
+                )
+
+            else:
+                logger.warn(
+                    "Unexpected exception waiting for linearizer lock %r for key %r",
+                    self.name, key,
+                )
+
+            # we just have to take ourselves back out of the queue.
+            del entry[1][new_defer]
+            return e
+
+        new_defer.addCallbacks(cb, eb)
+        return new_defer
 
 
 class ReadWriteLock(object):
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 861c24809c..187510576a 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -25,7 +25,7 @@ from six import itervalues, string_types
 from twisted.internet import defer
 
 from synapse.util import logcontext, unwrapFirstError
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
diff --git a/synapse/util/caches/response_cache.py b/synapse/util/caches/response_cache.py
index a8491b42d5..afb03b2e1b 100644
--- a/synapse/util/caches/response_cache.py
+++ b/synapse/util/caches/response_cache.py
@@ -16,7 +16,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 from synapse.util.caches import register_cache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
diff --git a/synapse/util/caches/snapshot_cache.py b/synapse/util/caches/snapshot_cache.py
index d03678b8c8..8318db8d2c 100644
--- a/synapse/util/caches/snapshot_cache.py
+++ b/synapse/util/caches/snapshot_cache.py
@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.async import ObservableDeferred
+from synapse.util.async_helpers import ObservableDeferred
 
 
 class SnapshotCache(object):
diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index 8dcae50b39..a0c2d37610 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -385,7 +385,13 @@ class LoggingContextFilter(logging.Filter):
         context = LoggingContext.current_context()
         for key, value in self.defaults.items():
             setattr(record, key, value)
-        context.copy_to(record)
+
+        # context should never be None, but if it somehow ends up being, then
+        # we end up in a death spiral of infinite loops, so let's check, for
+        # robustness' sake.
+        if context is not None:
+            context.copy_to(record)
+
         return True
 
 
@@ -396,7 +402,9 @@ class PreserveLoggingContext(object):
 
     __slots__ = ["current_context", "new_context", "has_parent"]
 
-    def __init__(self, new_context=LoggingContext.sentinel):
+    def __init__(self, new_context=None):
+        if new_context is None:
+            new_context = LoggingContext.sentinel
         self.new_context = new_context
 
     def __enter__(self):
@@ -526,7 +534,7 @@ _to_ignore = [
     "synapse.util.logcontext",
     "synapse.http.server",
     "synapse.storage._base",
-    "synapse.util.async",
+    "synapse.util.async_helpers",
 ]
 
 
diff --git a/synapse/util/logutils.py b/synapse/util/logutils.py
index 62a00189cc..ef31458226 100644
--- a/synapse/util/logutils.py
+++ b/synapse/util/logutils.py
@@ -20,6 +20,8 @@ import time
 from functools import wraps
 from inspect import getcallargs
 
+from six import PY3
+
 _TIME_FUNC_ID = 0
 
 
@@ -28,8 +30,12 @@ def _log_debug_as_f(f, msg, msg_args):
     logger = logging.getLogger(name)
 
     if logger.isEnabledFor(logging.DEBUG):
-        lineno = f.func_code.co_firstlineno
-        pathname = f.func_code.co_filename
+        if PY3:
+            lineno = f.__code__.co_firstlineno
+            pathname = f.__code__.co_filename
+        else:
+            lineno = f.func_code.co_firstlineno
+            pathname = f.func_code.co_filename
 
         record = logging.LogRecord(
             name=name,
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index 43d9db67ec..6f318c6a29 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -16,6 +16,7 @@
 import random
 import string
 
+from six import PY3
 from six.moves import range
 
 _string_with_symbols = (
@@ -34,6 +35,17 @@ def random_string_with_symbols(length):
 
 
 def is_ascii(s):
+
+    if PY3:
+        if isinstance(s, bytes):
+            try:
+                s.decode('ascii').encode('ascii')
+            except UnicodeDecodeError:
+                return False
+            except UnicodeEncodeError:
+                return False
+            return True
+
     try:
         s.encode("ascii")
     except UnicodeEncodeError:
@@ -49,6 +61,9 @@ def to_ascii(s):
 
     If given None then will return None.
     """
+    if PY3:
+        return s
+
     if s is None:
         return None
 
diff --git a/synapse/util/versionstring.py b/synapse/util/versionstring.py
index 1fbcd41115..3baba3225a 100644
--- a/synapse/util/versionstring.py
+++ b/synapse/util/versionstring.py
@@ -30,7 +30,7 @@ def get_version_string(module):
                 ['git', 'rev-parse', '--abbrev-ref', 'HEAD'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
             git_branch = "b=" + git_branch
         except subprocess.CalledProcessError:
             git_branch = ""
@@ -40,7 +40,7 @@ def get_version_string(module):
                 ['git', 'describe', '--exact-match'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
             git_tag = "t=" + git_tag
         except subprocess.CalledProcessError:
             git_tag = ""
@@ -50,7 +50,7 @@ def get_version_string(module):
                 ['git', 'rev-parse', '--short', 'HEAD'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
         except subprocess.CalledProcessError:
             git_commit = ""
 
@@ -60,7 +60,7 @@ def get_version_string(module):
                 ['git', 'describe', '--dirty=' + dirty_string],
                 stderr=null,
                 cwd=cwd,
-            ).strip().endswith(dirty_string)
+            ).strip().decode('ascii').endswith(dirty_string)
 
             git_dirty = "dirty" if is_dirty else ""
         except subprocess.CalledProcessError:
@@ -77,8 +77,8 @@ def get_version_string(module):
                 "%s (%s)" % (
                     module.__version__, git_version,
                 )
-            ).encode("ascii")
+            )
     except Exception as e:
         logger.info("Failed to check for git repository: %s", e)
 
-    return module.__version__.encode("ascii")
+    return module.__version__