Document Synapse's behaviour when multiple modules register the same
callback/web resource/etc.

Co-authored-by: reivilibre <oliverw@matrix.org>

Make sure that we correctly handle rooms where we do not yet have a
`min_depth`, and also add some comments and logging.

Fix broken export-data admin command and add a test for it to CI 

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

Instead of triggering `__exit__` manually on the replication handler's
logging context, use it as a context manager so that there is an
`__enter__` call to balance the `__exit__`.

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

Found while working on the Gitter backfill script and noticed
it only happened after we sent 7 batches, https://gitlab.com/gitterHQ/webapp/-/merge_requests/2229#note_665906390

When there are more than 5 backward extremities for a given depth,
backfill will throw an error because we sliced the extremity list
to 5 but then try to iterate over the full list. This causes
us to look for state that we never fetched and we get a `KeyError`.

Before when calling `/messages` when there are more than 5 backward extremities:
```
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/synapse/http/server.py", line 258, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "/usr/local/lib/python3.8/site-packages/synapse/http/server.py", line 446, in _async_render
    callback_return = await raw_callback_return
  File "/usr/local/lib/python3.8/site-packages/synapse/rest/client/room.py", line 580, in on_GET
    msgs = await self.pagination_handler.get_messages(
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/pagination.py", line 396, in get_messages
    await self.hs.get_federation_handler().maybe_backfill(
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/federation.py", line 133, in maybe_backfill
    return await self._maybe_backfill_inner(room_id, current_depth, limit)
  File "/usr/local/lib/python3.8/site-packages/synapse/handlers/federation.py", line 386, in _maybe_backfill_inner
    likely_extremeties_domains = get_domains_from_state(states[e_id])
KeyError: '$zpFflMEBtZdgcMQWTakaVItTLMjLFdKcRWUPHbbSZJl'
```

There's no point in trying more than once since it is guaranteed to
continually fail.

This follows similar logic to BeautifulSoup where we attempt different
character encodings until we find one which works.

Add a test for a workaround concerning the behaviour of third-party rule modules and `SynapseError`s. (#11071)

Synapse 1.45.0rc2 (2021-10-14)
==============================

**Note:** This release candidate [fixes](https://github.com/matrix-org/synapse/issues/11053) the user directory [bug](https://github.com/matrix-org/synapse/issues/11025) present in 1.45.0rc1. However, the [performance issue](https://github.com/matrix-org/synapse/issues/11049) which appeared in v1.44.0 is yet to be resolved.

Bugfixes
--------

- Fix a long-standing bug when using multiple event persister workers where events were not correctly sent down `/sync` due to a race. ([\#11045](https://github.com/matrix-org/synapse/issues/11045))
- Fix a bug introduced in Synapse 1.45.0rc1 where the user directory would stop updating if it processed an event from a
  user not in the `users` table. ([\#11053](https://github.com/matrix-org/synapse/issues/11053))
- Fix a bug introduced in Synapse v1.44.0 when logging errors during oEmbed processing. ([\#11061](https://github.com/matrix-org/synapse/issues/11061))

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

- Add an 'approximate difference' method to `StateFilter`. ([\#10825](https://github.com/matrix-org/synapse/issues/10825))
- Fix inconsistent behavior of `get_last_client_by_ip` when reporting data that has not been stored in the database yet. ([\#10970](https://github.com/matrix-org/synapse/issues/10970))
- Fix a bug introduced in Synapse 1.21.0 that causes opentracing and Prometheus metrics for replication requests to be measured incorrectly. ([\#10996](https://github.com/matrix-org/synapse/issues/10996))
- Ensure that cache config tests do not share state. ([\#11036](https://github.com/matrix-org/synapse/issues/11036))

Resolve and share `state_groups` for all historical events in batch.  This also helps for showing the appropriate avatar/displayname in Element and will work whenever `/messages` has one of the historical messages as the first message in the batch.

This does have the flaw where if you just insert a single historical event somewhere, it probably won't resolve the state correctly from `/messages` or `/context` since it will grab a non historical event above or below with resolved state which never included the historical state back then. For the same reasions, this also does not work in Element between the transition from actual messages to historical messages. In the Gitter case, this isn't really a problem since all of the historical messages are in one big lump at the beginning of the room.

For a future iteration, might be good to look at `/messages` and `/context` to additionally add the `state` for any historical messages in that batch.

---

How are the `state_groups` shared? To illustrate the `state_group` sharing, see this example:


**Before** (new `state_group` for every event , very inefficient):
```
# Tests from https://github.com/matrix-org/complement/pull/206
$ COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS=1 COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh TestBackfillingHistory/parallel/should_resolve_member_state_events_for_historical_events
create_new_client_event m.room.member event=$_JXfwUDIWS6xKGG4SmZXjSFrizhARM7QblhATVWWUcA state_group=None
create_new_client_event org.matrix.msc2716.insertion event=$1ZBfmBKEjg94d-vGYymKrVYeghwBOuGJ3wubU1-I9y0 state_group=9
create_new_client_event org.matrix.msc2716.insertion event=$Mq2JvRetTyclPuozRI682SAjYp3GqRuPc8_cH5-ezPY state_group=10
create_new_client_event m.room.message event=$MfmY4rBQkxrIp8jVwVMTJ4PKnxSigpG9E2cn7S0AtTo state_group=11
create_new_client_event m.room.message event=$uYOv6V8wiF7xHwOMt-60d1AoOIbqLgrDLz6ZIQDdWUI state_group=12
create_new_client_event m.room.message event=$PAbkJRMxb0bX4A6av463faiAhxkE3FEObM1xB4D0UG4 state_group=13
create_new_client_event org.matrix.msc2716.batch event=$Oy_S7AWN7rJQe_MYwGPEy6RtbYklrI-tAhmfiLrCaKI state_group=14
```

**After** (all events in batch sharing `state_group=10`) (the base insertion event has `state_group=8` which matches the `prev_event` we're inserting next to):

```
# Tests from https://github.com/matrix-org/complement/pull/206
$ COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS=1 COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh TestBackfillingHistory/parallel/should_resolve_member_state_events_for_historical_events
create_new_client_event m.room.member event=$PWomJ8PwENYEYuVNoG30gqtybuQQSZ55eldBUSs0i0U state_group=None
create_new_client_event org.matrix.msc2716.insertion event=$e_mCU7Eah9ABF6nQU7lu4E1RxIWccNF05AKaTT5m3lw state_group=9
create_new_client_event org.matrix.msc2716.insertion event=$ui7A3_GdXIcJq0C8GpyrF8X7B3DTjMd_WGCjogax7xU state_group=10
create_new_client_event m.room.message event=$EnTIM5rEGVezQJiYl62uFBl6kJ7B-sMxWqe2D_4FX1I state_group=10
create_new_client_event m.room.message event=$LGx5jGONnBPuNhAuZqHeEoXChd9ryVkuTZatGisOPjk state_group=10
create_new_client_event m.room.message event=$wW0zwoN50lbLu1KoKbybVMxLbKUj7GV_olozIc5i3M0 state_group=10
create_new_client_event org.matrix.msc2716.batch event=$5ZB6dtzqFBCEuMRgpkU201Qhx3WtXZGTz_YgldL6JrQ state_group=10
```

* Pull out `_handle_room_membership_event`
* Discard excluded users early
* Rearrange logic so the change is membership is effectively switched over. See PR for rationale.

Except `synapse/events/__init__.py`, which will be done in a follow-up.

Co-authored-by: Azrenbeth <7782548+Azrenbeth@users.noreply.github.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

The following scenarios would halt the user directory updater:

- user joins room
- user leaves room
- user present in room which switches from private to public, or vice versa.

for two classes of users:

- appservice senders
- users missing from the user table.

If this happened, the user directory would be stuck, unable to make forward progress.

Exclude both cases from the user directory, so that we ignore them.

Co-authored-by: Eric Eastwood <erice@element.io>
Co-authored-by: reivilibre <oliverw@matrix.org>
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

Mark Module API error imports as re-exported and mark Synapse as containing type annotations (#11054)

Instead of only dumping them if trial passes.

* support ubuntu 21.10 indri

* add changelog

* update to correct codename

Co-authored-by: Brendan Abolivier <github@brendanabolivier.com>

Co-authored-by: Brendan Abolivier <github@brendanabolivier.com>

The race allowed the current position to advance too far when stream IDs
are still being persisted.

This happened when it received a new stream ID from a remote write
between a new stream ID being allocated and it being added to the set of
unpersisted stream IDs.

Fixes #9424.

This reverts #11019 and structures the code a bit more like it was before #10985.

The global cache state must be reset before running the tests since other test
cases might have configured caching (and thus touched the global state).

Synapse 1.45.0rc1 (2021-10-12)
==============================

**Note:** We are aware of [a performance issue](https://github.com/matrix-org/synapse/issues/11049) introduced in Synapse v1.44.0, as well as [a bug](https://github.com/matrix-org/synapse/issues/11025) with the user directory when using application services. While this release candidate doesn't fix either of those issues, a second release candidate is expected to come out in a few days to address them.

Media storage providers module that read from Synapse's configuration need changes as of this version, see the [upgrade notes](https://matrix-org.github.io/synapse/develop/upgrade#upgrading-to-v1450) for more information.

Features
--------

- Add [MSC3069](https://github.com/matrix-org/matrix-doc/pull/3069) support to `/account/whoami`. ([\#9655](https://github.com/matrix-org/synapse/issues/9655))
- Support autodiscovery of oEmbed previews. ([\#10822](https://github.com/matrix-org/synapse/issues/10822))
- Add a `user_may_send_3pid_invite` spam checker callback for modules to allow or deny 3PID invites. ([\#10894](https://github.com/matrix-org/synapse/issues/10894))
- Add a spam checker callback to allow or deny room joins. ([\#10910](https://github.com/matrix-org/synapse/issues/10910))
- Include an `update_synapse_database` script in the distribution. Contributed by @Fizzadar at Beeper. ([\#10954](https://github.com/matrix-org/synapse/issues/10954))
- Include exception information in JSON logging output. Contributed by @Fizzadar at Beeper. ([\#11028](https://github.com/matrix-org/synapse/issues/11028))

Bugfixes
--------

- Fix a minor bug in the response to `/_matrix/client/r0/voip/turnServer`. Contributed by @lukaslihotzki. ([\#10922](https://github.com/matrix-org/synapse/issues/10922))
- Fix a bug where empty `yyyy-mm-dd/` directories would be left behind in the media store's `url_cache_thumbnails/` directory. ([\#10924](https://github.com/matrix-org/synapse/issues/10924))
- Fix a bug introduced in Synapse v1.40.0 where the signature checks for room version 8 and 9 could be applied to earlier room versions in some situations. ([\#10927](https://github.com/matrix-org/synapse/issues/10927))
- Fix a long-standing bug wherein deactivated users still count towards the monthly active users limit. ([\#10947](https://github.com/matrix-org/synapse/issues/10947))
- Fix a long-standing bug which meant that events received over federation were sometimes incorrectly accepted into the room state. ([\#10956](https://github.com/matrix-org/synapse/issues/10956))
- Fix a long-standing bug where rebuilding the user directory wouldn't exclude support and deactivated users. ([\#10960](https://github.com/matrix-org/synapse/issues/10960))
- Fix [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716) `/batch_send` endpoint rejecting subsequent batches with unknown batch ID error in existing room versions from the room creator. ([\#10962](https://github.com/matrix-org/synapse/issues/10962))
- Fix a bug that could leak local users' per-room nicknames and avatars when the user directory is rebuilt. ([\#10981](https://github.com/matrix-org/synapse/issues/10981))
- Fix a long-standing bug where the remainder of a batch of user directory changes would be silently dropped if the server left a room early in the batch. ([\#10982](https://github.com/matrix-org/synapse/issues/10982))
- Correct a bugfix introduced in Synapse v1.44.0 that would catch the wrong error if a connection is lost before a response could be written to it. ([\#10995](https://github.com/matrix-org/synapse/issues/10995))
- Fix a long-standing bug where local users' per-room nicknames/avatars were visible to anyone who could see you in the user directory. ([\#11002](https://github.com/matrix-org/synapse/issues/11002))
- Fix a long-standing bug where a user's per-room nickname/avatar would overwrite their profile in the user directory when a room was made public. ([\#11003](https://github.com/matrix-org/synapse/issues/11003))
- Work around a regression, introduced in Synapse v1.39.0, that caused `SynapseError`s raised by the experimental third-party rules module callback `check_event_allowed` to be ignored. ([\#11042](https://github.com/matrix-org/synapse/issues/11042))
- Fix a bug in [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716) insertion events in rooms that could cause cross-talk/conflicts between batches. ([\#10877](https://github.com/matrix-org/synapse/issues/10877))

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

- Change wording ("reference homeserver") in Synapse repository documentation. Contributed by @maxkratz. ([\#10971](https://github.com/matrix-org/synapse/issues/10971))
- Fix a dead URL in development documentation (SAML) and change wording from "Riot" to "Element". Contributed by @maxkratz. ([\#10973](https://github.com/matrix-org/synapse/issues/10973))
- Add additional content to the Welcome and Overview page of the documentation. ([\#10990](https://github.com/matrix-org/synapse/issues/10990))
- Update links to MSCs in documentation. Contributed by @dklimpel. ([\#10991](https://github.com/matrix-org/synapse/issues/10991))

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

- Improve type hinting in `synapse.util`. ([\#10888](https://github.com/matrix-org/synapse/issues/10888))
- Add further type hints to `synapse.storage.util`. ([\#10892](https://github.com/matrix-org/synapse/issues/10892))
- Fix type hints to be compatible with an upcoming change to Twisted. ([\#10895](https://github.com/matrix-org/synapse/issues/10895))
- Update utility code to handle C implementations of frozendict. ([\#10902](https://github.com/matrix-org/synapse/issues/10902))
- Drop old functionality which maintained database compatibility with Synapse versions before v1.31. ([\#10903](https://github.com/matrix-org/synapse/issues/10903))
- Clean-up configuration helper classes for the `ServerConfig` class. ([\#10915](https://github.com/matrix-org/synapse/issues/10915))
- Use direct references to config flags. ([\#10916](https://github.com/matrix-org/synapse/issues/10916), [\#10959](https://github.com/matrix-org/synapse/issues/10959), [\#10985](https://github.com/matrix-org/synapse/issues/10985))
- Clean up some of the federation event authentication code for clarity. ([\#10926](https://github.com/matrix-org/synapse/issues/10926), [\#10940](https://github.com/matrix-org/synapse/issues/10940), [\#10986](https://github.com/matrix-org/synapse/issues/10986), [\#10987](https://github.com/matrix-org/synapse/issues/10987), [\#10988](https://github.com/matrix-org/synapse/issues/10988), [\#11010](https://github.com/matrix-org/synapse/issues/11010), [\#11011](https://github.com/matrix-org/synapse/issues/11011))
- Refactor various parts of the codebase to use `RoomVersion` objects instead of room version identifier strings. ([\#10934](https://github.com/matrix-org/synapse/issues/10934))
- Refactor user directory tests in preparation for upcoming changes. ([\#10935](https://github.com/matrix-org/synapse/issues/10935))
- Include the event id in the logcontext when handling PDUs received over federation. ([\#10936](https://github.com/matrix-org/synapse/issues/10936))
- Fix logged errors in unit tests. ([\#10939](https://github.com/matrix-org/synapse/issues/10939))
- Fix a broken test to ensure that consent configuration works during registration. ([\#10945](https://github.com/matrix-org/synapse/issues/10945))
- Add type hints to filtering classes. ([\#10958](https://github.com/matrix-org/synapse/issues/10958))
- Add type-hint to `HomeserverTestcase.setup_test_homeserver`. ([\#10961](https://github.com/matrix-org/synapse/issues/10961))
- Fix the test utility function `create_room_as` so that `is_public=True` will explicitly set the `visibility` parameter of room creation requests to `public`. Contributed by @AndrewFerr. ([\#10963](https://github.com/matrix-org/synapse/issues/10963))
- Make the release script more robust and transparent. ([\#10966](https://github.com/matrix-org/synapse/issues/10966))
- Refactor [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716) `/batch_send` mega function into smaller handler functions. ([\#10974](https://github.com/matrix-org/synapse/issues/10974))
- Log stack traces when a missing opentracing span is detected. ([\#10983](https://github.com/matrix-org/synapse/issues/10983))
- Update GHA config to run tests against Python 3.10 and PostgreSQL 14. ([\#10992](https://github.com/matrix-org/synapse/issues/10992))
- Fix a long-standing bug where `ReadWriteLock`s could drop logging contexts on exit. ([\#10993](https://github.com/matrix-org/synapse/issues/10993))
- Add a `CODEOWNERS` file to automatically request reviews from the `@matrix-org/synapse-core` team on new pull requests. ([\#10994](https://github.com/matrix-org/synapse/issues/10994))
- Add further type hints to `synapse.state`. ([\#11004](https://github.com/matrix-org/synapse/issues/11004))
- Remove the deprecated `BaseHandler` object. ([\#11005](https://github.com/matrix-org/synapse/issues/11005))
- Bump mypy version for CI to 0.910, and pull in new type stubs for dependencies. ([\#11006](https://github.com/matrix-org/synapse/issues/11006))
- Fix CI to run the unit tests without optional deps. ([\#11017](https://github.com/matrix-org/synapse/issues/11017))
- Ensure that cache config tests do not share state. ([\#11019](https://github.com/matrix-org/synapse/issues/11019))
- Add additional type hints to `synapse.server_notices`. ([\#11021](https://github.com/matrix-org/synapse/issues/11021))
- Add additional type hints for `synapse.push`. ([\#11023](https://github.com/matrix-org/synapse/issues/11023))
- When installing the optional developer dependencies, also include the dependencies needed for type-checking and unit testing. ([\#11034](https://github.com/matrix-org/synapse/issues/11034))
- Remove unnecessary list comprehension from `synapse_port_db` to satisfy code style requirements. ([\#11043](https://github.com/matrix-org/synapse/issues/11043))