To handle cancellation, we ensure that `after_callback`s and
`exception_callback`s are always run, since the transaction will
complete on another thread regardless of cancellation.

We also wait until everything is done before releasing the
`CancelledError`, so that logging contexts won't get used after they
have been finished.

Signed-off-by: Sean Quah <seanq@element.io>

Adds a handler layer between the REST and datastore layers for relations.

* Moves the relation pagination tests to a separate class.
* Move the assertion of the response code into the `_send_relation` helper.
* Moves some helpers into the base-class.

By using urljoin from the standard library and reducing the number
of places URLs are rebased.

Instead of fetching the raw account data and re-parsing it. The
ignored_users table is a denormalised version of the account data
for quick searching.

Signed-off-by: Sean Quah <seanq@element.io>

These decorators mostly support cancellation already. Add cancellation
tests and fix use of finished logging contexts by delaying cancellation,
as suggested by @erikjohnston.

Signed-off-by: Sean Quah <seanq@element.io>

Also convert `ReadWriteLock` to use async context managers.

Signed-off-by: Sean Quah <seanq@element.io>

Signed-off-by: Sean Quah <seanq@element.io>

`delay_cancellation` behaves like `stop_cancellation`, except it
delays `CancelledError`s until the original `Deferred` resolves.
This is handy for unifying cleanup paths and ensuring that uncancelled
coroutines don't use finished logcontexts.

Signed-off-by: Sean Quah <seanq@element.io>

And rename the field used for caching from _id to _cache_key.

Fixes https://github.com/matrix-org/synapse/issues/12205

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

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

This test was relying on poking events which weren't in the database into
filter_events_for_client.

This includes the `typing`, `to_device`, `account_data`, `receipts`, and `presence`
streams (really anything except the `events` stream).

Remove workaround introduced in Synapse v1.50.0rc1 for Mjolnir compatibility. Breaks compatibility with Mjolnir v1.3.1 and earlier. (#11700)

The unstable identifiers are still supported if the experimental configuration
flag is enabled. The unstable identifiers will be removed in a future release.

Some stuff that came up while we were talking about #12173.

This is allowed per MSC2675, although the original implementation did
not allow for it and would return an empty chunk / not bundle aggregations.

The main thing to improve is that the various caches get cleared properly
when an event is redacted, and that edits must not leak if the original
event is redacted (as that would presumably leak something similar to
the original event content).

Since the object it returns is a ReplicationCommandHandler.

This is clean-up from adding support to Redis where the command handler
was added as an additional layer of abstraction from the TCP protocol.

Signed-off-by: Sean Quah <seanq@element.io>

Add third_party module callbacks to check if a user can delete a room and deactivate a user (#12028)

* Add check_can_deactivate_user

* Add check_can_shutdown_rooms

* Documentation

* callbacks, not functions

* Various suggested tweaks

* Add tests for test_check_can_shutdown_room and test_check_can_deactivate_user

* Update check_can_deactivate_user to not take a Requester

* Fix check_can_shutdown_room docs

* Renegade and use `by_admin` instead of `admin_user_id`

* fix lint

* Update docs/modules/third_party_rules_callbacks.md

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

* Update docs/modules/third_party_rules_callbacks.md

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

* Update docs/modules/third_party_rules_callbacks.md

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

* Update docs/modules/third_party_rules_callbacks.md

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

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

* `@cached` can now take an `uncached_args` which is an iterable of names to not use in the cache key.
* Requires `@cached`, @cachedList` and `@lru_cache` to use keyword arguments for clarity.
* Asserts that keyword-only arguments in cached functions are not accepted. (I tested this briefly and I don't believe this works properly.)

This allows for the target process to be down for around a minute
which provides time for restarts during synapse upgrades/config updates.

Closes: #12178

Signed off by Nick Mills-Barrett nick@beeper.com

We don't *have* the state at a backwards-extremity, so this is never going to
do anything useful.

* Rewrites the demo documentation to be clearer, accurate, and moves it to our documentation tree.
* Improvements to the demo scripts:
	* `clean.sh` now runs `stop.sh` first to avoid zombie processes.
	* Uses more modern Synapse configuration (and removes some obsolete configuration).
	* Consistently use the HTTP ports for server name, etc.
	* Remove the `demo/etc` directory and place everything into the `demo/808x` directories.

Signed-off-by: Sean Quah <seanq@element.io>