Add cancellation support to `ReadWriteLock` #12120

squahtx · 2022-03-01T16:50:16Z

Best reviewed commit by commit.

Part of #3528.

delay_cancellation comes from #12180.

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Has the side effect of fixing clean up for readers cancelled while waiting. Breaks the assumption that resolution of a writer `Deferred` means that previous readers and writers have completed, which will be fixed in the next commit. Signed-off-by: Sean Quah <seanq@element.io>

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

squahtx · 2022-03-01T16:57:03Z

synapse/util/async_helpers.py

+        @asynccontextmanager
+        async def _ctx_manager() -> AsyncIterator[None]:
            try:
+                # We wait for the latest writer to finish writing. We can safely ignore
+                # any existing readers... as they're readers.
+                # May raise a `CancelledError` if the `Deferred` wrapping us is
+                # cancelled. The `Deferred` we are waiting on must not be cancelled,
+                # since we do not own it.
+                if curr_writer:
+                    await make_deferred_yieldable(stop_cancellation(curr_writer))


I'm not sure of the benefit of using async context managers.
It mainly benefits the cleanup for the read path, where the cleanup for not-holding-the-lock and holding-the-lock happen to be the same. On the write path we have to handle both cases differently, by deferring the cleanup until we actually acquire the lock.

richvdh

nice. a few comments though.

richvdh · 2022-03-04T10:40:27Z

synapse/util/async_helpers.py

            try:
+                await make_deferred_yieldable(defer.gatherResults(to_wait_on))


I'm wondering if we should, for strict correctness, do all the to_wait_on calculation etc inside the ctx_manager. Otherwise it's possible for someone to do:

ctx = self.pagination_lock.write(room_id) await something_asynchronous() with await ctx: ...

... which is a stupid thing to do, but still.

I'm all in favour of removing footguns. I'lk move the setup of read() and write() into the context manager.

richvdh · 2022-03-04T10:48:31Z

tests/util/test_rwlock.py


-        self._assert_called_before_not_after(ds, 2)
+        self._assert_called_before_not_after(acquired_ds, 2)


it's hard to follow what _assert_called_before_not_after is doing. Assuming you've figured it out, could you add a comment/docstring/type annotation/etc or two?

Actually generally this test could do with a few comments, for example:

Suggested change

self._assert_called_before_not_after(acquired_ds, 2)

# we should have acquired the locks for the first two readers, but nothing else.

self._assert_called_before_not_after(acquired_ds, 2)

I found this test case hard to understand too. I'll try to make it more readable.

synapse/util/async_helpers.py

richvdh · 2022-03-04T10:54:50Z

synapse/util/async_helpers.py

+                    # `new_defer` must only resolve once all previous readers and
+                    # writers have finished.
+                    # NB: `release()` won't have a logcontext in this path.
+                    to_wait_on_defer.addCallback(lambda _: release())


presumably we need to do this even if to_wait_on_defer ends up erroring, so this needs to be

Suggested change

to_wait_on_defer.addCallback(lambda _: release())

to_wait_on_defer.addBoth(lambda _: release())

I'll make the change for the sake of robustness, but all of the Deferreds that represent lock release, and thus also to_wait_on_defer, should never error.

richvdh · 2022-03-04T11:09:07Z

synapse/util/async_helpers.py

+                    if self.key_to_current_writer.get(key) == new_defer:
+                        self.key_to_current_writer.pop(key)
+
+                if to_wait_on_defer.called:


could we, instead of all this, do:

to_wait_on_defer = defer.gatherResults(to_wait_on) to_wait_on_defer.addBoth(lambda _: release()) await make_deferred_yieldable(to_wait_on_defer) yield

... possibly with more stop_cancellation ? Or does that not work?

release() must only be called after the yield, so I'm guessing you meant:

try: await make_deferred_yieldable(stop_cancellation(to_wait_on_defer)) yield finally: to_wait_on_defer.addBoth(lambda _: release())

which I was originally hesitant to do because of re-entrancy in the happy path:

When we exit the await, it will be because we are inside a call to to_wait_on_defer.callback(...).

During the yield / body of the context manager, we may or may not do a blocking await. If we block, then the to_wait_on_defer.callback() call gets exited, otherwise we remain within the to_wait_on_defer.callback() call.

We reach the finally block.
If we're no longer inside the callback() call, release() will be called instantly with the current logging context.
Otherwise if we're still inside the callback() call, release() won't be called until we next block or terminate and will have the sentinel context.

The sometimes-extra delay before release() is tricky to reason about, but I think the proposed code would be alright.

As an alternative, I'm very tempted by @erikjohnston's suggestion of delaying CancelledErrors:

try: await make_deferred_yieldable(delay_cancellation(to_wait_on_defer)) yield finally: release() # but inline again

Where delay_cancellation would hold on to the CancelledError and only raise it once to_wait_on_defer resolves.

We'd get better maintainability at the cost of having the crud associated with cancelled requests lingering a little while longer, but maybe that's a worthwhile tradeoff.

release() must only be called after the yield,

oh, duh. Yes, of course.

The sometimes-extra delay before release() is tricky to reason about, but I think the proposed code would be alright.

ugh, right, yes, let's avoid that.

And yes, delay_cancellation looks like it might be worth exploring.

I had a go at using a delay in cadfe0a.
We now depend on #12180 for delay_cancellation of course.

richvdh · 2022-03-04T11:19:43Z

tests/util/test_rwlock.py

+        key: str,
+        name: str,
+    ) -> Tuple["Deferred[None]", "Deferred[None]"]:
+        """Starts a reader or writer which acquires the lock, blocks, then completes."""


some docs on the params and return vals would be helpful.

Sounds like a good idea. Added some docs.

richvdh · 2022-03-04T11:22:03Z

tests/util/test_rwlock.py

@@ -32,76 +34,120 @@ def _assert_called_before_not_after(self, lst, first_false):

    def test_rwlock(self):
        rwlock = ReadWriteLock()
+        key = "key"
+
+        def start_reader_or_writer(


it's a bit confusing that this is slightly different to the class-level _start_reader_or_writer. Can we combine them, even if it means returning three deferreds rather than two?

Yep, let's combine them.

…e docstrings.

… understandable, hopefully

`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>

…k is acquired

squahtx · 2022-03-08T17:08:12Z

I had a go at using a delay to simplify the write path in cadfe0a.
We now depend on #12180 for delay_cancellation of course.

richvdh

lgtm, subject to updates for consistency with #12180

synapse/util/async_helpers.py

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

@IronTooch

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([\#11700](matrix-org/synapse#11700; Mjolnir users should upgrade Mjolnir before upgrading Synapse to this version. This release also moves the location of the `synctl` script; see the [upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#synctl-script-has-been-moved) for more details. Internal Changes ---------------- - Tweak copy for default Single Sign-On account details template to better adhere to mobile app store guidelines. ([\#12265](matrix-org/synapse#12265), [\#12260](matrix-org/synapse#12260)) Synapse 1.55.0rc1 (2022-03-15) ============================== Features -------- - Add third-party rules callbacks `check_can_shutdown_room` and `check_can_deactivate_user`. ([\#12028](matrix-org/synapse#12028)) - Improve performance of logging in for large accounts. ([\#12132](matrix-org/synapse#12132)) - Add experimental env var `SYNAPSE_ASYNC_IO_REACTOR` that causes Synapse to use the asyncio reactor for Twisted. 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([\#12180](matrix-org/synapse#12180)) - Retry HTTP replication failures, this should prevent 502's when restarting stateful workers (main, event persisters, stream writers). Contributed by Nick @ Beeper. ([\#12182](matrix-org/synapse#12182)) - Add cancellation support to `@cached` and `@cachedList` decorators. ([\#12183](matrix-org/synapse#12183)) - Remove unused variables. ([\#12187](matrix-org/synapse#12187)) - Add combined test for HTTP pusher and push rule. Contributed by Nick @ Beeper. ([\#12188](matrix-org/synapse#12188)) - Rename `HomeServer.get_tcp_replication` to `get_replication_command_handler`. ([\#12192](matrix-org/synapse#12192)) - Remove some dead code. ([\#12197](matrix-org/synapse#12197)) - Fix a misleading comment in the function `check_event_for_spam`. ([\#12203](matrix-org/synapse#12203)) - Remove unnecessary `pass` statements. ([\#12206](matrix-org/synapse#12206)) - Update the SSO username picker template to comply with SIWA guidelines. ([\#12210](matrix-org/synapse#12210)) - Improve code documentation for the typing stream over replication. ([\#12211](matrix-org/synapse#12211))

Synapse 1.55.0 (2022-03-22) =========================== This release removes a workaround introduced in Synapse 1.50.0 for Mjolnir compatibility. **This breaks compatibility with Mjolnir 1.3.1 and earlier. ([\matrix-org#11700](matrix-org#11700; Mjolnir users should upgrade Mjolnir before upgrading Synapse to this version. This release also moves the location of the `synctl` script; see the [upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#synctl-script-has-been-moved) for more details. Internal Changes ---------------- - Tweak copy for default Single Sign-On account details template to better adhere to mobile app store guidelines. ([\matrix-org#12265](matrix-org#12265), [\matrix-org#12260](matrix-org#12260)) Synapse 1.55.0rc1 (2022-03-15) ============================== Features -------- - Add third-party rules callbacks `check_can_shutdown_room` and `check_can_deactivate_user`. ([\matrix-org#12028](matrix-org#12028)) - Improve performance of logging in for large accounts. ([\matrix-org#12132](matrix-org#12132)) - Add experimental env var `SYNAPSE_ASYNC_IO_REACTOR` that causes Synapse to use the asyncio reactor for Twisted. ([\matrix-org#12135](matrix-org#12135)) - Support the stable identifiers from [MSC3440](matrix-org/matrix-spec-proposals#3440): threads. ([\matrix-org#12151](matrix-org#12151)) - Add a new Jinja2 template filter to extract the local part of an email address. ([\matrix-org#12212](matrix-org#12212)) Bugfixes -------- - Use the proper serialization format for bundled thread aggregations. The bug has existed since Synapse v1.48.0. ([\matrix-org#12090](matrix-org#12090)) - Fix a long-standing bug when redacting events with relations. ([\matrix-org#12113](matrix-org#12113), [\matrix-org#12121](matrix-org#12121), [\matrix-org#12130](matrix-org#12130), [\matrix-org#12189](matrix-org#12189)) - Fix a bug introduced in Synapse 1.7.2 whereby background updates are never run with the default background batch size. ([\matrix-org#12157](matrix-org#12157)) - Fix a bug where non-standard information was returned from the `/hierarchy` API. Introduced in Synapse v1.41.0. ([\matrix-org#12175](matrix-org#12175)) - Fix a bug introduced in Synapse 1.54.0 that broke background updates on sqlite homeservers while search was disabled. ([\matrix-org#12215](matrix-org#12215)) - Fix a long-standing bug when a `filter` argument with `event_fields` which did not include the `unsigned` field could result in a 500 error on `/sync`. ([\matrix-org#12234](matrix-org#12234)) Improved Documentation ---------------------- - Fix complexity checking config example in [Resource Constrained Devices](https://matrix-org.github.io/synapse/v1.54/other/running_synapse_on_single_board_computers.html) docs page. ([\matrix-org#11998](matrix-org#11998)) - Improve documentation for demo scripts. ([\matrix-org#12143](matrix-org#12143)) - Updates to the Room DAG concepts development document. ([\matrix-org#12179](matrix-org#12179)) - Document that the `typing`, `to_device`, `account_data`, `receipts`, and `presence` stream writer can only be used on a single worker. ([\matrix-org#12196](matrix-org#12196)) - Document that contributors can sign off privately by email. ([\matrix-org#12204](matrix-org#12204)) Deprecations and Removals ------------------------- - **Remove workaround introduced in Synapse 1.50.0 for Mjolnir compatibility. Breaks compatibility with Mjolnir 1.3.1 and earlier. ([\matrix-org#11700](matrix-org#11700 - **`synctl` has been moved into into `synapse._scripts` and is exposed as an entry point; see [upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#synctl-script-has-been-moved). ([\matrix-org#12140](matrix-org#12140)) - Remove backwards compatibilty with pagination tokens from the `/relations` and `/aggregations` endpoints generated from Synapse < v1.52.0. ([\matrix-org#12138](matrix-org#12138)) - The groups/communities feature in Synapse has been deprecated. ([\matrix-org#12200](matrix-org#12200)) Internal Changes ---------------- - Simplify the `ApplicationService` class' set of public methods related to interest checking. ([\matrix-org#11915](matrix-org#11915)) - Add config settings for background update parameters. ([\matrix-org#11980](matrix-org#11980)) - Correct type hints for txredis. ([\matrix-org#12042](matrix-org#12042)) - Limit the size of `aggregation_key` on annotations. ([\matrix-org#12101](matrix-org#12101)) - Add type hints to tests files. ([\matrix-org#12108](matrix-org#12108), [\matrix-org#12146](matrix-org#12146), [\matrix-org#12207](matrix-org#12207), [\matrix-org#12208](matrix-org#12208)) - Move scripts to Synapse package and expose as setuptools entry points. ([\matrix-org#12118](matrix-org#12118)) - Add support for cancellation to `ReadWriteLock`. ([\matrix-org#12120](matrix-org#12120)) - Fix data validation to compare to lists, not sequences. ([\matrix-org#12128](matrix-org#12128)) - Fix CI not attaching source distributions and wheels to the GitHub releases. ([\matrix-org#12131](matrix-org#12131)) - Remove unused mocks from `test_typing`. ([\matrix-org#12136](matrix-org#12136)) - Give `scripts-dev` scripts suffixes for neater CI config. ([\matrix-org#12137](matrix-org#12137)) - Move the snapcraft configuration file to `contrib`. ([\matrix-org#12142](matrix-org#12142)) - Enable [MSC3030](matrix-org/matrix-spec-proposals#3030) Complement tests in CI. ([\matrix-org#12144](matrix-org#12144)) - Enable [MSC2716](matrix-org/matrix-spec-proposals#2716) Complement tests in CI. ([\matrix-org#12145](matrix-org#12145)) - Add test for `ObservableDeferred`'s cancellation behaviour. ([\matrix-org#12149](matrix-org#12149)) - Use `ParamSpec` in type hints for `synapse.logging.context`. ([\matrix-org#12150](matrix-org#12150)) - Prune unused jobs from `tox` config. ([\matrix-org#12152](matrix-org#12152)) - Move CI checks out of tox, to facilitate a move to using poetry. ([\matrix-org#12153](matrix-org#12153)) - Avoid generating state groups for local out-of-band leaves. ([\matrix-org#12154](matrix-org#12154)) - Avoid trying to calculate the state at outlier events. ([\matrix-org#12155](matrix-org#12155), [\matrix-org#12173](matrix-org#12173), [\matrix-org#12202](matrix-org#12202)) - Fix some type annotations. ([\matrix-org#12156](matrix-org#12156)) - Add type hints for `ObservableDeferred` attributes. ([\matrix-org#12159](matrix-org#12159)) - Use a prebuilt Action for the `tests-done` CI job. ([\matrix-org#12161](matrix-org#12161)) - Reduce number of DB queries made during processing of `/sync`. ([\matrix-org#12163](matrix-org#12163)) - Add `delay_cancellation` utility function, which behaves like `stop_cancellation` but waits until the original `Deferred` resolves before raising a `CancelledError`. ([\matrix-org#12180](matrix-org#12180)) - Retry HTTP replication failures, this should prevent 502's when restarting stateful workers (main, event persisters, stream writers). Contributed by Nick @ Beeper. ([\matrix-org#12182](matrix-org#12182)) - Add cancellation support to `@cached` and `@cachedList` decorators. ([\matrix-org#12183](matrix-org#12183)) - Remove unused variables. ([\matrix-org#12187](matrix-org#12187)) - Add combined test for HTTP pusher and push rule. Contributed by Nick @ Beeper. ([\matrix-org#12188](matrix-org#12188)) - Rename `HomeServer.get_tcp_replication` to `get_replication_command_handler`. ([\matrix-org#12192](matrix-org#12192)) - Remove some dead code. ([\matrix-org#12197](matrix-org#12197)) - Fix a misleading comment in the function `check_event_for_spam`. ([\matrix-org#12203](matrix-org#12203)) - Remove unnecessary `pass` statements. ([\matrix-org#12206](matrix-org#12206)) - Update the SSO username picker template to comply with SIWA guidelines. ([\matrix-org#12210](matrix-org#12210)) - Improve code documentation for the typing stream over replication. ([\matrix-org#12211](matrix-org#12211)) # -----BEGIN PGP SIGNATURE----- # # iQIzBAABCAAdFiEEgQG31Z317NrSMt0QiISIDS7+X/QFAmI53SwACgkQiISIDS7+ # X/RlgQ/9HX3moAXQw67uIII5BnSGAYdgovL2uM990urQ6HVYRxcnidRlWQUyqlJ0 # qbvpOrJXRpK5MvoFyrJg+ryJLEncoUiccs5WQHNt4t22zmUXusLH/Bxxc/U24s5D # 3gQVhYdjiyyR0dIzr/EwZsYGSgl9wANoKVJXbRInrE7gdMP5RT/IcifWBZETNWjQ # zPGp3R5RDYzFecDiZUcGJCldXC+WPOw0YlhMdR7Rm5NkiE6eM1kAREH+K5vxBM7i # H+nP//NLl+wL4nxb3f3paEgCakPkB+xuC6bZZ3NA7LfMw2OKBHdUqEl4rmXr4vCS # lboF9kDhb42uIKgVPBnVcf3hv4m5NbVA7f6k3tpFJOvqk9G58UhnqcjdXS8DBso6 # gQpk7Zk6ILU0j8i7N21R/aZLSwmQ96h1O3lNO+43usPbh6WjqMIHR/kv/ADyZEhZ # /6taXiOHtg7KaqtpHAy2UVuWjJ8c3a0vHbReRe77S+yMD7iggHbBTpSNMfgcM4yi # gimKq55Z0qhPLI7vjr4IOB5irEd64ciKnUI3IQfkyFoCMyJHo0fw7+boC/Kc5FgM # O7V69r+CBfJ9SsGeSlheiCTv6fGyh4n960ya2BQY+BHDjTFW+BUkTyjXkIeiIJ04 # CihTgluISePbrdRKL4JkceL+Im6NmpJhTOe1+Pjsncy/8WkOeos= # =HvNr # -----END PGP SIGNATURE----- # gpg: Signature made Tue Mar 22 14:29:00 2022 GMT # gpg: using RSA key 8101B7D59DF5ECDAD232DD108884880D2EFE5FF4 # gpg: Can't check signature: No public key # Conflicts: # synapse/appservice/__init__.py # synapse/handlers/pagination.py # synapse/push/baserules.py

Synapse 1.55.0 (2022-03-22) =========================== This release removes a workaround introduced in Synapse 1.50.0 for Mjolnir compatibility. **This breaks compatibility with Mjolnir 1.3.1 and earlier. ([\#11700](matrix-org/synapse#11700; Mjolnir users should upgrade Mjolnir before upgrading Synapse to this version. This release also moves the location of the `synctl` script; see the [upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#synctl-script-has-been-moved) for more details. Internal Changes ---------------- - Tweak copy for default Single Sign-On account details template to better adhere to mobile app store guidelines. ([\#12265](matrix-org/synapse#12265), [\#12260](matrix-org/synapse#12260)) Synapse 1.55.0rc1 (2022-03-15) ============================== Features -------- - Add third-party rules callbacks `check_can_shutdown_room` and `check_can_deactivate_user`. ([\#12028](matrix-org/synapse#12028)) - Improve performance of logging in for large accounts. ([\#12132](matrix-org/synapse#12132)) - Add experimental env var `SYNAPSE_ASYNC_IO_REACTOR` that causes Synapse to use the asyncio reactor for Twisted. ([\#12135](matrix-org/synapse#12135)) - Support the stable identifiers from [MSC3440](matrix-org/matrix-spec-proposals#3440): threads. ([\#12151](matrix-org/synapse#12151)) - Add a new Jinja2 template filter to extract the local part of an email address. ([\#12212](matrix-org/synapse#12212)) Bugfixes -------- - Use the proper serialization format for bundled thread aggregations. The bug has existed since Synapse v1.48.0. ([\#12090](matrix-org/synapse#12090)) - Fix a long-standing bug when redacting events with relations. ([\#12113](matrix-org/synapse#12113), [\#12121](matrix-org/synapse#12121), [\#12130](matrix-org/synapse#12130), [\#12189](matrix-org/synapse#12189)) - Fix a bug introduced in Synapse 1.7.2 whereby background updates are never run with the default background batch size. ([\#12157](matrix-org/synapse#12157)) - Fix a bug where non-standard information was returned from the `/hierarchy` API. Introduced in Synapse v1.41.0. ([\#12175](matrix-org/synapse#12175)) - Fix a bug introduced in Synapse 1.54.0 that broke background updates on sqlite homeservers while search was disabled. ([\#12215](matrix-org/synapse#12215)) - Fix a long-standing bug when a `filter` argument with `event_fields` which did not include the `unsigned` field could result in a 500 error on `/sync`. ([\#12234](matrix-org/synapse#12234)) Improved Documentation ---------------------- - Fix complexity checking config example in [Resource Constrained Devices](https://matrix-org.github.io/synapse/v1.54/other/running_synapse_on_single_board_computers.html) docs page. ([\#11998](matrix-org/synapse#11998)) - Improve documentation for demo scripts. ([\#12143](matrix-org/synapse#12143)) - Updates to the Room DAG concepts development document. ([\#12179](matrix-org/synapse#12179)) - Document that the `typing`, `to_device`, `account_data`, `receipts`, and `presence` stream writer can only be used on a single worker. ([\#12196](matrix-org/synapse#12196)) - Document that contributors can sign off privately by email. ([\#12204](matrix-org/synapse#12204)) Deprecations and Removals ------------------------- - **Remove workaround introduced in Synapse 1.50.0 for Mjolnir compatibility. Breaks compatibility with Mjolnir 1.3.1 and earlier. ([\#11700](matrix-org/synapse#11700 - **`synctl` has been moved into into `synapse._scripts` and is exposed as an entry point; see [upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#synctl-script-has-been-moved). ([\#12140](matrix-org/synapse#12140)) - Remove backwards compatibilty with pagination tokens from the `/relations` and `/aggregations` endpoints generated from Synapse < v1.52.0. ([\#12138](matrix-org/synapse#12138)) - The groups/communities feature in Synapse has been deprecated. ([\#12200](matrix-org/synapse#12200)) Internal Changes ---------------- - Simplify the `ApplicationService` class' set of public methods related to interest checking. ([\#11915](matrix-org/synapse#11915)) - Add config settings for background update parameters. ([\#11980](matrix-org/synapse#11980)) - Correct type hints for txredis. ([\#12042](matrix-org/synapse#12042)) - Limit the size of `aggregation_key` on annotations. ([\#12101](matrix-org/synapse#12101)) - Add type hints to tests files. ([\#12108](matrix-org/synapse#12108), [\#12146](matrix-org/synapse#12146), [\#12207](matrix-org/synapse#12207), [\#12208](matrix-org/synapse#12208)) - Move scripts to Synapse package and expose as setuptools entry points. ([\#12118](matrix-org/synapse#12118)) - Add support for cancellation to `ReadWriteLock`. ([\#12120](matrix-org/synapse#12120)) - Fix data validation to compare to lists, not sequences. ([\#12128](matrix-org/synapse#12128)) - Fix CI not attaching source distributions and wheels to the GitHub releases. ([\#12131](matrix-org/synapse#12131)) - Remove unused mocks from `test_typing`. ([\#12136](matrix-org/synapse#12136)) - Give `scripts-dev` scripts suffixes for neater CI config. ([\#12137](matrix-org/synapse#12137)) - Move the snapcraft configuration file to `contrib`. ([\#12142](matrix-org/synapse#12142)) - Enable [MSC3030](matrix-org/matrix-spec-proposals#3030) Complement tests in CI. ([\#12144](matrix-org/synapse#12144)) - Enable [MSC2716](matrix-org/matrix-spec-proposals#2716) Complement tests in CI. ([\#12145](matrix-org/synapse#12145)) - Add test for `ObservableDeferred`'s cancellation behaviour. ([\#12149](matrix-org/synapse#12149)) - Use `ParamSpec` in type hints for `synapse.logging.context`. ([\#12150](matrix-org/synapse#12150)) - Prune unused jobs from `tox` config. ([\#12152](matrix-org/synapse#12152)) - Move CI checks out of tox, to facilitate a move to using poetry. ([\#12153](matrix-org/synapse#12153)) - Avoid generating state groups for local out-of-band leaves. ([\#12154](matrix-org/synapse#12154)) - Avoid trying to calculate the state at outlier events. ([\#12155](matrix-org/synapse#12155), [\#12173](matrix-org/synapse#12173), [\#12202](matrix-org/synapse#12202)) - Fix some type annotations. ([\#12156](matrix-org/synapse#12156)) - Add type hints for `ObservableDeferred` attributes. ([\#12159](matrix-org/synapse#12159)) - Use a prebuilt Action for the `tests-done` CI job. ([\#12161](matrix-org/synapse#12161)) - Reduce number of DB queries made during processing of `/sync`. ([\#12163](matrix-org/synapse#12163)) - Add `delay_cancellation` utility function, which behaves like `stop_cancellation` but waits until the original `Deferred` resolves before raising a `CancelledError`. ([\#12180](matrix-org/synapse#12180)) - Retry HTTP replication failures, this should prevent 502's when restarting stateful workers (main, event persisters, stream writers). Contributed by Nick @ Beeper. ([\#12182](matrix-org/synapse#12182)) - Add cancellation support to `@cached` and `@cachedList` decorators. ([\#12183](matrix-org/synapse#12183)) - Remove unused variables. ([\#12187](matrix-org/synapse#12187)) - Add combined test for HTTP pusher and push rule. Contributed by Nick @ Beeper. ([\#12188](matrix-org/synapse#12188)) - Rename `HomeServer.get_tcp_replication` to `get_replication_command_handler`. ([\#12192](matrix-org/synapse#12192)) - Remove some dead code. ([\#12197](matrix-org/synapse#12197)) - Fix a misleading comment in the function `check_event_for_spam`. ([\#12203](matrix-org/synapse#12203)) - Remove unnecessary `pass` statements. ([\#12206](matrix-org/synapse#12206)) - Update the SSO username picker template to comply with SIWA guidelines. ([\#12210](matrix-org/synapse#12210)) - Improve code documentation for the typing stream over replication. ([\#12211](matrix-org/synapse#12211))

squahtx requested a review from a team as a code owner March 1, 2022 16:50

Sean Quah added 5 commits March 1, 2022 16:53

Fix clean up when waiting readers or writers are cancelled

f1f363d

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

Don't cancel Deferreds that readers or writers are waiting on

9744823

Add ReadWriteLock cancellation tests

3241adc

Add newsfile

68f5abe

squahtx force-pushed the squah/readwritelock_cancellation_support branch from 827198c to 68f5abe Compare March 1, 2022 16:53

squahtx commented Mar 1, 2022

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richvdh self-assigned this Mar 4, 2022

richvdh suggested changes Mar 4, 2022

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richvdh removed their assignment Mar 4, 2022

Sean Quah and others added 8 commits March 4, 2022 15:52

Move lock setup into context manager to eliminate footgun

28dbe41

Use addBoth instead of addCallback, just in case

c9f85e4

Refactor tests to deduplicate _start_reader_or_writer. And improve th…

716cded

…e docstrings.

Add comments/docstrings and rename variables to make test_rwlock more…

c4a2a58

… understandable, hopefully

Merge branch 'develop' into squah/readwritelock_cancellation_support

31a2bb2

Add missing space

65f97fa

Simplify release of write lock by delaying cancellation until the loc…

cadfe0a

…k is acquired

squahtx requested a review from richvdh March 8, 2022 17:08

richvdh approved these changes Mar 11, 2022

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synapse/util/async_helpers.py Outdated Show resolved Hide resolved

Sean Quah and others added 3 commits March 14, 2022 17:58

Merge branch 'develop' into squah/readwritelock_cancellation_support

1cd035b

Fixup merge, use latest version of delay_cancellation

4c47827

Update synapse/util/async_helpers.py

1b9ec9b

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

squahtx merged commit 605d161 into develop Mar 14, 2022

squahtx deleted the squah/readwritelock_cancellation_support branch March 14, 2022 18:49

squahtx mentioned this pull request Mar 30, 2022

we shouldn't process requests where the requester has timed out/gone away #3528

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Add cancellation support to `ReadWriteLock` #12120

Add cancellation support to `ReadWriteLock` #12120

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		try:
		await make_deferred_yieldable(defer.gatherResults(to_wait_on))


		self._assert_called_before_not_after(ds, 2)
		self._assert_called_before_not_after(acquired_ds, 2)

	self._assert_called_before_not_after(acquired_ds, 2)
	# we should have acquired the locks for the first two readers, but nothing else.
	self._assert_called_before_not_after(acquired_ds, 2)

	to_wait_on_defer.addCallback(lambda _: release())
	to_wait_on_defer.addBoth(lambda _: release())

Add cancellation support to ReadWriteLock #12120

Add cancellation support to ReadWriteLock #12120

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Add cancellation support to `ReadWriteLock` #12120

Add cancellation support to `ReadWriteLock` #12120

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