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Push some deferred wrangling down into DeferredCache #8572

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merged 3 commits into from
Oct 21, 2020

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@richvdh richvdh commented Oct 16, 2020

Rather than DeferredCache.get() sometimes returning an ObservableDeferred that you have to .observe, and sometimes returning an immediate result that you have to wrap with a Deferred, we can make it behave consistently. This removes complexity from the call site, improves type safety, and generally leasds to a cleaner API.

Based on #8568

Comment on lines -221 to -225
def onErr(f):
cache.invalidate(cache_key)
return f

ret.addErrback(onErr)
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this happens anyway, at

.

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ohh, except that's slightly different. I better write some tests.

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ok, I've stared at this harder and am pretty sure it's redundant. As noted above, if the function fails, then we call entry.invalidate() on the "temporary" entry in the pending_deferred_cache. The only difference between that and calling cache.invalidate(cache_key) as shown here would be if there was also an entry in the main cache. But we know that can't be the case, because we checked it at line 210, and there is no way for it to have been populated in the meantime.

https://github.com/matrix-org/synapse/pull/8572/files#diff-3aa4bc9d8830ffd035d53b8af86b548a21f2a4cddb3e5240445661614a88a08fR210

(unless someone decided to sidestep the CacheDescriptor and manually call cache.set or cache.prefill while this request was running? but that would be silly, and even if they did it's not obvious that we should invalidate it here.)

In short, I think this is handled correctly in DeferredCache itself.

@@ -470,9 +470,9 @@ def func(self, key):

a = A()

a.func.prefill(("foo",), ObservableDeferred(d))
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I don't think that prefilling with an ObservableDeferred is the way this API is meant to be used. At least, it hasn't been used that way for a long time.

@richvdh richvdh force-pushed the rav/cache_hacking/2 branch 3 times, most recently from 5cefe47 to 474e178 Compare October 19, 2020 17:26
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richvdh commented Oct 19, 2020

There's a fair bit going on in this PR, but the diff looks worse than it is thanks to 438ffc4 which is a lift & shift of an entire test class, so hopefully it is reasonably easy to review commit-by-commit.

@richvdh richvdh requested a review from a team October 19, 2020 20:24
@clokep clokep self-assigned this Oct 20, 2020
synapse/util/caches/deferred_cache.py Outdated Show resolved Hide resolved
synapse/util/caches/descriptors.py Outdated Show resolved Hide resolved

# now the original invalidation callback should have been called, but none of
# the others
self.assertSetEqual(callbacks, {"prefill"})
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Curious why you used assertSetEqual here? Was assertEqual not working for some reason / does this have slightly different behavior I'm unaware of?

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I wanted to make sure that they were compared as sets, rather than (say) lists which might cause false differences due to ordering. But I didn't think about it hard enough... I'll switch to assertEqual for consistency.

Comment on lines +179 to +182
# and a second call should work as normal
obj.result = defer.succeed(100)
d3 = obj.fn(1)
self.assertEqual(self.successResultOf(d3), 100)
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I believe that this now calls into the function again, should we assert obj.call_count == 2?

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sure, why not

Comment on lines +56 to +58
# TODO: Actually ObservableDeferred *doesn't* run its tests in order on py3.8.
# maybe we should fix that?
# get_d.addCallback(check1)
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Yeah this is confusing. I'm not sure it is worth fixing (in this PR, at least). Do you see any downsides to this in practice?

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well, at some level I suspect it means we end up processing requests that arrived later before those that arrived earlier, which isn't exactly forbidden but does feel like it might lead to some surprising behaviour.

But likewise, I'm not going to rush into fixing it right now.

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richvdh commented Oct 21, 2020

I'm going to rebase this into useful commits before merging.

@richvdh richvdh merged commit 9146a8a into develop Oct 21, 2020
@richvdh richvdh deleted the rav/cache_hacking/2 branch October 21, 2020 16:55
erikjohnston added a commit that referenced this pull request Oct 22, 2020
Synapse 1.22.0rc1 (2020-10-22)
==============================

Features
--------

- Add a configuration option for always using the "userinfo endpoint" for OpenID Connect. This fixes support for some identity providers, e.g. GitLab. Contributed by Benjamin Koch. ([\#7658](#7658))
- Add ability for `ThirdPartyEventRules` modules to query and manipulate whether a room is in the public rooms directory. ([\#8292](#8292), [\#8467](#8467))
- Add support for olm fallback keys ([MSC2732](matrix-org/matrix-spec-proposals#2732)). ([\#8312](#8312), [\#8501](#8501))
- Add support for running background tasks in a separate worker process. ([\#8369](#8369), [\#8458](#8458), [\#8489](#8489), [\#8513](#8513), [\#8544](#8544), [\#8599](#8599))
- Add support for device dehydration ([MSC2697](matrix-org/matrix-spec-proposals#2697)). ([\#8380](#8380))
- Add support for [MSC2409](matrix-org/matrix-spec-proposals#2409), which allows sending typing, read receipts, and presence events to appservices. ([\#8437](#8437), [\#8590](#8590))
- Change default room version to "6", per [MSC2788](matrix-org/matrix-spec-proposals#2788). ([\#8461](#8461))
- Add the ability to send non-membership events into a room via the `ModuleApi`. ([\#8479](#8479))
- Increase default upload size limit from 10M to 50M. Contributed by @Akkowicz. ([\#8502](#8502))
- Add support for modifying event content in `ThirdPartyRules` modules. ([\#8535](#8535), [\#8564](#8564))

Bugfixes
--------

- Fix a longstanding bug where invalid ignored users in account data could break clients. ([\#8454](#8454))
- Fix a bug where backfilling a room with an event that was missing the `redacts` field would break. ([\#8457](#8457))
- Don't attempt to respond to some requests if the client has already disconnected. ([\#8465](#8465))
- Fix message duplication if something goes wrong after persisting the event. ([\#8476](#8476))
- Fix incremental sync returning an incorrect `prev_batch` token in timeline section, which when used to paginate returned events that were included in the incremental sync. Broken since v0.16.0. ([\#8486](#8486))
- Expose the `uk.half-shot.msc2778.login.application_service` to clients from the login API. This feature was added in v1.21.0, but was not exposed as a potential login flow. ([\#8504](#8504))
- Fix error code for `/profile/{userId}/displayname` to be `M_BAD_JSON`. ([\#8517](#8517))
- Fix a bug introduced in v1.7.0 that could cause Synapse to insert values from non-state `m.room.retention` events into the `room_retention` database table. ([\#8527](#8527))
- Fix not sending events over federation when using sharded event writers. ([\#8536](#8536))
- Fix a long standing bug where email notifications for encrypted messages were blank. ([\#8545](#8545))
- Fix increase in the number of `There was no active span...` errors logged when using OpenTracing. ([\#8567](#8567))
- Fix a bug that prevented errors encountered during execution of the `synapse_port_db` from being correctly printed. ([\#8585](#8585))
- Fix appservice transactions to only include a maximum of 100 persistent and 100 ephemeral events. ([\#8606](#8606))

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

- Added multi-arch support (arm64,arm/v7) for the docker images. Contributed by @maquis196. ([\#7921](#7921))
- Add support for passing commandline args to the synapse process. Contributed by @samuel-p. ([\#8390](#8390))

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

- Update the directions for using the manhole with coroutines. ([\#8462](#8462))
- Improve readme by adding new shield.io badges. ([\#8493](#8493))
- Added note about docker in manhole.md regarding which ip address to bind to. Contributed by @maquis196. ([\#8526](#8526))
- Document the new behaviour of the `allowed_lifetime_min` and `allowed_lifetime_max` settings in the room retention configuration. ([\#8529](#8529))

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

- Drop unused `device_max_stream_id` table. ([\#8589](#8589))

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

- Check for unreachable code with mypy. ([\#8432](#8432))
- Add unit test for event persister sharding. ([\#8433](#8433))
- Allow events to be sent to clients sooner when using sharded event persisters. ([\#8439](#8439), [\#8488](#8488), [\#8496](#8496), [\#8499](#8499))
- Configure `public_baseurl` when using demo scripts. ([\#8443](#8443))
- Add SQL logging on queries that happen during startup. ([\#8448](#8448))
- Speed up unit tests when using PostgreSQL. ([\#8450](#8450))
- Remove redundant database loads of stream_ordering for events we already have. ([\#8452](#8452))
- Reduce inconsistencies between codepaths for membership and non-membership events. ([\#8463](#8463))
- Combine `SpamCheckerApi` with the more generic `ModuleApi`. ([\#8464](#8464))
- Additional testing for `ThirdPartyEventRules`. ([\#8468](#8468))
- Add `-d` option to `./scripts-dev/lint.sh` to lint files that have changed since the last git commit. ([\#8472](#8472))
- Unblacklist some sytests. ([\#8474](#8474))
- Include the log level in the phone home stats. ([\#8477](#8477))
- Remove outdated sphinx documentation, scripts and configuration. ([\#8480](#8480))
- Clarify error message when plugin config parsers raise an error. ([\#8492](#8492))
- Remove the deprecated `Handlers` object. ([\#8494](#8494))
- Fix a threadsafety bug in unit tests. ([\#8497](#8497))
- Add user agent to user_daily_visits table. ([\#8503](#8503))
- Add type hints to various parts of the code base. ([\#8407](#8407), [\#8505](#8505), [\#8507](#8507), [\#8547](#8547), [\#8562](#8562), [\#8609](#8609))
- Remove unused code from the test framework. ([\#8514](#8514))
- Apply some internal fixes to the `HomeServer` class to make its code more idiomatic and statically-verifiable. ([\#8515](#8515))
- Factor out common code between `RoomMemberHandler._locally_reject_invite` and `EventCreationHandler.create_event`. ([\#8537](#8537))
- Improve database performance by executing more queries without starting transactions. ([\#8542](#8542))
- Rename `Cache` to `DeferredCache`, to better reflect its purpose. ([\#8548](#8548))
- Move metric registration code down into `LruCache`. ([\#8561](#8561), [\#8591](#8591))
- Replace `DeferredCache` with the lighter-weight `LruCache` where possible. ([\#8563](#8563))
- Add virtualenv-generated folders to `.gitignore`. ([\#8566](#8566))
- Add `get_immediate` method to `DeferredCache`. ([\#8568](#8568))
- Fix mypy not properly checking across the codebase, additionally, fix a typing assertion error in `handlers/auth.py`. ([\#8569](#8569))
- Fix `synmark` benchmark runner. ([\#8571](#8571))
- Modify `DeferredCache.get()` to return `Deferred`s instead of `ObservableDeferred`s. ([\#8572](#8572))
- Adjust a protocol-type definition to fit `sqlite3` assertions. ([\#8577](#8577))
- Support macOS on the `synmark` benchmark runner. ([\#8578](#8578))
- Update `mypy` static type checker to 0.790. ([\#8583](#8583), [\#8600](#8600))
- Re-organize the structured logging code to separate the TCP transport handling from the JSON formatting. ([\#8587](#8587))
- Remove extraneous unittest logging decorators from unit tests. ([\#8592](#8592))
- Minor optimisations in caching code. ([\#8593](#8593), [\#8594](#8594))
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Oct 30, 2020
Synapse 1.22.0 (2020-10-27)
===========================

No significant changes.


Synapse 1.22.0rc2 (2020-10-26)
==============================

Bugfixes
--------

- Fix bugs where ephemeral events were not sent to appservices. Broke in v1.22.0rc1. ([\#8648](matrix-org/synapse#8648), [\#8656](matrix-org/synapse#8656))
- Fix `user_daily_visits` table to not have duplicate rows per user/device due to multiple user agents. Broke in v1.22.0rc1. ([\#8654](matrix-org/synapse#8654))

Synapse 1.22.0rc1 (2020-10-22)
==============================

Features
--------

- Add a configuration option for always using the "userinfo endpoint" for OpenID Connect. This fixes support for some identity providers, e.g. GitLab. Contributed by Benjamin Koch. ([\#7658](matrix-org/synapse#7658))
- Add ability for `ThirdPartyEventRules` modules to query and manipulate whether a room is in the public rooms directory. ([\#8292](matrix-org/synapse#8292), [\#8467](matrix-org/synapse#8467))
- Add support for olm fallback keys ([MSC2732](matrix-org/matrix-spec-proposals#2732)). ([\#8312](matrix-org/synapse#8312), [\#8501](matrix-org/synapse#8501))
- Add support for running background tasks in a separate worker process. ([\#8369](matrix-org/synapse#8369), [\#8458](matrix-org/synapse#8458), [\#8489](matrix-org/synapse#8489), [\#8513](matrix-org/synapse#8513), [\#8544](matrix-org/synapse#8544), [\#8599](matrix-org/synapse#8599))
- Add support for device dehydration ([MSC2697](matrix-org/matrix-spec-proposals#2697)). ([\#8380](matrix-org/synapse#8380))
- Add support for [MSC2409](matrix-org/matrix-spec-proposals#2409), which allows sending typing, read receipts, and presence events to appservices. ([\#8437](matrix-org/synapse#8437), [\#8590](matrix-org/synapse#8590))
- Change default room version to "6", per [MSC2788](matrix-org/matrix-spec-proposals#2788). ([\#8461](matrix-org/synapse#8461))
- Add the ability to send non-membership events into a room via the `ModuleApi`. ([\#8479](matrix-org/synapse#8479))
- Increase default upload size limit from 10M to 50M. Contributed by @Akkowicz. ([\#8502](matrix-org/synapse#8502))
- Add support for modifying event content in `ThirdPartyRules` modules. ([\#8535](matrix-org/synapse#8535), [\#8564](matrix-org/synapse#8564))


Bugfixes
--------

- Fix a longstanding bug where invalid ignored users in account data could break clients. ([\#8454](matrix-org/synapse#8454))
- Fix a bug where backfilling a room with an event that was missing the `redacts` field would break. ([\#8457](matrix-org/synapse#8457))
- Don't attempt to respond to some requests if the client has already disconnected. ([\#8465](matrix-org/synapse#8465))
- Fix message duplication if something goes wrong after persisting the event. ([\#8476](matrix-org/synapse#8476))
- Fix incremental sync returning an incorrect `prev_batch` token in timeline section, which when used to paginate returned events that were included in the incremental sync. Broken since v0.16.0. ([\#8486](matrix-org/synapse#8486))
- Expose the `uk.half-shot.msc2778.login.application_service` to clients from the login API. This feature was added in v1.21.0, but was not exposed as a potential login flow. ([\#8504](matrix-org/synapse#8504))
- Fix error code for `/profile/{userId}/displayname` to be `M_BAD_JSON`. ([\#8517](matrix-org/synapse#8517))
- Fix a bug introduced in v1.7.0 that could cause Synapse to insert values from non-state `m.room.retention` events into the `room_retention` database table. ([\#8527](matrix-org/synapse#8527))
- Fix not sending events over federation when using sharded event writers. ([\#8536](matrix-org/synapse#8536))
- Fix a long standing bug where email notifications for encrypted messages were blank. ([\#8545](matrix-org/synapse#8545))
- Fix increase in the number of `There was no active span...` errors logged when using OpenTracing. ([\#8567](matrix-org/synapse#8567))
- Fix a bug that prevented errors encountered during execution of the `synapse_port_db` from being correctly printed. ([\#8585](matrix-org/synapse#8585))
- Fix appservice transactions to only include a maximum of 100 persistent and 100 ephemeral events. ([\#8606](matrix-org/synapse#8606))


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

- Added multi-arch support (arm64,arm/v7) for the docker images. Contributed by @maquis196. ([\#7921](matrix-org/synapse#7921))
- Add support for passing commandline args to the synapse process. Contributed by @samuel-p. ([\#8390](matrix-org/synapse#8390))


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

- Update the directions for using the manhole with coroutines. ([\#8462](matrix-org/synapse#8462))
- Improve readme by adding new shield.io badges. ([\#8493](matrix-org/synapse#8493))
- Added note about docker in manhole.md regarding which ip address to bind to. Contributed by @maquis196. ([\#8526](matrix-org/synapse#8526))
- Document the new behaviour of the `allowed_lifetime_min` and `allowed_lifetime_max` settings in the room retention configuration. ([\#8529](matrix-org/synapse#8529))


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

- Drop unused `device_max_stream_id` table. ([\#8589](matrix-org/synapse#8589))


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

- Check for unreachable code with mypy. ([\#8432](matrix-org/synapse#8432))
- Add unit test for event persister sharding. ([\#8433](matrix-org/synapse#8433))
- Allow events to be sent to clients sooner when using sharded event persisters. ([\#8439](matrix-org/synapse#8439), [\#8488](matrix-org/synapse#8488), [\#8496](matrix-org/synapse#8496), [\#8499](matrix-org/synapse#8499))
- Configure `public_baseurl` when using demo scripts. ([\#8443](matrix-org/synapse#8443))
- Add SQL logging on queries that happen during startup. ([\#8448](matrix-org/synapse#8448))
- Speed up unit tests when using PostgreSQL. ([\#8450](matrix-org/synapse#8450))
- Remove redundant database loads of stream_ordering for events we already have. ([\#8452](matrix-org/synapse#8452))
- Reduce inconsistencies between codepaths for membership and non-membership events. ([\#8463](matrix-org/synapse#8463))
- Combine `SpamCheckerApi` with the more generic `ModuleApi`. ([\#8464](matrix-org/synapse#8464))
- Additional testing for `ThirdPartyEventRules`. ([\#8468](matrix-org/synapse#8468))
- Add `-d` option to `./scripts-dev/lint.sh` to lint files that have changed since the last git commit. ([\#8472](matrix-org/synapse#8472))
- Unblacklist some sytests. ([\#8474](matrix-org/synapse#8474))
- Include the log level in the phone home stats. ([\#8477](matrix-org/synapse#8477))
- Remove outdated sphinx documentation, scripts and configuration. ([\#8480](matrix-org/synapse#8480))
- Clarify error message when plugin config parsers raise an error. ([\#8492](matrix-org/synapse#8492))
- Remove the deprecated `Handlers` object. ([\#8494](matrix-org/synapse#8494))
- Fix a threadsafety bug in unit tests. ([\#8497](matrix-org/synapse#8497))
- Add user agent to user_daily_visits table. ([\#8503](matrix-org/synapse#8503))
- Add type hints to various parts of the code base. ([\#8407](matrix-org/synapse#8407), [\#8505](matrix-org/synapse#8505), [\#8507](matrix-org/synapse#8507), [\#8547](matrix-org/synapse#8547), [\#8562](matrix-org/synapse#8562), [\#8609](matrix-org/synapse#8609))
- Remove unused code from the test framework. ([\#8514](matrix-org/synapse#8514))
- Apply some internal fixes to the `HomeServer` class to make its code more idiomatic and statically-verifiable. ([\#8515](matrix-org/synapse#8515))
- Factor out common code between `RoomMemberHandler._locally_reject_invite` and `EventCreationHandler.create_event`. ([\#8537](matrix-org/synapse#8537))
- Improve database performance by executing more queries without starting transactions. ([\#8542](matrix-org/synapse#8542))
- Rename `Cache` to `DeferredCache`, to better reflect its purpose. ([\#8548](matrix-org/synapse#8548))
- Move metric registration code down into `LruCache`. ([\#8561](matrix-org/synapse#8561), [\#8591](matrix-org/synapse#8591))
- Replace `DeferredCache` with the lighter-weight `LruCache` where possible. ([\#8563](matrix-org/synapse#8563))
- Add virtualenv-generated folders to `.gitignore`. ([\#8566](matrix-org/synapse#8566))
- Add `get_immediate` method to `DeferredCache`. ([\#8568](matrix-org/synapse#8568))
- Fix mypy not properly checking across the codebase, additionally, fix a typing assertion error in `handlers/auth.py`. ([\#8569](matrix-org/synapse#8569))
- Fix `synmark` benchmark runner. ([\#8571](matrix-org/synapse#8571))
- Modify `DeferredCache.get()` to return `Deferred`s instead of `ObservableDeferred`s. ([\#8572](matrix-org/synapse#8572))
- Adjust a protocol-type definition to fit `sqlite3` assertions. ([\#8577](matrix-org/synapse#8577))
- Support macOS on the `synmark` benchmark runner. ([\#8578](matrix-org/synapse#8578))
- Update `mypy` static type checker to 0.790. ([\#8583](matrix-org/synapse#8583), [\#8600](matrix-org/synapse#8600))
- Re-organize the structured logging code to separate the TCP transport handling from the JSON formatting. ([\#8587](matrix-org/synapse#8587))
- Remove extraneous unittest logging decorators from unit tests. ([\#8592](matrix-org/synapse#8592))
- Minor optimisations in caching code. ([\#8593](matrix-org/synapse#8593), [\#8594](matrix-org/synapse#8594))
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