Merge pull request #8593 from matrix-org/rav/cache_hacking/3

Optimisation in DeferredCache.set
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Richard van der Hoff 2020-10-21 22:57:23 +01:00 committed by GitHub
commit 15d5553d9e
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2 changed files with 16 additions and 3 deletions

1
changelog.d/8593.misc Normal file
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@ -0,0 +1 @@
Minor optimisations in caching code.

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@ -31,6 +31,7 @@ from typing import (
from prometheus_client import Gauge from prometheus_client import Gauge
from twisted.internet import defer from twisted.internet import defer
from twisted.python import failure
from synapse.util.async_helpers import ObservableDeferred from synapse.util.async_helpers import ObservableDeferred
from synapse.util.caches.lrucache import LruCache from synapse.util.caches.lrucache import LruCache
@ -214,9 +215,6 @@ class DeferredCache(Generic[KT, VT]):
callbacks = [callback] if callback else [] callbacks = [callback] if callback else []
self.check_thread() self.check_thread()
observable = ObservableDeferred(value, consumeErrors=True)
observer = observable.observe()
entry = CacheEntry(deferred=observable, callbacks=callbacks)
existing_entry = self._pending_deferred_cache.pop(key, None) existing_entry = self._pending_deferred_cache.pop(key, None)
if existing_entry: if existing_entry:
@ -224,6 +222,20 @@ class DeferredCache(Generic[KT, VT]):
# XXX: why don't we invalidate the entry in `self.cache` yet? # XXX: why don't we invalidate the entry in `self.cache` yet?
# we can save a whole load of effort if the deferred is ready.
if value.called:
result = value.result
if not isinstance(result, failure.Failure):
self.cache.set(key, result, callbacks)
return value
# otherwise, we'll add an entry to the _pending_deferred_cache for now,
# and add callbacks to add it to the cache properly later.
observable = ObservableDeferred(value, consumeErrors=True)
observer = observable.observe()
entry = CacheEntry(deferred=observable, callbacks=callbacks)
self._pending_deferred_cache[key] = entry self._pending_deferred_cache[key] = entry
def compare_and_pop(): def compare_and_pop():