diff options
Diffstat (limited to '')
| -rw-r--r-- | synapse/util/caches/response_cache.py | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/synapse/util/caches/response_cache.py b/synapse/util/caches/response_cache.py index 0c2c347953..7f79333e96 100644 --- a/synapse/util/caches/response_cache.py +++ b/synapse/util/caches/response_cache.py @@ -14,6 +14,8 @@ # limitations under the License. import logging +from twisted.internet import defer + from synapse.util.async import ObservableDeferred from synapse.util.caches import metrics as cache_metrics from synapse.util.logcontext import make_deferred_yieldable, run_in_background @@ -48,15 +50,21 @@ class ResponseCache(object): def get(self, key): """Look up the given key. - Returns a deferred which doesn't follow the synapse logcontext rules, - so you'll probably want to make_deferred_yieldable it. + Can return either a new Deferred (which also doesn't follow the synapse + logcontext rules), or, if the request has completed, the actual + result. You will probably want to make_deferred_yieldable the result. + + If there is no entry for the key, returns None. It is worth noting that + this means there is no way to distinguish a completed result of None + from an absent cache entry. Args: key (hashable): Returns: - twisted.internet.defer.Deferred|None: None if there is no entry - for this key; otherwise a deferred result. + twisted.internet.defer.Deferred|None|E: None if there is no entry + for this key; otherwise either a deferred result or the result + itself. """ result = self.pending_result_cache.get(key) if result is not None: @@ -73,19 +81,17 @@ class ResponseCache(object): you should wrap normal synapse deferreds with logcontext.run_in_background). - Returns a new Deferred which also doesn't follow the synapse logcontext - rules, so you will want to make_deferred_yieldable it - - (TODO: before using this more widely, it might make sense to refactor - it and get() so that they do the necessary wrapping rather than having - to do it everywhere ResponseCache is used.) + Can return either a new Deferred (which also doesn't follow the synapse + logcontext rules), or, if *deferred* was already complete, the actual + result. You will probably want to make_deferred_yieldable the result. Args: key (hashable): - deferred (twisted.internet.defer.Deferred): + deferred (twisted.internet.defer.Deferred[T): Returns: - twisted.internet.defer.Deferred + twisted.internet.defer.Deferred[T]|T: a new deferred, or the actual + result. """ result = ObservableDeferred(deferred, consumeErrors=True) self.pending_result_cache[key] = result @@ -144,7 +150,7 @@ class ResponseCache(object): self._name, key) d = run_in_background(callback, *args, **kwargs) result = self.set(key, d) - elif result.called: + elif not isinstance(result, defer.Deferred) or result.called: logger.info("[%s]: using completed cached result for [%s]", self._name, key) else: |