diff options
Diffstat (limited to 'synapse/util/caches/descriptors.py')
| -rw-r--r-- | synapse/util/caches/descriptors.py | 131 |
1 files changed, 64 insertions, 67 deletions
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index f8a07df6b8..861c24809c 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -473,105 +473,101 @@ class CacheListDescriptor(_CacheDescriptorBase): @functools.wraps(self.orig) def wrapped(*args, **kwargs): - # If we're passed a cache_context then we'll want to call its invalidate() - # whenever we are invalidated + # If we're passed a cache_context then we'll want to call its + # invalidate() whenever we are invalidated invalidate_callback = kwargs.pop("on_invalidate", None) arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs) keyargs = [arg_dict[arg_nm] for arg_nm in self.arg_names] list_args = arg_dict[self.list_name] - # cached is a dict arg -> deferred, where deferred results in a - # 2-tuple (`arg`, `result`) results = {} - cached_defers = {} - missing = [] + + def update_results_dict(res, arg): + results[arg] = res + + # list of deferreds to wait for + cached_defers = [] + + missing = set() # If the cache takes a single arg then that is used as the key, # otherwise a tuple is used. if num_args == 1: - def cache_get(arg): - return cache.get(arg, callback=invalidate_callback) + def arg_to_cache_key(arg): + return arg else: - key = list(keyargs) + keylist = list(keyargs) - def cache_get(arg): - key[self.list_pos] = arg - return cache.get(tuple(key), callback=invalidate_callback) + def arg_to_cache_key(arg): + keylist[self.list_pos] = arg + return tuple(keylist) for arg in list_args: try: - res = cache_get(arg) - + res = cache.get(arg_to_cache_key(arg), + callback=invalidate_callback) if not isinstance(res, ObservableDeferred): results[arg] = res elif not res.has_succeeded(): res = res.observe() - res.addCallback(lambda r, arg: (arg, r), arg) - cached_defers[arg] = res + res.addCallback(update_results_dict, arg) + cached_defers.append(res) else: results[arg] = res.get_result() except KeyError: - missing.append(arg) + missing.add(arg) if missing: + # we need an observable deferred for each entry in the list, + # which we put in the cache. Each deferred resolves with the + # relevant result for that key. + deferreds_map = {} + for arg in missing: + deferred = defer.Deferred() + deferreds_map[arg] = deferred + key = arg_to_cache_key(arg) + observable = ObservableDeferred(deferred) + cache.set(key, observable, callback=invalidate_callback) + + def complete_all(res): + # the wrapped function has completed. It returns a + # a dict. We can now resolve the observable deferreds in + # the cache and update our own result map. + for e in missing: + val = res.get(e, None) + deferreds_map[e].callback(val) + results[e] = val + + def errback(f): + # the wrapped function has failed. Invalidate any cache + # entries we're supposed to be populating, and fail + # their deferreds. + for e in missing: + key = arg_to_cache_key(e) + cache.invalidate(key) + deferreds_map[e].errback(f) + + # return the failure, to propagate to our caller. + return f + args_to_call = dict(arg_dict) - args_to_call[self.list_name] = missing + args_to_call[self.list_name] = list(missing) - ret_d = defer.maybeDeferred( + cached_defers.append(defer.maybeDeferred( logcontext.preserve_fn(self.function_to_call), **args_to_call - ) - - ret_d = ObservableDeferred(ret_d) - - # We need to create deferreds for each arg in the list so that - # we can insert the new deferred into the cache. - for arg in missing: - observer = ret_d.observe() - observer.addCallback(lambda r, arg: r.get(arg, None), arg) - - observer = ObservableDeferred(observer) - - if num_args == 1: - cache.set( - arg, observer, - callback=invalidate_callback - ) - - def invalidate(f, key): - cache.invalidate(key) - return f - observer.addErrback(invalidate, arg) - else: - key = list(keyargs) - key[self.list_pos] = arg - cache.set( - tuple(key), observer, - callback=invalidate_callback - ) - - def invalidate(f, key): - cache.invalidate(key) - return f - observer.addErrback(invalidate, tuple(key)) - - res = observer.observe() - res.addCallback(lambda r, arg: (arg, r), arg) - - cached_defers[arg] = res + ).addCallbacks(complete_all, errback)) if cached_defers: - def update_results_dict(res): - results.update(res) - return results - - return logcontext.make_deferred_yieldable(defer.gatherResults( - list(cached_defers.values()), + d = defer.gatherResults( + cached_defers, consumeErrors=True, - ).addCallback(update_results_dict).addErrback( + ).addCallbacks( + lambda _: results, unwrapFirstError - )) + ) + return logcontext.make_deferred_yieldable(d) else: return results @@ -625,7 +621,8 @@ def cachedList(cached_method_name, list_name, num_args=None, inlineCallbacks=Fal cache. Args: - cache (Cache): The underlying cache to use. + cached_method_name (str): The name of the single-item lookup method. + This is only used to find the cache to use. list_name (str): The name of the argument that is the list to use to do batch lookups in the cache. num_args (int): Number of arguments to use as the key in the cache |