diff options
Diffstat (limited to 'synapse/util')
| -rw-r--r-- | synapse/util/async.py | 7 | ||||
| -rw-r--r-- | synapse/util/caches/descriptors.py | 70 | ||||
| -rw-r--r-- | synapse/util/logcontext.py | 29 |
3 files changed, 78 insertions, 28 deletions
diff --git a/synapse/util/async.py b/synapse/util/async.py index 35380bf8ed..1453faf0ef 100644 --- a/synapse/util/async.py +++ b/synapse/util/async.py @@ -89,6 +89,11 @@ class ObservableDeferred(object): deferred.addCallbacks(callback, errback) def observe(self): + """Observe the underlying deferred. + + Can return either a deferred if the underlying deferred is still pending + (or has failed), or the actual value. Callers may need to use maybeDeferred. + """ if not self._result: d = defer.Deferred() @@ -101,7 +106,7 @@ class ObservableDeferred(object): return d else: success, res = self._result - return defer.succeed(res) if success else defer.fail(res) + return res if success else defer.fail(res) def observers(self): return self._observers diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 19595df422..9d0d0be1f9 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -15,12 +15,9 @@ import logging from synapse.util.async import ObservableDeferred -from synapse.util import unwrapFirstError +from synapse.util import unwrapFirstError, logcontext from synapse.util.caches.lrucache import LruCache from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry -from synapse.util.logcontext import ( - PreserveLoggingContext, preserve_context_over_deferred, preserve_context_over_fn -) from . import DEBUG_CACHES, register_cache @@ -227,8 +224,20 @@ class _CacheDescriptorBase(object): ) self.num_args = num_args + + # list of the names of the args used as the cache key self.arg_names = all_args[1:num_args + 1] + # self.arg_defaults is a map of arg name to its default value for each + # argument that has a default value + if arg_spec.defaults: + self.arg_defaults = dict(zip( + all_args[-len(arg_spec.defaults):], + arg_spec.defaults + )) + else: + self.arg_defaults = {} + if "cache_context" in self.arg_names: raise Exception( "cache_context arg cannot be included among the cache keys" @@ -292,18 +301,31 @@ class CacheDescriptor(_CacheDescriptorBase): iterable=self.iterable, ) + def get_cache_key(args, kwargs): + """Given some args/kwargs return a generator that resolves into + the cache_key. + + We loop through each arg name, looking up if its in the `kwargs`, + otherwise using the next argument in `args`. If there are no more + args then we try looking the arg name up in the defaults + """ + pos = 0 + for nm in self.arg_names: + if nm in kwargs: + yield kwargs[nm] + elif pos < len(args): + yield args[pos] + pos += 1 + else: + yield self.arg_defaults[nm] + @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 invalidate_callback = kwargs.pop("on_invalidate", None) - # Add temp cache_context so inspect.getcallargs doesn't explode - if self.add_cache_context: - kwargs["cache_context"] = None - - arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs) - cache_key = tuple(arg_dict[arg_nm] for arg_nm in self.arg_names) + cache_key = tuple(get_cache_key(args, kwargs)) # Add our own `cache_context` to argument list if the wrapped function # has asked for one @@ -328,11 +350,9 @@ class CacheDescriptor(_CacheDescriptorBase): defer.returnValue(cached_result) observer.addCallback(check_result) - return preserve_context_over_deferred(observer) except KeyError: ret = defer.maybeDeferred( - preserve_context_over_fn, - self.function_to_call, + logcontext.preserve_fn(self.function_to_call), obj, *args, **kwargs ) @@ -342,10 +362,14 @@ class CacheDescriptor(_CacheDescriptorBase): ret.addErrback(onErr) - ret = ObservableDeferred(ret, consumeErrors=True) - cache.set(cache_key, ret, callback=invalidate_callback) + result_d = ObservableDeferred(ret, consumeErrors=True) + cache.set(cache_key, result_d, callback=invalidate_callback) + observer = result_d.observe() - return preserve_context_over_deferred(ret.observe()) + if isinstance(observer, defer.Deferred): + return logcontext.make_deferred_yieldable(observer) + else: + return observer wrapped.invalidate = cache.invalidate wrapped.invalidate_all = cache.invalidate_all @@ -362,7 +386,11 @@ class CacheListDescriptor(_CacheDescriptorBase): """Wraps an existing cache to support bulk fetching of keys. Given a list of keys it looks in the cache to find any hits, then passes - the list of missing keys to the wrapped fucntion. + the list of missing keys to the wrapped function. + + Once wrapped, the function returns either a Deferred which resolves to + the list of results, or (if all results were cached), just the list of + results. """ def __init__(self, orig, cached_method_name, list_name, num_args=None, @@ -433,8 +461,7 @@ class CacheListDescriptor(_CacheDescriptorBase): args_to_call[self.list_name] = missing ret_d = defer.maybeDeferred( - preserve_context_over_fn, - self.function_to_call, + logcontext.preserve_fn(self.function_to_call), **args_to_call ) @@ -443,8 +470,7 @@ class CacheListDescriptor(_CacheDescriptorBase): # 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: - with PreserveLoggingContext(): - observer = ret_d.observe() + observer = ret_d.observe() observer.addCallback(lambda r, arg: r.get(arg, None), arg) observer = ObservableDeferred(observer) @@ -471,7 +497,7 @@ class CacheListDescriptor(_CacheDescriptorBase): results.update(res) return results - return preserve_context_over_deferred(defer.gatherResults( + return logcontext.make_deferred_yieldable(defer.gatherResults( cached_defers.values(), consumeErrors=True, ).addCallback(update_results_dict).addErrback( diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py index ff67b1d794..990216145e 100644 --- a/synapse/util/logcontext.py +++ b/synapse/util/logcontext.py @@ -310,6 +310,10 @@ def preserve_context_over_fn(fn, *args, **kwargs): def preserve_context_over_deferred(deferred, context=None): """Given a deferred wrap it such that any callbacks added later to it will be invoked with the current context. + + Deprecated: this almost certainly doesn't do want you want, ie make + the deferred follow the synapse logcontext rules: try + ``make_deferred_yieldable`` instead. """ if context is None: context = LoggingContext.current_context() @@ -330,12 +334,8 @@ def preserve_fn(f): LoggingContext.set_current_context(LoggingContext.sentinel) return result - # XXX: why is this here rather than inside g? surely we want to preserve - # the context from the time the function was called, not when it was - # wrapped? - current = LoggingContext.current_context() - def g(*args, **kwargs): + current = LoggingContext.current_context() res = f(*args, **kwargs) if isinstance(res, defer.Deferred) and not res.called: # The function will have reset the context before returning, so @@ -359,6 +359,25 @@ def preserve_fn(f): return g +@defer.inlineCallbacks +def make_deferred_yieldable(deferred): + """Given a deferred, make it follow the Synapse logcontext rules: + + If the deferred has completed (or is not actually a Deferred), essentially + does nothing (just returns another completed deferred with the + result/failure). + + If the deferred has not yet completed, resets the logcontext before + returning a deferred. Then, when the deferred completes, restores the + current logcontext before running callbacks/errbacks. + + (This is more-or-less the opposite operation to preserve_fn.) + """ + with PreserveLoggingContext(): + r = yield deferred + defer.returnValue(r) + + # modules to ignore in `logcontext_tracer` _to_ignore = [ "synapse.util.logcontext", |