diff options
Diffstat (limited to 'synapse/util/caches/descriptors.py')
| -rw-r--r-- | synapse/util/caches/descriptors.py | 165 |
1 files changed, 86 insertions, 79 deletions
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 998de70d29..5c30ed235d 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 @@ -189,7 +186,55 @@ class Cache(object): self.cache.clear() -class CacheDescriptor(object): +class _CacheDescriptorBase(object): + def __init__(self, orig, num_args, inlineCallbacks, cache_context=False): + self.orig = orig + + if inlineCallbacks: + self.function_to_call = defer.inlineCallbacks(orig) + else: + self.function_to_call = orig + + arg_spec = inspect.getargspec(orig) + all_args = arg_spec.args + + if "cache_context" in all_args: + if not cache_context: + raise ValueError( + "Cannot have a 'cache_context' arg without setting" + " cache_context=True" + ) + elif cache_context: + raise ValueError( + "Cannot have cache_context=True without having an arg" + " named `cache_context`" + ) + + if num_args is None: + num_args = len(all_args) - 1 + if cache_context: + num_args -= 1 + + if len(all_args) < num_args + 1: + raise Exception( + "Not enough explicit positional arguments to key off for %r: " + "got %i args, but wanted %i. (@cached cannot key off *args or " + "**kwargs)" + % (orig.__name__, len(all_args), num_args) + ) + + self.num_args = num_args + self.arg_names = all_args[1:num_args + 1] + + if "cache_context" in self.arg_names: + raise Exception( + "cache_context arg cannot be included among the cache keys" + ) + + self.add_cache_context = cache_context + + +class CacheDescriptor(_CacheDescriptorBase): """ A method decorator that applies a memoizing cache around the function. This caches deferreds, rather than the results themselves. Deferreds that @@ -217,52 +262,24 @@ class CacheDescriptor(object): r2 = yield self.bar2(key, on_invalidate=cache_context.invalidate) defer.returnValue(r1 + r2) + Args: + num_args (int): number of positional arguments (excluding ``self`` and + ``cache_context``) to use as cache keys. Defaults to all named + args of the function. """ - def __init__(self, orig, max_entries=1000, num_args=1, tree=False, + def __init__(self, orig, max_entries=1000, num_args=None, tree=False, inlineCallbacks=False, cache_context=False, iterable=False): - max_entries = int(max_entries * CACHE_SIZE_FACTOR) - self.orig = orig + super(CacheDescriptor, self).__init__( + orig, num_args=num_args, inlineCallbacks=inlineCallbacks, + cache_context=cache_context) - if inlineCallbacks: - self.function_to_call = defer.inlineCallbacks(orig) - else: - self.function_to_call = orig + max_entries = int(max_entries * CACHE_SIZE_FACTOR) self.max_entries = max_entries - self.num_args = num_args self.tree = tree - self.iterable = iterable - all_args = inspect.getargspec(orig) - self.arg_names = all_args.args[1:num_args + 1] - - if "cache_context" in all_args.args: - if not cache_context: - raise ValueError( - "Cannot have a 'cache_context' arg without setting" - " cache_context=True" - ) - try: - self.arg_names.remove("cache_context") - except ValueError: - pass - elif cache_context: - raise ValueError( - "Cannot have cache_context=True without having an arg" - " named `cache_context`" - ) - - self.add_cache_context = cache_context - - if len(self.arg_names) < self.num_args: - raise Exception( - "Not enough explicit positional arguments to key off of for %r." - " (@cached cannot key off of *args or **kwargs)" - % (orig.__name__,) - ) - def __get__(self, obj, objtype=None): cache = Cache( name=self.orig.__name__, @@ -308,11 +325,9 @@ class CacheDescriptor(object): 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 ) @@ -322,10 +337,11 @@ class CacheDescriptor(object): 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()) + return logcontext.make_deferred_yieldable(observer) wrapped.invalidate = cache.invalidate wrapped.invalidate_all = cache.invalidate_all @@ -338,48 +354,40 @@ class CacheDescriptor(object): return wrapped -class CacheListDescriptor(object): +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=1, + def __init__(self, orig, cached_method_name, list_name, num_args=None, inlineCallbacks=False): """ Args: orig (function) - method_name (str); The name of the chached method. + cached_method_name (str): The name of the chached method. list_name (str): Name of the argument which is the bulk lookup list - num_args (int) + num_args (int): number of positional arguments (excluding ``self``, + but including list_name) to use as cache keys. Defaults to all + named args of the function. inlineCallbacks (bool): Whether orig is a generator that should be wrapped by defer.inlineCallbacks """ - self.orig = orig + super(CacheListDescriptor, self).__init__( + orig, num_args=num_args, inlineCallbacks=inlineCallbacks) - if inlineCallbacks: - self.function_to_call = defer.inlineCallbacks(orig) - else: - self.function_to_call = orig - - self.num_args = num_args self.list_name = list_name - self.arg_names = inspect.getargspec(orig).args[1:num_args + 1] self.list_pos = self.arg_names.index(self.list_name) - self.cached_method_name = cached_method_name self.sentinel = object() - if len(self.arg_names) < self.num_args: - raise Exception( - "Not enough explicit positional arguments to key off of for %r." - " (@cached cannot key off of *args or **kwars)" - % (orig.__name__,) - ) - if self.list_name not in self.arg_names: raise Exception( "Couldn't see arguments %r for %r." @@ -425,8 +433,7 @@ class CacheListDescriptor(object): 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 ) @@ -435,8 +442,7 @@ class CacheListDescriptor(object): # 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) @@ -463,7 +469,7 @@ class CacheListDescriptor(object): 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( @@ -487,7 +493,7 @@ class _CacheContext(namedtuple("_CacheContext", ("cache", "key"))): self.cache.invalidate(self.key) -def cached(max_entries=1000, num_args=1, tree=False, cache_context=False, +def cached(max_entries=1000, num_args=None, tree=False, cache_context=False, iterable=False): return lambda orig: CacheDescriptor( orig, @@ -499,8 +505,8 @@ def cached(max_entries=1000, num_args=1, tree=False, cache_context=False, ) -def cachedInlineCallbacks(max_entries=1000, num_args=1, tree=False, cache_context=False, - iterable=False): +def cachedInlineCallbacks(max_entries=1000, num_args=None, tree=False, + cache_context=False, iterable=False): return lambda orig: CacheDescriptor( orig, max_entries=max_entries, @@ -512,7 +518,7 @@ def cachedInlineCallbacks(max_entries=1000, num_args=1, tree=False, cache_contex ) -def cachedList(cached_method_name, list_name, num_args=1, inlineCallbacks=False): +def cachedList(cached_method_name, list_name, num_args=None, inlineCallbacks=False): """Creates a descriptor that wraps a function in a `CacheListDescriptor`. Used to do batch lookups for an already created cache. A single argument @@ -525,7 +531,8 @@ def cachedList(cached_method_name, list_name, num_args=1, inlineCallbacks=False) cache (Cache): The underlying 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. + num_args (int): Number of arguments to use as the key in the cache + (including list_name). Defaults to all named parameters. inlineCallbacks (bool): Should the function be wrapped in an `defer.inlineCallbacks`? |