diff options
Diffstat (limited to 'synapse/util/caches/descriptors.py')
| -rw-r--r-- | synapse/util/caches/descriptors.py | 128 |
1 files changed, 93 insertions, 35 deletions
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 5c30ed235d..48dcbafeef 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -18,8 +18,9 @@ from synapse.util.async import ObservableDeferred 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.stringutils import to_ascii -from . import DEBUG_CACHES, register_cache +from . import register_cache from twisted.internet import defer from collections import namedtuple @@ -76,7 +77,7 @@ class Cache(object): self.cache = LruCache( max_size=max_entries, keylen=keylen, cache_type=cache_type, - size_callback=(lambda d: len(d.result)) if iterable else None, + size_callback=(lambda d: len(d)) if iterable else None, ) self.name = name @@ -95,13 +96,26 @@ class Cache(object): "Cache objects can only be accessed from the main thread" ) - def get(self, key, default=_CacheSentinel, callback=None): + def get(self, key, default=_CacheSentinel, callback=None, update_metrics=True): + """Looks the key up in the caches. + + Args: + key(tuple) + default: What is returned if key is not in the caches. If not + specified then function throws KeyError instead + callback(fn): Gets called when the entry in the cache is invalidated + update_metrics (bool): whether to update the cache hit rate metrics + + Returns: + Either a Deferred or the raw result + """ callbacks = [callback] if callback else [] val = self._pending_deferred_cache.get(key, _CacheSentinel) if val is not _CacheSentinel: if val.sequence == self.sequence: val.callbacks.update(callbacks) - self.metrics.inc_hits() + if update_metrics: + self.metrics.inc_hits() return val.deferred val = self.cache.get(key, _CacheSentinel, callbacks=callbacks) @@ -109,7 +123,8 @@ class Cache(object): self.metrics.inc_hits() return val - self.metrics.inc_misses() + if update_metrics: + self.metrics.inc_misses() if default is _CacheSentinel: raise KeyError() @@ -137,7 +152,7 @@ class Cache(object): if self.sequence == entry.sequence: existing_entry = self._pending_deferred_cache.pop(key, None) if existing_entry is entry: - self.cache.set(key, entry.deferred, entry.callbacks) + self.cache.set(key, result, entry.callbacks) else: entry.invalidate() else: @@ -152,10 +167,6 @@ class Cache(object): def invalidate(self, key): self.check_thread() - if not isinstance(key, tuple): - raise TypeError( - "The cache key must be a tuple not %r" % (type(key),) - ) # Increment the sequence number so that any SELECT statements that # raced with the INSERT don't update the cache (SYN-369) @@ -224,8 +235,20 @@ 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" @@ -289,18 +312,47 @@ class CacheDescriptor(_CacheDescriptorBase): iterable=self.iterable, ) + def get_cache_key_gen(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] + + # By default our cache key is a tuple, but if there is only one item + # then don't bother wrapping in a tuple. This is to save memory. + if self.num_args == 1: + nm = self.arg_names[0] + + def get_cache_key(args, kwargs): + if nm in kwargs: + return kwargs[nm] + elif len(args): + return args[0] + else: + return self.arg_defaults[nm] + else: + def get_cache_key(args, kwargs): + return tuple(get_cache_key_gen(args, kwargs)) + @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 = get_cache_key(args, kwargs) # Add our own `cache_context` to argument list if the wrapped function # has asked for one @@ -310,20 +362,10 @@ class CacheDescriptor(_CacheDescriptorBase): try: cached_result_d = cache.get(cache_key, callback=invalidate_callback) - observer = cached_result_d.observe() - if DEBUG_CACHES: - @defer.inlineCallbacks - def check_result(cached_result): - actual_result = yield self.function_to_call(obj, *args, **kwargs) - if actual_result != cached_result: - logger.error( - "Stale cache entry %s%r: cached: %r, actual %r", - self.orig.__name__, cache_key, - cached_result, actual_result, - ) - raise ValueError("Stale cache entry") - defer.returnValue(cached_result) - observer.addCallback(check_result) + if isinstance(cached_result_d, ObservableDeferred): + observer = cached_result_d.observe() + else: + observer = cached_result_d except KeyError: ret = defer.maybeDeferred( @@ -337,16 +379,30 @@ class CacheDescriptor(_CacheDescriptorBase): ret.addErrback(onErr) + # If our cache_key is a string, try to convert to ascii to save + # a bit of space in large caches + if isinstance(cache_key, basestring): + cache_key = to_ascii(cache_key) + result_d = ObservableDeferred(ret, consumeErrors=True) cache.set(cache_key, result_d, callback=invalidate_callback) observer = result_d.observe() - return logcontext.make_deferred_yieldable(observer) + if isinstance(observer, defer.Deferred): + return logcontext.make_deferred_yieldable(observer) + else: + return observer + + if self.num_args == 1: + wrapped.invalidate = lambda key: cache.invalidate(key[0]) + wrapped.prefill = lambda key, val: cache.prefill(key[0], val) + else: + wrapped.invalidate = cache.invalidate + wrapped.invalidate_all = cache.invalidate_all + wrapped.invalidate_many = cache.invalidate_many + wrapped.prefill = cache.prefill - wrapped.invalidate = cache.invalidate wrapped.invalidate_all = cache.invalidate_all - wrapped.invalidate_many = cache.invalidate_many - wrapped.prefill = cache.prefill wrapped.cache = cache obj.__dict__[self.orig.__name__] = wrapped @@ -419,7 +475,9 @@ class CacheListDescriptor(_CacheDescriptorBase): try: res = cache.get(tuple(key), callback=invalidate_callback) - if not res.has_succeeded(): + 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 |