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
|
