diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 8f812f0fd7..73eea157a4 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -15,6 +15,7 @@
import logging
from synapse.api.errors import StoreError
+from synapse.util.async import ObservableDeferred
from synapse.util.logutils import log_function
from synapse.util.logcontext import preserve_context_over_fn, LoggingContext
from synapse.util.lrucache import LruCache
@@ -27,6 +28,7 @@ from twisted.internet import defer
from collections import namedtuple, OrderedDict
import functools
+import inspect
import sys
import time
import threading
@@ -55,9 +57,12 @@ cache_counter = metrics.register_cache(
)
+_CacheSentinel = object()
+
+
class Cache(object):
- def __init__(self, name, max_entries=1000, keylen=1, lru=False):
+ def __init__(self, name, max_entries=1000, keylen=1, lru=True):
if lru:
self.cache = LruCache(max_size=max_entries)
self.max_entries = None
@@ -81,45 +86,44 @@ class Cache(object):
"Cache objects can only be accessed from the main thread"
)
- def get(self, *keyargs):
- if len(keyargs) != self.keylen:
- raise ValueError("Expected a key to have %d items", self.keylen)
-
- if keyargs in self.cache:
+ def get(self, key, default=_CacheSentinel):
+ val = self.cache.get(key, _CacheSentinel)
+ if val is not _CacheSentinel:
cache_counter.inc_hits(self.name)
- return self.cache[keyargs]
+ return val
cache_counter.inc_misses(self.name)
- raise KeyError()
- def update(self, sequence, *args):
+ if default is _CacheSentinel:
+ raise KeyError()
+ else:
+ return default
+
+ def update(self, sequence, key, value):
self.check_thread()
if self.sequence == sequence:
# Only update the cache if the caches sequence number matches the
# number that the cache had before the SELECT was started (SYN-369)
- self.prefill(*args)
-
- def prefill(self, *args): # because I can't *keyargs, value
- keyargs = args[:-1]
- value = args[-1]
-
- if len(keyargs) != self.keylen:
- raise ValueError("Expected a key to have %d items", self.keylen)
+ self.prefill(key, value)
+ def prefill(self, key, value):
if self.max_entries is not None:
while len(self.cache) >= self.max_entries:
self.cache.popitem(last=False)
- self.cache[keyargs] = value
+ self.cache[key] = value
- def invalidate(self, *keyargs):
+ def invalidate(self, key):
self.check_thread()
- if len(keyargs) != self.keylen:
- raise ValueError("Expected a key to have %d items", self.keylen)
+ 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)
self.sequence += 1
- self.cache.pop(keyargs, None)
+ self.cache.pop(key, None)
def invalidate_all(self):
self.check_thread()
@@ -130,6 +134,9 @@ class Cache(object):
class CacheDescriptor(object):
""" A method decorator that applies a memoizing cache around the function.
+ This caches deferreds, rather than the results themselves. Deferreds that
+ fail are removed from the cache.
+
The function is presumed to take zero or more arguments, which are used in
a tuple as the key for the cache. Hits are served directly from the cache;
misses use the function body to generate the value.
@@ -141,58 +148,92 @@ class CacheDescriptor(object):
which can be used to insert values into the cache specifically, without
calling the calculation function.
"""
- def __init__(self, orig, max_entries=1000, num_args=1, lru=False):
+ def __init__(self, orig, max_entries=1000, num_args=1, lru=True,
+ inlineCallbacks=False):
self.orig = orig
+ if inlineCallbacks:
+ self.function_to_call = defer.inlineCallbacks(orig)
+ else:
+ self.function_to_call = orig
+
self.max_entries = max_entries
self.num_args = num_args
self.lru = lru
- def __get__(self, obj, objtype=None):
- cache = Cache(
+ self.arg_names = inspect.getargspec(orig).args[1:num_args+1]
+
+ 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__,)
+ )
+
+ self.cache = Cache(
name=self.orig.__name__,
max_entries=self.max_entries,
keylen=self.num_args,
lru=self.lru,
)
+ def __get__(self, obj, objtype=None):
+
@functools.wraps(self.orig)
- @defer.inlineCallbacks
- def wrapped(*keyargs):
+ def wrapped(*args, **kwargs):
+ arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs)
+ cache_key = tuple(arg_dict[arg_nm] for arg_nm in self.arg_names)
try:
- cached_result = cache.get(*keyargs[:self.num_args])
+ cached_result_d = self.cache.get(cache_key)
+
+ observer = cached_result_d.observe()
if DEBUG_CACHES:
- actual_result = yield self.orig(obj, *keyargs)
- if actual_result != cached_result:
- logger.error(
- "Stale cache entry %s%r: cached: %r, actual %r",
- self.orig.__name__, keyargs,
- cached_result, actual_result,
- )
- raise ValueError("Stale cache entry")
- defer.returnValue(cached_result)
+ @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)
+
+ return observer
except KeyError:
# Get the sequence number of the cache before reading from the
# database so that we can tell if the cache is invalidated
# while the SELECT is executing (SYN-369)
- sequence = cache.sequence
+ sequence = self.cache.sequence
+
+ ret = defer.maybeDeferred(
+ self.function_to_call,
+ obj, *args, **kwargs
+ )
+
+ def onErr(f):
+ self.cache.invalidate(cache_key)
+ return f
- ret = yield self.orig(obj, *keyargs)
+ ret.addErrback(onErr)
- cache.update(sequence, *keyargs[:self.num_args] + (ret,))
+ ret = ObservableDeferred(ret, consumeErrors=True)
+ self.cache.update(sequence, cache_key, ret)
- defer.returnValue(ret)
+ return ret.observe()
- wrapped.invalidate = cache.invalidate
- wrapped.invalidate_all = cache.invalidate_all
- wrapped.prefill = cache.prefill
+ wrapped.invalidate = self.cache.invalidate
+ wrapped.invalidate_all = self.cache.invalidate_all
+ wrapped.prefill = self.cache.prefill
obj.__dict__[self.orig.__name__] = wrapped
return wrapped
-def cached(max_entries=1000, num_args=1, lru=False):
+def cached(max_entries=1000, num_args=1, lru=True):
return lambda orig: CacheDescriptor(
orig,
max_entries=max_entries,
@@ -201,6 +242,16 @@ def cached(max_entries=1000, num_args=1, lru=False):
)
+def cachedInlineCallbacks(max_entries=1000, num_args=1, lru=False):
+ return lambda orig: CacheDescriptor(
+ orig,
+ max_entries=max_entries,
+ num_args=num_args,
+ lru=lru,
+ inlineCallbacks=True,
+ )
+
+
class LoggingTransaction(object):
"""An object that almost-transparently proxies for the 'txn' object
passed to the constructor. Adds logging and metrics to the .execute()
|
