Add concept of cache contexts
Erik Johnston
parent
5674ea3e6c
commit
4161ff2fc4
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@ -55,7 +55,7 @@ class Cache(object):
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)
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def __init__(self, name, max_entries=1000, keylen=1, lru=True, tree=False):
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if lru:
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if True:
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cache_type = TreeCache if tree else dict
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self.cache = LruCache(
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max_size=max_entries, keylen=keylen, cache_type=cache_type
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@ -81,8 +81,8 @@ class Cache(object):
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"Cache objects can only be accessed from the main thread"
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)
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def get(self, key, default=_CacheSentinel):
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val = self.cache.get(key, _CacheSentinel)
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def get(self, key, default=_CacheSentinel, callback=None):
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val = self.cache.get(key, _CacheSentinel, callback=callback)
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if val is not _CacheSentinel:
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self.metrics.inc_hits()
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return val
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@ -94,19 +94,19 @@ class Cache(object):
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else:
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return default
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def update(self, sequence, key, value):
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def update(self, sequence, key, value, callback=None):
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self.check_thread()
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if self.sequence == sequence:
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# Only update the cache if the caches sequence number matches the
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# number that the cache had before the SELECT was started (SYN-369)
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self.prefill(key, value)
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self.prefill(key, value, callback=callback)
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def prefill(self, key, value):
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def prefill(self, key, value, callback=None):
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if self.max_entries is not None:
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while len(self.cache) >= self.max_entries:
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self.cache.popitem(last=False)
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self.cache.popitem(last=False, callback=None)
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self.cache[key] = value
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self.cache.set(key, value, callback=callback)
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def invalidate(self, key):
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self.check_thread()
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@ -151,6 +151,18 @@ class CacheDescriptor(object):
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The wrapped function has another additional callable, called "prefill",
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which can be used to insert values into the cache specifically, without
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calling the calculation function.
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Cached functions can be "chained" (i.e. a cached function can call other cached
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functions and get appropriately invalidated when they called caches are
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invalidated) by adding a special "cache_context" argument to the function
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and passing that as a kwarg to all caches called. For example::
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@cachedInlineCallbacks()
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def foo(self, key, cache_context):
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r1 = yield self.bar1(key, cache_context=cache_context)
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r2 = yield self.bar2(key, cache_context=cache_context)
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defer.returnValue(r1 + r2)
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"""
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def __init__(self, orig, max_entries=1000, num_args=1, lru=True, tree=False,
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inlineCallbacks=False):
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@ -168,7 +180,13 @@ class CacheDescriptor(object):
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self.lru = lru
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self.tree = tree
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self.arg_names = inspect.getargspec(orig).args[1:num_args + 1]
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all_args = inspect.getargspec(orig)
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self.arg_names = all_args.args[1:num_args + 1]
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if "cache_context" in self.arg_names:
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self.arg_names.remove("cache_context")
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self.add_cache_context = "cache_context" in all_args.args
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if len(self.arg_names) < self.num_args:
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raise Exception(
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@ -188,10 +206,23 @@ class CacheDescriptor(object):
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@functools.wraps(self.orig)
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def wrapped(*args, **kwargs):
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cache_context = kwargs.pop("cache_context", None)
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if cache_context:
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context_callback = cache_context.invalidate
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else:
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context_callback = None
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self_context = _CacheContext(cache, None)
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if self.add_cache_context:
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kwargs["cache_context"] = self_context
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arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs)
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cache_key = tuple(arg_dict[arg_nm] for arg_nm in self.arg_names)
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self_context.key = cache_key
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try:
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cached_result_d = cache.get(cache_key)
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cached_result_d = cache.get(cache_key, callback=context_callback)
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observer = cached_result_d.observe()
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if DEBUG_CACHES:
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@ -228,7 +259,7 @@ class CacheDescriptor(object):
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ret.addErrback(onErr)
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ret = ObservableDeferred(ret, consumeErrors=True)
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cache.update(sequence, cache_key, ret)
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cache.update(sequence, cache_key, ret, callback=context_callback)
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return preserve_context_over_deferred(ret.observe())
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@ -297,6 +328,12 @@ class CacheListDescriptor(object):
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@functools.wraps(self.orig)
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def wrapped(*args, **kwargs):
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cache_context = kwargs.pop("cache_context", None)
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if cache_context:
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context_callback = cache_context.invalidate
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else:
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context_callback = None
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arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs)
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keyargs = [arg_dict[arg_nm] for arg_nm in self.arg_names]
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list_args = arg_dict[self.list_name]
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@ -311,7 +348,7 @@ class CacheListDescriptor(object):
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key[self.list_pos] = arg
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try:
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res = cache.get(tuple(key))
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res = cache.get(tuple(key), callback=context_callback)
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if not res.has_succeeded():
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res = res.observe()
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res.addCallback(lambda r, arg: (arg, r), arg)
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@ -345,7 +382,10 @@ class CacheListDescriptor(object):
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key = list(keyargs)
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key[self.list_pos] = arg
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cache.update(sequence, tuple(key), observer)
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cache.update(
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sequence, tuple(key), observer,
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callback=context_callback
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)
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def invalidate(f, key):
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cache.invalidate(key)
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@ -376,6 +416,17 @@ class CacheListDescriptor(object):
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return wrapped
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class _CacheContext(object):
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__slots__ = ["cache", "key"]
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def __init__(self, cache, key):
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self.cache = cache
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self.key = key
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def invalidate(self):
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self.cache.invalidate(self.key)
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def cached(max_entries=1000, num_args=1, lru=True, tree=False):
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return lambda orig: CacheDescriptor(
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orig,
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@ -30,13 +30,14 @@ def enumerate_leaves(node, depth):
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class _Node(object):
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__slots__ = ["prev_node", "next_node", "key", "value"]
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__slots__ = ["prev_node", "next_node", "key", "value", "callbacks"]
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def __init__(self, prev_node, next_node, key, value):
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def __init__(self, prev_node, next_node, key, value, callbacks=[]):
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self.prev_node = prev_node
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self.next_node = next_node
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self.key = key
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self.value = value
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self.callbacks = callbacks
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class LruCache(object):
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@ -44,6 +45,9 @@ class LruCache(object):
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Least-recently-used cache.
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Supports del_multi only if cache_type=TreeCache
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If cache_type=TreeCache, all keys must be tuples.
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Can also set callbacks on objects when getting/setting which are fired
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when that key gets invalidated/evicted.
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"""
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def __init__(self, max_size, keylen=1, cache_type=dict):
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cache = cache_type()
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@ -62,10 +66,10 @@ class LruCache(object):
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return inner
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def add_node(key, value):
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def add_node(key, value, callbacks=[]):
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prev_node = list_root
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next_node = prev_node.next_node
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node = _Node(prev_node, next_node, key, value)
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node = _Node(prev_node, next_node, key, value, callbacks)
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prev_node.next_node = node
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next_node.prev_node = node
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cache[key] = node
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@ -88,23 +92,41 @@ class LruCache(object):
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prev_node.next_node = next_node
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next_node.prev_node = prev_node
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for cb in node.callbacks:
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cb()
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node.callbacks = []
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@synchronized
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def cache_get(key, default=None):
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def cache_get(key, default=None, callback=None):
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node = cache.get(key, None)
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if node is not None:
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move_node_to_front(node)
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if callback:
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node.callbacks.append(callback)
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return node.value
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else:
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return default
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@synchronized
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def cache_set(key, value):
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def cache_set(key, value, callback=None):
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node = cache.get(key, None)
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if node is not None:
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if value != node.value:
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for cb in node.callbacks:
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cb()
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node.callbacks = []
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if callback:
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node.callbacks.append(callback)
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move_node_to_front(node)
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node.value = value
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else:
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add_node(key, value)
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if callback:
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callbacks = [callback]
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else:
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callbacks = []
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add_node(key, value, callbacks)
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if len(cache) > max_size:
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todelete = list_root.prev_node
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delete_node(todelete)
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@ -148,6 +170,9 @@ class LruCache(object):
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def cache_clear():
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list_root.next_node = list_root
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list_root.prev_node = list_root
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for node in cache.values():
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for cb in node.callbacks:
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cb()
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cache.clear()
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@synchronized
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@ -64,6 +64,9 @@ class TreeCache(object):
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self.size -= cnt
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return popped
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def values(self):
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return [e.value for e in self.root.values()]
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def __len__(self):
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return self.size
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@ -199,3 +199,69 @@ class CacheDecoratorTestCase(unittest.TestCase):
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self.assertEquals(a.func("foo").result, d.result)
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self.assertEquals(callcount[0], 0)
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@defer.inlineCallbacks
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def test_invalidate_context(self):
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callcount = [0]
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callcount2 = [0]
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class A(object):
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@cached()
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def func(self, key):
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callcount[0] += 1
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return key
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@cached()
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def func2(self, key, cache_context):
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callcount2[0] += 1
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return self.func(key, cache_context=cache_context)
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a = A()
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yield a.func2("foo")
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self.assertEquals(callcount[0], 1)
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self.assertEquals(callcount2[0], 1)
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a.func.invalidate(("foo",))
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yield a.func("foo")
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self.assertEquals(callcount[0], 2)
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self.assertEquals(callcount2[0], 1)
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yield a.func2("foo")
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self.assertEquals(callcount[0], 2)
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self.assertEquals(callcount2[0], 2)
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@defer.inlineCallbacks
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def test_eviction_context(self):
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callcount = [0]
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callcount2 = [0]
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class A(object):
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@cached(max_entries=2)
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def func(self, key):
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callcount[0] += 1
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return key
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@cached()
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def func2(self, key, cache_context):
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callcount2[0] += 1
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return self.func(key, cache_context=cache_context)
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a = A()
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yield a.func2("foo")
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yield a.func2("foo2")
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self.assertEquals(callcount[0], 2)
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self.assertEquals(callcount2[0], 2)
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yield a.func("foo3")
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self.assertEquals(callcount[0], 3)
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self.assertEquals(callcount2[0], 2)
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yield a.func2("foo")
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self.assertEquals(callcount[0], 4)
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self.assertEquals(callcount2[0], 3)
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@ -19,6 +19,8 @@ from .. import unittest
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from synapse.util.caches.lrucache import LruCache
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from synapse.util.caches.treecache import TreeCache
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from mock import Mock
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class LruCacheTestCase(unittest.TestCase):
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@ -79,3 +81,114 @@ class LruCacheTestCase(unittest.TestCase):
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cache["key"] = 1
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cache.clear()
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self.assertEquals(len(cache), 0)
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class LruCacheCallbacksTestCase(unittest.TestCase):
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def test_set(self):
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m = Mock()
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cache = LruCache(1)
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cache.set("key", "value", m)
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self.assertFalse(m.called)
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cache.set("key", "value")
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self.assertFalse(m.called)
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cache.set("key", "value2")
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self.assertEquals(m.call_count, 1)
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cache.set("key", "value")
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self.assertEquals(m.call_count, 1)
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def test_pop(self):
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m = Mock()
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cache = LruCache(1)
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cache.set("key", "value", m)
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self.assertFalse(m.called)
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cache.pop("key")
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self.assertEquals(m.call_count, 1)
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cache.set("key", "value")
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self.assertEquals(m.call_count, 1)
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cache.pop("key")
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self.assertEquals(m.call_count, 1)
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def test_del_multi(self):
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m1 = Mock()
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m2 = Mock()
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m3 = Mock()
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m4 = Mock()
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cache = LruCache(4, 2, cache_type=TreeCache)
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cache.set(("a", "1"), "value", m1)
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cache.set(("a", "2"), "value", m2)
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cache.set(("b", "1"), "value", m3)
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cache.set(("b", "2"), "value", m4)
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self.assertEquals(m1.call_count, 0)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 0)
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self.assertEquals(m4.call_count, 0)
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cache.del_multi(("a",))
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 1)
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self.assertEquals(m3.call_count, 0)
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self.assertEquals(m4.call_count, 0)
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def test_clear(self):
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m1 = Mock()
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m2 = Mock()
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cache = LruCache(5)
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cache.set("key1", "value", m1)
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cache.set("key2", "value", m2)
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self.assertEquals(m1.call_count, 0)
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self.assertEquals(m2.call_count, 0)
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cache.clear()
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 1)
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def test_eviction(self):
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m1 = Mock(name="m1")
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m2 = Mock(name="m2")
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m3 = Mock(name="m3")
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cache = LruCache(2)
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cache.set("key1", "value", m1)
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cache.set("key2", "value", m2)
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self.assertEquals(m1.call_count, 0)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 0)
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cache.set("key3", "value", m3)
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 0)
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cache.set("key3", "value")
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 0)
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cache.get("key2")
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 0)
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cache.set("key1", "value", m1)
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self.assertEquals(m1.call_count, 1)
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self.assertEquals(m2.call_count, 0)
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self.assertEquals(m3.call_count, 1)
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