diff options
Diffstat (limited to 'lru.py')
| -rw-r--r-- | lru.py | 52 |
1 files changed, 45 insertions, 7 deletions
@@ -44,9 +44,9 @@ class _dlnode(object): class lrucache(object): - def __init__(self, size): + def __init__(self, size, callback=None): - + self.callback = callback # Initialize the hash table as empty. self.table = {} @@ -68,6 +68,11 @@ class lrucache(object): return len(self.table) def clear(self): + if self.callback: + for key in self.table: + node = self.table[key] + self.callback(node.key, node.obj) + self.table.clear() node = self.head @@ -131,9 +136,11 @@ class lrucache(object): # If the node already contains something we need to remove the old key from # the dictionary. if node.key is not None: + if self.callback: + self.callback(node.key, node.obj) del self.table[node.key] - # Place the key and the object in the node + # Place the new key and object in the node node.key = key node.obj = obj @@ -201,6 +208,8 @@ class lrucache(object): assert self.listSize > 1 # Invarient node = self.head.prev if node.key is not None: + if self.callback: + self.callback(node.key, node.obj) del self.table[node.key] # Splice the tail node out of the list @@ -251,18 +260,31 @@ class lrucache(object): # Wrapper using write-through semantics class lruwrap(object): - def __init__(self, store, size): - self.cache = lrucache(size) + def __init__(self, store, size, writethrough=True): + self.writethrough = writethrough + + if self.writethrough: + self.cache = lrucache(size) + else: + self.cache = lrucache(size, self.ejectCallBack) + self.dirty = set() + self.store = store + + def __len__(self): + # XXX We could cache the size return len(self.store) def clear(self): self.cache.clear() + if self.writethrough: # XXX Remove this test XXX + assert len(self.dirty) == 0 self.store.clear() - + def __contains__(self, key): + # XXX Should this bring the key/value into the cache? if key in self.cache: return True if key in self.store: @@ -280,14 +302,30 @@ class lruwrap(object): def __setitem__(self, key, value): self.cache[key] = value - self.store[key] = value + if self.writethrough: + self.store[key] = value + else: + self.dirty.add(key) + def __delitem__(self, key): try: del self.cache[key] + if not self.writethrough: + self.dirty.remove(key) except KeyError: pass del self.store[key] + + def ejectCallback(self, key, value): + if key in self.dirty: + self.store[key] = value + self.dirty.remove(key) + + def __del__(self): + # Flush the dirty objects + self.sync() + class lrudecorator(object): |