implement clearCache() in DistributeRamCache by using different keys in low-level.

product/ERP5Type/CachePlugins/DistributedRamCache.py

@@ -56,6 +56,7 @@ class DistributedRamCache(BaseCache):
     )
 
   def __init__(self, uid, params={}):
+    self._uid = uid
     self._servers = params.get('server', '')
     self._expiration_time = params.get('expiration_time', 0)
     self._server_max_key_length = params.get('server_max_key_length', 250)
@@ -93,14 +94,15 @@ class DistributedRamCache(BaseCache):
   def getCacheStorage(self, **kw):
     """Follow MemcachedTool.getMemcachedDict implementation
     """
-    return SharedDict(self._getMemcachedDict(), prefix=self._key_prefix)
+    return SharedDict(self._getMemcachedDict(), prefix=self._key_prefix, uid=self._uid)
 
   def _getCacheId(self, cache_id, scope):
     return '%s_%s' % (scope, cache_id)
 
   def get(self, cache_id, scope, default=_MARKER):
     cache_storage = self.getCacheStorage()
-    cache_id = self._getCacheId(cache_id, scope)
+    revision = cache_storage.getRevision()
+    cache_id = '%s:%s' % (revision, self._getCacheId(cache_id, scope))
     cache_entry = cache_storage.get(cache_id)
     if isinstance(cache_entry, CacheEntry):
       # since some memcached-like products does not support expiration, we
@@ -117,7 +119,8 @@ class DistributedRamCache(BaseCache):
 
   def set(self, cache_id, scope, value, cache_duration=None, calculation_time=0):
     cache_storage = self.getCacheStorage()
-    cache_id = self._getCacheId(cache_id, scope)
+    revision = cache_storage.getRevision()
+    cache_id = '%s:%s' % (revision, self._getCacheId(cache_id, scope))
     cache_entry = CacheEntry(value, cache_duration, calculation_time)
     cache_storage.set(cache_id, cache_entry)
     self.markCacheMiss()
@@ -135,12 +138,14 @@ class DistributedRamCache(BaseCache):
 
   def delete(self, cache_id, scope):
     cache_storage = self.getCacheStorage()
-    cache_id = self._getCacheId(cache_id, scope)
+    revision = cache_storage.getRevision()
+    cache_id = '%s:%s' % (revision, self._getCacheId(cache_id, scope))
     del cache_storage[cache_id]
 
   def has_key(self, cache_id, scope):
     cache_storage = self.getCacheStorage()
-    cache_id = self._getCacheId(cache_id, scope)
+    revision = cache_storage.getRevision()
+    cache_id = '%s:%s' % (revision, self._getCacheId(cache_id, scope))
     cache_entry = cache_storage.get(cache_id)
     to_return = False
     if isinstance(cache_entry, CacheEntry):
@@ -164,7 +169,7 @@ class DistributedRamCache(BaseCache):
     Use expiration time instead.
     """
     BaseCache.clearCache(self)
-    LOG('DistributedRamCache', WARNING, 'not allowed to clear memcache storage')
+    self.getCacheStorage().increaseRevision()
 
   def clearCacheForScope(self, scope):
     ## memcached doesn't support namespaces (cache scopes) neither getting cached key list.

product/ERP5Type/Tool/MemcachedTool.py

@@ -136,6 +136,11 @@ if memcache is not None:
         for key, action in self.scheduled_action_dict.iteritems():
           encoded_key = encodeKey(key)
           if action is UPDATE_ACTION:
+            if key.endswith('/_revision'):
+              # We want to keep the revision value as long as possible.
+              succeed = self.memcached_connection.set(encoded_key,
+                                                      self.local_cache[key])
+            else:
               succeed = self.memcached_connection.set(encoded_key,
                                                       self.local_cache[key],
                                                       expiration_time)
@@ -226,15 +231,18 @@ if memcache is not None:
       Each "user" of the dictionary must get an instance of this class.
     """
 
-    def __init__(self, dictionary, prefix):
+    def __init__(self, dictionary, prefix, uid=None):
       """
         dictionary
           Instance of dictionary to share.
         prefix
           Prefix used by the "user" owning an instance of this class.
+        uid
+          Unique ID for the different scope of the revision.
       """
       self._dictionary = dictionary
       self.prefix = prefix
+      self._uid = uid
 
     def _prefixKey(self, key):
       if not isinstance(key, basestring):
@@ -261,6 +269,16 @@ if memcache is not None:
     def set(self, key, value):
       self._dictionary.set(self._prefixKey(key), value)
 
+    def getRevision(self):
+      revision = self.get('%s/_revision' % self._uid, None)
+      if revision is None:
+        revision = time.time()
+        self.set('%s/_revision' % self._uid, revision)
+      return revision
+
+    def increaseRevision(self):
+      self.set('%s/_revision' % self._uid, time.time())
+
   allow_class(SharedDict)
 
   class MemcachedTool(_MemcacheTool):
@@ -291,7 +309,7 @@ if memcache is not None:
       global_prefix = self.erp5_site_global_id
       if global_prefix:
         key_prefix = global_prefix + '_' + key_prefix
-      return SharedDict(memcached_plugin.getConnection(), prefix=key_prefix)
+      return SharedDict(memcached_plugin.getConnection(), prefix=key_prefix, uid=plugin_path)
 
   InitializeClass(MemcachedTool)
 else: