maybe_declare should not cache declaration if entity is not durable

kombu/abstract.py

@@ -46,6 +46,9 @@ class MaybeChannelBound(Object):
     _channel = None
     _is_bound = False
 
+    #: Defines whether maybe_declare can skip declaring this entity twice.
+    can_cache_declaration = False
+
     def __call__(self, channel):
         """`self(channel) -> self.bind(channel)`"""
         return self.bind(channel)

kombu/common.py

@@ -20,7 +20,7 @@ def maybe_declare(entity, channel):
     declared = declared_entities[channel.connection.client]
     if not entity.is_bound:
         entity = entity(channel)
-    if entity not in declared:
+    if not entity.can_cache_declaration or entity not in declared:
         entity.declare()
         declared.add(entity)
         return True

kombu/entity.py

@@ -236,6 +236,9 @@ class Exchange(MaybeChannelBound):
     def __repr__(self):
         return super(Exchange, self).__repr__("Exchange %s(%s)" % (self.name,
                                                                    self.type))
+    @property
+    def can_cache_declaration(self):
+        return self.durable
 
 
 class Queue(MaybeChannelBound):
@@ -512,3 +515,7 @@ class Queue(MaybeChannelBound):
                  "Queue %s -> %s -> %s" % (self.name,
                                            self.exchange,
                                            self.routing_key))
+
+    @property
+    def can_cache_declaration(self):
+        return self.durable