Consumer can now work with raw messages using a new on_message callback

kombu/messaging.py

@@ -233,6 +233,7 @@ class Consumer(object):
     :keyword no_ack: see :attr:`no_ack`.
     :keyword auto_declare: see :attr:`auto_declare`
     :keyword callbacks: see :attr:`callbacks`.
+    :keyword on_message: See :attr:`on_message`
     :keyword on_decode_error: see :attr:`on_decode_error`.
 
     """
@@ -259,6 +260,25 @@ class Consumer(object):
     #: :class:`~kombu.transport.base.Message`).
     callbacks = None
 
+    #: Optional function called whenever a message is received.
+    #:
+    #: When defined this function will be called instead of the
+    #: :meth:`receive` method, and :attr:`callbacks` will be disabled.
+    #:
+    #: So this can be used as an alternative to :attr:`callbacks` when
+    #: you don't want the body to be automatically decoded.
+    #: Note that the message will still be decompressed if the message
+    #: has the ``compression`` header set.
+    #:
+    #: The signature of the callback must take a single argument,
+    #: which is the raw message object (a subclass of
+    #: :class:`~kombu.transport.base.Message`).
+    #:
+    #: Also note that the ``message.body`` attribute, which is the raw
+    #: contents of the message body, may in some cases be a read-only
+    #: :class:`buffer` object.
+    on_message = None
+
     #: Callback called when a message can't be decoded.
     #:
     #: The signature of the callback must take two arguments: `(message,
@@ -269,12 +289,13 @@ class Consumer(object):
     _next_tag = count(1).next   # global
 
     def __init__(self, channel, queues=None, no_ack=None, auto_declare=None,
-            callbacks=None, on_decode_error=None):
+            callbacks=None, on_decode_error=None, on_message=None):
         self.channel = channel
         self.queues = self.queues or [] if queues is None else queues
         self.no_ack = self.no_ack if no_ack is None else no_ack
         self.callbacks = (self.callbacks or [] if callbacks is None
                                                else callbacks)
+        self.on_message = on_message
         self._active_tags = {}
         if auto_declare is not None:
             self.auto_declare = auto_declare
@@ -472,18 +493,18 @@ class Consumer(object):
         return tag
 
     def _receive_callback(self, message):
-        channel = self.channel
+        on_m, channel, decoded = self.on_message, self.channel, None
         try:
             m2p = getattr(channel, 'message_to_python', None)
             if m2p:
                 message = m2p(message)
-            decoded = message.decode()
+            decoded = None if on_m else message.decode()
         except Exception, exc:
             if not self.on_decode_error:
                 raise
             self.on_decode_error(message, exc)
-        else:
-            self.receive(decoded, message)
+
+        return on_m(message) if on_m else self.receive(decoded, message)
 
     def __repr__(self):
         return '<Consumer: %s>' % (self.queues, )