def consume(self, sock):
# TODO(ewindisch): use zero-copy (i.e. references, not copying)
data = sock.recv()
LOG.debug(_("CONSUMER RECEIVED DATA: %s"), data)
proxy = self.proxies[sock]
if data[2] == "cast": # Legacy protocol
packenv = data[3]
ctx, msg = _deserialize(packenv)
request = rpc_common.deserialize_msg(msg)
ctx = RpcContext.unmarshal(ctx)
elif data[2] == "impl_zmq_v2":
packenv = data[4:]
msg = unflatten_envelope(packenv)
request = rpc_common.deserialize_msg(msg)
# Unmarshal only after verifying the message.
ctx = RpcContext.unmarshal(data[3])
else:
LOG.error(_("ZMQ Envelope version unsupported or unknown."))
return
self.pool.spawn_n(self.process, proxy, ctx, request)
def consume(self):
"""Fetch the message and pass it to the callback object."""
message = self.receiver.fetch()
try:
self._unpack_json_msg(message)
msg = rpc_common.deserialize_msg(message.content)
self.callback(msg)
except Exception:
LOG.exception(_("Failed to process message... skipping it."))
finally:
# TODO(sandy): Need support for optional ack_on_error.
self.session.acknowledge(message)
def _callback_handler(self, message, callback):
"""Call callback with deserialized message.
Messages that are processed without exception are ack'ed.
If the message processing generates an exception, it will be
ack'ed if ack_on_error=True. Otherwise it will be .requeue()'ed.
"""
try:
msg = rpc_common.deserialize_msg(message.payload)
callback(msg)
except Exception:
if self.ack_on_error:
LOG.exception(_("Failed to process message"
" ... skipping it."))
message.ack()
else:
LOG.exception(_("Failed to process message"
" ... will requeue."))
message.requeue()
else:
message.ack()
def _call(addr, context, topic, msg, timeout=None, envelope=False):
# timeout_response is how long we wait for a response
timeout = timeout or CONF.rpc_response_timeout
# The msg_id is used to track replies.
msg_id = uuid.uuid4().hex
# Replies always come into the reply service.
reply_topic = "zmq_replies.%s" % CONF.rpc_zmq_host
LOG.debug(_("Creating payload"))
# Curry the original request into a reply method.
mcontext = RpcContext.marshal(context)
payload = {
"method": "-reply",
"args": {
"msg_id": msg_id,
"topic": reply_topic,
# TODO(ewindisch): safe to remove mcontext in I.
"msg": [mcontext, msg],
},
}
LOG.debug(_("Creating queue socket for reply waiter"))
# Messages arriving async.
# TODO(ewindisch): have reply consumer with dynamic subscription mgmt
with Timeout(timeout, exception=rpc_common.Timeout):
try:
msg_waiter = ZmqSocket(
"ipc://%s/zmq_topic_zmq_replies.%s" % (CONF.rpc_zmq_ipc_dir, CONF.rpc_zmq_host),
zmq.SUB,
subscribe=msg_id,
bind=False,
)
LOG.debug(_("Sending cast"))
_cast(addr, context, topic, payload, envelope)
LOG.debug(_("Cast sent; Waiting reply"))
# Blocks until receives reply
msg = msg_waiter.recv()
LOG.debug(_("Received message: %s"), msg)
LOG.debug(_("Unpacking response"))
if msg[2] == "cast": # Legacy version
raw_msg = _deserialize(msg[-1])[-1]
elif msg[2] == "impl_zmq_v2":
rpc_envelope = unflatten_envelope(msg[4:])
raw_msg = rpc_common.deserialize_msg(rpc_envelope)
else:
raise rpc_common.UnsupportedRpcEnvelopeVersion(_("Unsupported or unknown ZMQ envelope returned."))
responses = raw_msg["args"]["response"]
# ZMQError trumps the Timeout error.
except zmq.ZMQError:
raise RPCException("ZMQ Socket Error")
except (IndexError, KeyError):
raise RPCException(_("RPC Message Invalid."))
finally:
if "msg_waiter" in vars():
msg_waiter.close()
# It seems we don't need to do all of the following,
# but perhaps it would be useful for multicall?
# One effect of this is that we're checking all
# responses for Exceptions.
for resp in responses:
if isinstance(resp, types.DictType) and "exc" in resp:
raise rpc_common.deserialize_remote_exception(CONF, resp["exc"])
return responses[-1]