in recv, make sure all frames are read from the same channel. seems to fix #97

Author: Amichai Schreiber

Modules/_librabbitmq/connection.c

@@ -1302,6 +1302,7 @@ PyRabbitMQ_recv(PyRabbitMQ_Connection *self, PyObject *p,
                 amqp_connection_state_t conn, int piggyback)
 {
     amqp_frame_t frame;
+    amqp_channel_t cur_channel = 0;
     amqp_basic_deliver_t *deliver;
     amqp_basic_properties_t *props;
     PY_SIZE_TYPE body_target;
@@ -1330,6 +1331,8 @@ PyRabbitMQ_recv(PyRabbitMQ_Connection *self, PyObject *p,
             if (frame.frame_type != AMQP_FRAME_METHOD) continue;
             if (frame.payload.method.id != AMQP_BASIC_DELIVER_METHOD) goto altframe;
 
+            cur_channel = frame.channel;
+
             delivery_info = PyDict_New();
             deliver = (amqp_basic_deliver_t *)frame.payload.method.decoded;
             /* need consumer tag for later.
@@ -1348,7 +1351,9 @@ PyRabbitMQ_recv(PyRabbitMQ_Connection *self, PyObject *p,
         }
 
         Py_BEGIN_ALLOW_THREADS;
-        retval = amqp_simple_wait_frame(conn, &frame);
+        retval = cur_channel == 0 ?
+            amqp_simple_wait_frame(conn, &frame) :
+            amqp_simple_wait_frame_on_channel(conn, cur_channel, &frame);
         Py_END_ALLOW_THREADS;
         if (retval < 0) break;
 
@@ -1358,6 +1363,9 @@ PyRabbitMQ_recv(PyRabbitMQ_Connection *self, PyObject *p,
             goto finally;
         }
 
+        /* if piggybacked, 'channel' is still 0 at this point */
+        cur_channel = frame.channel;
+
         /* channel */
         channel = PyInt_FromLong((unsigned long)frame.channel);
 
@@ -1371,7 +1379,7 @@ PyRabbitMQ_recv(PyRabbitMQ_Connection *self, PyObject *p,
 
         for (i = 0; body_received < body_target; i++) {
             Py_BEGIN_ALLOW_THREADS;
-            retval = amqp_simple_wait_frame(conn, &frame);
+            retval = amqp_simple_wait_frame_on_channel(conn, cur_channel, &frame);
             Py_END_ALLOW_THREADS;
             if (retval < 0) break;