From c38857e1101027a734a35f4e80bc4084fabc034b Mon Sep 17 00:00:00 2001
From: Mehdi Abaakouk <sileht@redhat.com>
Date: Tue, 28 Nov 2017 15:47:54 +0100
Subject: [PATCH] rabbitmq: don't wait for message ack/requeue

I don't see any obvious reason why we should wait ack/requeue is done.

This waiter have already be removed from amqp1.

https://git.openstack.org/cgit/openstack/oslo.messaging/tree/oslo_messaging/_drivers/amqp1_driver/controller.py#n242

So, this change remove it from rabbitmq driver too.

Closes-bug: #1734788

Change-Id: I5ecedc762596181be19410b863851a0054fd6579
---
 oslo_messaging/_drivers/amqpdriver.py         | 27 +++----------------
 oslo_messaging/server.py                      | 12 ---------
 ...bbit-no-wait-for-ack-9e5de3e1320d7660.yaml | 12 +++++++++
 3 files changed, 16 insertions(+), 35 deletions(-)
 create mode 100644 releasenotes/notes/rabbit-no-wait-for-ack-9e5de3e1320d7660.yaml

diff --git a/oslo_messaging/_drivers/amqpdriver.py b/oslo_messaging/_drivers/amqpdriver.py
index 539e48b0b..deeaba29b 100644
--- a/oslo_messaging/_drivers/amqpdriver.py
+++ b/oslo_messaging/_drivers/amqpdriver.py
@@ -56,13 +56,6 @@ class MessageOperationsHandler(object):
             target=self._process_in_background)
         self._shutdown_thread.daemon = True
 
-        # HACK(sileht): this is set by the server.Server temporary
-        # to not have to rewrite the entire internal API to pass
-        # executor everywhere to make Listener aware of the server
-        # executor. All this hack is only for the blocking executor.
-        # And it's deprecated so...
-        self._executor = None
-
     def stop(self):
         self._shutdown.set()
 
@@ -82,26 +75,14 @@ class MessageOperationsHandler(object):
 
         while True:
             try:
-                task, event = self._tasks.get(block=False)
+                task = self._tasks.get(block=False)
             except moves.queue.Empty:
                 break
-            try:
-                task()
-            finally:
-                event.set()
+            task()
 
     def do(self, task):
-        "Put the task in the queue and waits until the task is completed."
-        if self._executor is None:
-            raise RuntimeError("Unexpected error, no executor is setuped")
-        elif self._executor == "blocking":
-            # NOTE(sileht): Blocking will hang forever if we waiting the
-            # polling thread
-            task()
-        else:
-            event = threading.Event()
-            self._tasks.put((task, event))
-            event.wait()
+        "Put the task in the queue."
+        self._tasks.put(task)
 
 
 class AMQPIncomingMessage(base.RpcIncomingMessage):
diff --git a/oslo_messaging/server.py b/oslo_messaging/server.py
index c8e77a673..d2e50ac46 100644
--- a/oslo_messaging/server.py
+++ b/oslo_messaging/server.py
@@ -417,18 +417,6 @@ class MessageHandlingServer(service.ServiceBase, _OrderedTaskRunner):
         except driver_base.TransportDriverError as ex:
             raise ServerListenError(self.target, ex)
 
-        # HACK(sileht): We temporary pass the executor to the rabbit
-        # listener to fix a race with the deprecated blocking executor.
-        # We do this hack because this is need only for 'synchronous'
-        # executor like blocking. And this one is deprecated. Making
-        # driver working in an sync and an async way is complicated
-        # and blocking have 0% tests coverage.
-        if hasattr(self.listener, '_poll_style_listener'):
-            l = self.listener._poll_style_listener
-            if hasattr(l, "_message_operations_handler"):
-                l._message_operations_handler._executor = (
-                    self.executor_type)
-
         self.listener.start(self._on_incoming)
 
     @ordered(after='start')
diff --git a/releasenotes/notes/rabbit-no-wait-for-ack-9e5de3e1320d7660.yaml b/releasenotes/notes/rabbit-no-wait-for-ack-9e5de3e1320d7660.yaml
new file mode 100644
index 000000000..4b9d47af3
--- /dev/null
+++ b/releasenotes/notes/rabbit-no-wait-for-ack-9e5de3e1320d7660.yaml
@@ -0,0 +1,12 @@
+---
+other:
+  - |
+    On rabbitmq, in the past, acknownlegement of messages was done within the
+    application callback thread/greenlet. This thread was blocked until the
+    message was ack. In newton, we rewrote the message acknownlegement to
+    ensure we haven't two threads writting the the socket at the same times.
+    Now all pendings ack are done by the main thread. They are no more reason
+    to block the application callback thread until the message is ack. Other
+    driver already release the application callback threads before the message
+    is acknownleged. This is also the case for rabbitmq, now.
+