Fix a few leaks in the AMQP 1.0 driver.

Break any references that can form a cyclic reference.  Several of
proton's python classes define __del__ methods, so a cyclic reference
must be broken manually.

Change-Id: Icabc7abd01a02cb80c7eb4a0de682e90308459ef
Closes-Bug: #1496540

oslo_messaging/_drivers/protocols/amqp/controller.py

@@ -72,6 +72,10 @@ class Replies(pyngus.ReceiverEventHandler):
         self._credit = 0
         self._receiver.open()
 
+    def destroy(self):
+        self._correlation = None
+        self._receiver = None
+
     def ready(self):
         return self._ready
 
@@ -157,6 +161,7 @@ class Server(pyngus.ReceiverEventHandler):
         self._incoming = incoming
         self._addresses = addresses
         self._capacity = 500   # credit per link
+        self._receivers = None
 
     def attach(self, connection):
         """Create receiver links over the given connection for all the
@@ -180,6 +185,9 @@ class Server(pyngus.ReceiverEventHandler):
             r.open()
             self._receivers.append(r)
 
+    def destroy(self):
+        self._receivers = None
+
     # Pyngus ReceiverLink event callbacks:
 
     def receiver_remote_closed(self, receiver, pn_condition):
@@ -310,6 +318,15 @@ class Controller(pyngus.ConnectionEventHandler):
             LOG.debug("Waiting for eventloop to exit")
             self.processor.shutdown(wait, timeout)
             self.processor = None
+        self._tasks = None
+        self._senders = None
+        for server in self._servers.values():
+            server.destroy()
+        self._servers.clear()
+        self._socket_connection = None
+        if self._replies:
+            self._replies.destroy()
+            self._replies = None
         LOG.debug("Eventloop exited, driver shut down")
 
     # The remaining methods are reserved to run from the eventloop thread only!

oslo_messaging/tests/test_amqp_driver.py

@@ -396,6 +396,7 @@ mech_list: ${mechs}
         super(TestCyrusAuthentication, self).tearDown()
         if self._broker:
             self._broker.stop()
+            self._broker = None
         if self._conf_dir:
             shutil.rmtree(self._conf_dir, ignore_errors=True)
 
@@ -546,12 +547,20 @@ class FakeBroker(threading.Thread):
                         self.connection.pn_sasl.server()
                 self.connection.open()
                 self.sender_links = set()
+                self.receiver_links = set()
                 self.closed = False
 
             def destroy(self):
                 """Destroy the test connection."""
-                while self.sender_links:
+                # destroy modifies the set, so make a copy
-                    link = self.sender_links.pop()
+                tmp = self.sender_links.copy()
+                while tmp:
+                    link = tmp.pop()
+                    link.destroy()
+                # destroy modifies the set, so make a copy
+                tmp = self.receiver_links.copy()
+                while tmp:
+                    link = tmp.pop()
                     link.destroy()
                 self.connection.destroy()
                 self.connection = None
@@ -622,16 +631,21 @@ class FakeBroker(threading.Thread):
             """An AMQP sending link."""
             def __init__(self, server, conn, handle, src_addr=None):
                 self.server = server
+                self.conn = conn
                 cnn = conn.connection
                 self.link = cnn.accept_sender(handle,
                                               source_override=src_addr,
                                               event_handler=self)
+                conn.sender_links.add(self)
                 self.link.open()
                 self.routed = False
 
             def destroy(self):
                 """Destroy the link."""
                 self._cleanup()
+                conn = self.conn
+                self.conn = None
+                conn.sender_links.remove(self)
                 if self.link:
                     self.link.destroy()
                     self.link = None
@@ -663,21 +677,31 @@ class FakeBroker(threading.Thread):
             """An AMQP Receiving link."""
             def __init__(self, server, conn, handle, addr=None):
                 self.server = server
+                self.conn = conn
                 cnn = conn.connection
                 self.link = cnn.accept_receiver(handle,
                                                 target_override=addr,
                                                 event_handler=self)
+                conn.receiver_links.add(self)
                 self.link.open()
                 self.link.add_capacity(10)
 
+            def destroy(self):
+                """Destroy the link."""
+                conn = self.conn
+                self.conn = None
+                conn.receiver_links.remove(self)
+                if self.link:
+                    self.link.destroy()
+                    self.link = None
+
             # ReceiverEventHandler callbacks:
 
             def receiver_remote_closed(self, receiver_link, error):
                 self.link.close()
 
             def receiver_closed(self, receiver_link):
-                self.link.destroy()
+                self.destroy()
-                self.link = None
 
             def message_received(self, receiver_link, message, handle):
                 """Forward this message out the proper sending link."""
@@ -802,8 +826,11 @@ class FakeBroker(threading.Thread):
 
         # Shutting down
         self._my_socket.close()
-        for conn in self._connections.itervalues():
+        for conn in self._connections.values():
             conn.destroy()
+        self._connections = None
+        self.container.destroy()
+        self.container = None
         return 0
 
     def add_route(self, address, link):