From 9acc959121735cc72cd68268892af7c277e3e8f2 Mon Sep 17 00:00:00 2001
From: Sean Robinson <seankrobinson@gmail.com>
Date: Sat, 12 Apr 2014 08:48:57 -0700
Subject: [PATCH] Make Dispatcher event loop thread more robust

This includes only allowing one such loop at a time and optionally
creating a Dispatcher without automatically starting the event loop.
The updated tests better reflect the way Dispatcher works now and
has worked since commit 5fd979f12f9dd5c4.

Signed-off-by: Sean Robinson <seankrobinson@gmail.com>
---
 test/unit/pubsub.py |  9 +--------
 wifiradar/pubsub.py | 18 ++++++++++++------
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/test/unit/pubsub.py b/test/unit/pubsub.py
index 8a5d576..f05641d 100644
--- a/test/unit/pubsub.py
+++ b/test/unit/pubsub.py
@@ -31,7 +31,7 @@ class TestLimitedDispatcher(unittest.TestCase):
     """ The Dispatcher tested here does not process messages. """
 
     def setUp(self):
-        self.dispatch = pubsub.Dispatcher()
+        self.dispatch = pubsub.Dispatcher(auto_start=False)
 
     def test_subscribe(self):
         """ Test subscribe method. """
@@ -63,7 +63,6 @@ class TestLimitedDispatcher(unittest.TestCase):
 class TestDispatcher(unittest.TestCase):
     def setUp(self):
         self.dispatch = pubsub.Dispatcher()
-        self.dispatch.start()
 
     def test_simple_msg(self):
         """ Test sending and receiving a message. """
@@ -126,16 +125,12 @@ class TestDispatcher(unittest.TestCase):
 
     def tearDown(self):
         self.dispatch.close()
-        self.dispatch.join()
 
 
 class TestConnectors(unittest.TestCase):
     def setUp(self):
         self.local_dispatch = pubsub.Dispatcher()
-        self.local_dispatch.start()
-
         self.foreign_dispatch = pubsub.Dispatcher()
-        self.foreign_dispatch.start()
 
     def test_connector(self):
         """ Test sending through a chain of Dispatchers. """
@@ -194,5 +189,3 @@ class TestConnectors(unittest.TestCase):
     def tearDown(self):
         self.local_dispatch.close()
         self.foreign_dispatch.close()
-        self.local_dispatch.join()
-        self.foreign_dispatch.join()
diff --git a/wifiradar/pubsub.py b/wifiradar/pubsub.py
index 6365960..7219f64 100644
--- a/wifiradar/pubsub.py
+++ b/wifiradar/pubsub.py
@@ -59,15 +59,17 @@ class Dispatcher(object):
         publish/subscribe pattern.  One Dispatcher should run in each
         process.
     """
-    def __init__(self):
+    def __init__(self, auto_start=True):
         """ Create an empty Dispatcher.
         """
         self.pipes = dict()
         self._pairs = dict()
+        self._thread = None
         self._pipes_lock = RLock()
         self._watching = Event()
         self._watching.set()
-        self.start()
+        if auto_start:
+            self.start()
 
     def __del__(self):
         """ Close all pipes when the Dispatcher object is garbage
@@ -172,11 +174,15 @@ class Dispatcher(object):
     def start(self):
         """ Start running the Dispatcher's event loop in a thread.
         """
-        self._thread = threading.Thread(None, self._run,
-            'dispatcher_event_loop:{NAME}'.format(NAME=self), ())
-        self._thread.start()
+        # Only allow one event loop thread.
+        if self._thread is None:
+            self._thread = threading.Thread(None, self._run,
+                'dispatcher_event_loop:{NAME}'.format(NAME=self), ())
+            self._thread.start()
 
     def join(self):
         """ Stop the Dispatcher's event loop thread.
         """
-        self._thread.join()
+        if self._thread is not None:
+            self._thread.join()
+            self._thread = None
-- 
2.11.4.GIT