issue #110: split process state out of strategy state

The strategy is reconstructed for every playbook that is included or
specified on the command line, therefore we can't store the global
Router there without losing all our SSH connections across playbooks.

ansible_mitogen/process.py

+# Copyright 2017, David Wilson
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its contributors
+# may be used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+from __future__ import absolute_import
+import threading
+import os
+
+import mitogen
+import mitogen.core
+import mitogen.master
+import mitogen.service
+import mitogen.unix
+import mitogen.utils
+
+import ansible_mitogen.logging
+import ansible_mitogen.services
+
+
+class State(object):
+    """
+    Process-global state that should persist across playbook runs.
+    """
+    #: ProcessState singleton.
+    _instance = None
+
+    @classmethod
+    def instance(cls):
+        """
+        Fetch the ProcessState singleton, constructing it as necessary.
+        """
+        if cls._instance is None:
+            cls._instance = cls()
+        return cls._instance
+
+    def __init__(self):
+        ansible_mitogen.logging.setup()
+        self._setup_master()
+        self._setup_services()
+
+    def _setup_master(self):
+        """
+        Construct a Router, Broker, and mitogen.unix listener
+        """
+        self.router = mitogen.master.Router()
+        self.router.responder.whitelist_prefix('ansible')
+        self.router.responder.whitelist_prefix('ansible_mitogen')
+        mitogen.core.listen(self.router.broker, 'shutdown', self.on_broker_shutdown)
+        self.listener = mitogen.unix.Listener(self.router)
+        os.environ['MITOGEN_LISTENER_PATH'] = self.listener.path
+        if 'MITOGEN_ROUTER_DEBUG' in os.environ:
+            self.router.enable_debug()
+
+    def _setup_services(self):
+        """
+        Construct a ContextService and a thread to service requests for it
+        arriving from worker processes.
+        """
+        self.service = ansible_mitogen.services.ContextService(self.router)
+        self.service_thread = threading.Thread(target=self.service.run)
+        self.service_thread.start()
+
+    def on_broker_shutdown(self):
+        """
+        Respond to the Router shutdown (indirectly triggered through exit of
+        the main thread) by unlinking the listening socket. Ideally this would
+        happen explicitly, but Ansible provides no hook to allow it.
+        """
+        os.unlink(self.listener.path)
+        self.service_thread.join(timeout=10)

ansible_mitogen/strategy.py

@@ -28,19 +28,11 @@
 
 from __future__ import absolute_import
 import os
-import threading
-
-import mitogen
-import mitogen.master
-import mitogen.service
-import mitogen.unix
-import mitogen.utils
 
 import ansible.errors
 import ansible.plugins.strategy.linear
-import ansible_mitogen.logging
 import ansible_mitogen.mixins
-import ansible_mitogen.services
+import ansible_mitogen.process
 
 try:
     from ansible.plugins.loader import action_loader
@@ -153,41 +145,6 @@ class StrategyModule(ansible.plugins.strategy.linear.StrategyModule):
         remote process, all the heavy lifting of transferring the action module
         and its dependencies are automatically handled by Mitogen.
     """
-    def _setup_master(self):
-        """
-        Construct a Router, Broker, and mitogen.unix listener
-        """
-        self.router = mitogen.master.Router()
-        if 'MITOGEN_ROUTER_DEBUG' in os.environ:
-            self.router.enable_debug()
-        self.router.responder.whitelist_prefix('ansible')
-        self.router.responder.whitelist_prefix('ansible_mitogen')
-        self.listener = mitogen.unix.Listener(self.router)
-        os.environ['MITOGEN_LISTENER_PATH'] = self.listener.path
-
-    def _setup_services(self):
-        """
-        Construct a ContextService and a thread to service requests for it
-        arriving from worker processes.
-        """
-        self.service = ansible_mitogen.services.ContextService(self.router)
-        self.service_thread = threading.Thread(target=self.service.run)
-        self.service_thread.start()
-
-    def _run_with_master(self, iterator, play_context, result):
-        """
-        Arrange for a mitogen.master.Router to be available for the duration of
-        the strategy's real run() method.
-        """
-        self._setup_master()
-        self._setup_services()
-        try:
-            return super(StrategyModule, self).run(iterator, play_context)
-        finally:
-            os.unlink(self.listener.path)
-            self.router.broker.shutdown()
-            self.service_thread.join(timeout=10)
-
     def _install_wrappers(self):
         """
         Install our PluginLoader monkey patches and update global variables
@@ -218,10 +175,14 @@ class StrategyModule(ansible.plugins.strategy.linear.StrategyModule):
         action_loader.add_directory(os.path.join(base_dir, 'actions'))
 
     def run(self, iterator, play_context, result=0):
-        ansible_mitogen.logging.setup()
+        """
+        Arrange for a mitogen.master.Router to be available for the duration of
+        the strategy's real run() method.
+        """
+        self.state = ansible_mitogen.process.State.instance()
         self._add_connection_plugin_path()
         self._install_wrappers()
         try:
-            return self._run_with_master(iterator, play_context, result)
+            return super(StrategyModule, self).run(iterator, play_context)
         finally:
             self._remove_wrappers()