Threaded plugin fixes:

* Added "Threaded" plugin interface for any plugin that uses threads
* Start plugin threads after daemonization
* Update existing plugins that use threads (Reporting, Snapshots, ThreadedStatistics interface)
* Update unit tests

4 files changed, 36 insertions, 7 deletions

diff --git a/src/lib/Bcfg2/Server/Core.py b/src/lib/Bcfg2/Server/Core.py
index 9a9061a51..040036fb2 100644
--- a/src/lib/Bcfg2/Server/Core.py
+++ b/src/lib/Bcfg2/Server/Core.py
@@ -229,20 +229,23 @@ class BaseCore(object):
                                   "Unloading %s" % (plugin, blacklist))
             for plug in blacklist:
                 del self.plugins[plug]
-        # This section logs the experimental plugins
+
+        # Log experimental plugins
         expl = [plug for plug in list(self.plugins.values())
                 if plug.experimental]
         if expl:
             self.logger.info("Loading experimental plugin(s): %s" %
                              (" ".join([x.name for x in expl])))
             self.logger.info("NOTE: Interfaces subject to change")
-        # This section logs the deprecated plugins
+
+        # Log deprecated plugins
         depr = [plug for plug in list(self.plugins.values())
                 if plug.deprecated]
         if depr:
             self.logger.info("Loading deprecated plugin(s): %s" %
                              (" ".join([x.name for x in depr])))
 
+        # Find the metadata plugin and set self.metadata
         mlist = self.plugins_by_type(Bcfg2.Server.Plugin.Metadata)
         if len(mlist) >= 1:
             #: The Metadata plugin
@@ -698,6 +701,9 @@ class BaseCore(object):
             self.fam.start()
             self.fam_thread.start()
             self.fam.AddMonitor(self.cfile, self)
+
+            for plug in self.plugins_by_type(Bcfg2.Server.Plugin.Threaded):
+                plug.start_threads()
         except:
             self.shutdown()
             raise
diff --git a/src/lib/Bcfg2/Server/Plugin/interfaces.py b/src/lib/Bcfg2/Server/Plugin/interfaces.py
index 202ec7533..f42ada773 100644
--- a/src/lib/Bcfg2/Server/Plugin/interfaces.py
+++ b/src/lib/Bcfg2/Server/Plugin/interfaces.py
@@ -299,12 +299,27 @@ class Statistics(Plugin):
         raise NotImplementedError
 
 
-class ThreadedStatistics(Statistics, threading.Thread):
+class Threaded(object):
+    """ Threaded plugins use threads in any way.  The thread must be
+    started after daemonization, so this class implements a single
+    method, :func:`start_threads`, that can be used to start threads
+    after daemonization of the server core. """
+
+    def start_threads(self):
+        """ Start this plugin's threads after daemonization.
+
+        :return: None
+        :raises: :class:`Bcfg2.Server.Plugin.exceptions.PluginInitError`
+        """
+        raise NotImplementedError
+
+class ThreadedStatistics(Statistics, Threaded, threading.Thread):
     """ ThreadedStatistics plugins process client statistics in a
     separate thread. """
 
     def __init__(self, core, datastore):
         Statistics.__init__(self, core, datastore)
+        Threaded.__init__(self)
         threading.Thread.__init__(self)
         # Event from the core signaling an exit
         self.terminate = core.terminate
@@ -312,6 +327,8 @@ class ThreadedStatistics(Statistics, threading.Thread):
         self.pending_file = os.path.join(datastore, "etc",
                                          "%s.pending" % self.name)
         self.daemon = False
+
+    def start_threads(self):
         self.start()
 
     def _save(self):
diff --git a/src/lib/Bcfg2/Server/Plugins/Reporting.py b/src/lib/Bcfg2/Server/Plugins/Reporting.py
index 1a8c3d941..b9d397590 100644
--- a/src/lib/Bcfg2/Server/Plugins/Reporting.py
+++ b/src/lib/Bcfg2/Server/Plugins/Reporting.py
@@ -7,8 +7,8 @@ import lxml.etree
 from Bcfg2.Reporting.Transport import load_transport_from_config, \
     TransportError
 from Bcfg2.Options import REPORTING_COMMON_OPTIONS
-from Bcfg2.Server.Plugin import Statistics, PullSource, PluginInitError, \
-    PluginExecutionError
+from Bcfg2.Server.Plugin import Statistics, PullSource, Threaded, \
+    PluginInitError, PluginExecutionError
 
 # required for reporting
 try:
@@ -31,7 +31,7 @@ def _rpc_call(method):
     return _real_rpc_call
 
 
-class Reporting(Statistics, PullSource):  # pylint: disable=W0223
+class Reporting(Statistics, Threaded, PullSource):  # pylint: disable=W0223
     """ Unified statistics and reporting plugin """
     __rmi__ = ['Ping', 'GetExtra', 'GetCurrentEntry']
 
@@ -41,6 +41,7 @@ class Reporting(Statistics, PullSource):  # pylint: disable=W0223
     def __init__(self, core, datastore):
         Statistics.__init__(self, core, datastore)
         PullSource.__init__(self)
+        Threaded.__init__(self)
         self.core = core
 
         self.whoami = platform.node()
@@ -54,8 +55,11 @@ class Reporting(Statistics, PullSource):  # pylint: disable=W0223
             self.logger.error(msg)
             raise PluginInitError(msg)
 
+        self.transport = None
+
+    def start_threads(self):
         try:
-            self.transport = load_transport_from_config(core.setup)
+            self.transport = load_transport_from_config(self.core.setup)
         except TransportError:
             msg = "%s: Failed to load transport: %s" % \
                 (self.name, traceback.format_exc().splitlines()[-1])
diff --git a/src/lib/Bcfg2/Server/Plugins/Snapshots.py b/src/lib/Bcfg2/Server/Plugins/Snapshots.py
index 1956af4ad..cc5946bb2 100644
--- a/src/lib/Bcfg2/Server/Plugins/Snapshots.py
+++ b/src/lib/Bcfg2/Server/Plugins/Snapshots.py
@@ -65,6 +65,8 @@ class Snapshots(Bcfg2.Server.Plugin.Statistics):
         self.session = Bcfg2.Server.Snapshots.setup_session(core.cfile)
         self.work_queue = Queue()
         self.loader = threading.Thread(target=self.load_snapshot)
+
+    def start_threads(self):
         self.loader.start()
 
     def load_snapshot(self):