Cinder service maintenance mode patch

gistfile1.diff

diff --git a/cinder/service.py b/cinder/service.py
index 6c557e8..60b4ce8 100644
--- a/cinder/service.py
+++ b/cinder/service.py
@@ -153,11 +153,23 @@ class ProcessLauncher(object):
         self.totalwrap = 0
         self.failedwrap = 0
         self.running = True
+        self.maintenance = False
         rfd, self.writepipe = os.pipe()
         self.readpipe = eventlet.greenio.GreenPipe(rfd, 'r')
 
         signal.signal(signal.SIGTERM, self._handle_signal)
         signal.signal(signal.SIGINT, self._handle_signal)
+        signal.signal(signal.SIGUSR1, self._handle_sigusr1)
+
+    def _handle_sigusr1(self, signo, frame):
+        self.maintenance = True
+        for pid in self.children:
+            # Pass USR1 on to our children.
+            try:
+                os.kill(pid, signal.SIGUSR1)
+            except OSError as exc:
+                if exc.errno != errno.ESRCH:
+                    raise
 
     def _handle_signal(self, signo, frame):
         self.sigcaught = signo
@@ -302,6 +314,9 @@ class ProcessLauncher(object):
                 eventlet.greenthread.sleep(.01)
                 continue
 
+            if self.maintenance:
+                break
+
             LOG.info(_('wait wrap.failed %s'), wrap.failed)
             while (self.running and len(wrap.children) < wrap.workers
                    and not wrap.failed):
@@ -312,12 +327,12 @@ class ProcessLauncher(object):
                        signal.SIGINT: 'SIGINT'}[self.sigcaught]
             LOG.info(_('Caught %s, stopping children'), signame)
 
-        for pid in self.children:
-            try:
-                os.kill(pid, signal.SIGTERM)
-            except OSError as exc:
-                if exc.errno != errno.ESRCH:
-                    raise
+            for pid in self.children:
+                try:
+                    os.kill(pid, signal.SIGTERM)
+                except OSError as exc:
+                    if exc.errno != errno.ESRCH:
+                        raise
 
         # Wait for children to die
         if self.children:
@@ -352,6 +367,35 @@ class Service(object):
         self.saved_args, self.saved_kwargs = args, kwargs
         self.timers = []
 
+    def maintenance_periodic(self):
+        """If no eventlet timers exist, assume done, so shut down."""
+        LOG.info(_('Maintenance, waiting for all eventlets to finish'))
+        hub = eventlet.hubs.get_hub()
+        if len(hub.timers) == 0:
+            LOG.info(_('No eventlet timers, exiting'))
+            self.stop()
+
+    def _handle_sigusr1(self, signo, frame):
+        """Handle SIGUSR1 to enter maintenance mode.
+
+        Stop processing new rpc messages. Stop running periodic tasks. The
+        service will keep running until it has no more RPC calls executing,
+        then it will cleanly exit.
+        """
+        try:
+            self.conn.close()
+        except Exception:
+            pass
+        for x in self.timers:
+            try:
+                x.stop()
+            except Exception:
+                pass
+        # This periodic task just exists to keep the manager running.
+        periodic = utils.LoopingCall(self.maintenance_periodic)
+        periodic.start(interval=10, initial_delay=0)
+        self.timers.append(periodic)
+
     def start(self):
         version_string = version.version_string()
         LOG.audit(_('Starting %(topic)s node (version %(version_string)s)'),
@@ -401,6 +445,8 @@ class Service(object):
                            initial_delay=initial_delay)
             self.timers.append(periodic)
 
+        signal.signal(signal.SIGUSR1, self._handle_sigusr1)
+
     def _create_service_ref(self, context):
         zone = CONF.storage_availability_zone
         service_ref = db.service_create(context,