celerybeat: Install SIGTERM+SIGINT handler that syncs the schedule to disk at shutdown.

celery/bin/celerybeat.py

@@ -91,6 +91,7 @@ def run_clockservice(loglevel=conf.CELERYBEAT_LOG_LEVEL,
         clockservice = ClockService(logger=logger, schedule_filename=schedule)
 
         try:
+            install_sync_handler(clockservice)
             clockservice.start()
         except Exception, e:
             emergency_error(logfile,
@@ -100,6 +101,18 @@ def run_clockservice(loglevel=conf.CELERYBEAT_LOG_LEVEL,
     _run_clock()
 
 
+def install_sync_handler(beat):
+    """Install a ``SIGTERM`` + ``SIGINT`` handler that saves
+    the celerybeat schedule."""
+
+    def _sync(signum, frame):
+        beat.sync()
+        raise SystemExit()
+
+    platform.install_signal_handler("SIGTERM", _sync)
+    platform.install_signal_handler("SIGINT", _sync)
+
+
 def parse_options(arguments):
     """Parse the available options to ``celeryd``."""
     parser = optparse.OptionParser(option_list=OPTION_LIST)