X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/110f49efa32793aaa17d565025c33b71c40eaa5a..b990eedd100be28469c65af95935f90e2583cafe:/lib/daemon.py diff --git a/lib/daemon.py b/lib/daemon.py index 7f5e9ef..1e41b80 100644 --- a/lib/daemon.py +++ b/lib/daemon.py @@ -75,7 +75,43 @@ class AsyncoreScheduler(sched.scheduler): """ def __init__(self, timefunc): - sched.scheduler.__init__(self, timefunc, AsyncoreDelayFunction) + """Initializes this class. + + """ + sched.scheduler.__init__(self, timefunc, self._LimitedDelay) + self._max_delay = None + + def run(self, max_delay=None): # pylint: disable=W0221 + """Run any pending events. + + @type max_delay: None or number + @param max_delay: Maximum delay (useful if caller has timeouts running) + + """ + assert self._max_delay is None + + # The delay function used by the scheduler can't be different on each run, + # hence an instance variable must be used. + if max_delay is None: + self._max_delay = None + else: + self._max_delay = utils.RunningTimeout(max_delay, False) + + try: + return sched.scheduler.run(self) + finally: + self._max_delay = None + + def _LimitedDelay(self, duration): + """Custom delay function for C{sched.scheduler}. + + """ + if self._max_delay is None: + timeout = duration + else: + timeout = min(duration, self._max_delay.Remaining()) + + return AsyncoreDelayFunction(timeout) class GanetiBaseAsyncoreDispatcher(asyncore.dispatcher): @@ -421,6 +457,47 @@ class AsyncAwaker(GanetiBaseAsyncoreDispatcher): self.out_socket.send("\0") +class _ShutdownCheck: + """Logic for L{Mainloop} shutdown. + + """ + def __init__(self, fn): + """Initializes this class. + + @type fn: callable + @param fn: Function returning C{None} if mainloop can be stopped or a + duration in seconds after which the function should be called again + @see: L{Mainloop.Run} + + """ + assert callable(fn) + + self._fn = fn + self._defer = None + + def CanShutdown(self): + """Checks whether mainloop can be stopped. + + @rtype: bool + + """ + if self._defer and self._defer.Remaining() > 0: + # A deferred check has already been scheduled + return False + + # Ask mainloop driver whether we can stop or should check again + timeout = self._fn() + + if timeout is None: + # Yes, can stop mainloop + return True + + # Schedule another check in the future + self._defer = utils.RunningTimeout(timeout, True) + + return False + + class Mainloop(object): """Generic mainloop for daemons @@ -428,6 +505,8 @@ class Mainloop(object): timed events """ + _SHUTDOWN_TIMEOUT_PRIORITY = -(sys.maxint - 1) + def __init__(self): """Constructs a new Mainloop instance. @@ -441,9 +520,13 @@ class Mainloop(object): @utils.SignalHandled([signal.SIGCHLD]) @utils.SignalHandled([signal.SIGTERM]) @utils.SignalHandled([signal.SIGINT]) - def Run(self, signal_handlers=None): + def Run(self, shutdown_wait_fn=None, signal_handlers=None): """Runs the mainloop. + @type shutdown_wait_fn: callable + @param shutdown_wait_fn: Function to check whether loop can be terminated; + B{important}: function must be idempotent and must return either None + for shutting down or a timeout for another call @type signal_handlers: dict @param signal_handlers: signal->L{utils.SignalHandler} passed by decorator @@ -451,24 +534,50 @@ class Mainloop(object): assert isinstance(signal_handlers, dict) and \ len(signal_handlers) > 0, \ "Broken SignalHandled decorator" - running = True + + # Counter for received signals + shutdown_signals = 0 + + # Logic to wait for shutdown + shutdown_waiter = None # Start actual main loop - while running: - if not self.scheduler.empty(): + while True: + if shutdown_signals == 1 and shutdown_wait_fn is not None: + if shutdown_waiter is None: + shutdown_waiter = _ShutdownCheck(shutdown_wait_fn) + + # Let mainloop driver decide if we can already abort + if shutdown_waiter.CanShutdown(): + break + + # Re-evaluate in a second + timeout = 1.0 + + elif shutdown_signals >= 1: + # Abort loop if more than one signal has been sent or no callback has + # been given + break + + else: + # Wait forever on I/O events + timeout = None + + if self.scheduler.empty(): + asyncore.loop(count=1, timeout=timeout, use_poll=True) + else: try: - self.scheduler.run() + self.scheduler.run(max_delay=timeout) except SchedulerBreakout: pass - else: - asyncore.loop(count=1, use_poll=True) # Check whether a signal was raised - for sig in signal_handlers: - handler = signal_handlers[sig] + for (sig, handler) in signal_handlers.items(): if handler.called: self._CallSignalWaiters(sig) - running = sig not in (signal.SIGTERM, signal.SIGINT) + if sig in (signal.SIGTERM, signal.SIGINT): + logging.info("Received signal %s asking for shutdown", sig) + shutdown_signals += 1 handler.Clear() def _CallSignalWaiters(self, signum): @@ -539,12 +648,12 @@ def _BeautifyError(err): err.errno) else: return str(err) - except Exception: # pylint: disable-msg=W0703 + except Exception: # pylint: disable=W0703 logging.exception("Error while handling existing error %s", err) return "%s" % str(err) -def _HandleSigHup(reopen_fn, signum, frame): # pylint: disable-msg=W0613 +def _HandleSigHup(reopen_fn, signum, frame): # pylint: disable=W0613 """Handler for SIGHUP. @param reopen_fn: List of callback functions for reopening log files @@ -687,7 +796,12 @@ def GenericMain(daemon_name, optionparser, signal.signal(signal.SIGHUP, compat.partial(_HandleSigHup, [log_reopen_fn, stdio_reopen_fn])) - utils.WritePidFile(utils.DaemonPidFileName(daemon_name)) + try: + utils.WritePidFile(utils.DaemonPidFileName(daemon_name)) + except errors.PidFileLockError, err: + print >> sys.stderr, "Error while locking PID file:\n%s" % err + sys.exit(constants.EXIT_FAILURE) + try: try: logging.info("%s daemon startup", daemon_name)