"""Module with helper classes and functions for daemons"""
-import select
+import asyncore
+import os
import signal
import errno
+import logging
+import sched
+import time
+import socket
+import sys
from ganeti import utils
+from ganeti import constants
+from ganeti import errors
+
+
+class SchedulerBreakout(Exception):
+ """Exception used to get out of the scheduler loop
+
+ """
+
+
+def AsyncoreDelayFunction(timeout):
+ """Asyncore-compatible scheduler delay function.
+
+ This is a delay function for sched that, rather than actually sleeping,
+ executes asyncore events happening in the meantime.
+
+ After an event has occurred, rather than returning, it raises a
+ SchedulerBreakout exception, which will force the current scheduler.run()
+ invocation to terminate, so that we can also check for signals. The main loop
+ will then call the scheduler run again, which will allow it to actually
+ process any due events.
+
+ This is needed because scheduler.run() doesn't support a count=..., as
+ asyncore loop, and the scheduler module documents throwing exceptions from
+ inside the delay function as an allowed usage model.
+
+ """
+ asyncore.loop(timeout=timeout, count=1, use_poll=True)
+ raise SchedulerBreakout()
+
+
+class AsyncoreScheduler(sched.scheduler):
+ """Event scheduler integrated with asyncore
+
+ """
+ def __init__(self, timefunc):
+ sched.scheduler.__init__(self, timefunc, AsyncoreDelayFunction)
+
+
+class AsyncUDPSocket(asyncore.dispatcher):
+ """An improved asyncore udp socket.
+
+ """
+ def __init__(self):
+ """Constructor for AsyncUDPSocket
+
+ """
+ asyncore.dispatcher.__init__(self)
+ self._out_queue = []
+ self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+ # this method is overriding an asyncore.dispatcher method
+ def handle_connect(self):
+ # Python thinks that the first udp message from a source qualifies as a
+ # "connect" and further ones are part of the same connection. We beg to
+ # differ and treat all messages equally.
+ pass
+
+ # this method is overriding an asyncore.dispatcher method
+ def handle_read(self):
+ try:
+ try:
+ payload, address = self.recvfrom(constants.MAX_UDP_DATA_SIZE)
+ except socket.error, err:
+ if err.errno == errno.EINTR:
+ # we got a signal while trying to read. no need to do anything,
+ # handle_read will be called again if there is data on the socket.
+ return
+ else:
+ raise
+ ip, port = address
+ self.handle_datagram(payload, ip, port)
+ except:
+ # we need to catch any exception here, log it, but proceed, because even
+ # if we failed handling a single request, we still want to continue.
+ logging.error("Unexpected exception", exc_info=True)
+
+ def handle_datagram(self, payload, ip, port):
+ """Handle an already read udp datagram
+
+ """
+ raise NotImplementedError
+
+ # this method is overriding an asyncore.dispatcher method
+ def writable(self):
+ # We should check whether we can write to the socket only if we have
+ # something scheduled to be written
+ return bool(self._out_queue)
+
+ def handle_write(self):
+ try:
+ if not self._out_queue:
+ logging.error("handle_write called with empty output queue")
+ return
+ (ip, port, payload) = self._out_queue[0]
+ try:
+ self.sendto(payload, 0, (ip, port))
+ except socket.error, err:
+ if err.errno == errno.EINTR:
+ # we got a signal while trying to write. no need to do anything,
+ # handle_write will be called again because we haven't emptied the
+ # _out_queue, and we'll try again
+ return
+ else:
+ raise
+ self._out_queue.pop(0)
+ except:
+ # we need to catch any exception here, log it, but proceed, because even
+ # if we failed sending a single datagram we still want to continue.
+ logging.error("Unexpected exception", exc_info=True)
+
+ def enqueue_send(self, ip, port, payload):
+ """Enqueue a datagram to be sent when possible
+
+ """
+ if len(payload) > constants.MAX_UDP_DATA_SIZE:
+ raise errors.UdpDataSizeError('Packet too big: %s > %s' % (len(payload),
+ constants.MAX_UDP_DATA_SIZE))
+ self._out_queue.append((ip, port, payload))
class Mainloop(object):
"""Generic mainloop for daemons
+ @ivar scheduler: A sched.scheduler object, which can be used to register
+ timed events
+
"""
def __init__(self):
- self._io_wait = []
+ """Constructs a new Mainloop instance.
+
+ """
self._signal_wait = []
- self.sigchld_handler = None
- self.sigterm_handler = None
- self.quit = False
-
- def Run(self):
- # TODO: Does not yet support adding new event sources while running
- poller = select.poll()
- for (owner, fd, conditions) in self._io_wait:
- poller.register(fd, conditions)
-
- self.sigchld_handler = utils.SignalHandler([signal.SIGCHLD])
- self.sigterm_handler = utils.SignalHandler([signal.SIGTERM])
- try:
- while not self.quit:
+ self.scheduler = AsyncoreScheduler(time.time)
+
+ @utils.SignalHandled([signal.SIGCHLD])
+ @utils.SignalHandled([signal.SIGTERM])
+ def Run(self, signal_handlers=None):
+ """Runs the mainloop.
+
+ @type signal_handlers: dict
+ @param signal_handlers: signal->L{utils.SignalHandler} passed by decorator
+
+ """
+ assert isinstance(signal_handlers, dict) and \
+ len(signal_handlers) > 0, \
+ "Broken SignalHandled decorator"
+ running = True
+ # Start actual main loop
+ while running:
+ if not self.scheduler.empty():
try:
- io_events = poller.poll(1000)
- except select.error, err:
- # EINTR can happen when signals are sent
- if err.args and err.args[0] in (errno.EINTR,):
- io_events = None
- else:
- raise
-
- if io_events:
- # Check for I/O events
- for (evfd, evcond) in io_events:
- for (owner, fd, conditions) in self._io_wait:
- if fd == evfd and evcond & conditions:
- owner.OnIO(fd, evcond)
-
- # Check whether signal was raised
- if self.sigchld_handler.called:
- for owner in self._signal_wait:
- owner.OnSignal(signal.SIGCHLD)
- self.sigchld_handler.Clear()
-
- if self.sigterm_handler.called:
- self.quit = True
- self.sigterm_handler.Clear()
- finally:
- self.sigchld_handler.Reset()
- self.sigchld_handler = None
- self.sigterm_handler.Reset()
- self.sigterm_handler = None
-
-
- def RegisterIO(self, owner, fd, condition):
- """Registers a receiver for I/O notifications
-
- The receiver must support a "OnIO(self, fd, conditions)" function.
+ self.scheduler.run()
+ except SchedulerBreakout:
+ pass
+ else:
+ asyncore.loop(count=1, use_poll=True)
- @type owner: instance
- @param owner: Receiver
- @type fd: int
- @param fd: File descriptor
- @type condition: int
- @param condition: ORed field of conditions to be notified
- (see select module)
+ # Check whether a signal was raised
+ for sig in signal_handlers:
+ handler = signal_handlers[sig]
+ if handler.called:
+ self._CallSignalWaiters(sig)
+ running = (sig != signal.SIGTERM)
+ handler.Clear()
+
+ def _CallSignalWaiters(self, signum):
+ """Calls all signal waiters for a certain signal.
+
+ @type signum: int
+ @param signum: Signal number
"""
- self._io_wait.append((owner, fd, condition))
+ for owner in self._signal_wait:
+ owner.OnSignal(signum)
def RegisterSignal(self, owner):
"""Registers a receiver for signal notifications
"""
self._signal_wait.append(owner)
+
+
+def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn):
+ """Shared main function for daemons.
+
+ @type daemon_name: string
+ @param daemon_name: daemon name
+ @type optionparser: optparse.OptionParser
+ @param optionparser: initialized optionparser with daemon-specific options
+ (common -f -d options will be handled by this module)
+ @type dirs: list of strings
+ @param dirs: list of directories that must exist for this daemon to work
+ @type check_fn: function which accepts (options, args)
+ @param check_fn: function that checks start conditions and exits if they're
+ not met
+ @type exec_fn: function which accepts (options, args)
+ @param exec_fn: function that's executed with the daemon's pid file held, and
+ runs the daemon itself.
+
+ """
+ optionparser.add_option("-f", "--foreground", dest="fork",
+ help="Don't detach from the current terminal",
+ default=True, action="store_false")
+ optionparser.add_option("-d", "--debug", dest="debug",
+ help="Enable some debug messages",
+ default=False, action="store_true")
+ if daemon_name in constants.DAEMONS_PORTS:
+ # for networked daemons we also allow choosing the bind port and address.
+ # by default we use the port provided by utils.GetDaemonPort, and bind to
+ # 0.0.0.0 (which is represented by and empty bind address.
+ port = utils.GetDaemonPort(daemon_name)
+ optionparser.add_option("-p", "--port", dest="port",
+ help="Network port (%s default)." % port,
+ default=port, type="int")
+ optionparser.add_option("-b", "--bind", dest="bind_address",
+ help="Bind address",
+ default="", metavar="ADDRESS")
+
+ if daemon_name in constants.DAEMONS_SSL:
+ default_cert, default_key = constants.DAEMONS_SSL[daemon_name]
+ optionparser.add_option("--no-ssl", dest="ssl",
+ help="Do not secure HTTP protocol with SSL",
+ default=True, action="store_false")
+ optionparser.add_option("-K", "--ssl-key", dest="ssl_key",
+ help="SSL key",
+ default=default_key, type="string")
+ optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert",
+ help="SSL certificate",
+ default=default_cert, type="string")
+
+ multithread = utils.no_fork = daemon_name in constants.MULTITHREADED_DAEMONS
+
+ options, args = optionparser.parse_args()
+
+ if hasattr(options, 'ssl') and options.ssl:
+ if not (options.ssl_cert and options.ssl_key):
+ print >> sys.stderr, "Need key and certificate to use ssl"
+ sys.exit(constants.EXIT_FAILURE)
+ for fname in (options.ssl_cert, options.ssl_key):
+ if not os.path.isfile(fname):
+ print >> sys.stderr, "Need ssl file %s to run" % fname
+ sys.exit(constants.EXIT_FAILURE)
+
+ if check_fn is not None:
+ check_fn(options, args)
+
+ utils.EnsureDirs(dirs)
+
+ if options.fork:
+ utils.CloseFDs()
+ utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name])
+
+ utils.WritePidFile(daemon_name)
+ try:
+ utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name],
+ debug=options.debug,
+ stderr_logging=not options.fork,
+ multithreaded=multithread)
+ logging.info("%s daemon startup", daemon_name)
+ exec_fn(options, args)
+ finally:
+ utils.RemovePidFile(daemon_name)
projects / ganeti-local / blobdiff