4 # Copyright (C) 2006, 2007, 2008 Google Inc.
6 # This program is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 2 of the License, or
9 # (at your option) any later version.
11 # This program is distributed in the hope that it will be useful, but
12 # WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 # General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with this program; if not, write to the Free Software
18 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
22 """Module with helper classes and functions for daemons"""
35 from ganeti import utils
36 from ganeti import constants
37 from ganeti import errors
40 class SchedulerBreakout(Exception):
41 """Exception used to get out of the scheduler loop
46 def AsyncoreDelayFunction(timeout):
47 """Asyncore-compatible scheduler delay function.
49 This is a delay function for sched that, rather than actually sleeping,
50 executes asyncore events happening in the meantime.
52 After an event has occurred, rather than returning, it raises a
53 SchedulerBreakout exception, which will force the current scheduler.run()
54 invocation to terminate, so that we can also check for signals. The main loop
55 will then call the scheduler run again, which will allow it to actually
56 process any due events.
58 This is needed because scheduler.run() doesn't support a count=..., as
59 asyncore loop, and the scheduler module documents throwing exceptions from
60 inside the delay function as an allowed usage model.
63 asyncore.loop(timeout=timeout, count=1, use_poll=True)
64 raise SchedulerBreakout()
67 class AsyncoreScheduler(sched.scheduler):
68 """Event scheduler integrated with asyncore
71 def __init__(self, timefunc):
72 sched.scheduler.__init__(self, timefunc, AsyncoreDelayFunction)
75 class AsyncUDPSocket(asyncore.dispatcher):
76 """An improved asyncore udp socket.
80 """Constructor for AsyncUDPSocket
83 asyncore.dispatcher.__init__(self)
85 self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
87 # this method is overriding an asyncore.dispatcher method
88 def handle_connect(self):
89 # Python thinks that the first udp message from a source qualifies as a
90 # "connect" and further ones are part of the same connection. We beg to
91 # differ and treat all messages equally.
94 # this method is overriding an asyncore.dispatcher method
95 def handle_read(self):
98 payload, address = self.recvfrom(constants.MAX_UDP_DATA_SIZE)
99 except socket.error, err:
100 if err.errno == errno.EINTR:
101 # we got a signal while trying to read. no need to do anything,
102 # handle_read will be called again if there is data on the socket.
107 self.handle_datagram(payload, ip, port)
108 except: # pylint: disable-msg=W0702
109 # we need to catch any exception here, log it, but proceed, because even
110 # if we failed handling a single request, we still want to continue.
111 logging.error("Unexpected exception", exc_info=True)
113 def handle_datagram(self, payload, ip, port):
114 """Handle an already read udp datagram
117 raise NotImplementedError
119 # this method is overriding an asyncore.dispatcher method
121 # We should check whether we can write to the socket only if we have
122 # something scheduled to be written
123 return bool(self._out_queue)
125 def handle_write(self):
127 if not self._out_queue:
128 logging.error("handle_write called with empty output queue")
130 (ip, port, payload) = self._out_queue[0]
132 self.sendto(payload, 0, (ip, port))
133 except socket.error, err:
134 if err.errno == errno.EINTR:
135 # we got a signal while trying to write. no need to do anything,
136 # handle_write will be called again because we haven't emptied the
137 # _out_queue, and we'll try again
141 self._out_queue.pop(0)
142 except: # pylint: disable-msg=W0702
143 # we need to catch any exception here, log it, but proceed, because even
144 # if we failed sending a single datagram we still want to continue.
145 logging.error("Unexpected exception", exc_info=True)
147 def enqueue_send(self, ip, port, payload):
148 """Enqueue a datagram to be sent when possible
151 if len(payload) > constants.MAX_UDP_DATA_SIZE:
152 raise errors.UdpDataSizeError('Packet too big: %s > %s' % (len(payload),
153 constants.MAX_UDP_DATA_SIZE))
154 self._out_queue.append((ip, port, payload))
157 class Mainloop(object):
158 """Generic mainloop for daemons
160 @ivar scheduler: A sched.scheduler object, which can be used to register
165 """Constructs a new Mainloop instance.
168 self._signal_wait = []
169 self.scheduler = AsyncoreScheduler(time.time)
171 @utils.SignalHandled([signal.SIGCHLD])
172 @utils.SignalHandled([signal.SIGTERM])
173 def Run(self, signal_handlers=None):
174 """Runs the mainloop.
176 @type signal_handlers: dict
177 @param signal_handlers: signal->L{utils.SignalHandler} passed by decorator
180 assert isinstance(signal_handlers, dict) and \
181 len(signal_handlers) > 0, \
182 "Broken SignalHandled decorator"
184 # Start actual main loop
186 if not self.scheduler.empty():
189 except SchedulerBreakout:
192 asyncore.loop(count=1, use_poll=True)
194 # Check whether a signal was raised
195 for sig in signal_handlers:
196 handler = signal_handlers[sig]
198 self._CallSignalWaiters(sig)
199 running = (sig != signal.SIGTERM)
202 def _CallSignalWaiters(self, signum):
203 """Calls all signal waiters for a certain signal.
206 @param signum: Signal number
209 for owner in self._signal_wait:
210 owner.OnSignal(signum)
212 def RegisterSignal(self, owner):
213 """Registers a receiver for signal notifications
215 The receiver must support a "OnSignal(self, signum)" function.
217 @type owner: instance
218 @param owner: Receiver
221 self._signal_wait.append(owner)
224 def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn):
225 """Shared main function for daemons.
227 @type daemon_name: string
228 @param daemon_name: daemon name
229 @type optionparser: optparse.OptionParser
230 @param optionparser: initialized optionparser with daemon-specific options
231 (common -f -d options will be handled by this module)
232 @type dirs: list of strings
233 @param dirs: list of directories that must exist for this daemon to work
234 @type check_fn: function which accepts (options, args)
235 @param check_fn: function that checks start conditions and exits if they're
237 @type exec_fn: function which accepts (options, args)
238 @param exec_fn: function that's executed with the daemon's pid file held, and
239 runs the daemon itself.
242 optionparser.add_option("-f", "--foreground", dest="fork",
243 help="Don't detach from the current terminal",
244 default=True, action="store_false")
245 optionparser.add_option("-d", "--debug", dest="debug",
246 help="Enable some debug messages",
247 default=False, action="store_true")
248 optionparser.add_option("--syslog", dest="syslog",
249 help="Enable logging to syslog (except debug"
250 " messages); one of 'no', 'yes' or 'only' [%s]" %
251 constants.SYSLOG_USAGE,
252 default=constants.SYSLOG_USAGE,
253 choices=["no", "yes", "only"])
254 if daemon_name in constants.DAEMONS_PORTS:
255 # for networked daemons we also allow choosing the bind port and address.
256 # by default we use the port provided by utils.GetDaemonPort, and bind to
257 # 0.0.0.0 (which is represented by and empty bind address.
258 port = utils.GetDaemonPort(daemon_name)
259 optionparser.add_option("-p", "--port", dest="port",
260 help="Network port (%s default)." % port,
261 default=port, type="int")
262 optionparser.add_option("-b", "--bind", dest="bind_address",
264 default="", metavar="ADDRESS")
266 if daemon_name in constants.DAEMONS_SSL:
267 default_cert, default_key = constants.DAEMONS_SSL[daemon_name]
268 optionparser.add_option("--no-ssl", dest="ssl",
269 help="Do not secure HTTP protocol with SSL",
270 default=True, action="store_false")
271 optionparser.add_option("-K", "--ssl-key", dest="ssl_key",
273 default=default_key, type="string")
274 optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert",
275 help="SSL certificate",
276 default=default_cert, type="string")
278 multithread = utils.no_fork = daemon_name in constants.MULTITHREADED_DAEMONS
280 options, args = optionparser.parse_args()
282 if hasattr(options, 'ssl') and options.ssl:
283 if not (options.ssl_cert and options.ssl_key):
284 print >> sys.stderr, "Need key and certificate to use ssl"
285 sys.exit(constants.EXIT_FAILURE)
286 for fname in (options.ssl_cert, options.ssl_key):
287 if not os.path.isfile(fname):
288 print >> sys.stderr, "Need ssl file %s to run" % fname
289 sys.exit(constants.EXIT_FAILURE)
291 if check_fn is not None:
292 check_fn(options, args)
294 utils.EnsureDirs(dirs)
298 utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name])
300 utils.WritePidFile(daemon_name)
302 utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name],
304 stderr_logging=not options.fork,
305 multithreaded=multithread,
307 syslog=options.syslog)
308 logging.info("%s daemon startup", daemon_name)
309 exec_fn(options, args)
311 utils.RemovePidFile(daemon_name)