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):
96 payload, address = utils.IgnoreSignals(self.recvfrom,
97 constants.MAX_UDP_DATA_SIZE)
99 self.handle_datagram(payload, ip, port)
101 def handle_datagram(self, payload, ip, port):
102 """Handle an already read udp datagram
105 raise NotImplementedError
107 # this method is overriding an asyncore.dispatcher method
109 # We should check whether we can write to the socket only if we have
110 # something scheduled to be written
111 return bool(self._out_queue)
113 # this method is overriding an asyncore.dispatcher method
114 def handle_write(self):
115 if not self._out_queue:
116 logging.error("handle_write called with empty output queue")
118 (ip, port, payload) = self._out_queue[0]
119 utils.IgnoreSignals(self.sendto, payload, 0, (ip, port))
120 self._out_queue.pop(0)
122 # this method is overriding an asyncore.dispatcher method
123 def handle_error(self):
124 """Log an error in handling any request, and proceed.
127 logging.exception("Error while handling asyncore request")
129 def enqueue_send(self, ip, port, payload):
130 """Enqueue a datagram to be sent when possible
133 if len(payload) > constants.MAX_UDP_DATA_SIZE:
134 raise errors.UdpDataSizeError('Packet too big: %s > %s' % (len(payload),
135 constants.MAX_UDP_DATA_SIZE))
136 self._out_queue.append((ip, port, payload))
138 def process_next_packet(self, timeout=0):
139 """Process the next datagram, waiting for it if necessary.
142 @param timeout: how long to wait for data
144 @return: True if some data has been handled, False otherwise
147 result = utils.WaitForFdCondition(self, select.POLLIN, timeout)
148 if result is not None and result & select.POLLIN:
155 class Mainloop(object):
156 """Generic mainloop for daemons
158 @ivar scheduler: A sched.scheduler object, which can be used to register
163 """Constructs a new Mainloop instance.
166 self._signal_wait = []
167 self.scheduler = AsyncoreScheduler(time.time)
169 @utils.SignalHandled([signal.SIGCHLD])
170 @utils.SignalHandled([signal.SIGTERM])
171 def Run(self, signal_handlers=None):
172 """Runs the mainloop.
174 @type signal_handlers: dict
175 @param signal_handlers: signal->L{utils.SignalHandler} passed by decorator
178 assert isinstance(signal_handlers, dict) and \
179 len(signal_handlers) > 0, \
180 "Broken SignalHandled decorator"
182 # Start actual main loop
184 if not self.scheduler.empty():
187 except SchedulerBreakout:
190 asyncore.loop(count=1, use_poll=True)
192 # Check whether a signal was raised
193 for sig in signal_handlers:
194 handler = signal_handlers[sig]
196 self._CallSignalWaiters(sig)
197 running = (sig != signal.SIGTERM)
200 def _CallSignalWaiters(self, signum):
201 """Calls all signal waiters for a certain signal.
204 @param signum: Signal number
207 for owner in self._signal_wait:
208 owner.OnSignal(signum)
210 def RegisterSignal(self, owner):
211 """Registers a receiver for signal notifications
213 The receiver must support a "OnSignal(self, signum)" function.
215 @type owner: instance
216 @param owner: Receiver
219 self._signal_wait.append(owner)
222 def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn,
223 multithreaded=False, console_logging=False,
224 default_ssl_cert=None, default_ssl_key=None):
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 (string, integer)
233 @param dirs: list of directories that must be created if they don't exist,
234 and the permissions to be used to create them
235 @type check_fn: function which accepts (options, args)
236 @param check_fn: function that checks start conditions and exits if they're
238 @type exec_fn: function which accepts (options, args)
239 @param exec_fn: function that's executed with the daemon's pid file held, and
240 runs the daemon itself.
241 @type multithreaded: bool
242 @param multithreaded: Whether the daemon uses threads
243 @type console_logging: boolean
244 @param console_logging: if True, the daemon will fall back to the system
245 console if logging fails
246 @type default_ssl_cert: string
247 @param default_ssl_cert: Default SSL certificate path
248 @type default_ssl_key: string
249 @param default_ssl_key: Default SSL key path
252 optionparser.add_option("-f", "--foreground", dest="fork",
253 help="Don't detach from the current terminal",
254 default=True, action="store_false")
255 optionparser.add_option("-d", "--debug", dest="debug",
256 help="Enable some debug messages",
257 default=False, action="store_true")
258 optionparser.add_option("--syslog", dest="syslog",
259 help="Enable logging to syslog (except debug"
260 " messages); one of 'no', 'yes' or 'only' [%s]" %
261 constants.SYSLOG_USAGE,
262 default=constants.SYSLOG_USAGE,
263 choices=["no", "yes", "only"])
265 if daemon_name in constants.DAEMONS_PORTS:
266 default_bind_address = "0.0.0.0"
267 default_port = utils.GetDaemonPort(daemon_name)
269 # For networked daemons we allow choosing the port and bind address
270 optionparser.add_option("-p", "--port", dest="port",
271 help="Network port (default: %s)" % default_port,
272 default=default_port, type="int")
273 optionparser.add_option("-b", "--bind", dest="bind_address",
274 help=("Bind address (default: %s)" %
275 default_bind_address),
276 default=default_bind_address, metavar="ADDRESS")
278 if default_ssl_key is not None and default_ssl_cert is not None:
279 optionparser.add_option("--no-ssl", dest="ssl",
280 help="Do not secure HTTP protocol with SSL",
281 default=True, action="store_false")
282 optionparser.add_option("-K", "--ssl-key", dest="ssl_key",
283 help=("SSL key path (default: %s)" %
285 default=default_ssl_key, type="string",
286 metavar="SSL_KEY_PATH")
287 optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert",
288 help=("SSL certificate path (default: %s)" %
290 default=default_ssl_cert, type="string",
291 metavar="SSL_CERT_PATH")
293 # Disable the use of fork(2) if the daemon uses threads
294 utils.no_fork = multithreaded
296 options, args = optionparser.parse_args()
298 if getattr(options, "ssl", False):
300 "certificate": options.ssl_cert,
301 "key": options.ssl_key,
304 for name, path in ssl_paths.iteritems():
305 if not os.path.isfile(path):
306 print >> sys.stderr, "SSL %s file '%s' was not found" % (name, path)
307 sys.exit(constants.EXIT_FAILURE)
309 # TODO: By initiating http.HttpSslParams here we would only read the files
310 # once and have a proper validation (isfile returns False on directories)
313 if check_fn is not None:
314 check_fn(options, args)
316 utils.EnsureDirs(dirs)
320 utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name])
322 utils.WritePidFile(daemon_name)
324 utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name],
326 stderr_logging=not options.fork,
327 multithreaded=multithreaded,
329 syslog=options.syslog,
330 console_logging=console_logging)
331 logging.info("%s daemon startup", daemon_name)
332 exec_fn(options, args)
334 utils.RemovePidFile(daemon_name)