root / lib / daemon.py @ 48bf6352
History | View | Annotate | Download (11.4 kB)
1 |
#
|
---|---|
2 |
#
|
3 |
|
4 |
# Copyright (C) 2006, 2007, 2008 Google Inc.
|
5 |
#
|
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.
|
10 |
#
|
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.
|
15 |
#
|
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
|
19 |
# 02110-1301, USA.
|
20 |
|
21 |
|
22 |
"""Module with helper classes and functions for daemons"""
|
23 |
|
24 |
|
25 |
import asyncore |
26 |
import os |
27 |
import signal |
28 |
import errno |
29 |
import logging |
30 |
import sched |
31 |
import time |
32 |
import socket |
33 |
import select |
34 |
import sys |
35 |
|
36 |
from ganeti import utils |
37 |
from ganeti import constants |
38 |
from ganeti import errors |
39 |
|
40 |
|
41 |
class SchedulerBreakout(Exception): |
42 |
"""Exception used to get out of the scheduler loop
|
43 |
|
44 |
"""
|
45 |
|
46 |
|
47 |
def AsyncoreDelayFunction(timeout): |
48 |
"""Asyncore-compatible scheduler delay function.
|
49 |
|
50 |
This is a delay function for sched that, rather than actually sleeping,
|
51 |
executes asyncore events happening in the meantime.
|
52 |
|
53 |
After an event has occurred, rather than returning, it raises a
|
54 |
SchedulerBreakout exception, which will force the current scheduler.run()
|
55 |
invocation to terminate, so that we can also check for signals. The main loop
|
56 |
will then call the scheduler run again, which will allow it to actually
|
57 |
process any due events.
|
58 |
|
59 |
This is needed because scheduler.run() doesn't support a count=..., as
|
60 |
asyncore loop, and the scheduler module documents throwing exceptions from
|
61 |
inside the delay function as an allowed usage model.
|
62 |
|
63 |
"""
|
64 |
asyncore.loop(timeout=timeout, count=1, use_poll=True) |
65 |
raise SchedulerBreakout()
|
66 |
|
67 |
|
68 |
class AsyncoreScheduler(sched.scheduler): |
69 |
"""Event scheduler integrated with asyncore
|
70 |
|
71 |
"""
|
72 |
def __init__(self, timefunc): |
73 |
sched.scheduler.__init__(self, timefunc, AsyncoreDelayFunction)
|
74 |
|
75 |
|
76 |
class AsyncUDPSocket(asyncore.dispatcher): |
77 |
"""An improved asyncore udp socket.
|
78 |
|
79 |
"""
|
80 |
def __init__(self): |
81 |
"""Constructor for AsyncUDPSocket
|
82 |
|
83 |
"""
|
84 |
asyncore.dispatcher.__init__(self)
|
85 |
self._out_queue = []
|
86 |
self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
|
87 |
|
88 |
# this method is overriding an asyncore.dispatcher method
|
89 |
def handle_connect(self): |
90 |
# Python thinks that the first udp message from a source qualifies as a
|
91 |
# "connect" and further ones are part of the same connection. We beg to
|
92 |
# differ and treat all messages equally.
|
93 |
pass
|
94 |
|
95 |
def do_read(self): |
96 |
try:
|
97 |
payload, address = self.recvfrom(constants.MAX_UDP_DATA_SIZE)
|
98 |
except socket.error, err:
|
99 |
if err.errno == errno.EINTR:
|
100 |
# we got a signal while trying to read. no need to do anything,
|
101 |
# handle_read will be called again if there is data on the socket.
|
102 |
return
|
103 |
else:
|
104 |
raise
|
105 |
ip, port = address |
106 |
self.handle_datagram(payload, ip, port)
|
107 |
|
108 |
# this method is overriding an asyncore.dispatcher method
|
109 |
def handle_read(self): |
110 |
try:
|
111 |
self.do_read()
|
112 |
except: # pylint: disable-msg=W0702 |
113 |
# we need to catch any exception here, log it, but proceed, because even
|
114 |
# if we failed handling a single request, we still want to continue.
|
115 |
logging.error("Unexpected exception", exc_info=True) |
116 |
|
117 |
def handle_datagram(self, payload, ip, port): |
118 |
"""Handle an already read udp datagram
|
119 |
|
120 |
"""
|
121 |
raise NotImplementedError |
122 |
|
123 |
# this method is overriding an asyncore.dispatcher method
|
124 |
def writable(self): |
125 |
# We should check whether we can write to the socket only if we have
|
126 |
# something scheduled to be written
|
127 |
return bool(self._out_queue) |
128 |
|
129 |
# this method is overriding an asyncore.dispatcher method
|
130 |
def handle_write(self): |
131 |
try:
|
132 |
if not self._out_queue: |
133 |
logging.error("handle_write called with empty output queue")
|
134 |
return
|
135 |
(ip, port, payload) = self._out_queue[0] |
136 |
try:
|
137 |
self.sendto(payload, 0, (ip, port)) |
138 |
except socket.error, err:
|
139 |
if err.errno == errno.EINTR:
|
140 |
# we got a signal while trying to write. no need to do anything,
|
141 |
# handle_write will be called again because we haven't emptied the
|
142 |
# _out_queue, and we'll try again
|
143 |
return
|
144 |
else:
|
145 |
raise
|
146 |
self._out_queue.pop(0) |
147 |
except: # pylint: disable-msg=W0702 |
148 |
# we need to catch any exception here, log it, but proceed, because even
|
149 |
# if we failed sending a single datagram we still want to continue.
|
150 |
logging.error("Unexpected exception", exc_info=True) |
151 |
|
152 |
def enqueue_send(self, ip, port, payload): |
153 |
"""Enqueue a datagram to be sent when possible
|
154 |
|
155 |
"""
|
156 |
if len(payload) > constants.MAX_UDP_DATA_SIZE: |
157 |
raise errors.UdpDataSizeError('Packet too big: %s > %s' % (len(payload), |
158 |
constants.MAX_UDP_DATA_SIZE)) |
159 |
self._out_queue.append((ip, port, payload))
|
160 |
|
161 |
def process_next_packet(self, timeout=0): |
162 |
"""Process the next datagram, waiting for it if necessary.
|
163 |
|
164 |
@type timeout: float
|
165 |
@param timeout: how long to wait for data
|
166 |
@rtype: boolean
|
167 |
@return: True if some data has been handled, False otherwise
|
168 |
|
169 |
"""
|
170 |
result = utils.WaitForFdCondition(self, select.POLLIN, timeout)
|
171 |
if result is not None and result & select.POLLIN: |
172 |
self.do_read()
|
173 |
return True |
174 |
else:
|
175 |
return False |
176 |
|
177 |
|
178 |
class Mainloop(object): |
179 |
"""Generic mainloop for daemons
|
180 |
|
181 |
@ivar scheduler: A sched.scheduler object, which can be used to register
|
182 |
timed events
|
183 |
|
184 |
"""
|
185 |
def __init__(self): |
186 |
"""Constructs a new Mainloop instance.
|
187 |
|
188 |
"""
|
189 |
self._signal_wait = []
|
190 |
self.scheduler = AsyncoreScheduler(time.time)
|
191 |
|
192 |
@utils.SignalHandled([signal.SIGCHLD])
|
193 |
@utils.SignalHandled([signal.SIGTERM])
|
194 |
def Run(self, signal_handlers=None): |
195 |
"""Runs the mainloop.
|
196 |
|
197 |
@type signal_handlers: dict
|
198 |
@param signal_handlers: signal->L{utils.SignalHandler} passed by decorator
|
199 |
|
200 |
"""
|
201 |
assert isinstance(signal_handlers, dict) and \ |
202 |
len(signal_handlers) > 0, \ |
203 |
"Broken SignalHandled decorator"
|
204 |
running = True
|
205 |
# Start actual main loop
|
206 |
while running:
|
207 |
if not self.scheduler.empty(): |
208 |
try:
|
209 |
self.scheduler.run()
|
210 |
except SchedulerBreakout:
|
211 |
pass
|
212 |
else:
|
213 |
asyncore.loop(count=1, use_poll=True) |
214 |
|
215 |
# Check whether a signal was raised
|
216 |
for sig in signal_handlers: |
217 |
handler = signal_handlers[sig] |
218 |
if handler.called:
|
219 |
self._CallSignalWaiters(sig)
|
220 |
running = (sig != signal.SIGTERM) |
221 |
handler.Clear() |
222 |
|
223 |
def _CallSignalWaiters(self, signum): |
224 |
"""Calls all signal waiters for a certain signal.
|
225 |
|
226 |
@type signum: int
|
227 |
@param signum: Signal number
|
228 |
|
229 |
"""
|
230 |
for owner in self._signal_wait: |
231 |
owner.OnSignal(signum) |
232 |
|
233 |
def RegisterSignal(self, owner): |
234 |
"""Registers a receiver for signal notifications
|
235 |
|
236 |
The receiver must support a "OnSignal(self, signum)" function.
|
237 |
|
238 |
@type owner: instance
|
239 |
@param owner: Receiver
|
240 |
|
241 |
"""
|
242 |
self._signal_wait.append(owner)
|
243 |
|
244 |
|
245 |
def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn, |
246 |
console_logging=False):
|
247 |
"""Shared main function for daemons.
|
248 |
|
249 |
@type daemon_name: string
|
250 |
@param daemon_name: daemon name
|
251 |
@type optionparser: optparse.OptionParser
|
252 |
@param optionparser: initialized optionparser with daemon-specific options
|
253 |
(common -f -d options will be handled by this module)
|
254 |
@type dirs: list of (string, integer)
|
255 |
@param dirs: list of directories that must be created if they don't exist,
|
256 |
and the permissions to be used to create them
|
257 |
@type check_fn: function which accepts (options, args)
|
258 |
@param check_fn: function that checks start conditions and exits if they're
|
259 |
not met
|
260 |
@type exec_fn: function which accepts (options, args)
|
261 |
@param exec_fn: function that's executed with the daemon's pid file held, and
|
262 |
runs the daemon itself.
|
263 |
@type console_logging: boolean
|
264 |
@param console_logging: if True, the daemon will fall back to the system
|
265 |
console if logging fails
|
266 |
|
267 |
"""
|
268 |
optionparser.add_option("-f", "--foreground", dest="fork", |
269 |
help="Don't detach from the current terminal",
|
270 |
default=True, action="store_false") |
271 |
optionparser.add_option("-d", "--debug", dest="debug", |
272 |
help="Enable some debug messages",
|
273 |
default=False, action="store_true") |
274 |
optionparser.add_option("--syslog", dest="syslog", |
275 |
help="Enable logging to syslog (except debug"
|
276 |
" messages); one of 'no', 'yes' or 'only' [%s]" %
|
277 |
constants.SYSLOG_USAGE, |
278 |
default=constants.SYSLOG_USAGE, |
279 |
choices=["no", "yes", "only"]) |
280 |
if daemon_name in constants.DAEMONS_PORTS: |
281 |
# for networked daemons we also allow choosing the bind port and address.
|
282 |
# by default we use the port provided by utils.GetDaemonPort, and bind to
|
283 |
# 0.0.0.0 (which is represented by and empty bind address.
|
284 |
port = utils.GetDaemonPort(daemon_name) |
285 |
optionparser.add_option("-p", "--port", dest="port", |
286 |
help="Network port (%s default)." % port,
|
287 |
default=port, type="int")
|
288 |
optionparser.add_option("-b", "--bind", dest="bind_address", |
289 |
help="Bind address",
|
290 |
default="", metavar="ADDRESS") |
291 |
|
292 |
if daemon_name in constants.DAEMONS_SSL: |
293 |
default_cert, default_key = constants.DAEMONS_SSL[daemon_name] |
294 |
optionparser.add_option("--no-ssl", dest="ssl", |
295 |
help="Do not secure HTTP protocol with SSL",
|
296 |
default=True, action="store_false") |
297 |
optionparser.add_option("-K", "--ssl-key", dest="ssl_key", |
298 |
help="SSL key",
|
299 |
default=default_key, type="string")
|
300 |
optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert", |
301 |
help="SSL certificate",
|
302 |
default=default_cert, type="string")
|
303 |
|
304 |
multithread = utils.no_fork = daemon_name in constants.MULTITHREADED_DAEMONS
|
305 |
|
306 |
options, args = optionparser.parse_args() |
307 |
|
308 |
if hasattr(options, 'ssl') and options.ssl: |
309 |
if not (options.ssl_cert and options.ssl_key): |
310 |
print >> sys.stderr, "Need key and certificate to use ssl" |
311 |
sys.exit(constants.EXIT_FAILURE) |
312 |
for fname in (options.ssl_cert, options.ssl_key): |
313 |
if not os.path.isfile(fname): |
314 |
print >> sys.stderr, "Need ssl file %s to run" % fname |
315 |
sys.exit(constants.EXIT_FAILURE) |
316 |
|
317 |
if check_fn is not None: |
318 |
check_fn(options, args) |
319 |
|
320 |
utils.EnsureDirs(dirs) |
321 |
|
322 |
if options.fork:
|
323 |
utils.CloseFDs() |
324 |
utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name]) |
325 |
|
326 |
utils.WritePidFile(daemon_name) |
327 |
try:
|
328 |
utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name], |
329 |
debug=options.debug, |
330 |
stderr_logging=not options.fork,
|
331 |
multithreaded=multithread, |
332 |
program=daemon_name, |
333 |
syslog=options.syslog, |
334 |
console_logging=console_logging) |
335 |
logging.info("%s daemon startup", daemon_name)
|
336 |
exec_fn(options, args) |
337 |
finally:
|
338 |
utils.RemovePidFile(daemon_name) |