root / lib / daemon.py @ b2efcd70
History | View | Annotate | Download (10.6 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 logging |
29 |
import sched |
30 |
import time |
31 |
import socket |
32 |
import select |
33 |
import sys |
34 |
|
35 |
from ganeti import utils |
36 |
from ganeti import constants |
37 |
from ganeti import errors |
38 |
|
39 |
|
40 |
class SchedulerBreakout(Exception): |
41 |
"""Exception used to get out of the scheduler loop
|
42 |
|
43 |
"""
|
44 |
|
45 |
|
46 |
def AsyncoreDelayFunction(timeout): |
47 |
"""Asyncore-compatible scheduler delay function.
|
48 |
|
49 |
This is a delay function for sched that, rather than actually sleeping,
|
50 |
executes asyncore events happening in the meantime.
|
51 |
|
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.
|
57 |
|
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.
|
61 |
|
62 |
"""
|
63 |
asyncore.loop(timeout=timeout, count=1, use_poll=True) |
64 |
raise SchedulerBreakout()
|
65 |
|
66 |
|
67 |
class AsyncoreScheduler(sched.scheduler): |
68 |
"""Event scheduler integrated with asyncore
|
69 |
|
70 |
"""
|
71 |
def __init__(self, timefunc): |
72 |
sched.scheduler.__init__(self, timefunc, AsyncoreDelayFunction)
|
73 |
|
74 |
|
75 |
class AsyncUDPSocket(asyncore.dispatcher): |
76 |
"""An improved asyncore udp socket.
|
77 |
|
78 |
"""
|
79 |
def __init__(self): |
80 |
"""Constructor for AsyncUDPSocket
|
81 |
|
82 |
"""
|
83 |
asyncore.dispatcher.__init__(self)
|
84 |
self._out_queue = []
|
85 |
self.create_socket(socket.AF_INET, socket.SOCK_DGRAM)
|
86 |
|
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.
|
92 |
pass
|
93 |
|
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) |
98 |
ip, port = address |
99 |
self.handle_datagram(payload, ip, port)
|
100 |
|
101 |
def handle_datagram(self, payload, ip, port): |
102 |
"""Handle an already read udp datagram
|
103 |
|
104 |
"""
|
105 |
raise NotImplementedError |
106 |
|
107 |
# this method is overriding an asyncore.dispatcher method
|
108 |
def writable(self): |
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) |
112 |
|
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")
|
117 |
return
|
118 |
(ip, port, payload) = self._out_queue[0] |
119 |
utils.IgnoreSignals(self.sendto, payload, 0, (ip, port)) |
120 |
self._out_queue.pop(0) |
121 |
|
122 |
# this method is overriding an asyncore.dispatcher method
|
123 |
def handle_error(self): |
124 |
"""Log an error in handling any request, and proceed.
|
125 |
|
126 |
"""
|
127 |
logging.exception("Error while handling asyncore request")
|
128 |
|
129 |
def enqueue_send(self, ip, port, payload): |
130 |
"""Enqueue a datagram to be sent when possible
|
131 |
|
132 |
"""
|
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))
|
137 |
|
138 |
def process_next_packet(self, timeout=0): |
139 |
"""Process the next datagram, waiting for it if necessary.
|
140 |
|
141 |
@type timeout: float
|
142 |
@param timeout: how long to wait for data
|
143 |
@rtype: boolean
|
144 |
@return: True if some data has been handled, False otherwise
|
145 |
|
146 |
"""
|
147 |
result = utils.WaitForFdCondition(self, select.POLLIN, timeout)
|
148 |
if result is not None and result & select.POLLIN: |
149 |
self.handle_read()
|
150 |
return True |
151 |
else:
|
152 |
return False |
153 |
|
154 |
|
155 |
class Mainloop(object): |
156 |
"""Generic mainloop for daemons
|
157 |
|
158 |
@ivar scheduler: A sched.scheduler object, which can be used to register
|
159 |
timed events
|
160 |
|
161 |
"""
|
162 |
def __init__(self): |
163 |
"""Constructs a new Mainloop instance.
|
164 |
|
165 |
"""
|
166 |
self._signal_wait = []
|
167 |
self.scheduler = AsyncoreScheduler(time.time)
|
168 |
|
169 |
@utils.SignalHandled([signal.SIGCHLD])
|
170 |
@utils.SignalHandled([signal.SIGTERM])
|
171 |
def Run(self, signal_handlers=None): |
172 |
"""Runs the mainloop.
|
173 |
|
174 |
@type signal_handlers: dict
|
175 |
@param signal_handlers: signal->L{utils.SignalHandler} passed by decorator
|
176 |
|
177 |
"""
|
178 |
assert isinstance(signal_handlers, dict) and \ |
179 |
len(signal_handlers) > 0, \ |
180 |
"Broken SignalHandled decorator"
|
181 |
running = True
|
182 |
# Start actual main loop
|
183 |
while running:
|
184 |
if not self.scheduler.empty(): |
185 |
try:
|
186 |
self.scheduler.run()
|
187 |
except SchedulerBreakout:
|
188 |
pass
|
189 |
else:
|
190 |
asyncore.loop(count=1, use_poll=True) |
191 |
|
192 |
# Check whether a signal was raised
|
193 |
for sig in signal_handlers: |
194 |
handler = signal_handlers[sig] |
195 |
if handler.called:
|
196 |
self._CallSignalWaiters(sig)
|
197 |
running = (sig != signal.SIGTERM) |
198 |
handler.Clear() |
199 |
|
200 |
def _CallSignalWaiters(self, signum): |
201 |
"""Calls all signal waiters for a certain signal.
|
202 |
|
203 |
@type signum: int
|
204 |
@param signum: Signal number
|
205 |
|
206 |
"""
|
207 |
for owner in self._signal_wait: |
208 |
owner.OnSignal(signum) |
209 |
|
210 |
def RegisterSignal(self, owner): |
211 |
"""Registers a receiver for signal notifications
|
212 |
|
213 |
The receiver must support a "OnSignal(self, signum)" function.
|
214 |
|
215 |
@type owner: instance
|
216 |
@param owner: Receiver
|
217 |
|
218 |
"""
|
219 |
self._signal_wait.append(owner)
|
220 |
|
221 |
|
222 |
def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn, |
223 |
console_logging=False):
|
224 |
"""Shared main function for daemons.
|
225 |
|
226 |
@type daemon_name: string
|
227 |
@param daemon_name: daemon name
|
228 |
@type optionparser: optparse.OptionParser
|
229 |
@param optionparser: initialized optionparser with daemon-specific options
|
230 |
(common -f -d options will be handled by this module)
|
231 |
@type dirs: list of (string, integer)
|
232 |
@param dirs: list of directories that must be created if they don't exist,
|
233 |
and the permissions to be used to create them
|
234 |
@type check_fn: function which accepts (options, args)
|
235 |
@param check_fn: function that checks start conditions and exits if they're
|
236 |
not met
|
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.
|
240 |
@type console_logging: boolean
|
241 |
@param console_logging: if True, the daemon will fall back to the system
|
242 |
console if logging fails
|
243 |
|
244 |
"""
|
245 |
optionparser.add_option("-f", "--foreground", dest="fork", |
246 |
help="Don't detach from the current terminal",
|
247 |
default=True, action="store_false") |
248 |
optionparser.add_option("-d", "--debug", dest="debug", |
249 |
help="Enable some debug messages",
|
250 |
default=False, action="store_true") |
251 |
optionparser.add_option("--syslog", dest="syslog", |
252 |
help="Enable logging to syslog (except debug"
|
253 |
" messages); one of 'no', 'yes' or 'only' [%s]" %
|
254 |
constants.SYSLOG_USAGE, |
255 |
default=constants.SYSLOG_USAGE, |
256 |
choices=["no", "yes", "only"]) |
257 |
if daemon_name in constants.DAEMONS_PORTS: |
258 |
# for networked daemons we also allow choosing the bind port and address.
|
259 |
# by default we use the port provided by utils.GetDaemonPort, and bind to
|
260 |
# 0.0.0.0 (which is represented by and empty bind address.
|
261 |
port = utils.GetDaemonPort(daemon_name) |
262 |
optionparser.add_option("-p", "--port", dest="port", |
263 |
help="Network port (%s default)." % port,
|
264 |
default=port, type="int")
|
265 |
optionparser.add_option("-b", "--bind", dest="bind_address", |
266 |
help="Bind address",
|
267 |
default="", metavar="ADDRESS") |
268 |
|
269 |
if daemon_name in constants.DAEMONS_SSL: |
270 |
default_cert, default_key = constants.DAEMONS_SSL[daemon_name] |
271 |
optionparser.add_option("--no-ssl", dest="ssl", |
272 |
help="Do not secure HTTP protocol with SSL",
|
273 |
default=True, action="store_false") |
274 |
optionparser.add_option("-K", "--ssl-key", dest="ssl_key", |
275 |
help="SSL key",
|
276 |
default=default_key, type="string")
|
277 |
optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert", |
278 |
help="SSL certificate",
|
279 |
default=default_cert, type="string")
|
280 |
|
281 |
multithread = utils.no_fork = daemon_name in constants.MULTITHREADED_DAEMONS
|
282 |
|
283 |
options, args = optionparser.parse_args() |
284 |
|
285 |
if hasattr(options, 'ssl') and options.ssl: |
286 |
if not (options.ssl_cert and options.ssl_key): |
287 |
print >> sys.stderr, "Need key and certificate to use ssl" |
288 |
sys.exit(constants.EXIT_FAILURE) |
289 |
for fname in (options.ssl_cert, options.ssl_key): |
290 |
if not os.path.isfile(fname): |
291 |
print >> sys.stderr, "Need ssl file %s to run" % fname |
292 |
sys.exit(constants.EXIT_FAILURE) |
293 |
|
294 |
if check_fn is not None: |
295 |
check_fn(options, args) |
296 |
|
297 |
utils.EnsureDirs(dirs) |
298 |
|
299 |
if options.fork:
|
300 |
utils.CloseFDs() |
301 |
utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name]) |
302 |
|
303 |
utils.WritePidFile(daemon_name) |
304 |
try:
|
305 |
utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name], |
306 |
debug=options.debug, |
307 |
stderr_logging=not options.fork,
|
308 |
multithreaded=multithread, |
309 |
program=daemon_name, |
310 |
syslog=options.syslog, |
311 |
console_logging=console_logging) |
312 |
logging.info("%s daemon startup", daemon_name)
|
313 |
exec_fn(options, args) |
314 |
finally:
|
315 |
utils.RemovePidFile(daemon_name) |