root / lib / daemon.py @ 577c90a3
History | View | Annotate | Download (9 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 os |
26 |
import select |
27 |
import signal |
28 |
import errno |
29 |
import logging |
30 |
|
31 |
from ganeti import utils |
32 |
from ganeti import constants |
33 |
|
34 |
|
35 |
class Mainloop(object): |
36 |
"""Generic mainloop for daemons
|
37 |
|
38 |
"""
|
39 |
def __init__(self): |
40 |
"""Constructs a new Mainloop instance.
|
41 |
|
42 |
"""
|
43 |
self._io_wait = {}
|
44 |
self._io_wait_add = []
|
45 |
self._io_wait_remove = []
|
46 |
self._signal_wait = []
|
47 |
|
48 |
def Run(self, handle_sigchld=True, handle_sigterm=True, stop_on_empty=False): |
49 |
"""Runs the mainloop.
|
50 |
|
51 |
@type handle_sigchld: bool
|
52 |
@param handle_sigchld: Whether to install handler for SIGCHLD
|
53 |
@type handle_sigterm: bool
|
54 |
@param handle_sigterm: Whether to install handler for SIGTERM
|
55 |
@type stop_on_empty: bool
|
56 |
@param stop_on_empty: Whether to stop mainloop once all I/O waiters
|
57 |
unregistered
|
58 |
|
59 |
"""
|
60 |
poller = select.poll() |
61 |
|
62 |
# Setup signal handlers
|
63 |
if handle_sigchld:
|
64 |
sigchld_handler = utils.SignalHandler([signal.SIGCHLD]) |
65 |
else:
|
66 |
sigchld_handler = None
|
67 |
try:
|
68 |
if handle_sigterm:
|
69 |
sigterm_handler = utils.SignalHandler([signal.SIGTERM]) |
70 |
else:
|
71 |
sigterm_handler = None
|
72 |
|
73 |
try:
|
74 |
running = True
|
75 |
|
76 |
# Start actual main loop
|
77 |
while running:
|
78 |
# Entries could be added again afterwards, hence removing first
|
79 |
if self._io_wait_remove: |
80 |
for fd in self._io_wait_remove: |
81 |
try:
|
82 |
poller.unregister(fd) |
83 |
except KeyError: |
84 |
pass
|
85 |
try:
|
86 |
del self._io_wait[fd] |
87 |
except KeyError: |
88 |
pass
|
89 |
self._io_wait_remove = []
|
90 |
|
91 |
# Add new entries
|
92 |
if self._io_wait_add: |
93 |
for (owner, fd, conditions) in self._io_wait_add: |
94 |
self._io_wait[fd] = owner
|
95 |
poller.register(fd, conditions) |
96 |
self._io_wait_add = []
|
97 |
|
98 |
# Stop if nothing is listening anymore
|
99 |
if stop_on_empty and not (self._io_wait): |
100 |
break
|
101 |
|
102 |
# Wait for I/O events
|
103 |
try:
|
104 |
io_events = poller.poll(None)
|
105 |
except select.error, err:
|
106 |
# EINTR can happen when signals are sent
|
107 |
if err.args and err.args[0] in (errno.EINTR,): |
108 |
io_events = None
|
109 |
else:
|
110 |
raise
|
111 |
|
112 |
if io_events:
|
113 |
# Check for I/O events
|
114 |
for (evfd, evcond) in io_events: |
115 |
owner = self._io_wait.get(evfd, None) |
116 |
if owner:
|
117 |
owner.OnIO(evfd, evcond) |
118 |
|
119 |
# Check whether signal was raised
|
120 |
if sigchld_handler and sigchld_handler.called: |
121 |
self._CallSignalWaiters(signal.SIGCHLD)
|
122 |
sigchld_handler.Clear() |
123 |
|
124 |
if sigterm_handler and sigterm_handler.called: |
125 |
self._CallSignalWaiters(signal.SIGTERM)
|
126 |
running = False
|
127 |
sigterm_handler.Clear() |
128 |
finally:
|
129 |
# Restore signal handlers
|
130 |
if sigterm_handler:
|
131 |
sigterm_handler.Reset() |
132 |
finally:
|
133 |
if sigchld_handler:
|
134 |
sigchld_handler.Reset() |
135 |
|
136 |
def _CallSignalWaiters(self, signum): |
137 |
"""Calls all signal waiters for a certain signal.
|
138 |
|
139 |
@type signum: int
|
140 |
@param signum: Signal number
|
141 |
|
142 |
"""
|
143 |
for owner in self._signal_wait: |
144 |
owner.OnSignal(signal.SIGCHLD) |
145 |
|
146 |
def RegisterIO(self, owner, fd, condition): |
147 |
"""Registers a receiver for I/O notifications
|
148 |
|
149 |
The receiver must support a "OnIO(self, fd, conditions)" function.
|
150 |
|
151 |
@type owner: instance
|
152 |
@param owner: Receiver
|
153 |
@type fd: int
|
154 |
@param fd: File descriptor
|
155 |
@type condition: int
|
156 |
@param condition: ORed field of conditions to be notified
|
157 |
(see select module)
|
158 |
|
159 |
"""
|
160 |
# select.Poller also supports file() like objects, but we don't.
|
161 |
assert isinstance(fd, (int, long)), \ |
162 |
"Only integers are supported for file descriptors"
|
163 |
|
164 |
self._io_wait_add.append((owner, fd, condition))
|
165 |
|
166 |
def UnregisterIO(self, fd): |
167 |
"""Unregister a file descriptor.
|
168 |
|
169 |
It'll be unregistered the next time the mainloop checks for it.
|
170 |
|
171 |
@type fd: int
|
172 |
@param fd: File descriptor
|
173 |
|
174 |
"""
|
175 |
# select.Poller also supports file() like objects, but we don't.
|
176 |
assert isinstance(fd, (int, long)), \ |
177 |
"Only integers are supported for file descriptors"
|
178 |
|
179 |
self._io_wait_remove.append(fd)
|
180 |
|
181 |
def RegisterSignal(self, owner): |
182 |
"""Registers a receiver for signal notifications
|
183 |
|
184 |
The receiver must support a "OnSignal(self, signum)" function.
|
185 |
|
186 |
@type owner: instance
|
187 |
@param owner: Receiver
|
188 |
|
189 |
"""
|
190 |
self._signal_wait.append(owner)
|
191 |
|
192 |
|
193 |
def GenericMain(daemon_name, optionparser, dirs, check_fn, exec_fn): |
194 |
"""Shared main function for daemons.
|
195 |
|
196 |
@type daemon_name: string
|
197 |
@param daemon_name: daemon name
|
198 |
@type optionparser: L{optparse.OptionParser}
|
199 |
@param optionparser: initialized optionparser with daemon-specific options
|
200 |
(common -f -d options will be handled by this module)
|
201 |
@type options: object @param options: OptionParser result, should contain at
|
202 |
least the fork and the debug options
|
203 |
@type dirs: list of strings
|
204 |
@param dirs: list of directories that must exist for this daemon to work
|
205 |
@type check_fn: function which accepts (options, args)
|
206 |
@param check_fn: function that checks start conditions and exits if they're
|
207 |
not met
|
208 |
@type exec_fn: function which accepts (options, args)
|
209 |
@param exec_fn: function that's executed with the daemon's pid file held, and
|
210 |
runs the daemon itself.
|
211 |
|
212 |
"""
|
213 |
optionparser.add_option("-f", "--foreground", dest="fork", |
214 |
help="Don't detach from the current terminal",
|
215 |
default=True, action="store_false") |
216 |
optionparser.add_option("-d", "--debug", dest="debug", |
217 |
help="Enable some debug messages",
|
218 |
default=False, action="store_true") |
219 |
if daemon_name in constants.DAEMONS_PORTS: |
220 |
# for networked daemons we also allow choosing the bind port and address.
|
221 |
# by default we use the port provided by utils.GetDaemonPort, and bind to
|
222 |
# 0.0.0.0 (which is represented by and empty bind address.
|
223 |
port = utils.GetDaemonPort(daemon_name) |
224 |
optionparser.add_option("-p", "--port", dest="port", |
225 |
help="Network port (%s default)." % port,
|
226 |
default=port, type="int")
|
227 |
optionparser.add_option("-b", "--bind", dest="bind_address", |
228 |
help="Bind address",
|
229 |
default="", metavar="ADDRESS") |
230 |
|
231 |
if daemon_name in constants.DAEMONS_SSL: |
232 |
default_cert, default_key = constants.DAEMONS_SSL[daemon_name] |
233 |
optionparser.add_option("--no-ssl", dest="ssl", |
234 |
help="Do not secure HTTP protocol with SSL",
|
235 |
default=True, action="store_false") |
236 |
optionparser.add_option("-K", "--ssl-key", dest="ssl_key", |
237 |
help="SSL key",
|
238 |
default=default_key, type="string")
|
239 |
optionparser.add_option("-C", "--ssl-cert", dest="ssl_cert", |
240 |
help="SSL certificate",
|
241 |
default=default_cert, type="string")
|
242 |
|
243 |
multithread = utils.no_fork = daemon_name in constants.MULTITHREADED_DAEMONS
|
244 |
|
245 |
options, args = optionparser.parse_args() |
246 |
|
247 |
if hasattr(options, 'ssl') and options.ssl: |
248 |
if not (options.ssl_cert and options.ssl_key): |
249 |
print >> sys.stderr, "Need key and certificate to use ssl" |
250 |
sys.exit(constants.EXIT_FAILURE) |
251 |
for fname in (options.ssl_cert, options.ssl_key): |
252 |
if not os.path.isfile(fname): |
253 |
print >> sys.stderr, "Need ssl file %s to run" % fname |
254 |
sys.exit(constants.EXIT_FAILURE) |
255 |
|
256 |
if check_fn is not None: |
257 |
check_fn(options, args) |
258 |
|
259 |
utils.EnsureDirs(dirs) |
260 |
|
261 |
if options.fork:
|
262 |
utils.CloseFDs() |
263 |
utils.Daemonize(logfile=constants.DAEMONS_LOGFILES[daemon_name]) |
264 |
|
265 |
utils.WritePidFile(daemon_name) |
266 |
try:
|
267 |
utils.SetupLogging(logfile=constants.DAEMONS_LOGFILES[daemon_name], |
268 |
debug=options.debug, |
269 |
stderr_logging=not options.fork,
|
270 |
multithreaded=multithread) |
271 |
logging.info("%s daemon startup" % daemon_name)
|
272 |
exec_fn(options, args) |
273 |
finally:
|
274 |
utils.RemovePidFile(daemon_name) |
275 |
|