root / lib / daemon.py @ a9fe7232
History | View | Annotate | Download (8.1 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 select |
26 |
import signal |
27 |
import errno |
28 |
import time |
29 |
|
30 |
from ganeti import utils |
31 |
|
32 |
|
33 |
class Timer(object): |
34 |
def __init__(self, owner, timer_id, start, interval, repeat): |
35 |
self.owner = owner
|
36 |
self.timer_id = timer_id
|
37 |
self.start = start
|
38 |
self.interval = interval
|
39 |
self.repeat = repeat
|
40 |
|
41 |
|
42 |
class Mainloop(object): |
43 |
"""Generic mainloop for daemons
|
44 |
|
45 |
"""
|
46 |
def __init__(self): |
47 |
"""Constructs a new Mainloop instance.
|
48 |
|
49 |
"""
|
50 |
self._io_wait = {}
|
51 |
self._io_wait_add = []
|
52 |
self._io_wait_remove = []
|
53 |
self._signal_wait = []
|
54 |
self._timer_id_last = 0 |
55 |
self._timer = {}
|
56 |
self._timer_add = []
|
57 |
self._timer_remove = []
|
58 |
|
59 |
def Run(self, handle_sigchld=True, handle_sigterm=True, stop_on_empty=False): |
60 |
"""Runs the mainloop.
|
61 |
|
62 |
@type handle_sigchld: bool
|
63 |
@param handle_sigchld: Whether to install handler for SIGCHLD
|
64 |
@type handle_sigterm: bool
|
65 |
@param handle_sigterm: Whether to install handler for SIGTERM
|
66 |
@type stop_on_empty: bool
|
67 |
@param stop_on_empty: Whether to stop mainloop once all I/O waiters
|
68 |
unregistered
|
69 |
|
70 |
"""
|
71 |
poller = select.poll() |
72 |
|
73 |
# Setup signal handlers
|
74 |
if handle_sigchld:
|
75 |
sigchld_handler = utils.SignalHandler([signal.SIGCHLD]) |
76 |
else:
|
77 |
sigchld_handler = None
|
78 |
try:
|
79 |
if handle_sigterm:
|
80 |
sigterm_handler = utils.SignalHandler([signal.SIGTERM]) |
81 |
else:
|
82 |
sigterm_handler = None
|
83 |
|
84 |
try:
|
85 |
running = True
|
86 |
timeout = None
|
87 |
timeout_needs_update = True
|
88 |
|
89 |
# Start actual main loop
|
90 |
while running:
|
91 |
# Entries could be added again afterwards, hence removing first
|
92 |
if self._io_wait_remove: |
93 |
for fd in self._io_wait_remove: |
94 |
try:
|
95 |
poller.unregister(fd) |
96 |
except KeyError: |
97 |
pass
|
98 |
try:
|
99 |
del self._io_wait[fd] |
100 |
except KeyError: |
101 |
pass
|
102 |
self._io_wait_remove = []
|
103 |
|
104 |
# Add new entries
|
105 |
if self._io_wait_add: |
106 |
for (owner, fd, conditions) in self._io_wait_add: |
107 |
self._io_wait[fd] = owner
|
108 |
poller.register(fd, conditions) |
109 |
self._io_wait_add = []
|
110 |
|
111 |
# Add new timers
|
112 |
if self._timer_add: |
113 |
timeout_needs_update = True
|
114 |
for timer in self._timer_add: |
115 |
self._timer[timer.timer_id] = timer
|
116 |
del self._timer_add[:] |
117 |
|
118 |
# Remove timers
|
119 |
if self._timer_remove: |
120 |
timeout_needs_update = True
|
121 |
for timer_id in self._timer_remove: |
122 |
try:
|
123 |
del self._timer[timer_id] |
124 |
except KeyError: |
125 |
pass
|
126 |
del self._timer_remove[:] |
127 |
|
128 |
# Stop if nothing is listening anymore
|
129 |
if stop_on_empty and not (self._io_wait or self._timer): |
130 |
break
|
131 |
|
132 |
# Calculate timeout again if required
|
133 |
if timeout_needs_update:
|
134 |
timeout = self._CalcTimeout(time.time())
|
135 |
timeout_needs_update = False
|
136 |
|
137 |
# Wait for I/O events
|
138 |
try:
|
139 |
io_events = poller.poll(timeout) |
140 |
except select.error, err:
|
141 |
# EINTR can happen when signals are sent
|
142 |
if err.args and err.args[0] in (errno.EINTR,): |
143 |
io_events = None
|
144 |
else:
|
145 |
raise
|
146 |
|
147 |
after_poll = time.time() |
148 |
|
149 |
if io_events:
|
150 |
# Check for I/O events
|
151 |
for (evfd, evcond) in io_events: |
152 |
owner = self._io_wait.get(evfd, None) |
153 |
if owner:
|
154 |
owner.OnIO(evfd, evcond) |
155 |
|
156 |
if self._timer: |
157 |
self._CheckTimers(after_poll)
|
158 |
|
159 |
# Check whether signal was raised
|
160 |
if sigchld_handler and sigchld_handler.called: |
161 |
self._CallSignalWaiters(signal.SIGCHLD)
|
162 |
sigchld_handler.Clear() |
163 |
|
164 |
if sigterm_handler and sigterm_handler.called: |
165 |
self._CallSignalWaiters(signal.SIGTERM)
|
166 |
running = False
|
167 |
sigterm_handler.Clear() |
168 |
finally:
|
169 |
# Restore signal handlers
|
170 |
if sigterm_handler:
|
171 |
sigterm_handler.Reset() |
172 |
finally:
|
173 |
if sigchld_handler:
|
174 |
sigchld_handler.Reset() |
175 |
|
176 |
def _CalcTimeout(self, now): |
177 |
if not self._timer: |
178 |
return None |
179 |
|
180 |
timeout = None
|
181 |
|
182 |
# TODO: Repeating timers
|
183 |
|
184 |
min_timeout = 0.001
|
185 |
|
186 |
for timer in self._timer.itervalues(): |
187 |
time_left = (timer.start + timer.interval) - now |
188 |
if timeout is None or time_left < timeout: |
189 |
timeout = time_left |
190 |
if timeout < 0: |
191 |
timeout = 0
|
192 |
break
|
193 |
elif timeout < min_timeout:
|
194 |
timeout = min_timeout |
195 |
break
|
196 |
|
197 |
return timeout * 1000.0 |
198 |
|
199 |
def _CheckTimers(self, now): |
200 |
# TODO: Repeating timers
|
201 |
for timer in self._timer.itervalues(): |
202 |
if now < (timer.start + timer.interval):
|
203 |
continue
|
204 |
|
205 |
timer.owner.OnTimer(timer.timer_id) |
206 |
|
207 |
# TODO: Repeating timers should not be removed
|
208 |
self._timer_remove.append(timer.timer_id)
|
209 |
|
210 |
def _CallSignalWaiters(self, signum): |
211 |
"""Calls all signal waiters for a certain signal.
|
212 |
|
213 |
@type signum: int
|
214 |
@param signum: Signal number
|
215 |
|
216 |
"""
|
217 |
for owner in self._signal_wait: |
218 |
owner.OnSignal(signum) |
219 |
|
220 |
def RegisterIO(self, owner, fd, condition): |
221 |
"""Registers a receiver for I/O notifications
|
222 |
|
223 |
The receiver must support a "OnIO(self, fd, conditions)" function.
|
224 |
|
225 |
@type owner: instance
|
226 |
@param owner: Receiver
|
227 |
@type fd: int
|
228 |
@param fd: File descriptor
|
229 |
@type condition: int
|
230 |
@param condition: ORed field of conditions to be notified
|
231 |
(see select module)
|
232 |
|
233 |
"""
|
234 |
# select.Poller also supports file() like objects, but we don't.
|
235 |
assert isinstance(fd, (int, long)), \ |
236 |
"Only integers are supported for file descriptors"
|
237 |
|
238 |
self._io_wait_add.append((owner, fd, condition))
|
239 |
|
240 |
def UnregisterIO(self, fd): |
241 |
"""Unregister a file descriptor.
|
242 |
|
243 |
It'll be unregistered the next time the mainloop checks for it.
|
244 |
|
245 |
@type fd: int
|
246 |
@param fd: File descriptor
|
247 |
|
248 |
"""
|
249 |
# select.Poller also supports file() like objects, but we don't.
|
250 |
assert isinstance(fd, (int, long)), \ |
251 |
"Only integers are supported for file descriptors"
|
252 |
|
253 |
self._io_wait_remove.append(fd)
|
254 |
|
255 |
def RegisterSignal(self, owner): |
256 |
"""Registers a receiver for signal notifications
|
257 |
|
258 |
The receiver must support a "OnSignal(self, signum)" function.
|
259 |
|
260 |
@type owner: instance
|
261 |
@param owner: Receiver
|
262 |
|
263 |
"""
|
264 |
self._signal_wait.append(owner)
|
265 |
|
266 |
def AddTimer(self, owner, interval, repeat): |
267 |
"""Add a new timer.
|
268 |
|
269 |
The receiver must support a "OnTimer(self, timer_id)" function.
|
270 |
|
271 |
@type owner: instance
|
272 |
@param owner: Receiver
|
273 |
@type interval: int or float
|
274 |
@param interval: Timer interval in seconds
|
275 |
@type repeat: bool
|
276 |
@param repeat: Whether this is a repeating timer or one-off
|
277 |
|
278 |
"""
|
279 |
# TODO: Implement repeating timers
|
280 |
assert not repeat, "Repeating timers are not yet supported" |
281 |
|
282 |
# Get new ID
|
283 |
self._timer_id_last += 1 |
284 |
|
285 |
timer_id = self._timer_id_last
|
286 |
|
287 |
self._timer_add.append(Timer(owner, timer_id, time.time(),
|
288 |
float(interval), repeat))
|
289 |
|
290 |
return timer_id
|
291 |
|
292 |
def RemoveTimer(self, timer_id): |
293 |
"""Removes a timer.
|
294 |
|
295 |
@type timer_id: int
|
296 |
@param timer_id: Timer ID
|
297 |
|
298 |
"""
|
299 |
self._timer_remove.append(timer_id)
|