root / lib / daemon.py @ 8c96d01f
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1 | 821d9e43 | Michael Hanselmann | #
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2 | 821d9e43 | Michael Hanselmann | #
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3 | 821d9e43 | Michael Hanselmann | |
4 | 821d9e43 | Michael Hanselmann | # Copyright (C) 2006, 2007, 2008 Google Inc.
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5 | 821d9e43 | Michael Hanselmann | #
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6 | 821d9e43 | Michael Hanselmann | # This program is free software; you can redistribute it and/or modify
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7 | 821d9e43 | Michael Hanselmann | # it under the terms of the GNU General Public License as published by
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8 | 821d9e43 | Michael Hanselmann | # the Free Software Foundation; either version 2 of the License, or
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9 | 821d9e43 | Michael Hanselmann | # (at your option) any later version.
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10 | 821d9e43 | Michael Hanselmann | #
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11 | 821d9e43 | Michael Hanselmann | # This program is distributed in the hope that it will be useful, but
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12 | 821d9e43 | Michael Hanselmann | # WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | 821d9e43 | Michael Hanselmann | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | 821d9e43 | Michael Hanselmann | # General Public License for more details.
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15 | 821d9e43 | Michael Hanselmann | #
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16 | 821d9e43 | Michael Hanselmann | # You should have received a copy of the GNU General Public License
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17 | 821d9e43 | Michael Hanselmann | # along with this program; if not, write to the Free Software
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18 | 821d9e43 | Michael Hanselmann | # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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19 | 821d9e43 | Michael Hanselmann | # 02110-1301, USA.
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20 | 821d9e43 | Michael Hanselmann | |
21 | 821d9e43 | Michael Hanselmann | |
22 | 821d9e43 | Michael Hanselmann | """Module with helper classes and functions for daemons"""
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23 | 821d9e43 | Michael Hanselmann | |
24 | 821d9e43 | Michael Hanselmann | |
25 | 821d9e43 | Michael Hanselmann | import select |
26 | 821d9e43 | Michael Hanselmann | import signal |
27 | 821d9e43 | Michael Hanselmann | import errno |
28 | b11c9e5c | Michael Hanselmann | import time |
29 | 821d9e43 | Michael Hanselmann | |
30 | 821d9e43 | Michael Hanselmann | from ganeti import utils |
31 | 821d9e43 | Michael Hanselmann | |
32 | 821d9e43 | Michael Hanselmann | |
33 | b11c9e5c | Michael Hanselmann | class Timer(object): |
34 | b11c9e5c | Michael Hanselmann | def __init__(self, owner, timer_id, start, interval, repeat): |
35 | b11c9e5c | Michael Hanselmann | self.owner = owner
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36 | b11c9e5c | Michael Hanselmann | self.timer_id = timer_id
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37 | b11c9e5c | Michael Hanselmann | self.start = start
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38 | b11c9e5c | Michael Hanselmann | self.interval = interval
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39 | b11c9e5c | Michael Hanselmann | self.repeat = repeat
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40 | b11c9e5c | Michael Hanselmann | |
41 | b11c9e5c | Michael Hanselmann | |
42 | 821d9e43 | Michael Hanselmann | class Mainloop(object): |
43 | 821d9e43 | Michael Hanselmann | """Generic mainloop for daemons
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44 | 821d9e43 | Michael Hanselmann |
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45 | 821d9e43 | Michael Hanselmann | """
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46 | 821d9e43 | Michael Hanselmann | def __init__(self): |
47 | b14b975f | Michael Hanselmann | """Constructs a new Mainloop instance.
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48 | b14b975f | Michael Hanselmann |
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49 | b14b975f | Michael Hanselmann | """
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50 | b14b975f | Michael Hanselmann | self._io_wait = {}
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51 | b14b975f | Michael Hanselmann | self._io_wait_add = []
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52 | b14b975f | Michael Hanselmann | self._io_wait_remove = []
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53 | 821d9e43 | Michael Hanselmann | self._signal_wait = []
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54 | b11c9e5c | Michael Hanselmann | self._timer_id_last = 0 |
55 | b11c9e5c | Michael Hanselmann | self._timer = {}
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56 | b11c9e5c | Michael Hanselmann | self._timer_add = []
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57 | b11c9e5c | Michael Hanselmann | self._timer_remove = []
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58 | 821d9e43 | Michael Hanselmann | |
59 | b14b975f | Michael Hanselmann | def Run(self, handle_sigchld=True, handle_sigterm=True, stop_on_empty=False): |
60 | b14b975f | Michael Hanselmann | """Runs the mainloop.
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61 | b14b975f | Michael Hanselmann |
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62 | b14b975f | Michael Hanselmann | @type handle_sigchld: bool
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63 | b14b975f | Michael Hanselmann | @param handle_sigchld: Whether to install handler for SIGCHLD
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64 | b14b975f | Michael Hanselmann | @type handle_sigterm: bool
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65 | b14b975f | Michael Hanselmann | @param handle_sigterm: Whether to install handler for SIGTERM
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66 | b14b975f | Michael Hanselmann | @type stop_on_empty: bool
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67 | b14b975f | Michael Hanselmann | @param stop_on_empty: Whether to stop mainloop once all I/O waiters
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68 | b14b975f | Michael Hanselmann | unregistered
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69 | b14b975f | Michael Hanselmann |
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70 | b14b975f | Michael Hanselmann | """
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71 | 821d9e43 | Michael Hanselmann | poller = select.poll() |
72 | 821d9e43 | Michael Hanselmann | |
73 | b14b975f | Michael Hanselmann | # Setup signal handlers
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74 | b14b975f | Michael Hanselmann | if handle_sigchld:
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75 | b14b975f | Michael Hanselmann | sigchld_handler = utils.SignalHandler([signal.SIGCHLD]) |
76 | b14b975f | Michael Hanselmann | else:
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77 | b14b975f | Michael Hanselmann | sigchld_handler = None
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78 | 821d9e43 | Michael Hanselmann | try:
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79 | b14b975f | Michael Hanselmann | if handle_sigterm:
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80 | b14b975f | Michael Hanselmann | sigterm_handler = utils.SignalHandler([signal.SIGTERM]) |
81 | b14b975f | Michael Hanselmann | else:
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82 | b14b975f | Michael Hanselmann | sigterm_handler = None
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83 | b14b975f | Michael Hanselmann | |
84 | b14b975f | Michael Hanselmann | try:
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85 | b14b975f | Michael Hanselmann | running = True
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86 | b11c9e5c | Michael Hanselmann | timeout = None
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87 | b11c9e5c | Michael Hanselmann | timeout_needs_update = True
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88 | b14b975f | Michael Hanselmann | |
89 | b14b975f | Michael Hanselmann | # Start actual main loop
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90 | b14b975f | Michael Hanselmann | while running:
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91 | b14b975f | Michael Hanselmann | # Entries could be added again afterwards, hence removing first
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92 | b14b975f | Michael Hanselmann | if self._io_wait_remove: |
93 | b14b975f | Michael Hanselmann | for fd in self._io_wait_remove: |
94 | b14b975f | Michael Hanselmann | try:
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95 | b14b975f | Michael Hanselmann | poller.unregister(fd) |
96 | b14b975f | Michael Hanselmann | except KeyError: |
97 | b14b975f | Michael Hanselmann | pass
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98 | b14b975f | Michael Hanselmann | try:
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99 | b14b975f | Michael Hanselmann | del self._io_wait[fd] |
100 | b14b975f | Michael Hanselmann | except KeyError: |
101 | b14b975f | Michael Hanselmann | pass
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102 | b14b975f | Michael Hanselmann | self._io_wait_remove = []
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103 | b14b975f | Michael Hanselmann | |
104 | b14b975f | Michael Hanselmann | # Add new entries
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105 | b14b975f | Michael Hanselmann | if self._io_wait_add: |
106 | b14b975f | Michael Hanselmann | for (owner, fd, conditions) in self._io_wait_add: |
107 | b14b975f | Michael Hanselmann | self._io_wait[fd] = owner
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108 | b14b975f | Michael Hanselmann | poller.register(fd, conditions) |
109 | b14b975f | Michael Hanselmann | self._io_wait_add = []
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110 | b14b975f | Michael Hanselmann | |
111 | b11c9e5c | Michael Hanselmann | # Add new timers
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112 | b11c9e5c | Michael Hanselmann | if self._timer_add: |
113 | b11c9e5c | Michael Hanselmann | timeout_needs_update = True
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114 | b11c9e5c | Michael Hanselmann | for timer in self._timer_add: |
115 | b11c9e5c | Michael Hanselmann | self._timer[timer.timer_id] = timer
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116 | b11c9e5c | Michael Hanselmann | del self._timer_add[:] |
117 | b11c9e5c | Michael Hanselmann | |
118 | b11c9e5c | Michael Hanselmann | # Remove timers
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119 | b11c9e5c | Michael Hanselmann | if self._timer_remove: |
120 | b11c9e5c | Michael Hanselmann | timeout_needs_update = True
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121 | b11c9e5c | Michael Hanselmann | for timer_id in self._timer_remove: |
122 | b11c9e5c | Michael Hanselmann | try:
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123 | b11c9e5c | Michael Hanselmann | del self._timer[timer_id] |
124 | b11c9e5c | Michael Hanselmann | except KeyError: |
125 | b11c9e5c | Michael Hanselmann | pass
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126 | b11c9e5c | Michael Hanselmann | del self._timer_remove[:] |
127 | b11c9e5c | Michael Hanselmann | |
128 | b14b975f | Michael Hanselmann | # Stop if nothing is listening anymore
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129 | b11c9e5c | Michael Hanselmann | if stop_on_empty and not (self._io_wait or self._timer): |
130 | b14b975f | Michael Hanselmann | break
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131 | b14b975f | Michael Hanselmann | |
132 | b11c9e5c | Michael Hanselmann | # Calculate timeout again if required
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133 | b11c9e5c | Michael Hanselmann | if timeout_needs_update:
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134 | b11c9e5c | Michael Hanselmann | timeout = self._CalcTimeout(time.time())
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135 | 53d47a06 | Guido Trotter | timeout_needs_update = False
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136 | b11c9e5c | Michael Hanselmann | |
137 | b14b975f | Michael Hanselmann | # Wait for I/O events
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138 | b14b975f | Michael Hanselmann | try:
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139 | b11c9e5c | Michael Hanselmann | io_events = poller.poll(timeout) |
140 | b14b975f | Michael Hanselmann | except select.error, err:
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141 | b14b975f | Michael Hanselmann | # EINTR can happen when signals are sent
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142 | b14b975f | Michael Hanselmann | if err.args and err.args[0] in (errno.EINTR,): |
143 | b14b975f | Michael Hanselmann | io_events = None
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144 | b14b975f | Michael Hanselmann | else:
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145 | b14b975f | Michael Hanselmann | raise
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146 | b14b975f | Michael Hanselmann | |
147 | b11c9e5c | Michael Hanselmann | after_poll = time.time() |
148 | b11c9e5c | Michael Hanselmann | |
149 | b14b975f | Michael Hanselmann | if io_events:
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150 | b14b975f | Michael Hanselmann | # Check for I/O events
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151 | b14b975f | Michael Hanselmann | for (evfd, evcond) in io_events: |
152 | b14b975f | Michael Hanselmann | owner = self._io_wait.get(evfd, None) |
153 | b14b975f | Michael Hanselmann | if owner:
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154 | b14b975f | Michael Hanselmann | owner.OnIO(evfd, evcond) |
155 | b14b975f | Michael Hanselmann | |
156 | b11c9e5c | Michael Hanselmann | if self._timer: |
157 | b11c9e5c | Michael Hanselmann | self._CheckTimers(after_poll)
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158 | b11c9e5c | Michael Hanselmann | |
159 | b14b975f | Michael Hanselmann | # Check whether signal was raised
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160 | b14b975f | Michael Hanselmann | if sigchld_handler and sigchld_handler.called: |
161 | b14b975f | Michael Hanselmann | self._CallSignalWaiters(signal.SIGCHLD)
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162 | b14b975f | Michael Hanselmann | sigchld_handler.Clear() |
163 | b14b975f | Michael Hanselmann | |
164 | b14b975f | Michael Hanselmann | if sigterm_handler and sigterm_handler.called: |
165 | b14b975f | Michael Hanselmann | self._CallSignalWaiters(signal.SIGTERM)
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166 | b14b975f | Michael Hanselmann | running = False
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167 | b14b975f | Michael Hanselmann | sigterm_handler.Clear() |
168 | b14b975f | Michael Hanselmann | finally:
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169 | b14b975f | Michael Hanselmann | # Restore signal handlers
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170 | b14b975f | Michael Hanselmann | if sigterm_handler:
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171 | b14b975f | Michael Hanselmann | sigterm_handler.Reset() |
172 | 821d9e43 | Michael Hanselmann | finally:
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173 | b14b975f | Michael Hanselmann | if sigchld_handler:
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174 | b14b975f | Michael Hanselmann | sigchld_handler.Reset() |
175 | a570e2a8 | Guido Trotter | |
176 | b11c9e5c | Michael Hanselmann | def _CalcTimeout(self, now): |
177 | b11c9e5c | Michael Hanselmann | if not self._timer: |
178 | b11c9e5c | Michael Hanselmann | return None |
179 | b11c9e5c | Michael Hanselmann | |
180 | b11c9e5c | Michael Hanselmann | timeout = None
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181 | b11c9e5c | Michael Hanselmann | |
182 | b11c9e5c | Michael Hanselmann | # TODO: Repeating timers
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183 | b11c9e5c | Michael Hanselmann | |
184 | b11c9e5c | Michael Hanselmann | min_timeout = 0.001
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185 | b11c9e5c | Michael Hanselmann | |
186 | b11c9e5c | Michael Hanselmann | for timer in self._timer.itervalues(): |
187 | b11c9e5c | Michael Hanselmann | time_left = (timer.start + timer.interval) - now |
188 | b11c9e5c | Michael Hanselmann | if timeout is None or time_left < timeout: |
189 | b11c9e5c | Michael Hanselmann | timeout = time_left |
190 | b11c9e5c | Michael Hanselmann | if timeout < 0: |
191 | b11c9e5c | Michael Hanselmann | timeout = 0
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192 | b11c9e5c | Michael Hanselmann | break
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193 | b11c9e5c | Michael Hanselmann | elif timeout < min_timeout:
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194 | b11c9e5c | Michael Hanselmann | timeout = min_timeout |
195 | b11c9e5c | Michael Hanselmann | break
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196 | b11c9e5c | Michael Hanselmann | |
197 | b11c9e5c | Michael Hanselmann | return timeout * 1000.0 |
198 | b11c9e5c | Michael Hanselmann | |
199 | b11c9e5c | Michael Hanselmann | def _CheckTimers(self, now): |
200 | b11c9e5c | Michael Hanselmann | # TODO: Repeating timers
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201 | b11c9e5c | Michael Hanselmann | for timer in self._timer.itervalues(): |
202 | b11c9e5c | Michael Hanselmann | if now < (timer.start + timer.interval):
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203 | b11c9e5c | Michael Hanselmann | continue
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204 | b11c9e5c | Michael Hanselmann | |
205 | b11c9e5c | Michael Hanselmann | timer.owner.OnTimer(timer.timer_id) |
206 | b11c9e5c | Michael Hanselmann | |
207 | b11c9e5c | Michael Hanselmann | # TODO: Repeating timers should not be removed
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208 | b11c9e5c | Michael Hanselmann | self._timer_remove.append(timer.timer_id)
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209 | b11c9e5c | Michael Hanselmann | |
210 | b14b975f | Michael Hanselmann | def _CallSignalWaiters(self, signum): |
211 | b14b975f | Michael Hanselmann | """Calls all signal waiters for a certain signal.
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212 | b14b975f | Michael Hanselmann |
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213 | b14b975f | Michael Hanselmann | @type signum: int
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214 | b14b975f | Michael Hanselmann | @param signum: Signal number
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215 | b14b975f | Michael Hanselmann |
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216 | b14b975f | Michael Hanselmann | """
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217 | b14b975f | Michael Hanselmann | for owner in self._signal_wait: |
218 | b14b975f | Michael Hanselmann | owner.OnSignal(signal.SIGCHLD) |
219 | 821d9e43 | Michael Hanselmann | |
220 | 821d9e43 | Michael Hanselmann | def RegisterIO(self, owner, fd, condition): |
221 | 821d9e43 | Michael Hanselmann | """Registers a receiver for I/O notifications
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222 | 821d9e43 | Michael Hanselmann |
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223 | 821d9e43 | Michael Hanselmann | The receiver must support a "OnIO(self, fd, conditions)" function.
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224 | 821d9e43 | Michael Hanselmann |
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225 | 821d9e43 | Michael Hanselmann | @type owner: instance
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226 | 821d9e43 | Michael Hanselmann | @param owner: Receiver
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227 | 821d9e43 | Michael Hanselmann | @type fd: int
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228 | 821d9e43 | Michael Hanselmann | @param fd: File descriptor
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229 | 821d9e43 | Michael Hanselmann | @type condition: int
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230 | 821d9e43 | Michael Hanselmann | @param condition: ORed field of conditions to be notified
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231 | 821d9e43 | Michael Hanselmann | (see select module)
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232 | 821d9e43 | Michael Hanselmann |
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233 | 821d9e43 | Michael Hanselmann | """
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234 | b14b975f | Michael Hanselmann | # select.Poller also supports file() like objects, but we don't.
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235 | b14b975f | Michael Hanselmann | assert isinstance(fd, (int, long)), \ |
236 | b14b975f | Michael Hanselmann | "Only integers are supported for file descriptors"
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237 | b14b975f | Michael Hanselmann | |
238 | b14b975f | Michael Hanselmann | self._io_wait_add.append((owner, fd, condition))
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239 | b14b975f | Michael Hanselmann | |
240 | b14b975f | Michael Hanselmann | def UnregisterIO(self, fd): |
241 | b14b975f | Michael Hanselmann | """Unregister a file descriptor.
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242 | b14b975f | Michael Hanselmann |
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243 | b14b975f | Michael Hanselmann | It'll be unregistered the next time the mainloop checks for it.
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244 | b14b975f | Michael Hanselmann |
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245 | b14b975f | Michael Hanselmann | @type fd: int
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246 | b14b975f | Michael Hanselmann | @param fd: File descriptor
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247 | b14b975f | Michael Hanselmann |
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248 | b14b975f | Michael Hanselmann | """
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249 | b14b975f | Michael Hanselmann | # select.Poller also supports file() like objects, but we don't.
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250 | b14b975f | Michael Hanselmann | assert isinstance(fd, (int, long)), \ |
251 | b14b975f | Michael Hanselmann | "Only integers are supported for file descriptors"
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252 | b14b975f | Michael Hanselmann | |
253 | b14b975f | Michael Hanselmann | self._io_wait_remove.append(fd)
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254 | 821d9e43 | Michael Hanselmann | |
255 | 821d9e43 | Michael Hanselmann | def RegisterSignal(self, owner): |
256 | 821d9e43 | Michael Hanselmann | """Registers a receiver for signal notifications
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257 | 821d9e43 | Michael Hanselmann |
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258 | 821d9e43 | Michael Hanselmann | The receiver must support a "OnSignal(self, signum)" function.
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259 | 821d9e43 | Michael Hanselmann |
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260 | 821d9e43 | Michael Hanselmann | @type owner: instance
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261 | 821d9e43 | Michael Hanselmann | @param owner: Receiver
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262 | 821d9e43 | Michael Hanselmann |
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263 | 821d9e43 | Michael Hanselmann | """
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264 | 821d9e43 | Michael Hanselmann | self._signal_wait.append(owner)
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265 | b11c9e5c | Michael Hanselmann | |
266 | b11c9e5c | Michael Hanselmann | def AddTimer(self, owner, interval, repeat): |
267 | b11c9e5c | Michael Hanselmann | """Add a new timer.
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268 | b11c9e5c | Michael Hanselmann |
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269 | b11c9e5c | Michael Hanselmann | The receiver must support a "OnTimer(self, timer_id)" function.
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270 | b11c9e5c | Michael Hanselmann |
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271 | b11c9e5c | Michael Hanselmann | @type owner: instance
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272 | b11c9e5c | Michael Hanselmann | @param owner: Receiver
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273 | b11c9e5c | Michael Hanselmann | @type interval: int or float
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274 | b11c9e5c | Michael Hanselmann | @param interval: Timer interval in seconds
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275 | b11c9e5c | Michael Hanselmann | @type repeat: bool
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276 | b11c9e5c | Michael Hanselmann | @param repeat: Whether this is a repeating timer or one-off
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277 | b11c9e5c | Michael Hanselmann |
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278 | b11c9e5c | Michael Hanselmann | """
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279 | b11c9e5c | Michael Hanselmann | # TODO: Implement repeating timers
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280 | b11c9e5c | Michael Hanselmann | assert not repeat, "Repeating timers are not yet supported" |
281 | b11c9e5c | Michael Hanselmann | |
282 | b11c9e5c | Michael Hanselmann | # Get new ID
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283 | b11c9e5c | Michael Hanselmann | self._timer_id_last += 1 |
284 | b11c9e5c | Michael Hanselmann | |
285 | b11c9e5c | Michael Hanselmann | timer_id = self._timer_id_last
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286 | b11c9e5c | Michael Hanselmann | |
287 | b11c9e5c | Michael Hanselmann | self._timer_add.append(Timer(owner, timer_id, time.time(),
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288 | b11c9e5c | Michael Hanselmann | float(interval), repeat))
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289 | b11c9e5c | Michael Hanselmann | |
290 | b11c9e5c | Michael Hanselmann | return timer_id
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291 | b11c9e5c | Michael Hanselmann | |
292 | b11c9e5c | Michael Hanselmann | def RemoveTimer(self, timer_id): |
293 | b11c9e5c | Michael Hanselmann | """Removes a timer.
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294 | b11c9e5c | Michael Hanselmann |
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295 | b11c9e5c | Michael Hanselmann | @type timer_id: int
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296 | b11c9e5c | Michael Hanselmann | @param timer_id: Timer ID
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297 | b11c9e5c | Michael Hanselmann |
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298 | b11c9e5c | Michael Hanselmann | """
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299 | b11c9e5c | Michael Hanselmann | self._timer_remove.append(timer_id) |