root / lib / daemon.py @ 686d7433
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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 | 821d9e43 | Michael Hanselmann | |
29 | 821d9e43 | Michael Hanselmann | from ganeti import utils |
30 | 821d9e43 | Michael Hanselmann | |
31 | 821d9e43 | Michael Hanselmann | |
32 | 821d9e43 | Michael Hanselmann | class Mainloop(object): |
33 | 821d9e43 | Michael Hanselmann | """Generic mainloop for daemons
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34 | 821d9e43 | Michael Hanselmann |
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35 | 821d9e43 | Michael Hanselmann | """
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36 | 821d9e43 | Michael Hanselmann | def __init__(self): |
37 | 821d9e43 | Michael Hanselmann | self._io_wait = []
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38 | 821d9e43 | Michael Hanselmann | self._signal_wait = []
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39 | 821d9e43 | Michael Hanselmann | self.sigchld_handler = {}
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40 | 821d9e43 | Michael Hanselmann | |
41 | 821d9e43 | Michael Hanselmann | def Run(self): |
42 | 821d9e43 | Michael Hanselmann | # TODO: Does not yet support adding new event sources while running
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43 | 821d9e43 | Michael Hanselmann | poller = select.poll() |
44 | 821d9e43 | Michael Hanselmann | for (owner, fd, conditions) in self._io_wait: |
45 | 821d9e43 | Michael Hanselmann | poller.register(fd, conditions) |
46 | 821d9e43 | Michael Hanselmann | |
47 | 821d9e43 | Michael Hanselmann | self.sigchld_handler = utils.SignalHandler([signal.SIGCHLD])
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48 | 821d9e43 | Michael Hanselmann | try:
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49 | 821d9e43 | Michael Hanselmann | while True: |
50 | 821d9e43 | Michael Hanselmann | try:
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51 | 821d9e43 | Michael Hanselmann | io_events = poller.poll(1000)
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52 | 821d9e43 | Michael Hanselmann | except select.error, err:
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53 | 821d9e43 | Michael Hanselmann | # EINTR can happen when signals are sent
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54 | 821d9e43 | Michael Hanselmann | if err.args and err.args[0] in (errno.EINTR,): |
55 | 821d9e43 | Michael Hanselmann | io_events = None
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56 | 821d9e43 | Michael Hanselmann | else:
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57 | 821d9e43 | Michael Hanselmann | raise
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58 | 821d9e43 | Michael Hanselmann | |
59 | 821d9e43 | Michael Hanselmann | if io_events:
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60 | 821d9e43 | Michael Hanselmann | # Check for I/O events
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61 | 821d9e43 | Michael Hanselmann | for (evfd, evcond) in io_events: |
62 | 821d9e43 | Michael Hanselmann | for (owner, fd, conditions) in self._io_wait: |
63 | 821d9e43 | Michael Hanselmann | if fd == evfd and evcond & conditions: |
64 | 821d9e43 | Michael Hanselmann | owner.OnIO(fd, evcond) |
65 | 821d9e43 | Michael Hanselmann | |
66 | 821d9e43 | Michael Hanselmann | # Check whether signal was raised
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67 | 821d9e43 | Michael Hanselmann | if self.sigchld_handler.called: |
68 | 821d9e43 | Michael Hanselmann | for owner in self._signal_wait: |
69 | 821d9e43 | Michael Hanselmann | owner.OnSignal(signal.SIGCHLD) |
70 | 821d9e43 | Michael Hanselmann | self.sigchld_handler.Clear()
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71 | 821d9e43 | Michael Hanselmann | finally:
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72 | 821d9e43 | Michael Hanselmann | self.sigchld_handler.Reset()
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73 | 821d9e43 | Michael Hanselmann | self.sigchld_handler = None |
74 | 821d9e43 | Michael Hanselmann | |
75 | 821d9e43 | Michael Hanselmann | def RegisterIO(self, owner, fd, condition): |
76 | 821d9e43 | Michael Hanselmann | """Registers a receiver for I/O notifications
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77 | 821d9e43 | Michael Hanselmann |
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78 | 821d9e43 | Michael Hanselmann | The receiver must support a "OnIO(self, fd, conditions)" function.
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79 | 821d9e43 | Michael Hanselmann |
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80 | 821d9e43 | Michael Hanselmann | @type owner: instance
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81 | 821d9e43 | Michael Hanselmann | @param owner: Receiver
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82 | 821d9e43 | Michael Hanselmann | @type fd: int
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83 | 821d9e43 | Michael Hanselmann | @param fd: File descriptor
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84 | 821d9e43 | Michael Hanselmann | @type condition: int
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85 | 821d9e43 | Michael Hanselmann | @param condition: ORed field of conditions to be notified
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86 | 821d9e43 | Michael Hanselmann | (see select module)
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87 | 821d9e43 | Michael Hanselmann |
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88 | 821d9e43 | Michael Hanselmann | """
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89 | 821d9e43 | Michael Hanselmann | self._io_wait.append((owner, fd, condition))
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90 | 821d9e43 | Michael Hanselmann | |
91 | 821d9e43 | Michael Hanselmann | def RegisterSignal(self, owner): |
92 | 821d9e43 | Michael Hanselmann | """Registers a receiver for signal notifications
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93 | 821d9e43 | Michael Hanselmann |
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94 | 821d9e43 | Michael Hanselmann | The receiver must support a "OnSignal(self, signum)" function.
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95 | 821d9e43 | Michael Hanselmann |
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96 | 821d9e43 | Michael Hanselmann | @type owner: instance
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97 | 821d9e43 | Michael Hanselmann | @param owner: Receiver
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98 | 821d9e43 | Michael Hanselmann |
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99 | 821d9e43 | Michael Hanselmann | """
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100 | 821d9e43 | Michael Hanselmann | self._signal_wait.append(owner) |