root / lib / jstore.py @ 82599b3e
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1 | 8b537bb0 | Michael Hanselmann | #
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2 | 8b537bb0 | Michael Hanselmann | #
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3 | 8b537bb0 | Michael Hanselmann | |
4 | 8b537bb0 | Michael Hanselmann | # Copyright (C) 2006, 2007 Google Inc.
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5 | 8b537bb0 | Michael Hanselmann | #
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6 | 8b537bb0 | Michael Hanselmann | # This program is free software; you can redistribute it and/or modify
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7 | 8b537bb0 | Michael Hanselmann | # it under the terms of the GNU General Public License as published by
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8 | 8b537bb0 | Michael Hanselmann | # the Free Software Foundation; either version 2 of the License, or
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9 | 8b537bb0 | Michael Hanselmann | # (at your option) any later version.
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10 | 8b537bb0 | Michael Hanselmann | #
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11 | 8b537bb0 | Michael Hanselmann | # This program is distributed in the hope that it will be useful, but
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12 | 8b537bb0 | Michael Hanselmann | # WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | 8b537bb0 | Michael Hanselmann | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | 8b537bb0 | Michael Hanselmann | # General Public License for more details.
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15 | 8b537bb0 | Michael Hanselmann | #
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16 | 8b537bb0 | Michael Hanselmann | # You should have received a copy of the GNU General Public License
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17 | 8b537bb0 | Michael Hanselmann | # along with this program; if not, write to the Free Software
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18 | 8b537bb0 | Michael Hanselmann | # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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19 | 8b537bb0 | Michael Hanselmann | # 02110-1301, USA.
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20 | 8b537bb0 | Michael Hanselmann | |
21 | 8b537bb0 | Michael Hanselmann | |
22 | 8b537bb0 | Michael Hanselmann | """Module implementing the job queue handling."""
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23 | 8b537bb0 | Michael Hanselmann | |
24 | 8b537bb0 | Michael Hanselmann | import errno |
25 | 8b537bb0 | Michael Hanselmann | |
26 | 8b537bb0 | Michael Hanselmann | from ganeti import constants |
27 | 8b537bb0 | Michael Hanselmann | from ganeti import errors |
28 | 82b22e19 | René Nussbaumer | from ganeti import runtime |
29 | 8b537bb0 | Michael Hanselmann | from ganeti import utils |
30 | 8b537bb0 | Michael Hanselmann | |
31 | 8b537bb0 | Michael Hanselmann | |
32 | 8b537bb0 | Michael Hanselmann | def _ReadNumericFile(file_name): |
33 | 8b537bb0 | Michael Hanselmann | """Reads a file containing a number.
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34 | 8b537bb0 | Michael Hanselmann |
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35 | 8b537bb0 | Michael Hanselmann | @rtype: None or int
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36 | 8b537bb0 | Michael Hanselmann | @return: None if file is not found, otherwise number
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37 | 8b537bb0 | Michael Hanselmann |
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38 | 8b537bb0 | Michael Hanselmann | """
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39 | 8b537bb0 | Michael Hanselmann | try:
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40 | 6358dbc2 | Guido Trotter | return int(utils.ReadFile(file_name)) |
41 | 6358dbc2 | Guido Trotter | except EnvironmentError, err: |
42 | 8b537bb0 | Michael Hanselmann | if err.errno in (errno.ENOENT, ): |
43 | 8b537bb0 | Michael Hanselmann | return None |
44 | 8b537bb0 | Michael Hanselmann | raise
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45 | 8b537bb0 | Michael Hanselmann | |
46 | 8b537bb0 | Michael Hanselmann | |
47 | 8b537bb0 | Michael Hanselmann | def ReadSerial(): |
48 | 8b537bb0 | Michael Hanselmann | """Read the serial file.
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49 | 8b537bb0 | Michael Hanselmann |
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50 | 8b537bb0 | Michael Hanselmann | The queue should be locked while this function is called.
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51 | 8b537bb0 | Michael Hanselmann |
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52 | 8b537bb0 | Michael Hanselmann | """
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53 | 8b537bb0 | Michael Hanselmann | return _ReadNumericFile(constants.JOB_QUEUE_SERIAL_FILE)
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54 | 8b537bb0 | Michael Hanselmann | |
55 | 8b537bb0 | Michael Hanselmann | |
56 | 8b537bb0 | Michael Hanselmann | def ReadVersion(): |
57 | 8b537bb0 | Michael Hanselmann | """Read the queue version.
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58 | 8b537bb0 | Michael Hanselmann |
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59 | 8b537bb0 | Michael Hanselmann | The queue should be locked while this function is called.
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60 | 8b537bb0 | Michael Hanselmann |
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61 | 8b537bb0 | Michael Hanselmann | """
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62 | 8b537bb0 | Michael Hanselmann | return _ReadNumericFile(constants.JOB_QUEUE_VERSION_FILE)
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63 | 8b537bb0 | Michael Hanselmann | |
64 | 8b537bb0 | Michael Hanselmann | |
65 | 5d6fb8eb | Michael Hanselmann | def InitAndVerifyQueue(must_lock): |
66 | 8b537bb0 | Michael Hanselmann | """Open and lock job queue.
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67 | 8b537bb0 | Michael Hanselmann |
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68 | 8b537bb0 | Michael Hanselmann | If necessary, the queue is automatically initialized.
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69 | 8b537bb0 | Michael Hanselmann |
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70 | 5d6fb8eb | Michael Hanselmann | @type must_lock: bool
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71 | 5d6fb8eb | Michael Hanselmann | @param must_lock: Whether an exclusive lock must be held.
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72 | 8b537bb0 | Michael Hanselmann | @rtype: utils.FileLock
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73 | 8b537bb0 | Michael Hanselmann | @return: Lock object for the queue. This can be used to change the
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74 | 8b537bb0 | Michael Hanselmann | locking mode.
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75 | 8b537bb0 | Michael Hanselmann |
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76 | 8b537bb0 | Michael Hanselmann | """
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77 | 82b22e19 | René Nussbaumer | getents = runtime.GetEnts() |
78 | 8b537bb0 | Michael Hanselmann | |
79 | 8b537bb0 | Michael Hanselmann | # Lock queue
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80 | b4478d34 | Michael Hanselmann | queue_lock = utils.FileLock.Open(constants.JOB_QUEUE_LOCK_FILE) |
81 | 8b537bb0 | Michael Hanselmann | try:
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82 | 5d6fb8eb | Michael Hanselmann | # The queue needs to be locked in exclusive mode to write to the serial and
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83 | 5d6fb8eb | Michael Hanselmann | # version files.
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84 | 5d6fb8eb | Michael Hanselmann | if must_lock:
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85 | 5d6fb8eb | Michael Hanselmann | queue_lock.Exclusive(blocking=True)
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86 | 5d6fb8eb | Michael Hanselmann | holding_lock = True
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87 | 8b537bb0 | Michael Hanselmann | else:
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88 | 5d6fb8eb | Michael Hanselmann | try:
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89 | 5d6fb8eb | Michael Hanselmann | queue_lock.Exclusive(blocking=False)
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90 | 5d6fb8eb | Michael Hanselmann | holding_lock = True
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91 | 5d6fb8eb | Michael Hanselmann | except errors.LockError:
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92 | 5d6fb8eb | Michael Hanselmann | # Ignore errors and assume the process keeping the lock checked
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93 | 5d6fb8eb | Michael Hanselmann | # everything.
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94 | 5d6fb8eb | Michael Hanselmann | holding_lock = False
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95 | 5d6fb8eb | Michael Hanselmann | |
96 | 5d6fb8eb | Michael Hanselmann | if holding_lock:
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97 | 5d6fb8eb | Michael Hanselmann | # Verify version
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98 | 8b537bb0 | Michael Hanselmann | version = ReadVersion() |
99 | 5d6fb8eb | Michael Hanselmann | if version is None: |
100 | 5d6fb8eb | Michael Hanselmann | # Write new version file
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101 | 5d6fb8eb | Michael Hanselmann | utils.WriteFile(constants.JOB_QUEUE_VERSION_FILE, |
102 | 82b22e19 | René Nussbaumer | uid=getents.masterd_uid, gid=getents.masterd_gid, |
103 | 5d6fb8eb | Michael Hanselmann | data="%s\n" % constants.JOB_QUEUE_VERSION)
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104 | 8b537bb0 | Michael Hanselmann | |
105 | 5d6fb8eb | Michael Hanselmann | # Read again
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106 | 5d6fb8eb | Michael Hanselmann | version = ReadVersion() |
107 | 8b537bb0 | Michael Hanselmann | |
108 | 5d6fb8eb | Michael Hanselmann | if version != constants.JOB_QUEUE_VERSION:
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109 | 5d6fb8eb | Michael Hanselmann | raise errors.JobQueueError("Found job queue version %s, expected %s", |
110 | 5d6fb8eb | Michael Hanselmann | version, constants.JOB_QUEUE_VERSION) |
111 | 8b537bb0 | Michael Hanselmann | |
112 | 8b537bb0 | Michael Hanselmann | serial = ReadSerial() |
113 | 5d6fb8eb | Michael Hanselmann | if serial is None: |
114 | 5d6fb8eb | Michael Hanselmann | # Write new serial file
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115 | 5d6fb8eb | Michael Hanselmann | utils.WriteFile(constants.JOB_QUEUE_SERIAL_FILE, |
116 | 82b22e19 | René Nussbaumer | uid=getents.masterd_uid, gid=getents.masterd_gid, |
117 | 5d6fb8eb | Michael Hanselmann | data="%s\n" % 0) |
118 | 5d6fb8eb | Michael Hanselmann | |
119 | 5d6fb8eb | Michael Hanselmann | # Read again
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120 | 5d6fb8eb | Michael Hanselmann | serial = ReadSerial() |
121 | 8b537bb0 | Michael Hanselmann | |
122 | 5d6fb8eb | Michael Hanselmann | if serial is None: |
123 | 5d6fb8eb | Michael Hanselmann | # There must be a serious problem
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124 | fe267188 | Iustin Pop | raise errors.JobQueueError("Can't read/parse the job queue" |
125 | fe267188 | Iustin Pop | " serial file")
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126 | 8b537bb0 | Michael Hanselmann | |
127 | f56377a3 | Michael Hanselmann | if not must_lock: |
128 | fe267188 | Iustin Pop | # There's no need for more error handling. Closing the lock
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129 | fe267188 | Iustin Pop | # file below in case of an error will unlock it anyway.
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130 | f56377a3 | Michael Hanselmann | queue_lock.Unlock() |
131 | f56377a3 | Michael Hanselmann | |
132 | 8b537bb0 | Michael Hanselmann | except:
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133 | 8b537bb0 | Michael Hanselmann | queue_lock.Close() |
134 | 8b537bb0 | Michael Hanselmann | raise
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135 | 8b537bb0 | Michael Hanselmann | |
136 | 8b537bb0 | Michael Hanselmann | return queue_lock |