root / lib / jstore.py @ 6869f673
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# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Module implementing the job queue handling."""
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import errno |
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import os |
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from ganeti import constants |
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from ganeti import errors |
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from ganeti import runtime |
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from ganeti import utils |
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from ganeti import pathutils |
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JOBS_PER_ARCHIVE_DIRECTORY = 10000
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def _ReadNumericFile(file_name): |
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"""Reads a file containing a number.
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@rtype: None or int
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@return: None if file is not found, otherwise number
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"""
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try:
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contents = utils.ReadFile(file_name) |
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except EnvironmentError, err: |
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if err.errno in (errno.ENOENT, ): |
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return None |
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raise
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try:
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return int(contents) |
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except (ValueError, TypeError), err: |
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# Couldn't convert to int
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raise errors.JobQueueError("Content of file '%s' is not numeric: %s" % |
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(file_name, err)) |
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def ReadSerial(): |
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"""Read the serial file.
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The queue should be locked while this function is called.
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"""
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return _ReadNumericFile(pathutils.JOB_QUEUE_SERIAL_FILE)
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def ReadVersion(): |
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"""Read the queue version.
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The queue should be locked while this function is called.
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"""
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return _ReadNumericFile(pathutils.JOB_QUEUE_VERSION_FILE)
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def InitAndVerifyQueue(must_lock): |
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"""Open and lock job queue.
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If necessary, the queue is automatically initialized.
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@type must_lock: bool
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@param must_lock: Whether an exclusive lock must be held.
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@rtype: utils.FileLock
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@return: Lock object for the queue. This can be used to change the
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locking mode.
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"""
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getents = runtime.GetEnts() |
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# Lock queue
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queue_lock = utils.FileLock.Open(pathutils.JOB_QUEUE_LOCK_FILE) |
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try:
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# The queue needs to be locked in exclusive mode to write to the serial and
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# version files.
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if must_lock:
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queue_lock.Exclusive(blocking=True)
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holding_lock = True
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else:
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try:
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queue_lock.Exclusive(blocking=False)
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holding_lock = True
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except errors.LockError:
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# Ignore errors and assume the process keeping the lock checked
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# everything.
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holding_lock = False
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if holding_lock:
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# Verify version
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version = ReadVersion() |
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if version is None: |
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# Write new version file
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utils.WriteFile(pathutils.JOB_QUEUE_VERSION_FILE, |
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uid=getents.masterd_uid, gid=getents.daemons_gid, |
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mode=constants.JOB_QUEUE_FILES_PERMS, |
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data="%s\n" % constants.JOB_QUEUE_VERSION)
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# Read again
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version = ReadVersion() |
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if version != constants.JOB_QUEUE_VERSION:
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raise errors.JobQueueError("Found job queue version %s, expected %s", |
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version, constants.JOB_QUEUE_VERSION) |
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serial = ReadSerial() |
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if serial is None: |
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# Write new serial file
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utils.WriteFile(pathutils.JOB_QUEUE_SERIAL_FILE, |
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uid=getents.masterd_uid, gid=getents.daemons_gid, |
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mode=constants.JOB_QUEUE_FILES_PERMS, |
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data="%s\n" % 0) |
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# Read again
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serial = ReadSerial() |
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if serial is None: |
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# There must be a serious problem
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raise errors.JobQueueError("Can't read/parse the job queue" |
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" serial file")
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if not must_lock: |
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# There's no need for more error handling. Closing the lock
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# file below in case of an error will unlock it anyway.
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queue_lock.Unlock() |
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except:
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queue_lock.Close() |
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raise
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return queue_lock
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def CheckDrainFlag(): |
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"""Check if the queue is marked to be drained.
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This currently uses the queue drain file, which makes it a per-node flag.
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In the future this can be moved to the config file.
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@rtype: boolean
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@return: True if the job queue is marked drained
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"""
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return os.path.exists(pathutils.JOB_QUEUE_DRAIN_FILE)
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def SetDrainFlag(drain_flag): |
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"""Sets the drain flag for the queue.
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@type drain_flag: boolean
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@param drain_flag: Whether to set or unset the drain flag
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@attention: This function should only called the current holder of the queue
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lock
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"""
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getents = runtime.GetEnts() |
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if drain_flag:
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utils.WriteFile(pathutils.JOB_QUEUE_DRAIN_FILE, data="",
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uid=getents.masterd_uid, gid=getents.daemons_gid, |
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mode=constants.JOB_QUEUE_FILES_PERMS) |
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else:
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utils.RemoveFile(pathutils.JOB_QUEUE_DRAIN_FILE) |
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assert (not drain_flag) ^ CheckDrainFlag() |
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def FormatJobID(job_id): |
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"""Convert a job ID to int format.
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Currently this just is a no-op that performs some checks, but if we
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want to change the job id format this will abstract this change.
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@type job_id: int or long
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@param job_id: the numeric job id
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@rtype: int
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@return: the formatted job id
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"""
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if not isinstance(job_id, (int, long)): |
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raise errors.ProgrammerError("Job ID '%s' not numeric" % job_id) |
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if job_id < 0: |
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raise errors.ProgrammerError("Job ID %s is negative" % job_id) |
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return job_id
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def GetArchiveDirectory(job_id): |
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"""Returns the archive directory for a job.
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@type job_id: str
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@param job_id: Job identifier
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@rtype: str
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@return: Directory name
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"""
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return str(ParseJobId(job_id) / JOBS_PER_ARCHIVE_DIRECTORY) |
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def ParseJobId(job_id): |
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"""Parses a job ID and converts it to integer.
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"""
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try:
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return int(job_id) |
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except (ValueError, TypeError): |
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raise errors.ParameterError("Invalid job ID '%s'" % job_id) |