Commit 8b537bb0 authored by Michael Hanselmann's avatar Michael Hanselmann

jstore: Add queue helper functions

This will be used to move common code out of jqueue.

Reviewed-by: iustinp
parent 94428652
...@@ -71,6 +71,7 @@ pkgpython_PYTHON = \ ...@@ -71,6 +71,7 @@ pkgpython_PYTHON = \
lib/errors.py \ lib/errors.py \
lib/http.py \ lib/http.py \
lib/jqueue.py \ lib/jqueue.py \
lib/jstore.py \
lib/locking.py \ lib/locking.py \
lib/logger.py \ lib/logger.py \
lib/luxi.py \ lib/luxi.py \
......
#
#
# Copyright (C) 2006, 2007 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.
"""Module implementing the job queue handling."""
import os
import logging
import errno
import re
from ganeti import constants
from ganeti import errors
from ganeti import utils
def _ReadNumericFile(file_name):
"""Reads a file containing a number.
@rtype: None or int
@return: None if file is not found, otherwise number
"""
try:
fd = open(file_name, "r")
except IOError, err:
if err.errno in (errno.ENOENT, ):
return None
raise
try:
return int(fd.read(128))
finally:
fd.close()
def ReadSerial():
"""Read the serial file.
The queue should be locked while this function is called.
"""
return _ReadNumericFile(constants.JOB_QUEUE_SERIAL_FILE)
def ReadVersion():
"""Read the queue version.
The queue should be locked while this function is called.
"""
return _ReadNumericFile(constants.JOB_QUEUE_VERSION_FILE)
def InitAndVerifyQueue(exclusive):
"""Open and lock job queue.
If necessary, the queue is automatically initialized.
@type exclusive: bool
@param exclusive: Whether to lock the queue in exclusive mode. Shared
mode otherwise.
@rtype: utils.FileLock
@return: Lock object for the queue. This can be used to change the
locking mode.
"""
# Make sure our directories exists
for path in (constants.QUEUE_DIR, constants.JOB_QUEUE_ARCHIVE_DIR):
try:
os.mkdir(path, 0700)
except OSError, err:
if err.errno not in (errno.EEXIST, ):
raise
# Lock queue
queue_lock = utils.FileLock(constants.JOB_QUEUE_LOCK_FILE)
try:
# Determine locking function and call it
if exclusive:
fn = queue_lock.Exclusive
else:
fn = queue_lock.Shared
fn(blocking=False)
# Verify version
version = ReadVersion()
if version is None:
# Write new version file
utils.WriteFile(constants.JOB_QUEUE_VERSION_FILE,
data="%s\n" % constants.JOB_QUEUE_VERSION)
# Read again
version = ReadVersion()
if version != constants.JOB_QUEUE_VERSION:
raise errors.JobQueueError("Found job queue version %s, expected %s",
version, constants.JOB_QUEUE_VERSION)
serial = ReadSerial()
if serial is None:
# Write new serial file
utils.WriteFile(constants.JOB_QUEUE_SERIAL_FILE,
data="%s\n" % 0)
# Read again
serial = ReadSerial()
if serial is None:
# There must be a serious problem
raise errors.JobQueueError("Can't read/parse the job queue serial file")
except:
queue_lock.Close()
raise
return queue_lock
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment