From 8b537bb0fd52a71c6f260f1f8ca0549423aa3d82 Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <hansmi@google.com>
Date: Mon, 4 Aug 2008 12:27:01 +0000
Subject: [PATCH] jstore: Add queue helper functions
This will be used to move common code out of jqueue.
Reviewed-by: iustinp
---
Makefile.am | 1 +
lib/jstore.py | 135 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 136 insertions(+)
create mode 100644 lib/jstore.py
diff --git a/Makefile.am b/Makefile.am
index 89e8b640f..4910ff380 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -71,6 +71,7 @@ pkgpython_PYTHON = \
lib/errors.py \
lib/http.py \
lib/jqueue.py \
+ lib/jstore.py \
lib/locking.py \
lib/logger.py \
lib/luxi.py \
diff --git a/lib/jstore.py b/lib/jstore.py
new file mode 100644
index 000000000..5065e862e
--- /dev/null
+++ b/lib/jstore.py
@@ -0,0 +1,135 @@
+#
+#
+
+# 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
--
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