def wrapper(*args, **kwargs):
# Locking in exclusive, blocking mode because there could be several
# children running at the same time. Waiting up to 10 seconds.
if _PrepareQueueLock() is not None:
raise errors.JobQueueError("Job queue failed initialization,"
" cannot update jobs")
queue_lock.Exclusive(blocking=True, timeout=QUEUE_LOCK_TIMEOUT)
try:
return fn(*args, **kwargs)
finally:
queue_lock.Unlock()
def _ReadNumericFile(file_name):
"""Reads a file containing a number.
@rtype: None or int
@return: None if file is not found, otherwise number
"""
try:
contents = utils.ReadFile(file_name)
except EnvironmentError as err:
if err.errno in (errno.ENOENT, ):
return None
raise
try:
return int(contents)
except (ValueError, TypeError) as err:
# Couldn't convert to int
raise errors.JobQueueError("Content of file '%s' is not numeric: %s" %
(file_name, err))
def InitAndVerifyQueue(must_lock):
"""Open and lock job queue.
If necessary, the queue is automatically initialized.
@type must_lock: bool
@param must_lock: Whether an exclusive lock must be held.
@rtype: utils.FileLock
@return: Lock object for the queue. This can be used to change the
locking mode.
"""
getents = runtime.GetEnts()
# Lock queue
queue_lock = utils.FileLock.Open(pathutils.JOB_QUEUE_LOCK_FILE)
try:
# The queue needs to be locked in exclusive mode to write to the serial and
# version files.
if must_lock:
queue_lock.Exclusive(blocking=True)
holding_lock = True
else:
try:
queue_lock.Exclusive(blocking=False)
holding_lock = True
except errors.LockError:
# Ignore errors and assume the process keeping the lock checked
# everything.
holding_lock = False
if holding_lock:
# Verify version
version = ReadVersion()
if version is None:
# Write new version file
utils.WriteFile(pathutils.JOB_QUEUE_VERSION_FILE,
uid=getents.masterd_uid,
gid=getents.daemons_gid,
mode=constants.JOB_QUEUE_FILES_PERMS,
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(pathutils.JOB_QUEUE_SERIAL_FILE,
uid=getents.masterd_uid,
gid=getents.daemons_gid,
mode=constants.JOB_QUEUE_FILES_PERMS,
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")
if not must_lock:
# There's no need for more error handling. Closing the lock
# file below in case of an error will unlock it anyway.
queue_lock.Unlock()
except:
queue_lock.Close()
raise
return queue_lock
@rtype: None or int
@return: None if file is not found, otherwise number
"""
try:
contents = utils.ReadFile(file_name)
except EnvironmentError, err:
if err.errno in (errno.ENOENT, ):
return None
raise
try:
return int(contents)
except (ValueError, TypeError), err:
# Couldn't convert to int
raise errors.JobQueueError("Content of file '%s' is not numeric: %s" %
(file_name, err))
def ReadSerial():
"""Read the serial file.
The queue should be locked while this function is called.
"""
return _ReadNumericFile(pathutils.JOB_QUEUE_SERIAL_FILE)
def ReadVersion():
"""Read the queue version.
The queue should be locked while this function is called.