class AcquireRunLock(object):
"""
Establishes a lockfile to avoid duplicate runs for same config.
"""
def __init__(self, pidfile):
"""
Create exclusive app lock
"""
if pidfile.startswith("/"):
piddir = os.path.dirname(pidfile)
pidpath = pidfile # use explicit path
else:
piddir = "/var/lib/zabbixsrv/"
pidpath = "{dir}{file}".format(dir=piddir, file=pidfile)
# Check lockdir exists
if not os.path.exists(piddir):
raise PidlockConflict("directory {0} is missing or insufficient permission".format(
piddir
)
)
# Check for orphaned pids
if os.path.isfile(pidpath):
with open(pidpath) as f:
conflictpid = f.read()
raise PidlockConflict("process {0} has lock in {1}".format(
conflictpid.strip(), pidpath
)
)
# Acquire lock
self.pidfile = PIDLockFile(pidpath)
self.locked = False
if not self.pidfile.is_locked():
self.pidfile.acquire()
self.locked = True
def release(self):
"""
Releases exclusive lock
"""
if self.pidfile.is_locked():
self.locked = False
return self.pidfile.release()
def islocked(self):
"""
Return true if exclusively locked
"""
return self.pidfile.is_locked()
def acquire_pidlock(pidfile):
"""Get the :class:`daemon.pidlockfile.PIDLockFile` handler for
``pidfile``.
If the ``pidfile`` already exists, but the process is not running the
``pidfile`` will be removed, a ``"stale pidfile"`` message is emitted
and execution continues as normally. However, if the process is still
running the program will exit complaning that the program is already
running in the background somewhere.
"""
from daemon.pidlockfile import PIDLockFile
import errno
pidlock = PIDLockFile(pidfile)
if not pidlock.is_locked():
return pidlock
pid = pidlock.read_pid()
try:
os.kill(pid, 0)
except os.error, exc:
if exc.errno == errno.ESRCH:
sys.stderr.write("Stale pidfile exists. Removing it.\n")
os.unlink(pidfile)
return PIDLockFile(pidfile)
