def _write(self, pid_file):
try:
pid_file.seek(0)
pid_file.write('{}\n'.format(os.getpid()))
pid_file.close()
except IOError as e:
raise exc.PidFileError(self.path) from e
def release(self):
with self._open() as pid_file:
self._ensure_owning(pid_file)
try:
os.unlink(self.path)
except OSError:
raise exc.PidFileError(self.path) from e
def _read(self, pid_file):
pid = None
try:
raw = pid_file.read(1024)
if raw:
pid = int(raw, 10)
except (IOError, ValueError) as e:
raise exc.PidFileError(self.path) from e
return pid
def ping_proc(self, pid):
try:
os.kill(pid, 0)
return True
except OSError as e:
if e.errno != errno.ESRCH:
raise exc.PidFileError(self.path) from e
return False
def _open(self):
for attempt in range(5):
pid_fd = None
try:
pid_fd = os.open(self.path, os.O_RDWR | os.O_CREAT)
fcntl.flock(pid_fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except OSError as e:
if pid_fd is not None:
os.close(pid_fd)
if e.errno != errno.EWOULDBLOCK:
raise exc.PidFileError(self.path) from e
time.sleep(0.1)
continue
break
else:
raise exc.PidFileLockError(self.path)
return os.fdopen(pid_fd, 'w+t')
