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Diffstat (limited to 'daemon/pidlockfile.py')
| -rw-r--r-- | daemon/pidlockfile.py | 194 |
1 files changed, 0 insertions, 194 deletions
diff --git a/daemon/pidlockfile.py b/daemon/pidlockfile.py deleted file mode 100644 index c38beae..0000000 --- a/daemon/pidlockfile.py +++ /dev/null @@ -1,194 +0,0 @@ -# -*- coding: utf-8 -*- - -# daemon/pidlockfile.py -# Part of python-daemon, an implementation of PEP 3143. -# -# Copyright © 2008–2010 Ben Finney <ben+python@benfinney.id.au> -# -# This is free software: you may copy, modify, and/or distribute this work -# under the terms of the Python Software Foundation License, version 2 or -# later as published by the Python Software Foundation. -# No warranty expressed or implied. See the file LICENSE.PSF-2 for details. - -""" Lockfile behaviour implemented via Unix PID files. - """ - -import os -import errno - -from lockfile import ( - LinkFileLock, - AlreadyLocked, LockFailed, - NotLocked, NotMyLock, - ) - - -class PIDFileError(Exception): - """ Abstract base class for errors specific to PID files. """ - -class PIDFileParseError(ValueError, PIDFileError): - """ Raised when parsing contents of PID file fails. """ - - -class PIDLockFile(LinkFileLock, object): - """ Lockfile implemented as a Unix PID file. - - The PID file is named by the attribute `path`. When locked, - the file will be created with a single line of text, - containing the process ID (PID) of the process that acquired - the lock. - - The lock is acquired and maintained as per `LinkFileLock`. - - """ - - def read_pid(self): - """ Get the PID from the lock file. - """ - result = read_pid_from_pidfile(self.path) - return result - - def acquire(self, *args, **kwargs): - """ Acquire the lock. - - Locks the PID file then creates the PID file for this - lock. The `timeout` parameter is used as for the - `LinkFileLock` class. - - """ - super(PIDLockFile, self).acquire(*args, **kwargs) - try: - write_pid_to_pidfile(self.path) - except OSError, exc: - error = LockFailed("%(exc)s" % vars()) - raise error - - def release(self): - """ Release the lock. - - Removes the PID file then releases the lock, or raises an - error if the current process does not hold the lock. - - """ - if self.i_am_locking(): - remove_existing_pidfile(self.path) - super(PIDLockFile, self).release() - - def break_lock(self): - """ Break an existing lock. - - If the lock is held, breaks the lock and removes the PID - file. - - """ - super(PIDLockFile, self).break_lock() - remove_existing_pidfile(self.path) - - -class TimeoutPIDLockFile(PIDLockFile): - """ Lockfile with default timeout, implemented as a Unix PID file. - - This uses the ``PIDLockFile`` implementation, with the - following changes: - - * The `acquire_timeout` parameter to the initialiser will be - used as the default `timeout` parameter for the `acquire` - method. - - """ - - def __init__(self, path, acquire_timeout=None, *args, **kwargs): - """ Set up the parameters of a DaemonRunnerLock. """ - self.acquire_timeout = acquire_timeout - super(TimeoutPIDLockFile, self).__init__(path, *args, **kwargs) - - def acquire(self, timeout=None, *args, **kwargs): - """ Acquire the lock. """ - if timeout is None: - timeout = self.acquire_timeout - super(TimeoutPIDLockFile, self).acquire(timeout, *args, **kwargs) - - -def read_pid_from_pidfile(pidfile_path): - """ Read the PID recorded in the named PID file. - - Read and return the numeric PID recorded as text in the named - PID file. If the PID file does not exist, return ``None``. If - the content is not a valid PID, raise ``PIDFileParseError``. - - """ - pid = None - pidfile = None - try: - pidfile = open(pidfile_path, 'r') - except IOError, exc: - if exc.errno == errno.ENOENT: - pass - else: - raise - - if pidfile: - # According to the FHS 2.3 section on PID files in ‘/var/run’: - # - # The file must consist of the process identifier in - # ASCII-encoded decimal, followed by a newline character. … - # - # Programs that read PID files should be somewhat flexible - # in what they accept; i.e., they should ignore extra - # whitespace, leading zeroes, absence of the trailing - # newline, or additional lines in the PID file. - - line = pidfile.readline().strip() - try: - pid = int(line) - except ValueError: - raise PIDFileParseError( - "PID file %(pidfile_path)r contents invalid" % vars()) - pidfile.close() - - return pid - - -def write_pid_to_pidfile(pidfile_path): - """ Write the PID in the named PID file. - - Get the numeric process ID (“PID”) of the current process - and write it to the named file as a line of text. - - """ - open_flags = (os.O_CREAT | os.O_EXCL | os.O_WRONLY) - open_mode = ( - ((os.R_OK | os.W_OK) << 6) | - ((os.R_OK) << 3) | - ((os.R_OK))) - pidfile_fd = os.open(pidfile_path, open_flags, open_mode) - pidfile = os.fdopen(pidfile_fd, 'w') - - # According to the FHS 2.3 section on PID files in ‘/var/run’: - # - # The file must consist of the process identifier in - # ASCII-encoded decimal, followed by a newline character. For - # example, if crond was process number 25, /var/run/crond.pid - # would contain three characters: two, five, and newline. - - pid = os.getpid() - line = "%(pid)d\n" % vars() - pidfile.write(line) - pidfile.close() - - -def remove_existing_pidfile(pidfile_path): - """ Remove the named PID file if it exists. - - Remove the named PID file. Ignore the condition if the file - does not exist, since that only means we are already in the - desired state. - - """ - try: - os.remove(pidfile_path) - except OSError, exc: - if exc.errno == errno.ENOENT: - pass - else: - raise |