diff lockfile-0.10.2/lockfile/__init__.py @ 33:7ceb967147c3

start xena with no gui add library files

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lockfile-0.10.2/lockfile/__init__.py	Wed Jul 22 13:24:44 2015 -0700
@@ -0,0 +1,326 @@
+"""
+lockfile.py - Platform-independent advisory file locks.
+
+Requires Python 2.5 unless you apply 2.4.diff
+Locking is done on a per-thread basis instead of a per-process basis.
+
+Usage:
+
+>>> lock = LockFile('somefile')
+>>> try:
+...     lock.acquire()
+... except AlreadyLocked:
+...     print 'somefile', 'is locked already.'
+... except LockFailed:
+...     print 'somefile', 'can\\'t be locked.'
+... else:
+...     print 'got lock'
+got lock
+>>> print lock.is_locked()
+True
+>>> lock.release()
+
+>>> lock = LockFile('somefile')
+>>> print lock.is_locked()
+False
+>>> with lock:
+...    print lock.is_locked()
+True
+>>> print lock.is_locked()
+False
+
+>>> lock = LockFile('somefile')
+>>> # It is okay to lock twice from the same thread...
+>>> with lock:
+...     lock.acquire()
+...
+>>> # Though no counter is kept, so you can't unlock multiple times...
+>>> print lock.is_locked()
+False
+
+Exceptions:
+
+    Error - base class for other exceptions
+        LockError - base class for all locking exceptions
+            AlreadyLocked - Another thread or process already holds the lock
+            LockFailed - Lock failed for some other reason
+        UnlockError - base class for all unlocking exceptions
+            AlreadyUnlocked - File was not locked.
+            NotMyLock - File was locked but not by the current thread/process
+"""
+
+from __future__ import absolute_import
+
+import sys
+import socket
+import os
+import threading
+import time
+import urllib
+import warnings
+import functools
+
+# Work with PEP8 and non-PEP8 versions of threading module.
+if not hasattr(threading, "current_thread"):
+    threading.current_thread = threading.currentThread
+if not hasattr(threading.Thread, "get_name"):
+    threading.Thread.get_name = threading.Thread.getName
+
+__all__ = ['Error', 'LockError', 'LockTimeout', 'AlreadyLocked',
+           'LockFailed', 'UnlockError', 'NotLocked', 'NotMyLock',
+           'LinkLockFile', 'MkdirLockFile', 'SQLiteLockFile',
+           'LockBase', 'locked']
+
+class Error(Exception):
+    """
+    Base class for other exceptions.
+
+    >>> try:
+    ...   raise Error
+    ... except Exception:
+    ...   pass
+    """
+    pass
+
+class LockError(Error):
+    """
+    Base class for error arising from attempts to acquire the lock.
+
+    >>> try:
+    ...   raise LockError
+    ... except Error:
+    ...   pass
+    """
+    pass
+
+class LockTimeout(LockError):
+    """Raised when lock creation fails within a user-defined period of time.
+
+    >>> try:
+    ...   raise LockTimeout
+    ... except LockError:
+    ...   pass
+    """
+    pass
+
+class AlreadyLocked(LockError):
+    """Some other thread/process is locking the file.
+
+    >>> try:
+    ...   raise AlreadyLocked
+    ... except LockError:
+    ...   pass
+    """
+    pass
+
+class LockFailed(LockError):
+    """Lock file creation failed for some other reason.
+
+    >>> try:
+    ...   raise LockFailed
+    ... except LockError:
+    ...   pass
+    """
+    pass
+
+class UnlockError(Error):
+    """
+    Base class for errors arising from attempts to release the lock.
+
+    >>> try:
+    ...   raise UnlockError
+    ... except Error:
+    ...   pass
+    """
+    pass
+
+class NotLocked(UnlockError):
+    """Raised when an attempt is made to unlock an unlocked file.
+
+    >>> try:
+    ...   raise NotLocked
+    ... except UnlockError:
+    ...   pass
+    """
+    pass
+
+class NotMyLock(UnlockError):
+    """Raised when an attempt is made to unlock a file someone else locked.
+
+    >>> try:
+    ...   raise NotMyLock
+    ... except UnlockError:
+    ...   pass
+    """
+    pass
+
+class LockBase:
+    """Base class for platform-specific lock classes."""
+    def __init__(self, path, threaded=True, timeout=None):
+        """
+        >>> lock = LockBase('somefile')
+        >>> lock = LockBase('somefile', threaded=False)
+        """
+        self.path = path
+        self.lock_file = os.path.abspath(path) + ".lock"
+        self.hostname = socket.gethostname()
+        self.pid = os.getpid()
+        if threaded:
+            t = threading.current_thread()
+            # Thread objects in Python 2.4 and earlier do not have ident
+            # attrs.  Worm around that.
+            ident = getattr(t, "ident", hash(t))
+            self.tname = "-%x" % (ident & 0xffffffff)
+        else:
+            self.tname = ""
+        dirname = os.path.dirname(self.lock_file)
+
+        # unique name is mostly about the current process, but must
+        # also contain the path -- otherwise, two adjacent locked
+        # files conflict (one file gets locked, creating lock-file and
+        # unique file, the other one gets locked, creating lock-file
+        # and overwriting the already existing lock-file, then one
+        # gets unlocked, deleting both lock-file and unique file,
+        # finally the last lock errors out upon releasing.
+        self.unique_name = os.path.join(dirname,
+                                        "%s%s.%s%s" % (self.hostname,
+                                                       self.tname,
+                                                       self.pid,
+                                                       hash(self.path)))
+        self.timeout = timeout
+
+    def acquire(self, timeout=None):
+        """
+        Acquire the lock.
+
+        * If timeout is omitted (or None), wait forever trying to lock the
+          file.
+
+        * If timeout > 0, try to acquire the lock for that many seconds.  If
+          the lock period expires and the file is still locked, raise
+          LockTimeout.
+
+        * If timeout <= 0, raise AlreadyLocked immediately if the file is
+          already locked.
+        """
+        raise NotImplemented("implement in subclass")
+
+    def release(self):
+        """
+        Release the lock.
+
+        If the file is not locked, raise NotLocked.
+        """
+        raise NotImplemented("implement in subclass")
+
+    def is_locked(self):
+        """
+        Tell whether or not the file is locked.
+        """
+        raise NotImplemented("implement in subclass")
+
+    def i_am_locking(self):
+        """
+        Return True if this object is locking the file.
+        """
+        raise NotImplemented("implement in subclass")
+
+    def break_lock(self):
+        """
+        Remove a lock.  Useful if a locking thread failed to unlock.
+        """
+        raise NotImplemented("implement in subclass")
+
+    def __enter__(self):
+        """
+        Context manager support.
+        """
+        self.acquire()
+        return self
+
+    def __exit__(self, *_exc):
+        """
+        Context manager support.
+        """
+        self.release()
+
+    def __repr__(self):
+        return "<%s: %r -- %r>" % (self.__class__.__name__, self.unique_name,
+                                   self.path)
+
+def _fl_helper(cls, mod, *args, **kwds):
+    warnings.warn("Import from %s module instead of lockfile package" % mod,
+                  DeprecationWarning, stacklevel=2)
+    # This is a bit funky, but it's only for awhile.  The way the unit tests
+    # are constructed this function winds up as an unbound method, so it
+    # actually takes three args, not two.  We want to toss out self.
+    if not isinstance(args[0], str):
+        # We are testing, avoid the first arg
+        args = args[1:]
+    if len(args) == 1 and not kwds:
+        kwds["threaded"] = True
+    return cls(*args, **kwds)
+
+def LinkFileLock(*args, **kwds):
+    """Factory function provided for backwards compatibility.
+
+    Do not use in new code.  Instead, import LinkLockFile from the
+    lockfile.linklockfile module.
+    """
+    from . import linklockfile
+    return _fl_helper(linklockfile.LinkLockFile, "lockfile.linklockfile",
+                      *args, **kwds)
+
+def MkdirFileLock(*args, **kwds):
+    """Factory function provided for backwards compatibility.
+
+    Do not use in new code.  Instead, import MkdirLockFile from the
+    lockfile.mkdirlockfile module.
+    """
+    from . import mkdirlockfile
+    return _fl_helper(mkdirlockfile.MkdirLockFile, "lockfile.mkdirlockfile",
+                      *args, **kwds)
+
+def SQLiteFileLock(*args, **kwds):
+    """Factory function provided for backwards compatibility.
+
+    Do not use in new code.  Instead, import SQLiteLockFile from the
+    lockfile.mkdirlockfile module.
+    """
+    from . import sqlitelockfile
+    return _fl_helper(sqlitelockfile.SQLiteLockFile, "lockfile.sqlitelockfile",
+                      *args, **kwds)
+
+def locked(path, timeout=None):
+    """Decorator which enables locks for decorated function.
+
+    Arguments:
+     - path: path for lockfile.
+     - timeout (optional): Timeout for acquiring lock.
+
+     Usage:
+         @locked('/var/run/myname', timeout=0)
+         def myname(...):
+             ...
+    """
+    def decor(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            lock = FileLock(path, timeout=timeout)
+            lock.acquire()
+            try:
+                return func(*args, **kwargs)
+            finally:
+                lock.release()
+        return wrapper
+    return decor
+
+if hasattr(os, "link"):
+    from . import linklockfile as _llf
+    LockFile = _llf.LinkLockFile
+else:
+    from . import mkdirlockfile as _mlf
+    LockFile = _mlf.MkdirLockFile
+
+FileLock = LockFile
+