Remove third_party/twisted_8_1

third_party/twisted_8_1/twisted/python/lockfile.py

-# -*- test-case-name: twisted.test.test_lockfile -*-
-# Copyright (c) 2005 Divmod, Inc.
-# See LICENSE for details.
-
-
-"""
-Lock files.
-"""
-
-__metaclass__ = type
-
-import errno, os
-
-from time import time as _uniquefloat
-
-def unique():
-    return str(long(_uniquefloat() * 1000))
-
-try:
-    from os import symlink
-    from os import readlink
-    from os import remove as rmlink
-    from os import rename as mvlink
-except:
-    # XXX Implement an atomic thingamajig for win32
-    import shutil
-    def symlink(value, filename):
-        newlinkname = filename+"."+unique()+'.newlink'
-        newvalname = os.path.join(newlinkname,"symlink")
-        os.mkdir(newlinkname)
-        f = open(newvalname,'wb')
-        f.write(value)
-        f.flush()
-        f.close()
-        try:
-            os.rename(newlinkname, filename)
-        except:
-            os.remove(newvalname)
-            os.rmdir(newlinkname)
-            raise
-
-    def readlink(filename):
-        return open(os.path.join(filename,'symlink'),'rb').read()
-
-    def rmlink(filename):
-        shutil.rmtree(filename)
-
-    def mvlink(src, dest):
-        try:
-            shutil.rmtree(dest)
-        except:
-            pass
-        os.rename(src,dest)
-
-
-class FilesystemLock:
-    """A mutex.
-
-    This relies on the filesystem property that creating
-    a symlink is an atomic operation and that it will
-    fail if the symlink already exists.  Deleting the
-    symlink will release the lock.
-
-    @ivar name: The name of the file associated with this lock.
-    @ivar clean: Indicates whether this lock was released cleanly by its
-    last owner.  Only meaningful after C{lock} has been called and returns
-    True.
-    """
-
-    clean = None
-    locked = False
-
-    def __init__(self, name):
-        self.name = name
-
-    def lock(self):
-        """Acquire this lock.
-
-        @rtype: C{bool}
-        @return: True if the lock is acquired, false otherwise.
-
-        @raise: Any exception os.symlink() may raise, other than
-        EEXIST.
-        """
-        try:
-            pid = readlink(self.name)
-        except (OSError, IOError), e:
-            if e.errno != errno.ENOENT:
-                raise
-            self.clean = True
-        else:
-            if not hasattr(os, 'kill'):
-                return False
-            try:
-                os.kill(int(pid), 0)
-            except (OSError, IOError), e:
-                if e.errno != errno.ESRCH:
-                    raise
-                rmlink(self.name)
-                self.clean = False
-            else:
-                return False
-
-        symlink(str(os.getpid()), self.name)
-        self.locked = True
-        return True
-
-    def unlock(self):
-        """Release this lock.
-
-        This deletes the directory with the given name.
-
-        @raise: Any exception os.readlink() may raise, or
-        ValueError if the lock is not owned by this process.
-        """
-        pid = readlink(self.name)
-        if int(pid) != os.getpid():
-            raise ValueError("Lock %r not owned by this process" % (self.name,))
-        rmlink(self.name)
-        self.locked = False
-
-
-def isLocked(name):
-    """Determine if the lock of the given name is held or not.
-
-    @type name: C{str}
-    @param name: The filesystem path to the lock to test
-
-    @rtype: C{bool}
-    @return: True if the lock is held, False otherwise.
-    """
-    l = FilesystemLock(name)
-    result = None
-    try:
-        result = l.lock()
-    finally:
-        if result:
-            l.unlock()
-    return not result
-
-
-__all__ = ['FilesystemLock', 'isLocked']
-