FM / python

/usr/lib/python3/dist-packages/twisted/python/

/usr/lib/python3/dist-packages/twisted/python

Name	Size	Mode	Actions
test/	-	0755	rm
_pydoctortemplates/	-	0755	rm
__pycache__/	-	0755	rm
compat.py	23194	0644	edit dl rm
components.py	14295	0644	edit dl rm
constants.py	544	0644	edit dl rm
context.py	4024	0644	edit dl rm
deprecate.py	26775	0644	edit dl rm
failure.py	26638	0644	edit dl rm
fakepwd.py	6138	0644	edit dl rm
filepath.py	58887	0644	edit dl rm
formmethod.py	11460	0644	edit dl rm
htmlizer.py	3541	0644	edit dl rm
lockfile.py	7718	0644	edit dl rm
log.py	22472	0644	edit dl rm
logfile.py	10083	0644	edit dl rm
modules.py	27141	0644	edit dl rm
monkey.py	2227	0644	edit dl rm
procutils.py	1419	0644	edit dl rm
randbytes.py	3959	0644	edit dl rm
rebuild.py	9268	0644	edit dl rm
reflect.py	19477	0644	edit dl rm
release.py	1192	0644	edit dl rm
roots.py	7404	0644	edit dl rm
runtime.py	6270	0644	edit dl rm
sendmsg.py	3420	0644	edit dl rm
shortcut.py	2253	0644	edit dl rm
syslog.py	3730	0644	edit dl rm
systemd.py	2834	0644	edit dl rm
text.py	5482	0644	edit dl rm
threadable.py	3297	0644	edit dl rm
threadpool.py	9840	0644	edit dl rm
twisted-completion.zsh	1371	0644	edit dl rm
url.py	244	0644	edit dl rm
urlpath.py	9084	0644	edit dl rm
usage.py	35010	0644	edit dl rm
util.py	27931	0644	edit dl rm
versions.py	322	0644	edit dl rm
win32.py	4317	0644	edit dl rm
zippath.py	9237	0644	edit dl rm
zipstream.py	9757	0644	edit dl rm
_appdirs.py	788	0644	edit dl rm
_inotify.py	3455	0644	edit dl rm
_oldstyle.py	2593	0644	edit dl rm
_release.py	18548	0644	edit dl rm
_setup.py	12953	0644	edit dl rm
_shellcomp.py	24830	0644	edit dl rm
_textattributes.py	9079	0644	edit dl rm
_tzhelper.py	3192	0644	edit dl rm
_url.py	253	0644	edit dl rm
__init__.py	674	0644	edit dl rm

Edit: /usr/lib/python3/dist-packages/twisted/python/lockfile.py (7718B)

# -*- test-case-name: twisted.test.test_lockfile -*-
# Copyright (c) 2005 Divmod, Inc.
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Filesystem-based interprocess mutex.
"""

from __future__ import absolute_import, division

import errno
import os

from time import time as _uniquefloat

from twisted.python.runtime import platform
from twisted.python.compat import _PY3

def unique():
    return str(int(_uniquefloat() * 1000))

from os import rename

if not platform.isWindows():
    from os import kill
    from os import symlink
    from os import readlink
    from os import remove as rmlink
    _windows = False
else:
    _windows = True

# On UNIX, a symlink can be made to a nonexistent location, and
    # FilesystemLock uses this by making the target of the symlink an
    # imaginary, non-existing file named that of the PID of the process with
    # the lock. This has some benefits on UNIX -- making and removing this
    # symlink is atomic. However, because Windows doesn't support symlinks (at
    # least as how we know them), we have to fake this and actually write a
    # file with the PID of the process holding the lock instead.
    # These functions below perform that unenviable, probably-fraught-with-
    # race-conditions duty. - hawkie

try:
        from win32api import OpenProcess
        import pywintypes
    except ImportError:
        kill = None
    else:
        ERROR_ACCESS_DENIED = 5
        ERROR_INVALID_PARAMETER = 87

def kill(pid, signal):
            try:
                OpenProcess(0, 0, pid)
            except pywintypes.error as e:
                if e.args[0] == ERROR_ACCESS_DENIED:
                    return
                elif e.args[0] == ERROR_INVALID_PARAMETER:
                    raise OSError(errno.ESRCH, None)
                raise
            else:
                raise RuntimeError("OpenProcess is required to fail.")

# For monkeypatching in tests
    _open = open

def symlink(value, filename):
        """
        Write a file at C{filename} with the contents of C{value}. See the
        above comment block as to why this is needed.
        """
        # XXX Implement an atomic thingamajig for win32
        newlinkname = filename + "." + unique() + '.newlink'
        newvalname = os.path.join(newlinkname, "symlink")
        os.mkdir(newlinkname)

# Python 3 does not support the 'commit' flag of fopen in the MSVCRT
        # (http://msdn.microsoft.com/en-us/library/yeby3zcb%28VS.71%29.aspx)
        if _PY3:
            mode = 'w'
        else:
            mode = 'wc'

with _open(newvalname, mode) as f:
            f.write(value)
            f.flush()

try:
            rename(newlinkname, filename)
        except:
            os.remove(newvalname)
            os.rmdir(newlinkname)
            raise

def readlink(filename):
        """
        Read the contents of C{filename}. See the above comment block as to why
        this is needed.
        """
        try:
            fObj = _open(os.path.join(filename, 'symlink'), 'r')
        except IOError as e:
            if e.errno == errno.ENOENT or e.errno == errno.EIO:
                raise OSError(e.errno, None)
            raise
        else:
            with fObj:
                result = fObj.read()
            return result

def rmlink(filename):
        os.remove(os.path.join(filename, 'symlink'))
        os.rmdir(filename)

class FilesystemLock(object):
    """
    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.

@ivar locked: Indicates whether the lock is currently held by this
        object.
    """

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.
        """
        clean = True
        while True:
            try:
                symlink(str(os.getpid()), self.name)
            except OSError as e:
                if _windows and e.errno in (errno.EACCES, errno.EIO):
                    # The lock is in the middle of being deleted because we're
                    # on Windows where lock removal isn't atomic.  Give up, we
                    # don't know how long this is going to take.
                    return False
                if e.errno == errno.EEXIST:
                    try:
                        pid = readlink(self.name)
                    except (IOError, OSError) as e:
                        if e.errno == errno.ENOENT:
                            # The lock has vanished, try to claim it in the
                            # next iteration through the loop.
                            continue
                        elif _windows and e.errno == errno.EACCES:
                            # The lock is in the middle of being
                            # deleted because we're on Windows where
                            # lock removal isn't atomic.  Give up, we
                            # don't know how long this is going to
                            # take.
                            return False
                        raise
                    try:
                        if kill is not None:
                            kill(int(pid), 0)
                    except OSError as e:
                        if e.errno == errno.ESRCH:
                            # The owner has vanished, try to claim it in the
                            # next iteration through the loop.
                            try:
                                rmlink(self.name)
                            except OSError as e:
                                if e.errno == errno.ENOENT:
                                    # Another process cleaned up the lock.
                                    # Race them to acquire it in the next
                                    # iteration through the loop.
                                    continue
                                raise
                            clean = False
                            continue
                        raise
                    return False
                raise
            self.locked = True
            self.clean = clean
            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']

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