FM / lockfile

/usr/lib/python3.6/site-packages/pip/_vendor/lockfile/

/usr/lib/python3.6/site-packages/pip/_vendor/lockfile

Name	Size	Mode	Actions
__pycache__/	-	0755	rm
linklockfile.py	2652	0644	edit dl rm
mkdirlockfile.py	3096	0644	edit dl rm
pidlockfile.py	6090	0644	edit dl rm
sqlitelockfile.py	5506	0644	edit dl rm
symlinklockfile.py	2616	0644	edit dl rm
__init__.py	9371	0644	edit dl rm

Edit: /usr/lib/python3.6/site-packages/pip/_vendor/lockfile/symlinklockfile.py (2616B)

from __future__ import absolute_import

import os
import time

from . import (LockBase, NotLocked, NotMyLock, LockTimeout,
               AlreadyLocked)

class SymlinkLockFile(LockBase):
    """Lock access to a file using symlink(2)."""

def __init__(self, path, threaded=True, timeout=None):
        # super(SymlinkLockFile).__init(...)
        LockBase.__init__(self, path, threaded, timeout)
        # split it back!
        self.unique_name = os.path.split(self.unique_name)[1]

def acquire(self, timeout=None):
        # Hopefully unnecessary for symlink.
        # try:
        #     open(self.unique_name, "wb").close()
        # except IOError:
        #     raise LockFailed("failed to create %s" % self.unique_name)
        timeout = timeout if timeout is not None else self.timeout
        end_time = time.time()
        if timeout is not None and timeout > 0:
            end_time += timeout

while True:
            # Try and create a symbolic link to it.
            try:
                os.symlink(self.unique_name, self.lock_file)
            except OSError:
                # Link creation failed.  Maybe we've double-locked?
                if self.i_am_locking():
                    # Linked to out unique name. Proceed.
                    return
                else:
                    # Otherwise the lock creation failed.
                    if timeout is not None and time.time() > end_time:
                        if timeout > 0:
                            raise LockTimeout("Timeout waiting to acquire"
                                              " lock for %s" %
                                              self.path)
                        else:
                            raise AlreadyLocked("%s is already locked" %
                                                self.path)
                    time.sleep(timeout / 10 if timeout is not None else 0.1)
            else:
                # Link creation succeeded.  We're good to go.
                return

def release(self):
        if not self.is_locked():
            raise NotLocked("%s is not locked" % self.path)
        elif not self.i_am_locking():
            raise NotMyLock("%s is locked, but not by me" % self.path)
        os.unlink(self.lock_file)

def is_locked(self):
        return os.path.islink(self.lock_file)

def i_am_locking(self):
        return (os.path.islink(self.lock_file)
                and os.readlink(self.lock_file) == self.unique_name)

def break_lock(self):
        if os.path.islink(self.lock_file):  # exists && link
            os.unlink(self.lock_file)

cmd: