Initial push to external_lib migration

6 files changed, 899 insertions, 0 deletions

diff --git a/external_libs/python/lockfile-0.10.2/lockfile/__init__.py b/external_libs/python/lockfile-0.10.2/lockfile/__init__.py
new file mode 100644
index 00000000..d905af96
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/__init__.py
@@ -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
+
diff --git a/external_libs/python/lockfile-0.10.2/lockfile/linklockfile.py b/external_libs/python/lockfile-0.10.2/lockfile/linklockfile.py
new file mode 100644
index 00000000..9c506734
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/linklockfile.py
@@ -0,0 +1,73 @@
+from __future__ import absolute_import
+
+import time
+import os
+
+from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout,
+               AlreadyLocked)
+
+class LinkLockFile(LockBase):
+    """Lock access to a file using atomic property of link(2).
+
+    >>> lock = LinkLockFile('somefile')
+    >>> lock = LinkLockFile('somefile', threaded=False)
+    """
+
+    def acquire(self, timeout=None):
+        try:
+            open(self.unique_name, "wb").close()
+        except IOError:
+            raise LockFailed("failed to create %s" % self.unique_name)
+
+        timeout = timeout is not None and timeout or self.timeout
+        end_time = time.time()
+        if timeout is not None and timeout > 0:
+            end_time += timeout
+
+        while True:
+            # Try and create a hard link to it.
+            try:
+                os.link(self.unique_name, self.lock_file)
+            except OSError:
+                # Link creation failed.  Maybe we've double-locked?
+                nlinks = os.stat(self.unique_name).st_nlink
+                if nlinks == 2:
+                    # The original link plus the one I created == 2.  We're
+                    # good to go.
+                    return
+                else:
+                    # Otherwise the lock creation failed.
+                    if timeout is not None and time.time() > end_time:
+                        os.unlink(self.unique_name)
+                        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 is not None and timeout/10 or 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 os.path.exists(self.unique_name):
+            raise NotMyLock("%s is locked, but not by me" % self.path)
+        os.unlink(self.unique_name)
+        os.unlink(self.lock_file)
+
+    def is_locked(self):
+        return os.path.exists(self.lock_file)
+
+    def i_am_locking(self):
+        return (self.is_locked() and
+                os.path.exists(self.unique_name) and
+                os.stat(self.unique_name).st_nlink == 2)
+
+    def break_lock(self):
+        if os.path.exists(self.lock_file):
+            os.unlink(self.lock_file)
+
diff --git a/external_libs/python/lockfile-0.10.2/lockfile/mkdirlockfile.py b/external_libs/python/lockfile-0.10.2/lockfile/mkdirlockfile.py
new file mode 100644
index 00000000..8d2c801f
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/mkdirlockfile.py
@@ -0,0 +1,83 @@
+from __future__ import absolute_import, division
+
+import time
+import os
+import sys
+import errno
+
+from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout,
+               AlreadyLocked)
+
+class MkdirLockFile(LockBase):
+    """Lock file by creating a directory."""
+    def __init__(self, path, threaded=True, timeout=None):
+        """
+        >>> lock = MkdirLockFile('somefile')
+        >>> lock = MkdirLockFile('somefile', threaded=False)
+        """
+        LockBase.__init__(self, path, threaded, timeout)
+        # Lock file itself is a directory.  Place the unique file name into
+        # it.
+        self.unique_name  = os.path.join(self.lock_file,
+                                         "%s.%s%s" % (self.hostname,
+                                                      self.tname,
+                                                      self.pid))
+
+    def acquire(self, timeout=None):
+        timeout = timeout is not None and timeout or self.timeout
+        end_time = time.time()
+        if timeout is not None and timeout > 0:
+            end_time += timeout
+
+        if timeout is None:
+            wait = 0.1
+        else:
+            wait = max(0, timeout / 10)
+
+        while True:
+            try:
+                os.mkdir(self.lock_file)
+            except OSError:
+                err = sys.exc_info()[1]
+                if err.errno == errno.EEXIST:
+                    # Already locked.
+                    if os.path.exists(self.unique_name):
+                        # Already locked by me.
+                        return
+                    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:
+                            # Someone else has the lock.
+                            raise AlreadyLocked("%s is already locked" %
+                                                self.path)
+                    time.sleep(wait)
+                else:
+                    # Couldn't create the lock for some other reason
+                    raise LockFailed("failed to create %s" % self.lock_file)
+            else:
+                open(self.unique_name, "wb").close()
+                return
+
+    def release(self):
+        if not self.is_locked():
+            raise NotLocked("%s is not locked" % self.path)
+        elif not os.path.exists(self.unique_name):
+            raise NotMyLock("%s is locked, but not by me" % self.path)
+        os.unlink(self.unique_name)
+        os.rmdir(self.lock_file)
+
+    def is_locked(self):
+        return os.path.exists(self.lock_file)
+
+    def i_am_locking(self):
+        return (self.is_locked() and
+                os.path.exists(self.unique_name))
+
+    def break_lock(self):
+        if os.path.exists(self.lock_file):
+            for name in os.listdir(self.lock_file):
+                os.unlink(os.path.join(self.lock_file, name))
+            os.rmdir(self.lock_file)
diff --git a/external_libs/python/lockfile-0.10.2/lockfile/pidlockfile.py b/external_libs/python/lockfile-0.10.2/lockfile/pidlockfile.py
new file mode 100644
index 00000000..e92f9ead
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/pidlockfile.py
@@ -0,0 +1,193 @@
+# -*- coding: utf-8 -*-
+
+# pidlockfile.py
+#
+# Copyright © 2008–2009 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.
+    """
+
+from __future__ import absolute_import
+
+import os
+import sys
+import errno
+import time
+
+from . import (LockBase, AlreadyLocked, LockFailed, NotLocked, NotMyLock,
+               LockTimeout)
+
+
+class PIDLockFile(LockBase):
+    """ Lockfile implemented as a Unix PID file.
+
+    The lock file is a normal file named by the attribute `path`.
+    A lock's PID file contains a single line of text, containing
+    the process ID (PID) of the process that acquired the lock.
+
+    >>> lock = PIDLockFile('somefile')
+    >>> lock = PIDLockFile('somefile')
+    """
+
+    def __init__(self, path, threaded=False, timeout=None):
+        # pid lockfiles don't support threaded operation, so always force
+        # False as the threaded arg.
+        LockBase.__init__(self, path, False, timeout)
+        dirname = os.path.dirname(self.lock_file)
+        basename = os.path.split(self.path)[-1]
+        self.unique_name = self.path
+
+    def read_pid(self):
+        """ Get the PID from the lock file.
+            """
+        return read_pid_from_pidfile(self.path)
+
+    def is_locked(self):
+        """ Test if the lock is currently held.
+
+            The lock is held if the PID file for this lock exists.
+
+            """
+        return os.path.exists(self.path)
+
+    def i_am_locking(self):
+        """ Test if the lock is held by the current process.
+
+        Returns ``True`` if the current process ID matches the
+        number stored in the PID file.
+        """
+        return self.is_locked() and os.getpid() == self.read_pid()
+
+    def acquire(self, timeout=None):
+        """ Acquire the lock.
+
+        Creates the PID file for this lock, or raises an error if
+        the lock could not be acquired.
+        """
+
+        timeout = timeout is not None and timeout or self.timeout
+        end_time = time.time()
+        if timeout is not None and timeout > 0:
+            end_time += timeout
+
+        while True:
+            try:
+                write_pid_to_pidfile(self.path)
+            except OSError as exc:
+                if exc.errno == errno.EEXIST:
+                    # The lock creation failed.  Maybe sleep a bit.
+                    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 is not None and timeout/10 or 0.1)
+                else:
+                    raise LockFailed("failed to create %s" % self.path)
+            else:
+                return
+
+    def release(self):
+        """ Release the lock.
+
+            Removes the PID file to release the lock, or raises an
+            error if the current process does not hold the lock.
+
+            """
+        if not self.is_locked():
+            raise NotLocked("%s is not locked" % self.path)
+        if not self.i_am_locking():
+            raise NotMyLock("%s is locked, but not by me" % self.path)
+        remove_existing_pidfile(self.path)
+
+    def break_lock(self):
+        """ Break an existing lock.
+
+            Removes the PID file if it already exists, otherwise does
+            nothing.
+
+            """
+        remove_existing_pidfile(self.path)
+
+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 cannot be read, or if the content is
+        not a valid PID, return ``None``.
+
+        """
+    pid = None
+    try:
+        pidfile = open(pidfile_path, 'r')
+    except IOError:
+        pass
+    else:
+        # 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:
+            pass
+        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 = 0o644
+    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.
+
+        Removing a PID file that doesn't already exist puts us in the
+        desired state, so we ignore the condition if the file does not
+        exist.
+
+        """
+    try:
+        os.remove(pidfile_path)
+    except OSError as exc:
+        if exc.errno == errno.ENOENT:
+            pass
+        else:
+            raise
diff --git a/external_libs/python/lockfile-0.10.2/lockfile/sqlitelockfile.py b/external_libs/python/lockfile-0.10.2/lockfile/sqlitelockfile.py
new file mode 100644
index 00000000..7dee4a85
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/sqlitelockfile.py
@@ -0,0 +1,155 @@
+from __future__ import absolute_import, division
+
+import time
+import os
+
+try:
+    unicode
+except NameError:
+    unicode = str
+
+from . import LockBase, NotLocked, NotMyLock, LockTimeout, AlreadyLocked
+
+class SQLiteLockFile(LockBase):
+    "Demonstrate SQL-based locking."
+
+    testdb = None
+
+    def __init__(self, path, threaded=True, timeout=None):
+        """
+        >>> lock = SQLiteLockFile('somefile')
+        >>> lock = SQLiteLockFile('somefile', threaded=False)
+        """
+        LockBase.__init__(self, path, threaded, timeout)
+        self.lock_file = unicode(self.lock_file)
+        self.unique_name = unicode(self.unique_name)
+
+        if SQLiteLockFile.testdb is None:
+            import tempfile
+            _fd, testdb = tempfile.mkstemp()
+            os.close(_fd)
+            os.unlink(testdb)
+            del _fd, tempfile
+            SQLiteLockFile.testdb = testdb
+
+        import sqlite3
+        self.connection = sqlite3.connect(SQLiteLockFile.testdb)
+        
+        c = self.connection.cursor()
+        try:
+            c.execute("create table locks"
+                      "("
+                      "   lock_file varchar(32),"
+                      "   unique_name varchar(32)"
+                      ")")
+        except sqlite3.OperationalError:
+            pass
+        else:
+            self.connection.commit()
+            import atexit
+            atexit.register(os.unlink, SQLiteLockFile.testdb)
+
+    def acquire(self, timeout=None):
+        timeout = timeout is not None and timeout or self.timeout
+        end_time = time.time()
+        if timeout is not None and timeout > 0:
+            end_time += timeout
+
+        if timeout is None:
+            wait = 0.1
+        elif timeout <= 0:
+            wait = 0
+        else:
+            wait = timeout / 10
+
+        cursor = self.connection.cursor()
+
+        while True:
+            if not self.is_locked():
+                # Not locked.  Try to lock it.
+                cursor.execute("insert into locks"
+                               "  (lock_file, unique_name)"
+                               "  values"
+                               "  (?, ?)",
+                               (self.lock_file, self.unique_name))
+                self.connection.commit()
+
+                # Check to see if we are the only lock holder.
+                cursor.execute("select * from locks"
+                               "  where unique_name = ?",
+                               (self.unique_name,))
+                rows = cursor.fetchall()
+                if len(rows) > 1:
+                    # Nope.  Someone else got there.  Remove our lock.
+                    cursor.execute("delete from locks"
+                                   "  where unique_name = ?",
+                                   (self.unique_name,))
+                    self.connection.commit()
+                else:
+                    # Yup.  We're done, so go home.
+                    return
+            else:
+                # Check to see if we are the only lock holder.
+                cursor.execute("select * from locks"
+                               "  where unique_name = ?",
+                               (self.unique_name,))
+                rows = cursor.fetchall()
+                if len(rows) == 1:
+                    # We're the locker, so go home.
+                    return
+                    
+            # Maybe we should wait a bit longer.
+            if timeout is not None and time.time() > end_time:
+                if timeout > 0:
+                    # No more waiting.
+                    raise LockTimeout("Timeout waiting to acquire"
+                                      " lock for %s" %
+                                      self.path)
+                else:
+                    # Someone else has the lock and we are impatient..
+                    raise AlreadyLocked("%s is already locked" % self.path)
+
+            # Well, okay.  We'll give it a bit longer.
+            time.sleep(wait)
+
+    def release(self):
+        if not self.is_locked():
+            raise NotLocked("%s is not locked" % self.path)
+        if not self.i_am_locking():
+            raise NotMyLock("%s is locked, but not by me (by %s)" %
+                            (self.unique_name, self._who_is_locking()))
+        cursor = self.connection.cursor()
+        cursor.execute("delete from locks"
+                       "  where unique_name = ?",
+                       (self.unique_name,))
+        self.connection.commit()
+
+    def _who_is_locking(self):
+        cursor = self.connection.cursor()
+        cursor.execute("select unique_name from locks"
+                       "  where lock_file = ?",
+                       (self.lock_file,))
+        return cursor.fetchone()[0]
+        
+    def is_locked(self):
+        cursor = self.connection.cursor()
+        cursor.execute("select * from locks"
+                       "  where lock_file = ?",
+                       (self.lock_file,))
+        rows = cursor.fetchall()
+        return not not rows
+
+    def i_am_locking(self):
+        cursor = self.connection.cursor()
+        cursor.execute("select * from locks"
+                       "  where lock_file = ?"
+                       "    and unique_name = ?",
+                       (self.lock_file, self.unique_name))
+        return not not cursor.fetchall()
+
+    def break_lock(self):
+        cursor = self.connection.cursor()
+        cursor.execute("delete from locks"
+                       "  where lock_file = ?",
+                       (self.lock_file,))
+        self.connection.commit()
diff --git a/external_libs/python/lockfile-0.10.2/lockfile/symlinklockfile.py b/external_libs/python/lockfile-0.10.2/lockfile/symlinklockfile.py
new file mode 100644
index 00000000..57551a36
--- /dev/null
+++ b/external_libs/python/lockfile-0.10.2/lockfile/symlinklockfile.py
@@ -0,0 +1,69 @@
+from __future__ import absolute_import
+
+import time
+import os
+
+from . import (LockBase, LockFailed, 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 is not None and timeout or 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)