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Viewing changes to vendor/lockfile/lockfile/mkdirlockfile.py

  • Committer: Jesse Andrews
  • Date: 2010-05-28 06:05:26 UTC
  • Revision ID: git-v1:bf6e6e718cdc7488e2da87b21e258ccc065fe499
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vendor/lockfile/lockfile/mkdirlockfile.py
 
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from __future__ import absolute_import, division
 
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import time
 
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import os
 
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import sys
 
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import errno
 
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from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout,
 
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               AlreadyLocked)
 
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class MkdirLockFile(LockBase):
 
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    """Lock file by creating a directory."""
 
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    def __init__(self, path, threaded=True):
 
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        """
 
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        >>> lock = MkdirLockFile('somefile')
 
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        >>> lock = MkdirLockFile('somefile', threaded=False)
 
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        """
 
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        LockBase.__init__(self, path, threaded)
 
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        # Lock file itself is a directory.  Place the unique file name into
 
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        # it.
 
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        self.unique_name  = os.path.join(self.lock_file,
 
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                                         "%s.%s%s" % (self.hostname,
 
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                                                      self.tname,
 
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                                                      self.pid))
 
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    def acquire(self, timeout=None):
 
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        end_time = time.time()
 
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        if timeout is not None and timeout > 0:
 
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            end_time += timeout
 
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        if timeout is None:
 
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            wait = 0.1
 
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        else:
 
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            wait = max(0, timeout / 10)
 
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        while True:
 
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            try:
 
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                os.mkdir(self.lock_file)
 
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            except OSError:
 
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                err = sys.exc_info()[1]
 
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                if err.errno == errno.EEXIST:
 
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                    # Already locked.
 
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                    if os.path.exists(self.unique_name):
 
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                        # Already locked by me.
 
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                        return
 
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                    if timeout is not None and time.time() > end_time:
 
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                        if timeout > 0:
 
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                            raise LockTimeout
 
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                        else:
 
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                            # Someone else has the lock.
 
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                            raise AlreadyLocked
 
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                    time.sleep(wait)
 
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                else:
 
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                    # Couldn't create the lock for some other reason
 
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                    raise LockFailed("failed to create %s" % self.lock_file)
 
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            else:
 
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                open(self.unique_name, "wb").close()
 
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                return
 
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    def release(self):
 
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        if not self.is_locked():
 
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            raise NotLocked
 
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        elif not os.path.exists(self.unique_name):
 
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            raise NotMyLock
 
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        os.unlink(self.unique_name)
 
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        os.rmdir(self.lock_file)
 
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    def is_locked(self):
 
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        return os.path.exists(self.lock_file)
 
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    def i_am_locking(self):
 
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        return (self.is_locked() and
 
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                os.path.exists(self.unique_name))
 
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    def break_lock(self):
 
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        if os.path.exists(self.lock_file):
 
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            for name in os.listdir(self.lock_file):
 
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                os.unlink(os.path.join(self.lock_file, name))
 
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            os.rmdir(self.lock_file)