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Viewing changes to bzrlib/counted_lock.py

  • Committer: John Arbash Meinel
  • Date: 2008-10-04 14:10:13 UTC
  • mto: This revision was merged to the branch mainline in revision 3805.
  • Revision ID: john@arbash-meinel.com-20081004141013-yskxjlwtuy2k18ue
Playing around with expanding requests for btree index nodes into neighboring nodes.

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bzrlib/counted_lock.py
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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"""Counted lock class"""
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    This can be used with any object that provides a basic Lock interface,
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    including LockDirs and OS file locks.
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    :ivar _token: While a write lock is held, this is the token 
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        for it.
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    """
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    def __init__(self, real_lock):
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        self._lock_mode = None
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        self._lock_count = 0
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    def get_physical_lock_status(self):
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        """Return physical lock status.
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        Returns true if a lock is held on the transport. If no lock is held, or
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        the underlying locking mechanism does not support querying lock
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        status, false is returned.
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        """
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        try:
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            return self._real_lock.peek() is not None
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        except NotImplementedError:
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            return False
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    def is_locked(self):
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        return self._lock_mode is not None
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        If the lock was originally acquired in read mode this will fail.
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        :param token: If given and the lock is already held, 
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            then validate that we already hold the real
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            lock with this token.
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        :returns: The token from the underlying lock.
 
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        :param token: If non-None, reacquire the lock using this token.
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        """
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        if self._lock_count == 0:
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            self._token = self._real_lock.lock_write(token=token)
 
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            return_token = self._real_lock.lock_write(token)
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            self._lock_mode = 'w'
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            self._lock_count += 1
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            return self._token
 
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            return return_token
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        elif self._lock_mode != 'w':
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            raise errors.ReadOnlyError(self)
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        else:
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            self._real_lock.validate_token(token)
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            self._lock_count += 1
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            return self._token
 
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            return token
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    def unlock(self):
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        if self._lock_count == 0: