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bzrlib/decorators.py
 
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# Copyright (C) 2005 Canonical Ltd
 
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# This program is free software; you can redistribute it and/or modify
 
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# it under the terms of the GNU General Public License as published by
 
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# the Free Software Foundation; either version 2 of the License, or
 
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# (at your option) any later version.
 
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#
 
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# This program is distributed in the hope that it will be useful,
 
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
 
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
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# GNU General Public License for more details.
 
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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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
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__all__ = ['needs_read_lock',
 
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           'needs_write_lock',
 
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           ]
 
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def needs_read_lock(unbound):
 
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    """Decorate unbound to take out and release a read lock.
 
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    This decorator can be applied to methods of any class with lock_read() and
 
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    unlock() methods.
 
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    Typical usage:
 
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    class Branch(...):
 
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        @needs_read_lock
 
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        def branch_method(self, ...):
 
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            stuff
 
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    """
 
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    def decorated(self, *args, **kwargs):
 
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        self.lock_read()
 
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        try:
 
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            return unbound(self, *args, **kwargs)
 
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        finally:
 
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            self.unlock()
 
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    decorated.__doc__ = unbound.__doc__
 
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    decorated.__name__ = unbound.__name__
 
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    return decorated
 
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def needs_write_lock(unbound):
 
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    """Decorate unbound to take out and release a write lock."""
 
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    def decorated(self, *args, **kwargs):
 
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        self.lock_write()
 
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        try:
 
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            return unbound(self, *args, **kwargs)
 
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        finally:
 
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            self.unlock()
 
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    decorated.__doc__ = unbound.__doc__
 
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    decorated.__name__ = unbound.__name__
 
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    return decorated
 
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