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a6b3caad41
opening the DB to implement legacy interface flag='n' support as BerkeleyDB 4.2.52 no longer allows it in transaction protected environments. Do the os.unlink ourselves.
379 lines
12 KiB
Python
379 lines
12 KiB
Python
#----------------------------------------------------------------------
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# Copyright (c) 1999-2001, Digital Creations, Fredericksburg, VA, USA
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# and Andrew Kuchling. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# o Redistributions of source code must retain the above copyright
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# notice, this list of conditions, and the disclaimer that follows.
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#
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# o Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions, and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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#
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# o Neither the name of Digital Creations nor the names of its
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# contributors may be used to endorse or promote products derived
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# from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY DIGITAL CREATIONS AND CONTRIBUTORS *AS
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# IS* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DIGITAL
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# CREATIONS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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# TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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# DAMAGE.
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#----------------------------------------------------------------------
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"""Support for BerkeleyDB 3.2 through 4.2.
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"""
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try:
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if __name__ == 'bsddb3':
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# import _pybsddb binary as it should be the more recent version from
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# a standalone pybsddb addon package than the version included with
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# python as bsddb._bsddb.
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import _pybsddb
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_bsddb = _pybsddb
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else:
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import _bsddb
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except ImportError:
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# Remove ourselves from sys.modules
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import sys
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del sys.modules[__name__]
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raise
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# bsddb3 calls it db, but provide _db for backwards compatibility
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db = _db = _bsddb
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__version__ = db.__version__
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error = db.DBError # So bsddb.error will mean something...
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#----------------------------------------------------------------------
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import sys, os
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# for backwards compatibility with python versions older than 2.3, the
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# iterator interface is dynamically defined and added using a mixin
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# class. old python can't tokenize it due to the yield keyword.
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if sys.version >= '2.3':
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exec """
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import UserDict
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from weakref import ref
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class _iter_mixin(UserDict.DictMixin):
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def _make_iter_cursor(self):
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cur = self.db.cursor()
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key = id(cur)
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self._cursor_refs[key] = ref(cur, self._gen_cref_cleaner(key))
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return cur
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def _gen_cref_cleaner(self, key):
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# use generate the function for the weakref callback here
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# to ensure that we do not hold a strict reference to cur
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# in the callback.
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return lambda ref: self._cursor_refs.pop(key, None)
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def __iter__(self):
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try:
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cur = self._make_iter_cursor()
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# FIXME-20031102-greg: race condition. cursor could
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# be closed by another thread before this call.
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# since we're only returning keys, we call the cursor
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# methods with flags=0, dlen=0, dofs=0
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key = cur.first(0,0,0)[0]
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yield key
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next = cur.next
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while 1:
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try:
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key = next(0,0,0)[0]
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yield key
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except _bsddb.DBCursorClosedError:
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cur = self._make_iter_cursor()
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# FIXME-20031101-greg: race condition. cursor could
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# be closed by another thread before this call.
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cur.set(key,0,0,0)
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next = cur.next
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except _bsddb.DBNotFoundError:
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return
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except _bsddb.DBCursorClosedError:
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# the database was modified during iteration. abort.
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return
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def iteritems(self):
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try:
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cur = self._make_iter_cursor()
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# FIXME-20031102-greg: race condition. cursor could
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# be closed by another thread before this call.
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kv = cur.first()
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key = kv[0]
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yield kv
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next = cur.next
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while 1:
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try:
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kv = next()
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key = kv[0]
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yield kv
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except _bsddb.DBCursorClosedError:
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cur = self._make_iter_cursor()
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# FIXME-20031101-greg: race condition. cursor could
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# be closed by another thread before this call.
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cur.set(key,0,0,0)
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next = cur.next
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except _bsddb.DBNotFoundError:
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return
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except _bsddb.DBCursorClosedError:
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# the database was modified during iteration. abort.
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return
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"""
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else:
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class _iter_mixin: pass
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class _DBWithCursor(_iter_mixin):
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"""
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A simple wrapper around DB that makes it look like the bsddbobject in
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the old module. It uses a cursor as needed to provide DB traversal.
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"""
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def __init__(self, db):
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self.db = db
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self.db.set_get_returns_none(0)
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# FIXME-20031101-greg: I believe there is still the potential
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# for deadlocks in a multithreaded environment if someone
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# attempts to use the any of the cursor interfaces in one
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# thread while doing a put or delete in another thread. The
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# reason is that _checkCursor and _closeCursors are not atomic
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# operations. Doing our own locking around self.dbc,
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# self.saved_dbc_key and self._cursor_refs could prevent this.
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# TODO: A test case demonstrating the problem needs to be written.
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# self.dbc is a DBCursor object used to implement the
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# first/next/previous/last/set_location methods.
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self.dbc = None
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self.saved_dbc_key = None
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# a collection of all DBCursor objects currently allocated
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# by the _iter_mixin interface.
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self._cursor_refs = {}
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def __del__(self):
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self.close()
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def _checkCursor(self):
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if self.dbc is None:
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self.dbc = self.db.cursor()
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if self.saved_dbc_key is not None:
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self.dbc.set(self.saved_dbc_key)
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self.saved_dbc_key = None
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# This method is needed for all non-cursor DB calls to avoid
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# BerkeleyDB deadlocks (due to being opened with DB_INIT_LOCK
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# and DB_THREAD to be thread safe) when intermixing database
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# operations that use the cursor internally with those that don't.
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def _closeCursors(self, save=1):
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if self.dbc:
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c = self.dbc
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self.dbc = None
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if save:
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self.saved_dbc_key = c.current(0,0,0)[0]
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c.close()
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del c
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for cref in self._cursor_refs.values():
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c = cref()
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if c is not None:
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c.close()
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def _checkOpen(self):
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if self.db is None:
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raise error, "BSDDB object has already been closed"
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def isOpen(self):
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return self.db is not None
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def __len__(self):
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self._checkOpen()
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return len(self.db)
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def __getitem__(self, key):
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self._checkOpen()
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return self.db[key]
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def __setitem__(self, key, value):
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self._checkOpen()
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self._closeCursors()
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self.db[key] = value
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def __delitem__(self, key):
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self._checkOpen()
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self._closeCursors()
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del self.db[key]
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def close(self):
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self._closeCursors(save=0)
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if self.dbc is not None:
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self.dbc.close()
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v = 0
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if self.db is not None:
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v = self.db.close()
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self.dbc = None
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self.db = None
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return v
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def keys(self):
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self._checkOpen()
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return self.db.keys()
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def has_key(self, key):
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self._checkOpen()
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return self.db.has_key(key)
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def set_location(self, key):
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self._checkOpen()
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self._checkCursor()
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return self.dbc.set_range(key)
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def next(self):
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self._checkOpen()
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self._checkCursor()
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rv = self.dbc.next()
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return rv
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def previous(self):
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self._checkOpen()
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self._checkCursor()
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rv = self.dbc.prev()
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return rv
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def first(self):
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self._checkOpen()
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self._checkCursor()
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rv = self.dbc.first()
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return rv
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def last(self):
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self._checkOpen()
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self._checkCursor()
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rv = self.dbc.last()
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return rv
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def sync(self):
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self._checkOpen()
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return self.db.sync()
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#----------------------------------------------------------------------
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# Compatibility object factory functions
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def hashopen(file, flag='c', mode=0666, pgsize=None, ffactor=None, nelem=None,
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cachesize=None, lorder=None, hflags=0):
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flags = _checkflag(flag, file)
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e = _openDBEnv()
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d = db.DB(e)
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d.set_flags(hflags)
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if cachesize is not None: d.set_cachesize(0, cachesize)
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if pgsize is not None: d.set_pagesize(pgsize)
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if lorder is not None: d.set_lorder(lorder)
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if ffactor is not None: d.set_h_ffactor(ffactor)
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if nelem is not None: d.set_h_nelem(nelem)
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d.open(file, db.DB_HASH, flags, mode)
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return _DBWithCursor(d)
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#----------------------------------------------------------------------
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def btopen(file, flag='c', mode=0666,
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btflags=0, cachesize=None, maxkeypage=None, minkeypage=None,
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pgsize=None, lorder=None):
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flags = _checkflag(flag, file)
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e = _openDBEnv()
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d = db.DB(e)
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if cachesize is not None: d.set_cachesize(0, cachesize)
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if pgsize is not None: d.set_pagesize(pgsize)
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if lorder is not None: d.set_lorder(lorder)
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d.set_flags(btflags)
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if minkeypage is not None: d.set_bt_minkey(minkeypage)
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if maxkeypage is not None: d.set_bt_maxkey(maxkeypage)
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d.open(file, db.DB_BTREE, flags, mode)
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return _DBWithCursor(d)
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#----------------------------------------------------------------------
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def rnopen(file, flag='c', mode=0666,
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rnflags=0, cachesize=None, pgsize=None, lorder=None,
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rlen=None, delim=None, source=None, pad=None):
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flags = _checkflag(flag, file)
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e = _openDBEnv()
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d = db.DB(e)
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if cachesize is not None: d.set_cachesize(0, cachesize)
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if pgsize is not None: d.set_pagesize(pgsize)
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if lorder is not None: d.set_lorder(lorder)
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d.set_flags(rnflags)
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if delim is not None: d.set_re_delim(delim)
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if rlen is not None: d.set_re_len(rlen)
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if source is not None: d.set_re_source(source)
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if pad is not None: d.set_re_pad(pad)
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d.open(file, db.DB_RECNO, flags, mode)
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return _DBWithCursor(d)
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#----------------------------------------------------------------------
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def _openDBEnv():
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e = db.DBEnv()
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e.open('.', db.DB_PRIVATE | db.DB_CREATE | db.DB_THREAD | db.DB_INIT_LOCK | db.DB_INIT_MPOOL)
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return e
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def _checkflag(flag, file):
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if flag == 'r':
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flags = db.DB_RDONLY
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elif flag == 'rw':
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flags = 0
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elif flag == 'w':
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flags = db.DB_CREATE
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elif flag == 'c':
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flags = db.DB_CREATE
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elif flag == 'n':
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flags = db.DB_CREATE
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#flags = db.DB_CREATE | db.DB_TRUNCATE
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# we used db.DB_TRUNCATE flag for this before but BerkeleyDB
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# 4.2.52 changed to disallowed truncate with txn environments.
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if os.path.isfile(file):
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os.unlink(file)
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else:
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raise error, "flags should be one of 'r', 'w', 'c' or 'n'"
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return flags | db.DB_THREAD
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#----------------------------------------------------------------------
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# This is a silly little hack that allows apps to continue to use the
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# DB_THREAD flag even on systems without threads without freaking out
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# BerkeleyDB.
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#
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# This assumes that if Python was built with thread support then
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# BerkeleyDB was too.
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try:
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import thread
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del thread
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except ImportError:
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db.DB_THREAD = 0
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#----------------------------------------------------------------------
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