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# Copyright (C) 2006 Robey Pointer <robey@lag.net>
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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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# 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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
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a cache for chewed-up 'file change' data structures, which are basically just
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a different way of storing a revision delta. the cache improves lookup times
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10x over bazaar's xml revision structure, though, so currently still worth
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once a revision is committed in bazaar, it never changes, so once we have
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cached a change, it's good forever.
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from sqlite3 import dbapi2
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# We take an optimistic approach to concurrency here: we might do work twice
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# in the case of races, but not crash or corrupt data.
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def safe_init_db(filename, init_sql):
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# To avoid races around creating the database, we create the db in
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# a temporary file and rename it into the ultimate location.
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fd, temp_path = tempfile.mkstemp(dir=os.path.dirname(filename))
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con = dbapi2.connect(temp_path)
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os.rename(temp_path, filename)
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class FakeShelf(object):
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def __init__(self, filename):
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create_table = not os.path.exists(filename)
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filename, "create table RevisionData "
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"(revid binary primary key, data binary)")
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self.connection = dbapi2.connect(filename)
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self.cursor = self.connection.cursor()
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def _create_table(self, filename):
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con = dbapi2.connect(filename)
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"create table RevisionData "
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"(revid binary primary key, data binary)")
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def _serialize(self, obj):
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return dbapi2.Binary(pickle.dumps(obj, protocol=2))
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def _unserialize(self, data):
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return pickle.loads(str(data))
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"select data from revisiondata where revid = ?", (revid, ))
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filechange = self.cursor.fetchone()
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if filechange is None:
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return self._unserialize(filechange[0])
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def add(self, revid, object):
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"insert into revisiondata (revid, data) values (?, ?)",
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(revid, self._serialize(object)))
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self.connection.commit()
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except dbapi2.IntegrityError:
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# If another thread or process attempted to set the same key, we
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# assume it set it to the same value and carry on with our day.
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class RevInfoDiskCache(object):
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"""Like `RevInfoMemoryCache` but backed in a sqlite DB."""
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def __init__(self, cache_path):
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if not os.path.exists(cache_path):
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filename = os.path.join(cache_path, 'revinfo.sql')
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create_table = not os.path.exists(filename)
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filename, "create table Data "
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"(key binary primary key, revid binary, data binary)")
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self.connection = dbapi2.connect(filename)
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self.cursor = self.connection.cursor()
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def get(self, key, revid):
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if not isinstance(key, bytes):
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if not isinstance(revid, bytes):
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raise TypeError(revid)
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"select revid, data from data where key = ?", (dbapi2.Binary(key),))
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row = self.cursor.fetchone()
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elif str(row[0]) != revid:
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return marshal.loads(zlib.decompress(row[1]))
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except (EOFError, ValueError, TypeError):
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def set(self, key, revid, data):
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if not isinstance(key, bytes):
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if not isinstance(revid, bytes):
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raise TypeError(revid)
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'delete from data where key = ?', (dbapi2.Binary(key), ))
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blob = zlib.compress(marshal.dumps(data, 2))
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"insert into data (key, revid, data) values (?, ?, ?)",
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list(map(dbapi2.Binary, [key, revid, blob])))
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self.connection.commit()
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except dbapi2.IntegrityError:
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# If another thread or process attempted to set the same key, we
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# don't care too much -- it's only a cache after all!
added
removed
loggerhead/changecache.py
