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#
# Copyright (C) 2006 Robey Pointer <robey@lag.net>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
"""
a cache for chewed-up "change" data structures, which are basically just a
different way of storing a revision. the cache improves lookup times 10x
over bazaar's xml revision structure, though, so currently still worth doing.
once a revision is committed in bazaar, it never changes, so once we have
cached a change, it's good forever.
"""
import cPickle
import os
from loggerhead import util
from loggerhead.lockfile import LockFile
with_lock = util.with_lock('_lock', 'ChangeCache')
SQLITE_INTERFACE = os.environ.get('SQLITE_INTERFACE', 'sqlite')
if SQLITE_INTERFACE == 'pysqlite2':
from pysqlite2 import dbapi2
_param_marker = '?'
elif SQLITE_INTERFACE == 'sqlite':
import sqlite as dbapi2
_param_marker = '%s'
_select_stmt = ("select data from revisiondata where revid = ?"
).replace('?', _param_marker)
_insert_stmt = ("insert into revisiondata (revid, data) "
"values (?, ?)").replace('?', _param_marker)
class FakeShelf(object):
def __init__(self, filename):
create_table = not os.path.exists(filename)
self.connection = dbapi2.connect(filename)
self.cursor = self.connection.cursor()
if create_table:
self._create_table()
def _create_table(self):
self.cursor.execute(
"create table RevisionData "
"(revid binary primary key, data binary)")
self.connection.commit()
def _serialize(self, obj):
r = dbapi2.Binary(cPickle.dumps(obj, protocol=2))
return r
def _unserialize(self, data):
return cPickle.loads(str(data))
def get(self, revid):
self.cursor.execute(_select_stmt, (revid,))
filechange = self.cursor.fetchone()
if filechange is None:
return None
else:
return self._unserialize(filechange[0])
def add(self, revid_obj_pairs):
for (r, d) in revid_obj_pairs:
self.cursor.execute(_insert_stmt, (r, self._serialize(d)))
self.connection.commit()
class FileChangeCache(object):
def __init__(self, history, cache_path):
self.history = history
if not os.path.exists(cache_path):
os.mkdir(cache_path)
self._changes_filename = os.path.join(cache_path, 'filechanges.sql')
# use a lockfile since the cache folder could be shared across
# different processes.
self._lock = LockFile(os.path.join(cache_path, 'filechange-lock'))
@with_lock
def get_file_changes(self, entries):
out = []
missing_entries = []
missing_entry_indices = []
cache = FakeShelf(self._changes_filename)
for entry in entries:
changes = cache.get(entry.revid)
if changes is not None:
out.append(changes)
else:
missing_entries.append(entry)
missing_entry_indices.append(len(out))
out.append(None)
if missing_entries:
missing_changes = self.history.get_file_changes_uncached(missing_entries)
revid_changes_pairs = []
for i, entry, changes in zip(
missing_entry_indices, missing_entries, missing_changes):
revid_changes_pairs.append((entry.revid, changes))
out[i] = changes
cache.add(revid_changes_pairs)
return out
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