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# Copyright (C) 2005 by Canonical Ltd
# 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
from trace import mutter
from bzrlib.store import ImmutableStore
class CachedStore:
"""A store that caches data locally, to avoid repeated downloads.
The precacache method should be used to avoid server round-trips for
every piece of data.
"""
def __init__(self, store, cache_dir):
self.source_store = store
self.cache_store = ImmutableStore(cache_dir)
def __getitem__(self, id):
mutter("Cache add %s" % id)
if id not in self.cache_store:
self.cache_store.add(self.source_store[id], id)
return self.cache_store[id]
def prefetch(self, ids):
"""Copy a series of ids into the cache, before they are used.
For remote stores that support pipelining or async downloads, this can
increase speed considerably.
"""
mutter("Prefetch of ids %s" % ",".join(ids))
self.cache_store.copy_multi(self.source_store, ids)
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