/brz/remove-bazaar

# 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)