~bzr-pqm/bzr/bzr.dev

790 by Martin Pool
Merge from aaron:
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# Copyright (C) 2005 by Canonical Ltd
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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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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from trace import mutter
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from bzrlib.store import ImmutableStore
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class CachedStore:
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    """A store that caches data locally, to avoid repeated downloads.
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    The precacache method should be used to avoid server round-trips for
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    every piece of data.
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    """
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    def __init__(self, store, cache_dir):
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        self.source_store = store
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        self.cache_store = ImmutableStore(cache_dir)
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    def __getitem__(self, id):
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        mutter("Cache add %s" % id)
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        if id not in self.cache_store:
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            self.cache_store.add(self.source_store[id], id)
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        return self.cache_store[id]
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    def prefetch(self, ids):
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        """Copy a series of ids into the cache, before they are used.
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        For remote stores that support pipelining or async downloads, this can
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        increase speed considerably.
974.1.77 by Aaron Bentley
Fixed branch handling of missing revisions
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        Failures while prefetching are ignored.
790 by Martin Pool
Merge from aaron:
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        """
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        mutter("Prefetch of ids %s" % ",".join(ids))
974.1.77 by Aaron Bentley
Fixed branch handling of missing revisions
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        self.cache_store.copy_multi(self.source_store, ids, 
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                                    permit_failure=True)