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  • Committer: John Arbash Meinel
  • Date: 2005-09-16 14:57:59 UTC
  • mto: (1393.2.1)
  • mto: This revision was merged to the branch mainline in revision 1396.
  • Revision ID: john@arbash-meinel.com-20050916145758-ad06c9ae86840f17
Merged up-to-date against mainline, still broken.

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bzrlib/meta_store.py
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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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from bzrlib.store import Storage, CompressedTextStore
 
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from bzrlib.local_transport import LocalTransport
 
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try:
 
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    set
 
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except NameError:
 
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    from sets import Set as set
 
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class CachedStore(Storage):
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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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        self.cache_store = CompressedTextStore(LocalTransport(cache_dir))
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    def __getitem__(self, id):
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        mutter("Cache add %s" % id)
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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 __contains__(self, fileid):
 
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        if fileid in self.cache_store:
 
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            return True
 
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        if fileid in self.source_store:
 
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            # We could copy at this time
 
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            return True
 
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        return False
 
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    def get(self, fileids, pb=None):
 
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        fileids = list(fileids)
 
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        hasids = self.cache_store.has(fileids)
 
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        needs = set()
 
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        for has, fileid in zip(hasids, fileids):
 
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            if not has:
 
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                needs.add(fileid)
 
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        if needs:
 
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            self.cache_store.copy_multi(self.source_store, needs)
 
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        return self.cache_store.get(fileids, pb=pb)
 
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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.
 
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        Failures while prefetching are ignored.
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        """
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        mutter("Prefetch of ids %s" % ",".join(ids))
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        self.cache_store.copy_multi(self.source_store, ids)
 
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        self.cache_store.copy_multi(self.source_store, ids, 
 
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                                    permit_failure=True)