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  • Committer: Canonical.com Patch Queue Manager
  • Date: 2007-10-19 04:28:39 UTC
  • mfrom: (2911.4.3 graph)
  • Revision ID: pqm@pqm.ubuntu.com-20071019042839-xwvsz0loa77yokxm
(robertc) Create a reusable HeadsCache in graph.HeadsCache. (Robert Collins)

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bzrlib/graph.py
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        return False
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class HeadsCache(object):
 
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    """A cache of results for graph heads calls."""
 
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    def __init__(self, graph):
 
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        self.graph = graph
 
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        self._heads = {}
 
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    def heads(self, keys):
 
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        """Return the heads of keys.
 
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        This matches the API of Graph.heads(), specifically the return value is
 
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        a set which can be mutated, and ordering of the input is not preserved
 
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        in the output.
 
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        :see also: Graph.heads.
 
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        :param keys: The keys to calculate heads for.
 
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        :return: A set containing the heads, which may be mutated without
 
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            affecting future lookups.
 
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        """
 
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        keys = frozenset(keys)
 
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        try:
 
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            return set(self._heads[keys])
 
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        except KeyError:
 
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            heads = self.graph.heads(keys)
 
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            self._heads[keys] = heads
 
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            return set(heads)
 
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class _BreadthFirstSearcher(object):
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    """Parallel search the breadth-first the ancestry of revisions.
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