mercurial/revlogutils/deltas.py

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            and revlog.length(deltainfo.base) < deltainfo.deltalen):
        return False

    return True

class deltacomputer(object):
    def __init__(self, revlog):
        self.revlog = revlog

    def _getcandidaterevs(self, p1, p2, cachedelta):
        """
        Provides revisions that present an interest to be diffed against,
        grouped by level of easiness.
        """
        revlog = self.revlog
        gdelta = revlog._generaldelta
        curr = len(revlog)
        prev = curr - 1
        p1r, p2r = revlog.rev(p1), revlog.rev(p2)

        # should we try to build a delta?
        if prev != nullrev and revlog._storedeltachains:
            tested = set()
            # This condition is true most of the time when processing
            # changegroup data into a generaldelta repo. The only time it
            # isn't true is if this is the first revision in a delta chain
            # or if ``format.generaldelta=true`` disabled ``lazydeltabase``.
            if cachedelta and gdelta and revlog._lazydeltabase:
                # Assume what we received from the server is a good choice
                # build delta will reuse the cache
                yield (cachedelta[0],)
                tested.add(cachedelta[0])

            if gdelta:
                # exclude already lazy tested base if any
                parents = [p for p in (p1r, p2r)
                           if p != nullrev and p not in tested]

                if not revlog._deltabothparents and len(parents) == 2:
                    parents.sort()
                    # To minimize the chance of having to build a fulltext,
                    # pick first whichever parent is closest to us (max rev)
                    yield (parents[1],)
                    # then the other one (min rev) if the first did not fit
                    yield (parents[0],)
                    tested.update(parents)
                elif len(parents) > 0:
                    # Test all parents (1 or 2), and keep the best candidate
                    yield parents
                    tested.update(parents)

            if prev not in tested:
                # other approach failed try against prev to hopefully save us a
                # fulltext.
                yield (prev,)
                tested.add(prev)

    def buildtext(self, revinfo, fh):
        """Builds a fulltext version of a revision

        revinfo: _revisioninfo instance that contains all needed info

        revinfo: information about the revision (instance of _revisioninfo)
        fh:      file handle to either the .i or the .d revlog file,
                 depending on whether it is inlined or not

        Returns the first acceptable candidate revision, as ordered by
        _getcandidaterevs

        If no suitable deltabase is found, we return delta info for a full
        snapshot.
        """
        if not revinfo.textlen:

        deltalength = self.revlog.length
        deltaparent = self.revlog.deltaparent

        deltainfo = None
        deltas_limit = revinfo.textlen * LIMIT_DELTA2TEXT
        for candidaterevs in self._getcandidaterevs(p1, p2, cachedelta):
            # filter out delta base that will never produce good delta
            candidaterevs = [r for r in candidaterevs
                             if self.revlog.length(r) <= deltas_limit]
            nominateddeltas = []
            for candidaterev in candidaterevs:

39361:507f5b1dd7c8

            and revlog.length(deltainfo.base) < deltainfo.deltalen):
        return False

    return True

def _candidategroups(revlog, p1, p2, cachedelta):
    """
    Provides revisions that present an interest to be diffed against,
    grouped by level of easiness.
    """
    gdelta = revlog._generaldelta
    curr = len(revlog)
    prev = curr - 1
    p1r, p2r = revlog.rev(p1), revlog.rev(p2)

    # should we try to build a delta?
    if prev != nullrev and revlog._storedeltachains:
        tested = set()
        # This condition is true most of the time when processing
        # changegroup data into a generaldelta repo. The only time it
        # isn't true is if this is the first revision in a delta chain
        # or if ``format.generaldelta=true`` disabled ``lazydeltabase``.
        if cachedelta and gdelta and revlog._lazydeltabase:
            # Assume what we received from the server is a good choice
            # build delta will reuse the cache
            yield (cachedelta[0],)
            tested.add(cachedelta[0])

        if gdelta:
            # exclude already lazy tested base if any
            parents = [p for p in (p1r, p2r)
                       if p != nullrev and p not in tested]

            if not revlog._deltabothparents and len(parents) == 2:
                parents.sort()
                # To minimize the chance of having to build a fulltext,
                # pick first whichever parent is closest to us (max rev)
                yield (parents[1],)
                # then the other one (min rev) if the first did not fit
                yield (parents[0],)
                tested.update(parents)
            elif len(parents) > 0:
                # Test all parents (1 or 2), and keep the best candidate
                yield parents
                tested.update(parents)

        if prev not in tested:
            # other approach failed try against prev to hopefully save us a
            # fulltext.
            yield (prev,)
            tested.add(prev)

class deltacomputer(object):
    def __init__(self, revlog):
        self.revlog = revlog

    def buildtext(self, revinfo, fh):
        """Builds a fulltext version of a revision

        revinfo: _revisioninfo instance that contains all needed info

        revinfo: information about the revision (instance of _revisioninfo)
        fh:      file handle to either the .i or the .d revlog file,
                 depending on whether it is inlined or not

        Returns the first acceptable candidate revision, as ordered by
        _candidategroups

        If no suitable deltabase is found, we return delta info for a full
        snapshot.
        """
        if not revinfo.textlen:

        deltalength = self.revlog.length
        deltaparent = self.revlog.deltaparent

        deltainfo = None
        deltas_limit = revinfo.textlen * LIMIT_DELTA2TEXT
        groups = _candidategroups(self.revlog, p1, p2, cachedelta)
        for candidaterevs in groups:
            # filter out delta base that will never produce good delta
            candidaterevs = [r for r in candidaterevs
                             if self.revlog.length(r) <= deltas_limit]
            nominateddeltas = []
            for candidaterev in candidaterevs: