comparison mercurial/revlogutils/deltas.py @ 51347:555826073625

delta-find: introduce and use specialized _DeltaSearch class

For now, we introduce some very simple variant, but they are still useful to
display how having the class can helps keeping the simple case simple and
their special case out of more advanced logic.

51346:2a333d791ecf

    @abc.abstractmethod
    def _init_group(self):
        pass


class _DeltaSearch(_BaseDeltaSearch):
    def _init_group(self):
        self._candidates_iterator = self._candidate_groups()
        self._last_good = None
        self.current_group = self._candidates_iterator.send(self._last_good)

    def next_group(self, good_delta=None):

        This top level function focus on emitting groups with unique and
        worthwhile content. See _raw_candidate_groups for details about the
        group order.
        """
        # should we try to build a delta?
        if not (len(self.revlog) and self.revlog._storedeltachains):
            yield None
            return

        if not self.revlog.delta_config.general_delta:
            # before general delta, there is only one possible delta base
            yield (self.target_rev - 1,)
            yield None
            return

        good = None

        group_chunk_size = self.revlog.delta_config.candidate_group_chunk_size

        tested = self.tested  # prefetch for speed and code compactness

        This lower level function focus on emitting delta theorically
        interresting without looking it any practical details.

        The group order aims at providing fast or small candidates first.
        """
        # Why search for delta base if we cannot use a delta base ?
        assert self.revlog.delta_config.general_delta
        # also see issue6056
        sparse = self.revlog.delta_config.sparse_revlog
        prev = self.target_rev - 1
        deltachain = lambda rev: self.revlog._deltachain(rev)[0]

        # exclude already lazy tested base if any

        if self._debug_search:
            msg = b"DBG-DELTAS-SEARCH: SEARCH rev=%d\n"
            msg %= target_rev
            self._write_debug(msg)

        search = _DeltaSearch(
            self.revlog,
            revinfo,
            p1r,
            p2r,
            cachedelta,

51347:555826073625

    @abc.abstractmethod
    def _init_group(self):
        pass


class _NoDeltaSearch(_BaseDeltaSearch):
    """Search for no delta.

    This search variant is to be used in case where we should not store delta.
    """

    def _init_group(self):
        pass

    def next_group(self, good_delta=None):
        pass


class _PrevDeltaSearch(_BaseDeltaSearch):
    """Search for delta against the previous revision only

    This search variant is to be used when the format does not allow for delta
    against arbitrary bases.
    """

    def _init_group(self):
        self.current_group = [self.target_rev - 1]

    def next_group(self, good_delta=None):
        self.current_group = None


class _DeltaSearch(_BaseDeltaSearch):
    """Generic delta search variants

    (expect this to be split further)
    """

    def _init_group(self):
        # Why search for delta base if we cannot use a delta base ?
        # also see issue6056
        assert self.revlog.delta_config.general_delta
        self._candidates_iterator = self._candidate_groups()
        self._last_good = None
        self.current_group = self._candidates_iterator.send(self._last_good)

    def next_group(self, good_delta=None):

        This top level function focus on emitting groups with unique and
        worthwhile content. See _raw_candidate_groups for details about the
        group order.
        """
        good = None

        group_chunk_size = self.revlog.delta_config.candidate_group_chunk_size

        tested = self.tested  # prefetch for speed and code compactness

        This lower level function focus on emitting delta theorically
        interresting without looking it any practical details.

        The group order aims at providing fast or small candidates first.
        """
        sparse = self.revlog.delta_config.sparse_revlog
        prev = self.target_rev - 1
        deltachain = lambda rev: self.revlog._deltachain(rev)[0]

        # exclude already lazy tested base if any

        if self._debug_search:
            msg = b"DBG-DELTAS-SEARCH: SEARCH rev=%d\n"
            msg %= target_rev
            self._write_debug(msg)

        # should we try to build a delta?
        if not (len(self.revlog) and self.revlog._storedeltachains):
            search_cls = _NoDeltaSearch
        elif not self.revlog.delta_config.general_delta:
            # before general delta, there is only one possible delta base
            search_cls = _PrevDeltaSearch
        else:
            search_cls = _DeltaSearch

        search = search_cls(
            self.revlog,
            revinfo,
            p1r,
            p2r,
            cachedelta,