comparison mercurial/revlog.py @ 26115:748347e0e8d4

revlog: move delta check to it's own function

This moves the delta vs fulltext comparison to its own function. This will allow
us to reuse the function in future patches for more efficient delta choices. As
a side effect, this will also allow extensions to modify our delta criteria.

26114:9d6d3fee0c3f

            if text[0] == '\0':
                return ("", text)
            return ('u', text)
        return ("", bin)

    def _addrevision(self, node, text, transaction, link, p1, p2, flags,
                     cachedelta, ifh, dfh):
        """internal function to add revisions to the log

        see addrevision for argument descriptions.

            textlen = mdiff.patchedsize(self.rawsize(cachedelta[0]),
                                        cachedelta[1])
        else:
            textlen = len(text)

        # - 'dist' is the distance from the base revision -- bounding it limits
        #   the amount of I/O we need to do.
        # - 'compresseddeltalen' is the sum of the total size of deltas we need
        #   to apply -- bounding it limits the amount of CPU we consume.
        if (d is None or dist > textlen * 4 or l > textlen or
            compresseddeltalen > textlen * 2 or
            (self._maxchainlen and chainlen > self._maxchainlen)):
            text = buildtext()
            data = self.compress(text)
            l = len(data[1]) + len(data[0])
            base = chainbase = curr

26115:748347e0e8d4

            if text[0] == '\0':
                return ("", text)
            return ('u', text)
        return ("", bin)

    def _isgooddelta(self, d, textlen):
        """Returns True if the given delta is good. Good means that it is within
        the disk span, disk size, and chain length bounds that we know to be
        performant."""
        if d is None:
            return False

        # - 'dist' is the distance from the base revision -- bounding it limits
        #   the amount of I/O we need to do.
        # - 'compresseddeltalen' is the sum of the total size of deltas we need
        #   to apply -- bounding it limits the amount of CPU we consume.
        dist, l, data, base, chainbase, chainlen, compresseddeltalen = d
        if (dist > textlen * 4 or l > textlen or
            compresseddeltalen > textlen * 2 or
            (self._maxchainlen and chainlen > self._maxchainlen)):
            return False

        return True

    def _addrevision(self, node, text, transaction, link, p1, p2, flags,
                     cachedelta, ifh, dfh):
        """internal function to add revisions to the log

        see addrevision for argument descriptions.

            textlen = mdiff.patchedsize(self.rawsize(cachedelta[0]),
                                        cachedelta[1])
        else:
            textlen = len(text)

        if not self._isgooddelta(d, textlen):
            text = buildtext()
            data = self.compress(text)
            l = len(data[1]) + len(data[0])
            base = chainbase = curr