comparison mercurial/manifest.py @ 17983:c64e646af81e

commit: increase perf by building a new addlist instead of editing the old one

When commiting to a repo with lots of files (>170000),
manifest.py:addlistdelta takes some time because it's editing a large
array many times. Changing it to build a new array instead of editing
the old one saves around 0.04 seconds on a 1.64 second commit. A 2.5%
gain.

The gain here is pretty minor, but it was blatantly at the top of the
profiler report and the fix is straight forward.

I tested it by comparing the arrays produced by the new and old logic
while running all of the tests.

17982:e06e9fd2d99f

    def add(self, map, transaction, link, p1=None, p2=None,
            changed=None):
        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # start from the bottom up
            # so changes to the offsets don't mess things up.
            for start, end, content in reversed(x):
                if content:
                    addlist[start:end] = array.array('c', content)
                else:
                    del addlist[start:end]
            return "".join(struct.pack(">lll", start, end, len(content))
                           + content for start, end, content in x)

        def checkforbidden(l):
            for f in l:
                if '\n' in f or '\r' in f:
                    raise error.RevlogError(

                    dline = [l]

            if dstart is not None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            cachedelta = (self.rev(p1), addlistdelta(addlist, delta))
            arraytext = addlist
            text = util.buffer(arraytext)

        n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
        self._mancache = (n, map, arraytext)

17983:c64e646af81e

    def add(self, map, transaction, link, p1=None, p2=None,
            changed=None):
        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # for large addlist arrays, building a new array is cheaper
            # than repeatedly modifying the existing one
            currentposition = 0
            newaddlist = array.array('c')

            for start, end, content in x:
                newaddlist += addlist[currentposition:start]
                if content:
                    newaddlist += array.array('c', content)

                currentposition = end

            newaddlist += addlist[currentposition:]

            deltatext = "".join(struct.pack(">lll", start, end, len(content))
                           + content for start, end, content in x)
            return deltatext, newaddlist

        def checkforbidden(l):
            for f in l:
                if '\n' in f or '\r' in f:
                    raise error.RevlogError(

                    dline = [l]

            if dstart is not None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            deltatext, addlist = addlistdelta(addlist, delta)
            cachedelta = (self.rev(p1), deltatext)
            arraytext = addlist
            text = util.buffer(arraytext)

        n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
        self._mancache = (n, map, arraytext)