view tests/fakedirstatewritetime.py @ 30441:3633403888ae

bdiff: give slight preference to appending lines

[This change could be folded into the previous changeset to minimize the repo
churn ...]

The general preference to matches in the middle of bdiff ranges helps getting
balanced recursion and efficient computation. But, as previous changes have
shown, it might also give diffs that seems "obviously wrong".

To mitigate that: If the best match on the A side starts at the beginning of
the bdiff range, don't aim for the middle-most B side match but for the
earliest.

This will make the matches balanced (by both sides being "early") even though
the bisection will be less balanced. Still, this case only apply if the *best*
and middle-most match was fully unbalanced on the A side. Each recursion will
thus even in this worst case reduce the problem significantly and we are not
re-introducing the problem that was fixed in f1ca249696ed.

The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from
22806817 to 22807275 bytes - a 0.002% increase.

This make the recent test-bdiff.py changes give a more pretty output ... but
they no longer show that the recursion is around middle matches (because it in
these cases isn't).

# extension to emulate invoking 'dirstate.write()' at the time
# specified by '[fakedirstatewritetime] fakenow', only when
# 'dirstate.write()' is invoked via functions below:
#
#   - 'workingctx._checklookup()' (= 'repo.status()')
#   - 'committablectx.markcommitted()'

from __future__ import absolute_import

from mercurial import (
    context,
    dirstate,
    extensions,
    parsers,
    util,
)

def pack_dirstate(fakenow, orig, dmap, copymap, pl, now):
    # execute what original parsers.pack_dirstate should do actually
    # for consistency
    actualnow = int(now)
    for f, e in dmap.iteritems():
        if e[0] == 'n' and e[3] == actualnow:
            e = parsers.dirstatetuple(e[0], e[1], e[2], -1)
            dmap[f] = e

    return orig(dmap, copymap, pl, fakenow)

def fakewrite(ui, func):
    # fake "now" of 'pack_dirstate' only if it is invoked while 'func'

    fakenow = ui.config('fakedirstatewritetime', 'fakenow')
    if not fakenow:
        # Execute original one, if fakenow isn't configured. This is
        # useful to prevent subrepos from executing replaced one,
        # because replacing 'parsers.pack_dirstate' is also effective
        # in subrepos.
        return func()

    # parsing 'fakenow' in YYYYmmddHHMM format makes comparison between
    # 'fakenow' value and 'touch -t YYYYmmddHHMM' argument easy
    fakenow = util.parsedate(fakenow, ['%Y%m%d%H%M'])[0]

    orig_pack_dirstate = parsers.pack_dirstate
    orig_dirstate_getfsnow = dirstate._getfsnow
    wrapper = lambda *args: pack_dirstate(fakenow, orig_pack_dirstate, *args)

    parsers.pack_dirstate = wrapper
    dirstate._getfsnow = lambda *args: fakenow
    try:
        return func()
    finally:
        parsers.pack_dirstate = orig_pack_dirstate
        dirstate._getfsnow = orig_dirstate_getfsnow

def _checklookup(orig, workingctx, files):
    ui = workingctx.repo().ui
    return fakewrite(ui, lambda : orig(workingctx, files))

def markcommitted(orig, committablectx, node):
    ui = committablectx.repo().ui
    return fakewrite(ui, lambda : orig(committablectx, node))

def extsetup(ui):
    extensions.wrapfunction(context.workingctx, '_checklookup',
                            _checklookup)
    extensions.wrapfunction(context.committablectx, 'markcommitted',
                            markcommitted)