comparison mercurial/revlogutils/deltas.py @ 39502:e4d4361d0bcd

snapshot: try to refine new snapshot base down the chain

There are cases where doing a diff against a snapshot's parent will be shorter
than against the snapshot itself. Reusing snapshot not directly related to the
revision we are trying to store increase this odd.

So once we found a possible candidate, we check the snapshots lower in the
chain.

This will involve extra processing, but this extra processing will only happen
when we are doing building a snapshot, a rare situation.

39501:993d7e2c8b79

            return
    for candidates in _rawgroups(revlog, p1, p2, cachedelta):
        good = yield candidates
        if good is not None:
            break
    # we have found nothing
    yield None

def _rawgroups(revlog, p1, p2, cachedelta):
    """Provides group of revision to be tested as delta base

39502:e4d4361d0bcd

            return
    for candidates in _rawgroups(revlog, p1, p2, cachedelta):
        good = yield candidates
        if good is not None:
            break

    # if we have a refinable value, try to refine it
    if good is not None and good not in (p1, p2) and revlog.issnapshot(good):
        # refine snapshot down
        previous = None
        while previous != good:
            previous = good
            base = revlog.deltaparent(good)
            if base == nullrev:
                break
            good = yield (base,)
    # we have found nothing
    yield None

def _rawgroups(revlog, p1, p2, cachedelta):
    """Provides group of revision to be tested as delta base