comparison mercurial/revlogutils/deltas.py @ 40979:ba09db267cb6

delta: ignore base whose chains already don't match expectations

If we know the existing chain does not match our criteria, there is no point
to build a delta to append. This is especially useful when dealing with a full
text much smaller than its parent. In that case, the parent chain is probably
already too large.

example affected manifest write
before: 1.421005s
after:  0.815520s (-42%)

40978:42f59d3f714d

                continue
            if sparse and revlog.rawsize(rev) < (textlen // LIMIT_BASE2TEXT):
                continue
            # no delta for rawtext-changing revs (see "candelta" for why)
            if revlog.flags(rev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
                continue
            group.append(rev)
        if group:
            # XXX: in the sparse revlog case, group can become large,
            #      impacting performances. Some bounding or slicing mecanism

40979:ba09db267cb6

                continue
            if sparse and revlog.rawsize(rev) < (textlen // LIMIT_BASE2TEXT):
                continue
            # no delta for rawtext-changing revs (see "candelta" for why)
            if revlog.flags(rev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
                continue
            # If we reach here, we are about to build and test a delta.
            # The delta building process will compute the chaininfo in all
            # case, since that computation is cached, it is fine to access it
            # here too.
            chainlen, chainsize = revlog._chaininfo(rev)
            # if chain will be too long, skip base
            if revlog._maxchainlen and chainlen >= revlog._maxchainlen:
                continue
            # if chain already have too much data, skip base
            if deltas_limit < chainsize:
                continue
            group.append(rev)
        if group:
            # XXX: in the sparse revlog case, group can become large,
            #      impacting performances. Some bounding or slicing mecanism