contrib/undumprevlog

performance: speedup computation of obsolete revisions

In their current state, revset calls can be very costly as we test
predicates on the entire repository. As obsolete computation is used
by the "hidden" filter, it needs to be very fast.

This changet drops the revset call in favor of direct testing of
the phase of a changeset.

Performance test on my Mercurial checkout

- 19857 total changesets,
- 1584 obsolete changesets,
- 13310 obsolescence markers.

Before:
  ! obsolete
  ! wall 0.047041

After:
  ! obsolete
  ! wall 0.004590


Performance test on a Mozilla central checkout:

- 117293 total changesets,
- 1 obsolete changeset,
- 1 obsolescence marker.

Before:
  ! obsolete
  ! wall 0.001539

After:
  ! obsolete
  ! wall 0.000017

#!/usr/bin/env python
# Undump a dump from dumprevlog
# $ hg init
# $ undumprevlog < repo.dump

import sys
from mercurial import revlog, node, scmutil, util, transaction

for fp in (sys.stdin, sys.stdout, sys.stderr):
    util.setbinary(fp)

opener = scmutil.opener('.', False)
tr = transaction.transaction(sys.stderr.write, opener, "undump.journal")
while 1:
    l = sys.stdin.readline()
    if not l:
        break
    if l.startswith("file:"):
        f = l[6:-1]
        r = revlog.revlog(opener, f)
        print f
    elif l.startswith("node:"):
        n = node.bin(l[6:-1])
    elif l.startswith("linkrev:"):
        lr = int(l[9:-1])
    elif l.startswith("parents:"):
        p = l[9:-1].split()
        p1 = node.bin(p[0])
        p2 = node.bin(p[1])
    elif l.startswith("length:"):
        length = int(l[8:-1])
        sys.stdin.readline() # start marker
        d = sys.stdin.read(length)
        sys.stdin.readline() # end marker
        r.addrevision(d, tr, lr, p1, p2)

tr.close()