mercurial/repair.py

revlog.revision: avoid opening the datafile without need.

If there's no inline data, revlog.revision opens the data file every
time it's called.  This is useful if we're going to call chunk many
times, but, if we're going to call it only once, it's better to let
chunk open the file - if we're lucky, all the data we're going to need
is already cached and we won't need to even look at the file.

# repair.py - functions for repository repair for mercurial
#
# Copyright 2005, 2006 Chris Mason <[e-mail]>
# Copyright 2007 Matt Mackall
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import changegroup, os
from node import *

def _limitheads(cl, stoprev):
    """return the list of all revs >= stoprev that have no children"""
    seen = {}
    heads = []

    for r in xrange(cl.count() - 1, stoprev - 1, -1):
        if r not in seen:
            heads.append(r)
        for p in cl.parentrevs(r):
            seen[p] = 1
    return heads

def _bundle(repo, bases, heads, node, suffix, extranodes=None):
    """create a bundle with the specified revisions as a backup"""
    cg = repo.changegroupsubset(bases, heads, 'strip', extranodes)
    backupdir = repo.join("strip-backup")
    if not os.path.isdir(backupdir):
        os.mkdir(backupdir)
    name = os.path.join(backupdir, "%s-%s" % (short(node), suffix))
    repo.ui.warn("saving bundle to %s\n" % name)
    return changegroup.writebundle(cg, name, "HG10BZ")

def _collectfiles(repo, striprev):
    """find out the filelogs affected by the strip"""
    files = {}

    for x in xrange(striprev, repo.changelog.count()):
        for name in repo.changectx(x).files():
            if name in files:
                continue
            files[name] = 1

    files = files.keys()
    files.sort()
    return files

def _collectextranodes(repo, files, link):
    """return the nodes that have to be saved before the strip"""
    def collectone(revlog):
        extra = []
        startrev = count = revlog.count()
        # find the truncation point of the revlog
        for i in xrange(0, count):
            node = revlog.node(i)
            lrev = revlog.linkrev(node)
            if lrev >= link:
                startrev = i + 1
                break

        # see if any revision after that point has a linkrev less than link
        # (we have to manually save these guys)
        for i in xrange(startrev, count):
            node = revlog.node(i)
            lrev = revlog.linkrev(node)
            if lrev < link:
                extra.append((node, cl.node(lrev)))

        return extra

    extranodes = {}
    cl = repo.changelog
    extra = collectone(repo.manifest)
    if extra:
        extranodes[1] = extra
    for fname in files:
        f = repo.file(fname)
        extra = collectone(f)
        if extra:
            extranodes[fname] = extra

    return extranodes

def strip(ui, repo, node, backup="all"):
    cl = repo.changelog
    # TODO delete the undo files, and handle undo of merge sets
    pp = cl.parents(node)
    striprev = cl.rev(node)

    # save is a list of all the branches we are truncating away
    # that we actually want to keep.  changegroup will be used
    # to preserve them and add them back after the truncate
    saveheads = []
    savebases = {}

    heads = [cl.node(r) for r in _limitheads(cl, striprev)]
    seen = {}

    # search through all the heads, finding those where the revision
    # we want to strip away is an ancestor.  Also look for merges
    # that might be turned into new heads by the strip.
    while heads:
        h = heads.pop()
        n = h
        while True:
            seen[n] = 1
            pp = cl.parents(n)
            if pp[1] != nullid:
                for p in pp:
                    if cl.rev(p) > striprev and p not in seen:
                        heads.append(p)
            if pp[0] == nullid:
                break
            if cl.rev(pp[0]) < striprev:
                break
            n = pp[0]
            if n == node:
                break
        r = cl.reachable(h, node)
        if node not in r:
            saveheads.append(h)
            for x in r:
                if cl.rev(x) > striprev:
                    savebases[x] = 1

    files = _collectfiles(repo, striprev)

    extranodes = _collectextranodes(repo, files, striprev)

    # create a changegroup for all the branches we need to keep
    if backup == "all":
        _bundle(repo, [node], cl.heads(), node, 'backup')
    if saveheads or extranodes:
        chgrpfile = _bundle(repo, savebases.keys(), saveheads, node, 'temp',
                            extranodes)

    cl.strip(striprev)
    repo.manifest.strip(striprev)
    for name in files:
        f = repo.file(name)
        f.strip(striprev)

    if saveheads or extranodes:
        ui.status("adding branch\n")
        f = open(chgrpfile, "rb")
        gen = changegroup.readbundle(f, chgrpfile)
        repo.addchangegroup(gen, 'strip', 'bundle:' + chgrpfile, True)
        f.close()
        if backup != "strip":
            os.unlink(chgrpfile)