view mercurial/repair.py @ 9820:0b999aec64e8

bundle: don't send too many changesets (Issue1704)

The fast path in changegroupsubset can send too many csets. This happens
because it uses the parents of all bases as common nodes and then goes
forward from this again. If a base has a parent that has another child,
which is -not- a base, then this other child will nevertheless end up in
the changegroup.

The fix is to not use findmissing(), but use nodesbetween() instead, as
do the slow path and incoming/outgoing.

The change to test-notify.out is correct, because it actually hits this
bug, as can be seen by glog'ing the two repos:

@    22c88
|\
| o  0a184
| |
o |  0647d
|/
o  cb9a9

and

o  0647d
|
@  cb9a9

It used to pull 0647d again, which is unnecessary.

# 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 version 2, incorporated herein by reference.

import changegroup
from node import nullrev, short
from i18n import _
import os

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 = set()

    for x in xrange(striprev, len(repo)):
        files.update(repo[x].files())

    return sorted(files)

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

    # Some revisions with rev > striprev may not be descendants of striprev.
    # We have to find these revisions and put them in a bundle, so that
    # we can restore them after the truncations.
    # To create the bundle we use repo.changegroupsubset which requires
    # the list of heads and bases of the set of interesting revisions.
    # (head = revision in the set that has no descendant in the set;
    #  base = revision in the set that has no ancestor in the set)
    tostrip = set((striprev,))
    saveheads = set()
    savebases = []
    for r in xrange(striprev + 1, len(cl)):
        parents = cl.parentrevs(r)
        if parents[0] in tostrip or parents[1] in tostrip:
            # r is a descendant of striprev
            tostrip.add(r)
            # if this is a merge and one of the parents does not descend
            # from striprev, mark that parent as a savehead.
            if parents[1] != nullrev:
                for p in parents:
                    if p not in tostrip and p > striprev:
                        saveheads.add(p)
        else:
            # if no parents of this revision will be stripped, mark it as
            # a savebase
            if parents[0] < striprev and parents[1] < striprev:
                savebases.append(cl.node(r))

            saveheads.difference_update(parents)
            saveheads.add(r)

    saveheads = [cl.node(r) for r in saveheads]
    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, saveheads, node, 'temp',
                            extranodes)

    mfst = repo.manifest

    tr = repo.transaction()
    offset = len(tr.entries)

    tr.startgroup()
    cl.strip(striprev, tr)
    mfst.strip(striprev, tr)
    for fn in files:
        repo.file(fn).strip(striprev, tr)
    tr.endgroup()

    try:
        for i in xrange(offset, len(tr.entries)):
            file, troffset, ignore = tr.entries[i]
            repo.sopener(file, 'a').truncate(troffset)
        tr.close()
    except:
        tr.abort()
        raise

    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)

    repo.destroyed()