view hgext/strip.py @ 25561:50a6c3c55db1 stable

parsers: do not cache RevlogError type (issue4451)

Index lookups raise RevlogError when the lookup fails. The previous
implementation was caching a reference to the RevlogError type in a
static variable. This assumed that the "mercurial.error" module was
only loaded once and there was only a single copy of it floating
around in memory. Unfortunately, in some situations - including
certain mod_wsgi configurations - this was not the case: the
"mercurial.error" module could be reloaded. It was possible for a
"RevlogError" reference from the first interpreter to be used by
a second interpreter. While the underlying thing was a
"mercurial.error.RevlogError," the object IDs were different, so
the Python code in revlog.py was failing to catch the exception! This
error has existed since the C index lookup code was implemented in
changeset e8d37b78acfb, which was first released in Mercurial 2.2 in
2012.
http://emptysqua.re/blog/python-c-extensions-and-mod-wsgi/#static-variables-are-shared
contains more details.

This patch removes the caching of the RevlogError type from the
function.

Since pretty much the entire function was refactored and the return
value of the function wasn't used, I changed the function signature
to not return anything.

For reasons unknown to me, we were calling PyErr_SetObject()
with the type of RevlogError and an instance of RevlogError. This
was equivalent to the Python code "raise RevlogError(RevlogError)".
This seemed wonky and completely unnecessary. The Python code only
cares about the type of the exception, not its contents. So I got
rid of this complexity.

This is my first Python C extension patch. Please give extra scrutiny
to it during review.

"""strip changesets and their descendants from history

This extension allows you to strip changesets and all their descendants from the
repository. See the command help for details.
"""
from mercurial.i18n import _
from mercurial.node import nullid
from mercurial.lock import release
from mercurial import cmdutil, hg, scmutil, util
from mercurial import repair, bookmarks, merge

cmdtable = {}
command = cmdutil.command(cmdtable)
testedwith = 'internal'

def checksubstate(repo, baserev=None):
    '''return list of subrepos at a different revision than substate.
    Abort if any subrepos have uncommitted changes.'''
    inclsubs = []
    wctx = repo[None]
    if baserev:
        bctx = repo[baserev]
    else:
        bctx = wctx.parents()[0]
    for s in sorted(wctx.substate):
        wctx.sub(s).bailifchanged(True)
        if s not in bctx.substate or bctx.sub(s).dirty():
            inclsubs.append(s)
    return inclsubs

def checklocalchanges(repo, force=False, excsuffix=''):
    cmdutil.checkunfinished(repo)
    s = repo.status()
    if not force:
        if s.modified or s.added or s.removed or s.deleted:
            _("local changes found") # i18n tool detection
            raise util.Abort(_("local changes found" + excsuffix))
        if checksubstate(repo):
            _("local changed subrepos found") # i18n tool detection
            raise util.Abort(_("local changed subrepos found" + excsuffix))
    return s

def strip(ui, repo, revs, update=True, backup=True, force=None, bookmark=None):
    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()

        if update:
            checklocalchanges(repo, force=force)
            urev, p2 = repo.changelog.parents(revs[0])
            if (util.safehasattr(repo, 'mq') and
                p2 != nullid
                and p2 in [x.node for x in repo.mq.applied]):
                urev = p2
            hg.clean(repo, urev)
            repo.dirstate.write()

        repair.strip(ui, repo, revs, backup)

        marks = repo._bookmarks
        if bookmark:
            if bookmark == repo._bookmarkcurrent:
                bookmarks.unsetcurrent(repo)
            del marks[bookmark]
            marks.write()
            ui.write(_("bookmark '%s' deleted\n") % bookmark)
    finally:
        release(lock, wlock)


@command("strip",
         [
          ('r', 'rev', [], _('strip specified revision (optional, '
                               'can specify revisions without this '
                               'option)'), _('REV')),
          ('f', 'force', None, _('force removal of changesets, discard '
                                 'uncommitted changes (no backup)')),
          ('', 'no-backup', None, _('no backups')),
          ('', 'nobackup', None, _('no backups (DEPRECATED)')),
          ('n', '', None, _('ignored  (DEPRECATED)')),
          ('k', 'keep', None, _("do not modify working directory during "
                                "strip")),
          ('B', 'bookmark', '', _("remove revs only reachable from given"
                                  " bookmark"))],
          _('hg strip [-k] [-f] [-n] [-B bookmark] [-r] REV...'))
def stripcmd(ui, repo, *revs, **opts):
    """strip changesets and all their descendants from the repository

    The strip command removes the specified changesets and all their
    descendants. If the working directory has uncommitted changes, the
    operation is aborted unless the --force flag is supplied, in which
    case changes will be discarded.

    If a parent of the working directory is stripped, then the working
    directory will automatically be updated to the most recent
    available ancestor of the stripped parent after the operation
    completes.

    Any stripped changesets are stored in ``.hg/strip-backup`` as a
    bundle (see :hg:`help bundle` and :hg:`help unbundle`). They can
    be restored by running :hg:`unbundle .hg/strip-backup/BUNDLE`,
    where BUNDLE is the bundle file created by the strip. Note that
    the local revision numbers will in general be different after the
    restore.

    Use the --no-backup option to discard the backup bundle once the
    operation completes.

    Strip is not a history-rewriting operation and can be used on
    changesets in the public phase. But if the stripped changesets have
    been pushed to a remote repository you will likely pull them again.

    Return 0 on success.
    """
    backup = True
    if opts.get('no_backup') or opts.get('nobackup'):
        backup = False

    cl = repo.changelog
    revs = list(revs) + opts.get('rev')
    revs = set(scmutil.revrange(repo, revs))

    wlock = repo.wlock()
    try:
        if opts.get('bookmark'):
            mark = opts.get('bookmark')
            marks = repo._bookmarks
            if mark not in marks:
                raise util.Abort(_("bookmark '%s' not found") % mark)

            # If the requested bookmark is not the only one pointing to a
            # a revision we have to only delete the bookmark and not strip
            # anything. revsets cannot detect that case.
            uniquebm = True
            for m, n in marks.iteritems():
                if m != mark and n == repo[mark].node():
                    uniquebm = False
                    break
            if uniquebm:
                rsrevs = repo.revs("ancestors(bookmark(%s)) - "
                                   "ancestors(head() and not bookmark(%s)) - "
                                   "ancestors(bookmark() and not bookmark(%s))",
                                   mark, mark, mark)
                revs.update(set(rsrevs))
            if not revs:
                del marks[mark]
                marks.write()
                ui.write(_("bookmark '%s' deleted\n") % mark)

        if not revs:
            raise util.Abort(_('empty revision set'))

        descendants = set(cl.descendants(revs))
        strippedrevs = revs.union(descendants)
        roots = revs.difference(descendants)

        update = False
        # if one of the wdir parent is stripped we'll need
        # to update away to an earlier revision
        for p in repo.dirstate.parents():
            if p != nullid and cl.rev(p) in strippedrevs:
                update = True
                break

        rootnodes = set(cl.node(r) for r in roots)

        q = getattr(repo, 'mq', None)
        if q is not None and q.applied:
            # refresh queue state if we're about to strip
            # applied patches
            if cl.rev(repo.lookup('qtip')) in strippedrevs:
                q.applieddirty = True
                start = 0
                end = len(q.applied)
                for i, statusentry in enumerate(q.applied):
                    if statusentry.node in rootnodes:
                        # if one of the stripped roots is an applied
                        # patch, only part of the queue is stripped
                        start = i
                        break
                del q.applied[start:end]
                q.savedirty()

        revs = sorted(rootnodes)
        if update and opts.get('keep'):
            urev, p2 = repo.changelog.parents(revs[0])
            if (util.safehasattr(repo, 'mq') and p2 != nullid
                and p2 in [x.node for x in repo.mq.applied]):
                urev = p2
            uctx = repo[urev]

            # only reset the dirstate for files that would actually change
            # between the working context and uctx
            descendantrevs = repo.revs("%s::." % uctx.rev())
            changedfiles = []
            for rev in descendantrevs:
                # blindly reset the files, regardless of what actually changed
                changedfiles.extend(repo[rev].files())

            # reset files that only changed in the dirstate too
            dirstate = repo.dirstate
            dirchanges = [f for f in dirstate if dirstate[f] != 'n']
            changedfiles.extend(dirchanges)

            repo.dirstate.rebuild(urev, uctx.manifest(), changedfiles)
            repo.dirstate.write()

            # clear resolve state
            ms = merge.mergestate(repo)
            ms.reset(repo['.'].node())

            update = False


        strip(ui, repo, revs, backup=backup, update=update,
              force=opts.get('force'), bookmark=opts.get('bookmark'))
    finally:
        wlock.release()

    return 0