mercurial/hg.py

dirstate: avoid a race with multiple commits in the same process
(issue2264, issue2516)

The race happens when two commits in a row change the same file
without changing its size, *if* those two commits happen in the same
second in the same process while holding the same repo lock.  For
example:

  commit 1:
    M a
    M b
  commit 2:           # same process, same second, same repo lock
    M b               # modify b without changing its size
    M c

This first manifested in transplant, which is the most common way to
do multiple commits in the same process. But it can manifest in any
script or extension that does multiple commits under the same repo
lock. (Thus, the test script tests both transplant and a custom script.)

The problem was that dirstate.status() failed to notice the change to
b when localrepo is about to do the second commit, meaning that change
gets left in the working directory. In the context of transplant, that
means either a crash ("RuntimeError: nothing committed after
transplant") or a silently inaccurate transplant, depending on whether
any other files were modified by the second transplanted changeset.

The fix is to make status() work a little harder when we have
previously marked files as clean (state 'normal') in the same process.
Specifically, dirstate.normal() adds files to self._lastnormal, and
other state-changing methods remove them. Then dirstate.status() puts
any files in self._lastnormal into state 'lookup', which will make
localrepository.status() read file contents to see if it has really
changed.  So we pay a small performance penalty for the second (and
subsequent) commits in the same process, without affecting the common
case.  Anything that does lots of status updates and checks in the
same process could suffer a performance hit.

Incidentally, there is a simpler fix: call dirstate.normallookup() on
every file updated by commit() at the end of the commit.  The trouble
with that solution is that it imposes a performance penalty on the
common case: it means the next status-dependent hg command after every
"hg commit" will be a little bit slower.  The patch here is more
complex, but only affects performance for the uncommon case.

# hg.py - repository classes for mercurial
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from i18n import _
from lock import release
from node import hex, nullid, nullrev, short
import localrepo, bundlerepo, httprepo, sshrepo, statichttprepo, bookmarks
import lock, util, extensions, error, encoding, node
import cmdutil, discovery, url
import merge as mergemod
import verify as verifymod
import errno, os, shutil

def _local(path):
    path = util.expandpath(util.drop_scheme('file', path))
    return (os.path.isfile(path) and bundlerepo or localrepo)

def addbranchrevs(lrepo, repo, branches, revs):
    hashbranch, branches = branches
    if not hashbranch and not branches:
        return revs or None, revs and revs[0] or None
    revs = revs and list(revs) or []
    if not repo.capable('branchmap'):
        if branches:
            raise util.Abort(_("remote branch lookup not supported"))
        revs.append(hashbranch)
        return revs, revs[0]
    branchmap = repo.branchmap()

    def primary(branch):
        if branch == '.':
            if not lrepo or not lrepo.local():
                raise util.Abort(_("dirstate branch not accessible"))
            branch = lrepo.dirstate.branch()
        if branch in branchmap:
            revs.extend(node.hex(r) for r in reversed(branchmap[branch]))
            return True
        else:
            return False

    for branch in branches:
        if not primary(branch):
            raise error.RepoLookupError(_("unknown branch '%s'") % branch)
    if hashbranch:
        if not primary(hashbranch):
            revs.append(hashbranch)
    return revs, revs[0]

def parseurl(url, branches=None):
    '''parse url#branch, returning (url, (branch, branches))'''

    if '#' not in url:
        return url, (None, branches or [])
    url, branch = url.split('#', 1)
    return url, (branch, branches or [])

schemes = {
    'bundle': bundlerepo,
    'file': _local,
    'http': httprepo,
    'https': httprepo,
    'ssh': sshrepo,
    'static-http': statichttprepo,
}

def _lookup(path):
    scheme = 'file'
    if path:
        c = path.find(':')
        if c > 0:
            scheme = path[:c]
    thing = schemes.get(scheme) or schemes['file']
    try:
        return thing(path)
    except TypeError:
        return thing

def islocal(repo):
    '''return true if repo or path is local'''
    if isinstance(repo, str):
        try:
            return _lookup(repo).islocal(repo)
        except AttributeError:
            return False
    return repo.local()

def repository(ui, path='', create=False):
    """return a repository object for the specified path"""
    repo = _lookup(path).instance(ui, path, create)
    ui = getattr(repo, "ui", ui)
    for name, module in extensions.extensions():
        hook = getattr(module, 'reposetup', None)
        if hook:
            hook(ui, repo)
    return repo

def defaultdest(source):
    '''return default destination of clone if none is given'''
    return os.path.basename(os.path.normpath(source))

def localpath(path):
    if path.startswith('file://localhost/'):
        return path[16:]
    if path.startswith('file://'):
        return path[7:]
    if path.startswith('file:'):
        return path[5:]
    return path

def share(ui, source, dest=None, update=True):
    '''create a shared repository'''

    if not islocal(source):
        raise util.Abort(_('can only share local repositories'))

    if not dest:
        dest = defaultdest(source)
    else:
        dest = ui.expandpath(dest)

    if isinstance(source, str):
        origsource = ui.expandpath(source)
        source, branches = parseurl(origsource)
        srcrepo = repository(ui, source)
        rev, checkout = addbranchrevs(srcrepo, srcrepo, branches, None)
    else:
        srcrepo = source
        origsource = source = srcrepo.url()
        checkout = None

    sharedpath = srcrepo.sharedpath # if our source is already sharing

    root = os.path.realpath(dest)
    roothg = os.path.join(root, '.hg')

    if os.path.exists(roothg):
        raise util.Abort(_('destination already exists'))

    if not os.path.isdir(root):
        os.mkdir(root)
    os.mkdir(roothg)

    requirements = ''
    try:
        requirements = srcrepo.opener('requires').read()
    except IOError, inst:
        if inst.errno != errno.ENOENT:
            raise

    requirements += 'shared\n'
    file(os.path.join(roothg, 'requires'), 'w').write(requirements)
    file(os.path.join(roothg, 'sharedpath'), 'w').write(sharedpath)

    default = srcrepo.ui.config('paths', 'default')
    if default:
        f = file(os.path.join(roothg, 'hgrc'), 'w')
        f.write('[paths]\ndefault = %s\n' % default)
        f.close()

    r = repository(ui, root)

    if update:
        r.ui.status(_("updating working directory\n"))
        if update is not True:
            checkout = update
        for test in (checkout, 'default', 'tip'):
            if test is None:
                continue
            try:
                uprev = r.lookup(test)
                break
            except error.RepoLookupError:
                continue
        _update(r, uprev)

def clone(ui, source, dest=None, pull=False, rev=None, update=True,
          stream=False, branch=None):
    """Make a copy of an existing repository.

    Create a copy of an existing repository in a new directory.  The
    source and destination are URLs, as passed to the repository
    function.  Returns a pair of repository objects, the source and
    newly created destination.

    The location of the source is added to the new repository's
    .hg/hgrc file, as the default to be used for future pulls and
    pushes.

    If an exception is raised, the partly cloned/updated destination
    repository will be deleted.

    Arguments:

    source: repository object or URL

    dest: URL of destination repository to create (defaults to base
    name of source repository)

    pull: always pull from source repository, even in local case

    stream: stream raw data uncompressed from repository (fast over
    LAN, slow over WAN)

    rev: revision to clone up to (implies pull=True)

    update: update working directory after clone completes, if
    destination is local repository (True means update to default rev,
    anything else is treated as a revision)

    branch: branches to clone
    """

    if isinstance(source, str):
        origsource = ui.expandpath(source)
        source, branch = parseurl(origsource, branch)
        src_repo = repository(ui, source)
    else:
        src_repo = source
        branch = (None, branch or [])
        origsource = source = src_repo.url()
    rev, checkout = addbranchrevs(src_repo, src_repo, branch, rev)

    if dest is None:
        dest = defaultdest(source)
        ui.status(_("destination directory: %s\n") % dest)
    else:
        dest = ui.expandpath(dest)

    dest = localpath(dest)
    source = localpath(source)

    if os.path.exists(dest):
        if not os.path.isdir(dest):
            raise util.Abort(_("destination '%s' already exists") % dest)
        elif os.listdir(dest):
            raise util.Abort(_("destination '%s' is not empty") % dest)

    class DirCleanup(object):
        def __init__(self, dir_):
            self.rmtree = shutil.rmtree
            self.dir_ = dir_
        def close(self):
            self.dir_ = None
        def cleanup(self):
            if self.dir_:
                self.rmtree(self.dir_, True)

    src_lock = dest_lock = dir_cleanup = None
    try:
        if islocal(dest):
            dir_cleanup = DirCleanup(dest)

        abspath = origsource
        copy = False
        if src_repo.cancopy() and islocal(dest):
            abspath = os.path.abspath(util.drop_scheme('file', origsource))
            copy = not pull and not rev

        if copy:
            try:
                # we use a lock here because if we race with commit, we
                # can end up with extra data in the cloned revlogs that's
                # not pointed to by changesets, thus causing verify to
                # fail
                src_lock = src_repo.lock(wait=False)
            except error.LockError:
                copy = False

        if copy:
            src_repo.hook('preoutgoing', throw=True, source='clone')
            hgdir = os.path.realpath(os.path.join(dest, ".hg"))
            if not os.path.exists(dest):
                os.mkdir(dest)
            else:
                # only clean up directories we create ourselves
                dir_cleanup.dir_ = hgdir
            try:
                dest_path = hgdir
                os.mkdir(dest_path)
            except OSError, inst:
                if inst.errno == errno.EEXIST:
                    dir_cleanup.close()
                    raise util.Abort(_("destination '%s' already exists")
                                     % dest)
                raise

            hardlink = None
            num = 0
            for f in src_repo.store.copylist():
                src = os.path.join(src_repo.sharedpath, f)
                dst = os.path.join(dest_path, f)
                dstbase = os.path.dirname(dst)
                if dstbase and not os.path.exists(dstbase):
                    os.mkdir(dstbase)
                if os.path.exists(src):
                    if dst.endswith('data'):
                        # lock to avoid premature writing to the target
                        dest_lock = lock.lock(os.path.join(dstbase, "lock"))
                    hardlink, n = util.copyfiles(src, dst, hardlink)
                    num += n
            if hardlink:
                ui.debug("linked %d files\n" % num)
            else:
                ui.debug("copied %d files\n" % num)

            # we need to re-init the repo after manually copying the data
            # into it
            dest_repo = repository(ui, dest)
            src_repo.hook('outgoing', source='clone',
                          node=node.hex(node.nullid))
        else:
            try:
                dest_repo = repository(ui, dest, create=True)
            except OSError, inst:
                if inst.errno == errno.EEXIST:
                    dir_cleanup.close()
                    raise util.Abort(_("destination '%s' already exists")
                                     % dest)
                raise

            revs = None
            if rev:
                if 'lookup' not in src_repo.capabilities:
                    raise util.Abort(_("src repository does not support "
                                       "revision lookup and so doesn't "
                                       "support clone by revision"))
                revs = [src_repo.lookup(r) for r in rev]
                checkout = revs[0]
            if dest_repo.local():
                dest_repo.clone(src_repo, heads=revs, stream=stream)
            elif src_repo.local():
                src_repo.push(dest_repo, revs=revs)
            else:
                raise util.Abort(_("clone from remote to remote not supported"))

        if dir_cleanup:
            dir_cleanup.close()

        if dest_repo.local():
            fp = dest_repo.opener("hgrc", "w", text=True)
            fp.write("[paths]\n")
            fp.write("default = %s\n" % abspath)
            fp.close()

            dest_repo.ui.setconfig('paths', 'default', abspath)

            if update:
                if update is not True:
                    checkout = update
                    if src_repo.local():
                        checkout = src_repo.lookup(update)
                for test in (checkout, 'default', 'tip'):
                    if test is None:
                        continue
                    try:
                        uprev = dest_repo.lookup(test)
                        break
                    except error.RepoLookupError:
                        continue
                bn = dest_repo[uprev].branch()
                dest_repo.ui.status(_("updating to branch %s\n") % bn)
                _update(dest_repo, uprev)

        # clone all bookmarks
        if dest_repo.local() and src_repo.capable("pushkey"):
            rb = src_repo.listkeys('bookmarks')
            for k, n in rb.iteritems():
                try:
                    m = dest_repo.lookup(n)
                    dest_repo._bookmarks[k] = m
                except:
                    pass
            if rb:
                bookmarks.write(dest_repo)
        elif src_repo.local() and dest_repo.capable("pushkey"):
            for k, n in src_repo._bookmarks.iteritems():
                dest_repo.pushkey('bookmarks', k, '', hex(n))

        return src_repo, dest_repo
    finally:
        release(src_lock, dest_lock)
        if dir_cleanup is not None:
            dir_cleanup.cleanup()

def _showstats(repo, stats):
    repo.ui.status(_("%d files updated, %d files merged, "
                     "%d files removed, %d files unresolved\n") % stats)

def update(repo, node):
    """update the working directory to node, merging linear changes"""
    stats = mergemod.update(repo, node, False, False, None)
    _showstats(repo, stats)
    if stats[3]:
        repo.ui.status(_("use 'hg resolve' to retry unresolved file merges\n"))
    return stats[3] > 0

# naming conflict in clone()
_update = update

def clean(repo, node, show_stats=True):
    """forcibly switch the working directory to node, clobbering changes"""
    stats = mergemod.update(repo, node, False, True, None)
    if show_stats:
        _showstats(repo, stats)
    return stats[3] > 0

def merge(repo, node, force=None, remind=True):
    """Branch merge with node, resolving changes. Return true if any
    unresolved conflicts."""
    stats = mergemod.update(repo, node, True, force, False)
    _showstats(repo, stats)
    if stats[3]:
        repo.ui.status(_("use 'hg resolve' to retry unresolved file merges "
                         "or 'hg update -C .' to abandon\n"))
    elif remind:
        repo.ui.status(_("(branch merge, don't forget to commit)\n"))
    return stats[3] > 0

def _incoming(displaychlist, subreporecurse, ui, repo, source,
        opts, buffered=False):
    """
    Helper for incoming / gincoming.
    displaychlist gets called with
        (remoterepo, incomingchangesetlist, displayer) parameters,
    and is supposed to contain only code that can't be unified.
    """
    source, branches = parseurl(ui.expandpath(source), opts.get('branch'))
    other = repository(remoteui(repo, opts), source)
    ui.status(_('comparing with %s\n') % url.hidepassword(source))
    revs, checkout = addbranchrevs(repo, other, branches, opts.get('rev'))

    if revs:
        revs = [other.lookup(rev) for rev in revs]
    other, incoming, bundle = bundlerepo.getremotechanges(ui, repo, other, revs,
                                opts["bundle"], opts["force"])
    if incoming is None:
        ui.status(_("no changes found\n"))
        return subreporecurse()

    try:
        chlist = other.changelog.nodesbetween(incoming, revs)[0]
        displayer = cmdutil.show_changeset(ui, other, opts, buffered)

        # XXX once graphlog extension makes it into core,
        # should be replaced by a if graph/else
        displaychlist(other, chlist, displayer)

        displayer.close()
    finally:
        if hasattr(other, 'close'):
            other.close()
        if bundle:
            os.unlink(bundle)
    subreporecurse()
    return 0 # exit code is zero since we found incoming changes

def incoming(ui, repo, source, opts):
    def subreporecurse():
        ret = 1
        if opts.get('subrepos'):
            ctx = repo[None]
            for subpath in sorted(ctx.substate):
                sub = ctx.sub(subpath)
                ret = min(ret, sub.incoming(ui, source, opts))
        return ret

    def display(other, chlist, displayer):
        limit = cmdutil.loglimit(opts)
        if opts.get('newest_first'):
            chlist.reverse()
        count = 0
        for n in chlist:
            if limit is not None and count >= limit:
                break
            parents = [p for p in other.changelog.parents(n) if p != nullid]
            if opts.get('no_merges') and len(parents) == 2:
                continue
            count += 1
            displayer.show(other[n])
    return _incoming(display, subreporecurse, ui, repo, source, opts)

def _outgoing(ui, repo, dest, opts):
    dest = ui.expandpath(dest or 'default-push', dest or 'default')
    dest, branches = parseurl(dest, opts.get('branch'))
    ui.status(_('comparing with %s\n') % url.hidepassword(dest))
    revs, checkout = addbranchrevs(repo, repo, branches, opts.get('rev'))
    if revs:
        revs = [repo.lookup(rev) for rev in revs]

    other = repository(remoteui(repo, opts), dest)
    o = discovery.findoutgoing(repo, other, force=opts.get('force'))
    if not o:
        ui.status(_("no changes found\n"))
        return None

    return repo.changelog.nodesbetween(o, revs)[0]

def outgoing(ui, repo, dest, opts):
    def recurse():
        ret = 1
        if opts.get('subrepos'):
            ctx = repo[None]
            for subpath in sorted(ctx.substate):
                sub = ctx.sub(subpath)
                ret = min(ret, sub.outgoing(ui, dest, opts))
        return ret

    limit = cmdutil.loglimit(opts)
    o = _outgoing(ui, repo, dest, opts)
    if o is None:
        return recurse()

    if opts.get('newest_first'):
        o.reverse()
    displayer = cmdutil.show_changeset(ui, repo, opts)
    count = 0
    for n in o:
        if limit is not None and count >= limit:
            break
        parents = [p for p in repo.changelog.parents(n) if p != nullid]
        if opts.get('no_merges') and len(parents) == 2:
            continue
        count += 1
        displayer.show(repo[n])
    displayer.close()
    recurse()
    return 0 # exit code is zero since we found outgoing changes

def revert(repo, node, choose):
    """revert changes to revision in node without updating dirstate"""
    return mergemod.update(repo, node, False, True, choose)[3] > 0

def verify(repo):
    """verify the consistency of a repository"""
    return verifymod.verify(repo)

def remoteui(src, opts):
    'build a remote ui from ui or repo and opts'
    if hasattr(src, 'baseui'): # looks like a repository
        dst = src.baseui.copy() # drop repo-specific config
        src = src.ui # copy target options from repo
    else: # assume it's a global ui object
        dst = src.copy() # keep all global options

    # copy ssh-specific options
    for o in 'ssh', 'remotecmd':
        v = opts.get(o) or src.config('ui', o)
        if v:
            dst.setconfig("ui", o, v)

    # copy bundle-specific options
    r = src.config('bundle', 'mainreporoot')
    if r:
        dst.setconfig('bundle', 'mainreporoot', r)

    # copy selected local settings to the remote ui
    for sect in ('auth', 'hostfingerprints', 'http_proxy'):
        for key, val in src.configitems(sect):
            dst.setconfig(sect, key, val)
    v = src.config('web', 'cacerts')
    if v:
        dst.setconfig('web', 'cacerts', util.expandpath(v))

    return dst