Patchwork [2,of,4,V2] shelve: add a shelve extension to save/restore working changes

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Submitter David Soria Parra
Date Oct. 1, 2013, 10:29 a.m.
Message ID <552cab75b8442c4aa110.1380623362@achird.localdomain>
Download mbox | patch
Permalink /patch/2685/
State Accepted
Commit 49d4919d21c2fe79957d160d64acd048bf6a2e7b
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David Soria Parra - Oct. 1, 2013, 10:29 a.m.
# HG changeset patch
# User David Soria Parra <dsp@experimentalworks.net>
# Date 1377793333 25200
#      Thu Aug 29 09:22:13 2013 -0700
# Node ID 552cab75b8442c4aa110b9d0349939061913f913
# Parent  a13c59f8506b0096508e4c8cbcc27612eabd5272
shelve: add a shelve extension to save/restore working changes

This extension saves shelved changes using a temporary draft commit,
and bundles the temporary commit and its draft ancestors, then
strips them.

This strategy makes it possible to use Mercurial's bundle and merge
machinery to resolve conflicts if necessary when unshelving, even
when the destination commit or its ancestors have been amended,
squashed, or evolved. (Once a change has been unshelved, its
associated unbundled commits are either rolled back or stripped.)

Storing the shelved change as a bundle also avoids the difficulty
that hidden commits would cause, of making it impossible to amend
the parent if it is a draft commits (a common scenario).

Although this extension shares its name and some functionality with
the third party hgshelve extension, it has little else in common.
Notably, the hgshelve extension shelves changes as unified diffs,
which makes conflict resolution a matter of finding .rej files and
conflict markers, and cleaning up the mess by hand.

We do not yet allow hunk-level choosing of changes to record.
Compared to the hgshelve extension, this is a small regression in
usability, but we hope to integrate that at a later point, once the
record machinery becomes more reusable and robust.
v - Oct. 2, 2013, 6:57 a.m.
David Soria Parra-3 wrote
> Storing the shelved change as a bundle also avoids the difficulty
> that hidden commits would cause, of making it impossible to amend
> the parent if it is a draft commits (a common scenario).

I'm interested in this common scenario. I was thinking of writing a shelve
extension that used hidden commits, because I've never needed to change a
shelf's ancestors during its lifetime.



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David Soria Parra - Oct. 2, 2013, 7:52 a.m.
On 10/02/2013 08:57 AM, harry wrote:
> David Soria Parra-3 wrote
>> Storing the shelved change as a bundle also avoids the difficulty
>> that hidden commits would cause, of making it impossible to amend
>> the parent if it is a draft commits (a common scenario).
> 
> I'm interested in this common scenario. I was thinking of writing a shelve
> extension that used hidden commits, because I've never needed to change a
> shelf's ancestors during its lifetime.

A common scenario would be: you edit something but you find a typo in a
change that you made before. Therefore you shelve your current changes
and amend the previous commit with then new change and then reapply your
shelved changes.

Hope that helps.

David
Laurens Holst - Oct. 2, 2013, 8:34 a.m.
Op 02-10-13 09:52, David Soria Parra schreef:
> On 10/02/2013 08:57 AM, harry wrote:
>> David Soria Parra-3 wrote
>>> Storing the shelved change as a bundle also avoids the difficulty
>>> that hidden commits would cause, of making it impossible to amend
>>> the parent if it is a draft commits (a common scenario).
>> I'm interested in this common scenario. I was thinking of writing a shelve
>> extension that used hidden commits, because I've never needed to change a
>> shelf's ancestors during its lifetime.
> A common scenario would be: you edit something but you find a typo in a
> change that you made before. Therefore you shelve your current changes
> and amend the previous commit with then new change and then reapply your
> shelved changes.

Hmm, with evolve, I don’t see a reason why you couldn’t amend an older 
changeset?

Just because this functionality is not currently present for amend, 
should you really let that influence a core design decision of the 
extension?

~Laurens
v - Oct. 2, 2013, 8:40 a.m.
David Soria Parra-3 wrote
> On 10/02/2013 08:57 AM, harry wrote:
>> David Soria Parra-3 wrote
>>> Storing the shelved change as a bundle also avoids the difficulty
>>> that hidden commits would cause, of making it impossible to amend
>>> the parent if it is a draft commits (a common scenario).
>> 
>> I'm interested in this common scenario. I was thinking of writing a
>> shelve
>> extension that used hidden commits, because I've never needed to change a
>> shelf's ancestors during its lifetime.
> 
> A common scenario would be: you edit something but you find a typo in a
> change that you made before. Therefore you shelve your current changes
> and amend the previous commit with then new change and then reapply your
> shelved changes.

This should work fine with histedit if the shelf was a hidden commit. Maybe
even better, because you'd be rebasing each change as it occurs, not an
accumulation of potentially many changes when unshelving.



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David Soria Parra - Oct. 2, 2013, 9:12 a.m.
On 10/02/2013 10:34 AM, Laurens Holst wrote:
> Op 02-10-13 09:52, David Soria Parra schreef:
>> On 10/02/2013 08:57 AM, harry wrote:
> 
> Hmm, with evolve, I don’t see a reason why you couldn’t amend an older
> changeset?
> 
> Just because this functionality is not currently present for amend,
> should you really let that influence a core design decision of the
> extension?

It is possible to do everything with obsolete markers and phases (like
it would be possible to do with mq), but shelve is a much more
convenient way to move around temporary changes and clean the working
directory for a short period while doing other.
v - Oct. 2, 2013, 10:19 a.m.
David Soria Parra-3 wrote
> It is possible to do everything with obsolete markers and phases (like
> it would be possible to do with mq), but shelve is a much more
> convenient way to move around temporary changes and clean the working
> directory for a short period while doing other.

I'm not asking why we need a shelve extension, just why unbundling the
changes is better than hidden changesets. Every change to the anscestors
should rebase the shelf if it was still in the graph, which would seem to be
an improvement over trying to merge everything at once when unshelving.



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Laurens Holst - Oct. 2, 2013, 10:56 a.m.
Op 02-10-13 12:19, harry schreef:
> David Soria Parra-3 wrote
>> It is possible to do everything with obsolete markers and phases (like
>> it would be possible to do with mq), but shelve is a much more
>> convenient way to move around temporary changes and clean the working
>> directory for a short period while doing other.
> I'm not asking why we need a shelve extension, just why unbundling the
> changes is better than hidden changesets. Every change to the anscestors
> should rebase the shelf if it was still in the graph, which would seem to be
> an improvement over trying to merge everything at once when unshelving.

Indeed.

Or the shelf wouldn’t even need to be rebased, just marked as obsolete 
and then “stabilised” once the shelf gets unshelved. I guess this 
depends on amend behaviour for non-head changesets.

~Laurens
Idan Kamara - Oct. 2, 2013, 11:51 a.m.
On Wed, Oct 2, 2013 at 1:19 PM, harry <voldermort@hotmail.com> wrote:

> David Soria Parra-3 wrote
> > It is possible to do everything with obsolete markers and phases (like
> > it would be possible to do with mq), but shelve is a much more
> > convenient way to move around temporary changes and clean the working
> > directory for a short period while doing other.
>
> I'm not asking why we need a shelve extension, just why unbundling the
> changes is better than hidden changesets. Every change to the anscestors
> should rebase the shelf if it was still in the graph, which would seem to
> be
> an improvement over trying to merge everything at once when unshelving.


One problem of keeping the stash in history is that it's incompatible with
MQ.

See this thread http://mercurial.markmail.org/thread/p2fkoj5welx6nmkb
Pierre-Yves David - Oct. 2, 2013, 12:16 p.m.
On 10/02/2013 12:56 PM, Laurens Holst wrote:
> Op 02-10-13 12:19, harry schreef:
>> David Soria Parra-3 wrote
>>> It is possible to do everything with obsolete markers and phases (like
>>> it would be possible to do with mq), but shelve is a much more
>>> convenient way to move around temporary changes and clean the working
>>> directory for a short period while doing other.
>> I'm not asking why we need a shelve extension, just why unbundling the
>> changes is better than hidden changesets. Every change to the anscestors
>> should rebase the shelf if it was still in the graph, which would 
>> seem to be
>> an improvement over trying to merge everything at once when unshelving.
>
> Indeed.
>
> Or the shelf wouldn’t even need to be rebased, just marked as obsolete 
> and then “stabilised” once the shelf gets unshelved. I guess this 
> depends on amend behaviour for non-head changesets.

Storing shelve in bundle is an implementation details. It's a more 
robust approach that makes sure the shelve survive our current world 
where changeset stripping is common.
It could be stored as an hidden changeset it would not change how it work.

Shelve *may* need to be "merge" if it is unshelve on another changeset 
than the one it was shelved from (most common: hg shelve, hg merge, hg 
unshelve).

Merge, rebase, evolve will all do the very same thing.

I think everybody agrees here. We just use different word.
v - Oct. 2, 2013, 12:39 p.m.
The issue I'm concerned with is the case where a user shelves some changes,
makes lots of changes to the ancestors, then tries to unshevle.

If the shelf is a hidden changeset (granted that this wouldn't be possible
on top of MQ), each change will rebase the shelf, and the user will get a
chance to abort changes that will make it impossible to apply the shelf
afterwards. If the shelf is unbundled, they'll be hit with everything
together when they try to unshelve.



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Pierre-Yves David - Oct. 2, 2013, 12:50 p.m.
On 10/02/2013 02:39 PM, harry wrote:
> The issue I'm concerned with is the case where a user shelves some changes,
> makes lots of changes to the ancestors, then tries to unshevle.
>
> If the shelf is a hidden changeset (granted that this wouldn't be possible
> on top of MQ), each change will rebase the shelf, and the user will get a
> chance to abort changes that will make it impossible to apply the shelf
> afterwards.

No every change would not do that. A shelve is created once and sleeps 
until someone tries to unshelve it.

If you really want such behavior you should do a secret commit ontop of 
the part you are going to heavily rewrite.

> If the shelf is unbundled, they'll be hit with everything
> together when they try to unshelve.

Again, there would not have any differences in behavior between:
1. the shelve commit stay in the repo as hidden one
2. the shelve is super-hidden outside of the repo in a bundle.

We could even use the two at the same time, falling back to the bundle 
if something terrible happened to the hidden version.
v - Oct. 2, 2013, 1:17 p.m.
pierre-yves.david wrote
> Again, there would not have any differences in behavior between:
> 1. the shelve commit stay in the repo as hidden one
> 2. the shelve is super-hidden outside of the repo in a bundle.

Use histedit to make several changes to the shelf's ancestors.

1. The shelf will be merged after each change. If one of the changes makes
it impossible to merge the shelf, the user has a chance to abort.
2. All the changes will be applied with no warning. When the user tries to
unshelve, they'll have one big, perhaps impossible merge.

This is the difference in behaviour between the two approaches. Have I
misunderstood you?



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Pierre-Yves David - Oct. 2, 2013, 4:41 p.m.
On 10/02/2013 03:17 PM, harry wrote:
> pierre-yves.david wrote
>> Again, there would not have any differences in behavior between:
>> 1. the shelve commit stay in the repo as hidden one
>> 2. the shelve is super-hidden outside of the repo in a bundle.
> Use histedit to make several changes to the shelf's ancestors.
>
> 1. The shelf will be merged after each change. If one of the changes makes
> it impossible to merge the shelf, the user has a chance to abort.
> 2. All the changes will be applied with no warning. When the user tries to
> unshelve, they'll have one big, perhaps impossible merge.
>
> This is the difference in behaviour between the two approaches. Have I
> misunderstood you?
This is wrong. There is no reason shelved should be moved along with 
there ancestors.
v - Oct. 3, 2013, 6:45 a.m.
pierre-yves.david wrote
> This is wrong. There is no reason shelved should be moved along with 
> there ancestors.

The reasons are:

1) Several small rebases are a lot easier than one big rebase.
2) One big rebase may be impossible to complete automatically whereas the
individual rebases could have been completed automatically.
3) The user has a chance to abort a rebase which will make the shelf
un-unshelvable.



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Patch

diff --git a/hgext/color.py b/hgext/color.py
--- a/hgext/color.py
+++ b/hgext/color.py
@@ -63,6 +63,10 @@ 
   rebase.rebased = blue
   rebase.remaining = red bold
 
+  shelve.age = cyan
+  shelve.newest = green bold
+  shelve.name = blue bold
+
   histedit.remaining = red bold
 
 The available effects in terminfo mode are 'blink', 'bold', 'dim',
@@ -259,6 +263,9 @@ 
            'rebase.remaining': 'red bold',
            'resolve.resolved': 'green bold',
            'resolve.unresolved': 'red bold',
+           'shelve.age': 'cyan',
+           'shelve.newest': 'green bold',
+           'shelve.name': 'blue bold',
            'status.added': 'green bold',
            'status.clean': 'none',
            'status.copied': 'none',
diff --git a/hgext/shelve.py b/hgext/shelve.py
new file mode 100644
--- /dev/null
+++ b/hgext/shelve.py
@@ -0,0 +1,607 @@ 
+# shelve.py - save/restore working directory state
+#
+# Copyright 2013 Facebook, Inc.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+"""save and restore changes to the working directory
+
+The "hg shelve" command saves changes made to the working directory
+and reverts those changes, resetting the working directory to a clean
+state.
+
+Later on, the "hg unshelve" command restores the changes saved by "hg
+shelve". Changes can be restored even after updating to a different
+parent, in which case Mercurial's merge machinery will resolve any
+conflicts if necessary.
+
+You can have more than one shelved change outstanding at a time; each
+shelved change has a distinct name. For details, see the help for "hg
+shelve".
+"""
+
+try:
+    import cPickle as pickle
+    pickle.dump # import now
+except ImportError:
+    import pickle
+from mercurial.i18n import _
+from mercurial.node import nullid
+from mercurial import changegroup, cmdutil, scmutil, phases
+from mercurial import error, hg, mdiff, merge, patch, repair, util
+from mercurial import templatefilters
+from mercurial import lock as lockmod
+import errno
+
+cmdtable = {}
+command = cmdutil.command(cmdtable)
+testedwith = 'internal'
+
+class shelvedfile(object):
+    """Handles common functions on shelve files (.hg/.files/.patch) using
+    the vfs layer"""
+    def __init__(self, repo, name, filetype=None):
+        self.repo = repo
+        self.name = name
+        self.vfs = scmutil.vfs(repo.join('shelved'))
+        if filetype:
+            self.fname = name + '.' + filetype
+        else:
+            self.fname = name
+
+    def exists(self):
+        return self.vfs.exists(self.fname)
+
+    def filename(self):
+        return self.vfs.join(self.fname)
+
+    def unlink(self):
+        util.unlink(self.filename())
+
+    def stat(self):
+        return self.vfs.stat(self.fname)
+
+    def opener(self, mode='rb'):
+        try:
+            return self.vfs(self.fname, mode)
+        except IOError, err:
+            if err.errno != errno.ENOENT:
+                raise
+            if mode[0] in 'wa':
+                try:
+                    self.vfs.mkdir()
+                    return self.vfs(self.fname, mode)
+                except IOError, err:
+                    if err.errno != errno.EEXIST:
+                        raise
+            elif mode[0] == 'r':
+                raise util.Abort(_("shelved change '%s' not found") %
+                                 self.name)
+
+class shelvedstate(object):
+    """Handles saving and restoring a shelved state. Ensures that different
+    versions of a shelved state are possible and handles them appropriate"""
+    _version = 1
+    _filename = 'shelvedstate'
+
+    @classmethod
+    def load(cls, repo):
+        fp = repo.opener(cls._filename)
+        (version, name, parents, stripnodes) = pickle.load(fp)
+
+        if version != cls._version:
+            raise util.Abort(_('this version of shelve is incompatible '
+                               'with the version used in this repo'))
+
+        obj = cls()
+        obj.name = name
+        obj.parents = parents
+        obj.stripnodes = stripnodes
+
+        return obj
+
+    @classmethod
+    def save(cls, repo, name, stripnodes):
+        fp = repo.opener(cls._filename, 'wb')
+        pickle.dump((cls._version, name,
+                     repo.dirstate.parents(),
+                     stripnodes), fp)
+        fp.close()
+
+    @staticmethod
+    def clear(repo):
+        util.unlinkpath(repo.join('shelvedstate'), ignoremissing=True)
+
+def createcmd(ui, repo, pats, opts):
+    def publicancestors(ctx):
+        """Compute the heads of the public ancestors of a commit.
+
+        Much faster than the revset heads(ancestors(ctx) - draft())"""
+        seen = set()
+        visit = util.deque()
+        visit.append(ctx)
+        while visit:
+            ctx = visit.popleft()
+            for parent in ctx.parents():
+                rev = parent.rev()
+                if rev not in seen:
+                    seen.add(rev)
+                    if parent.mutable():
+                        visit.append(parent)
+                    else:
+                        yield parent.node()
+
+    wctx = repo[None]
+    parents = wctx.parents()
+    if len(parents) > 1:
+        raise util.Abort(_('cannot shelve while merging'))
+    parent = parents[0]
+
+    # we never need the user, so we use a generic user for all shelve operations
+    user = 'shelve@localhost'
+    label = repo._bookmarkcurrent or parent.branch() or 'default'
+
+    # slashes aren't allowed in filenames, therefore we rename it
+    origlabel, label = label, label.replace('/', '_')
+
+    def gennames():
+        yield label
+        for i in xrange(1, 100):
+            yield '%s-%02d' % (label, i)
+
+    shelvedfiles = []
+
+    def commitfunc(ui, repo, message, match, opts):
+        # check modified, added, removed, deleted only
+        for flist in repo.status(match=match)[:4]:
+            shelvedfiles.extend(flist)
+        return repo.commit(message, user, opts.get('date'), match)
+
+    if parent.node() != nullid:
+        desc = parent.description().split('\n', 1)[0]
+        desc = _('shelved from %s (%s): %s') % (label, str(parent)[:8], desc)
+    else:
+        desc = '(empty repository)'
+
+    if not opts['message']:
+        opts['message'] = desc
+
+    name = opts['name']
+
+    wlock = lock = tr = None
+    try:
+        wlock = repo.wlock()
+        lock = repo.lock()
+
+        # use an uncommited transaction to generate the bundle to avoid
+        # pull races. ensure we don't print the abort message to stderr.
+        tr = repo.transaction('commit', report=lambda x: None)
+
+        if name:
+            if shelvedfile(repo, name, 'hg').exists():
+                raise util.Abort(_("a shelved change named '%s' already exists")
+                                 % name)
+        else:
+            for n in gennames():
+                if not shelvedfile(repo, n, 'hg').exists():
+                    name = n
+                    break
+            else:
+                raise util.Abort(_("too many shelved changes named '%s'") %
+                                 label)
+
+        # ensure we are not creating a subdirectory or a hidden file
+        if '/' in name or '\\' in name:
+            raise util.Abort(_('shelved change names may not contain slashes'))
+        if name.startswith('.'):
+            raise util.Abort(_("shelved change names may not start with '.'"))
+
+        node = cmdutil.commit(ui, repo, commitfunc, pats, opts)
+
+        if not node:
+            stat = repo.status(match=scmutil.match(repo[None], pats, opts))
+            if stat[3]:
+                ui.status(_("nothing changed (%d missing files, see "
+                            "'hg status')\n") % len(stat[3]))
+            else:
+                ui.status(_("nothing changed\n"))
+            return 1
+
+        phases.retractboundary(repo, phases.secret, [node])
+
+        fp = shelvedfile(repo, name, 'files').opener('wb')
+        fp.write('\0'.join(shelvedfiles))
+
+        bases = list(publicancestors(repo[node]))
+        cg = repo.changegroupsubset(bases, [node], 'shelve')
+        changegroup.writebundle(cg, shelvedfile(repo, name, 'hg').filename(),
+                                'HG10UN')
+        cmdutil.export(repo, [node],
+                       fp=shelvedfile(repo, name, 'patch').opener('wb'),
+                       opts=mdiff.diffopts(git=True))
+
+        if ui.formatted():
+            desc = util.ellipsis(desc, ui.termwidth())
+        ui.status(desc + '\n')
+        ui.status(_('shelved as %s\n') % name)
+        hg.update(repo, parent.node())
+    finally:
+        if tr:
+            tr.abort()
+        lockmod.release(lock, wlock)
+
+def cleanupcmd(ui, repo):
+    wlock = None
+    try:
+        wlock = repo.wlock()
+        for (name, _) in repo.vfs.readdir('shelved'):
+            suffix = name.rsplit('.', 1)[-1]
+            if suffix in ('hg', 'files', 'patch'):
+                shelvedfile(repo, name).unlink()
+    finally:
+        lockmod.release(wlock)
+
+def deletecmd(ui, repo, pats):
+    if not pats:
+        raise util.Abort(_('no shelved changes specified!'))
+    wlock = None
+    try:
+        wlock = repo.wlock()
+        try:
+            for name in pats:
+                for suffix in 'hg files patch'.split():
+                    shelvedfile(repo, name, suffix).unlink()
+        except OSError, err:
+            if err.errno != errno.ENOENT:
+                raise
+            raise util.Abort(_("shelved change '%s' not found") % name)
+    finally:
+        lockmod.release(wlock)
+
+def listshelves(repo):
+    try:
+        names = repo.vfs.readdir('shelved')
+    except OSError, err:
+        if err.errno != errno.ENOENT:
+            raise
+        return []
+    info = []
+    for (name, _) in names:
+        pfx, sfx = name.rsplit('.', 1)
+        if not pfx or sfx != 'patch':
+            continue
+        st = shelvedfile(repo, name).stat()
+        info.append((st.st_mtime, shelvedfile(repo, pfx).filename()))
+    return sorted(info, reverse=True)
+
+def listcmd(ui, repo, pats, opts):
+    pats = set(pats)
+    width = 80
+    if not ui.plain():
+        width = ui.termwidth()
+    namelabel = 'shelve.newest'
+    for mtime, name in listshelves(repo):
+        sname = util.split(name)[1]
+        if pats and sname not in pats:
+            continue
+        ui.write(sname, label=namelabel)
+        namelabel = 'shelve.name'
+        if ui.quiet:
+            ui.write('\n')
+            continue
+        ui.write(' ' * (16 - len(sname)))
+        used = 16
+        age = '[%s]' % templatefilters.age(util.makedate(mtime))
+        ui.write(age, label='shelve.age')
+        ui.write(' ' * (18 - len(age)))
+        used += 18
+        fp = open(name + '.patch', 'rb')
+        try:
+            while True:
+                line = fp.readline()
+                if not line:
+                    break
+                if not line.startswith('#'):
+                    desc = line.rstrip()
+                    if ui.formatted():
+                        desc = util.ellipsis(desc, width - used)
+                    ui.write(desc)
+                    break
+            ui.write('\n')
+            if not (opts['patch'] or opts['stat']):
+                continue
+            difflines = fp.readlines()
+            if opts['patch']:
+                for chunk, label in patch.difflabel(iter, difflines):
+                    ui.write(chunk, label=label)
+            if opts['stat']:
+                for chunk, label in patch.diffstatui(difflines, width=width,
+                                                     git=True):
+                    ui.write(chunk, label=label)
+        finally:
+            fp.close()
+
+def readshelvedfiles(repo, basename):
+    fp = shelvedfile(repo, basename, 'files').opener()
+    return fp.read().split('\0')
+
+def checkparents(repo, state):
+    if state.parents != repo.dirstate.parents():
+        raise util.Abort(_('working directory parents do not match unshelve '
+                           'state'))
+
+def unshelveabort(ui, repo, state, opts):
+    wlock = repo.wlock()
+    lock = None
+    try:
+        checkparents(repo, state)
+        lock = repo.lock()
+        merge.mergestate(repo).reset()
+        if opts['keep']:
+            repo.setparents(repo.dirstate.parents()[0])
+        else:
+            revertfiles = readshelvedfiles(repo, state.name)
+            wctx = repo.parents()[0]
+            cmdutil.revert(ui, repo, wctx, [wctx.node(), nullid],
+                           *revertfiles, no_backup=True)
+            # fix up the weird dirstate states the merge left behind
+            mf = wctx.manifest()
+            dirstate = repo.dirstate
+            for f in revertfiles:
+                if f in mf:
+                    dirstate.normallookup(f)
+                else:
+                    dirstate.drop(f)
+            dirstate._pl = (wctx.node(), nullid)
+            dirstate._dirty = True
+        repair.strip(ui, repo, state.stripnodes, backup='none', topic='shelve')
+        shelvedstate.clear(repo)
+        ui.warn(_("unshelve of '%s' aborted\n") % state.name)
+    finally:
+        lockmod.release(lock, wlock)
+
+def unshelvecleanup(ui, repo, name, opts):
+    if not opts['keep']:
+        for filetype in 'hg files patch'.split():
+            shelvedfile(repo, name, filetype).unlink()
+
+def finishmerge(ui, repo, ms, stripnodes, name, opts):
+    # Reset the working dir so it's no longer in a merge state.
+    dirstate = repo.dirstate
+    for f in ms:
+        if dirstate[f] == 'm':
+            dirstate.normallookup(f)
+    dirstate._pl = (dirstate._pl[0], nullid)
+    dirstate._dirty = dirstate._dirtypl = True
+    shelvedstate.clear(repo)
+
+def unshelvecontinue(ui, repo, state, opts):
+    # We're finishing off a merge. First parent is our original
+    # parent, second is the temporary "fake" commit we're unshelving.
+    wlock = repo.wlock()
+    lock = None
+    try:
+        checkparents(repo, state)
+        ms = merge.mergestate(repo)
+        if [f for f in ms if ms[f] == 'u']:
+            raise util.Abort(
+                _("unresolved conflicts, can't continue"),
+                hint=_("see 'hg resolve', then 'hg unshelve --continue'"))
+        finishmerge(ui, repo, ms, state.stripnodes, state.name, opts)
+        lock = repo.lock()
+        repair.strip(ui, repo, state.stripnodes, backup='none', topic='shelve')
+        unshelvecleanup(ui, repo, state.name, opts)
+        ui.status(_("unshelve of '%s' complete\n") % state.name)
+    finally:
+        lockmod.release(lock, wlock)
+
+@command('unshelve',
+         [('a', 'abort', None,
+           _('abort an incomplete unshelve operation')),
+          ('c', 'continue', None,
+           _('continue an incomplete unshelve operation')),
+          ('', 'keep', None,
+           _('keep shelve after unshelving'))],
+         _('hg unshelve [SHELVED]'))
+def unshelve(ui, repo, *shelved, **opts):
+    """restore a shelved change to the working directory
+
+    This command accepts an optional name of a shelved change to
+    restore. If none is given, the most recent shelved change is used.
+
+    If a shelved change is applied successfully, the bundle that
+    contains the shelved changes is deleted afterwards.
+
+    Since you can restore a shelved change on top of an arbitrary
+    commit, it is possible that unshelving will result in a conflict
+    between your changes and the commits you are unshelving onto. If
+    this occurs, you must resolve the conflict, then use
+    ``--continue`` to complete the unshelve operation. (The bundle
+    will not be deleted until you successfully complete the unshelve.)
+
+    (Alternatively, you can use ``--abort`` to abandon an unshelve
+    that causes a conflict. This reverts the unshelved changes, and
+    does not delete the bundle.)
+    """
+    abortf = opts['abort']
+    continuef = opts['continue']
+    if not abortf and not continuef:
+        cmdutil.checkunfinished(repo)
+
+    if abortf or continuef:
+        if abortf and continuef:
+            raise util.Abort(_('cannot use both abort and continue'))
+        if shelved:
+            raise util.Abort(_('cannot combine abort/continue with '
+                               'naming a shelved change'))
+
+        try:
+            state = shelvedstate.load(repo)
+        except IOError, err:
+            if err.errno != errno.ENOENT:
+                raise
+            raise util.Abort(_('no unshelve operation underway'))
+
+        if abortf:
+            return unshelveabort(ui, repo, state, opts)
+        elif continuef:
+            return unshelvecontinue(ui, repo, state, opts)
+    elif len(shelved) > 1:
+        raise util.Abort(_('can only unshelve one change at a time'))
+    elif not shelved:
+        shelved = listshelves(repo)
+        if not shelved:
+            raise util.Abort(_('no shelved changes to apply!'))
+        basename = util.split(shelved[0][1])[1]
+        ui.status(_("unshelving change '%s'\n") % basename)
+    else:
+        basename = shelved[0]
+
+    shelvedfiles = readshelvedfiles(repo, basename)
+
+    m, a, r, d = repo.status()[:4]
+    unsafe = set(m + a + r + d).intersection(shelvedfiles)
+    if unsafe:
+        ui.warn(_('the following shelved files have been modified:\n'))
+        for f in sorted(unsafe):
+            ui.warn('  %s\n' % f)
+        ui.warn(_('you must commit, revert, or shelve your changes before you '
+                  'can proceed\n'))
+        raise util.Abort(_('cannot unshelve due to local changes\n'))
+
+    wlock = lock = tr = None
+    try:
+        lock = repo.lock()
+
+        tr = repo.transaction('unshelve', report=lambda x: None)
+        oldtiprev = len(repo)
+        try:
+            fp = shelvedfile(repo, basename, 'hg').opener()
+            gen = changegroup.readbundle(fp, fp.name)
+            repo.addchangegroup(gen, 'unshelve', 'bundle:' + fp.name)
+            nodes = [ctx.node() for ctx in repo.set('%d:', oldtiprev)]
+            phases.retractboundary(repo, phases.secret, nodes)
+            tr.close()
+        finally:
+            fp.close()
+
+        tip = repo['tip']
+        wctx = repo['.']
+        ancestor = tip.ancestor(wctx)
+
+        wlock = repo.wlock()
+
+        if ancestor.node() != wctx.node():
+            conflicts = hg.merge(repo, tip.node(), force=True, remind=False)
+            ms = merge.mergestate(repo)
+            stripnodes = [repo.changelog.node(rev)
+                          for rev in xrange(oldtiprev, len(repo))]
+            if conflicts:
+                shelvedstate.save(repo, basename, stripnodes)
+                # Fix up the dirstate entries of files from the second
+                # parent as if we were not merging, except for those
+                # with unresolved conflicts.
+                parents = repo.parents()
+                revertfiles = set(parents[1].files()).difference(ms)
+                cmdutil.revert(ui, repo, parents[1],
+                               (parents[0].node(), nullid),
+                               *revertfiles, no_backup=True)
+                raise error.InterventionRequired(
+                    _("unresolved conflicts (see 'hg resolve', then "
+                      "'hg unshelve --continue')"))
+            finishmerge(ui, repo, ms, stripnodes, basename, opts)
+        else:
+            parent = tip.parents()[0]
+            hg.update(repo, parent.node())
+            cmdutil.revert(ui, repo, tip, repo.dirstate.parents(), *tip.files(),
+                           no_backup=True)
+
+        prevquiet = ui.quiet
+        ui.quiet = True
+        try:
+            repo.rollback(force=True)
+        finally:
+            ui.quiet = prevquiet
+
+        unshelvecleanup(ui, repo, basename, opts)
+    finally:
+        if tr:
+            tr.release()
+        lockmod.release(lock, wlock)
+
+@command('shelve',
+         [('A', 'addremove', None,
+           _('mark new/missing files as added/removed before shelving')),
+          ('', 'cleanup', None,
+           _('delete all shelved changes')),
+          ('', 'date', '',
+           _('shelve with the specified commit date'), _('DATE')),
+          ('d', 'delete', None,
+           _('delete the named shelved change(s)')),
+          ('l', 'list', None,
+           _('list current shelves')),
+          ('m', 'message', '',
+           _('use text as shelve message'), _('TEXT')),
+          ('n', 'name', '',
+           _('use the given name for the shelved commit'), _('NAME')),
+          ('p', 'patch', None,
+           _('show patch')),
+          ('', 'stat', None,
+           _('output diffstat-style summary of changes'))],
+         _('hg shelve'))
+def shelvecmd(ui, repo, *pats, **opts):
+    '''save and set aside changes from the working directory
+
+    Shelving takes files that "hg status" reports as not clean, saves
+    the modifications to a bundle (a shelved change), and reverts the
+    files so that their state in the working directory becomes clean.
+
+    To restore these changes to the working directory, using "hg
+    unshelve"; this will work even if you switch to a different
+    commit.
+
+    When no files are specified, "hg shelve" saves all not-clean
+    files. If specific files or directories are named, only changes to
+    those files are shelved.
+
+    Each shelved change has a name that makes it easier to find later.
+    The name of a shelved change defaults to being based on the active
+    bookmark, or if there is no active bookmark, the current named
+    branch.  To specify a different name, use ``--name``.
+
+    To see a list of existing shelved changes, use the ``--list``
+    option. For each shelved change, this will print its name, age,
+    and description; use ``--patch`` or ``--stat`` for more details.
+
+    To delete specific shelved changes, use ``--delete``. To delete
+    all shelved changes, use ``--cleanup``.
+    '''
+    cmdutil.checkunfinished(repo)
+
+    def checkopt(opt, incompatible):
+        if opts[opt]:
+            for i in incompatible.split():
+                if opts[i]:
+                    raise util.Abort(_("options '--%s' and '--%s' may not be "
+                                       "used together") % (opt, i))
+            return True
+    if checkopt('cleanup', 'addremove delete list message name patch stat'):
+        if pats:
+            raise util.Abort(_("cannot specify names when using '--cleanup'"))
+        return cleanupcmd(ui, repo)
+    elif checkopt('delete', 'addremove cleanup list message name patch stat'):
+        return deletecmd(ui, repo, pats)
+    elif checkopt('list', 'addremove cleanup delete message name'):
+        return listcmd(ui, repo, pats, opts)
+    else:
+        for i in ('patch', 'stat'):
+            if opts[i]:
+                raise util.Abort(_("option '--%s' may not be "
+                                   "used when shelving a change") % (i,))
+        return createcmd(ui, repo, pats, opts)
+
+def extsetup(ui):
+    cmdutil.unfinishedstates.append(
+        [shelvedstate._filename, False, True, _('unshelve already in progress'),
+         _("use 'hg unshelve --continue' or 'hg unshelve --abort'")])
diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -341,6 +341,7 @@ 
     hgrc.write('[defaults]\n')
     hgrc.write('backout = -d "0 0"\n')
     hgrc.write('commit = -d "0 0"\n')
+    hgrc.write('shelve = --date "0 0"\n')
     hgrc.write('tag = -d "0 0"\n')
     if options.inotify:
         hgrc.write('[extensions]\n')
diff --git a/tests/test-commandserver.py.out b/tests/test-commandserver.py.out
--- a/tests/test-commandserver.py.out
+++ b/tests/test-commandserver.py.out
@@ -73,6 +73,7 @@ 
 bundle.mainreporoot=$TESTTMP
 defaults.backout=-d "0 0"
 defaults.commit=-d "0 0"
+defaults.shelve=--date "0 0"
 defaults.tag=-d "0 0"
 ui.slash=True
 ui.interactive=False
@@ -81,6 +82,7 @@ 
  runcommand -R foo showconfig ui defaults
 defaults.backout=-d "0 0"
 defaults.commit=-d "0 0"
+defaults.shelve=--date "0 0"
 defaults.tag=-d "0 0"
 ui.slash=True
 ui.interactive=False
diff --git a/tests/test-shelve.t b/tests/test-shelve.t
new file mode 100644
--- /dev/null
+++ b/tests/test-shelve.t
@@ -0,0 +1,420 @@ 
+  $ echo "[extensions]" >> $HGRCPATH
+  $ echo "shelve=" >> $HGRCPATH
+  $ echo "[defaults]" >> $HGRCPATH
+  $ echo "diff = --nodates --git" >> $HGRCPATH
+
+  $ hg init repo
+  $ cd repo
+  $ mkdir a b
+  $ echo a > a/a
+  $ echo b > b/b
+  $ echo c > c
+  $ echo d > d
+  $ echo x > x
+  $ hg addremove -q
+
+shelving in an empty repo should be possible
+
+  $ hg shelve
+  (empty repository)
+  shelved as default
+  0 files updated, 0 files merged, 5 files removed, 0 files unresolved
+
+  $ hg unshelve
+  unshelving change 'default'
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 5 changes to 5 files
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+  $ hg commit -q -m 'initial commit'
+
+  $ hg shelve
+  nothing changed
+  [1]
+
+create another commit
+
+  $ echo n > n
+  $ hg add n
+  $ hg commit n -m second
+
+shelve a change that we will delete later
+
+  $ echo a >> a/a
+  $ hg shelve
+  shelved from default (bb4fec6d): second
+  shelved as default
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+set up some more complex changes to shelve
+
+  $ echo a >> a/a
+  $ hg mv b b.rename
+  moving b/b to b.rename/b (glob)
+  $ hg cp c c.copy
+  $ hg status -C
+  M a/a
+  A b.rename/b
+    b/b
+  A c.copy
+    c
+  R b/b
+
+prevent some foot-shooting
+
+  $ hg shelve -n foo/bar
+  abort: shelved change names may not contain slashes
+  [255]
+  $ hg shelve -n .baz
+  abort: shelved change names may not start with '.'
+  [255]
+
+the common case - no options or filenames
+
+  $ hg shelve
+  shelved from default (bb4fec6d): second
+  shelved as default-01
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ hg status -C
+
+ensure that our shelved changes exist
+
+  $ hg shelve -l
+  default-01      [*]    shelved from default (bb4fec6d): second (glob)
+  default         [*]    shelved from default (bb4fec6d): second (glob)
+
+  $ hg shelve -l -p default
+  default         [*]    shelved from default (bb4fec6d): second (glob)
+  
+  diff --git a/a/a b/a/a
+  --- a/a/a
+  +++ b/a/a
+  @@ -1,1 +1,2 @@
+   a
+  +a
+
+delete our older shelved change
+
+  $ hg shelve -d default
+
+local edits should prevent a shelved change from applying
+
+  $ echo e>>a/a
+  $ hg unshelve
+  unshelving change 'default-01'
+  the following shelved files have been modified:
+    a/a
+  you must commit, revert, or shelve your changes before you can proceed
+  abort: cannot unshelve due to local changes
+  
+  [255]
+
+  $ hg revert -C a/a
+
+apply it and make sure our state is as expected
+
+  $ hg unshelve
+  unshelving change 'default-01'
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 3 changes to 8 files
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg status -C
+  M a/a
+  A b.rename/b
+    b/b
+  A c.copy
+    c
+  R b/b
+  $ hg shelve -l
+
+  $ hg unshelve
+  abort: no shelved changes to apply!
+  [255]
+  $ hg unshelve foo
+  abort: shelved change 'foo' not found
+  [255]
+
+named shelves, specific filenames, and "commit messages" should all work
+
+  $ hg status -C
+  M a/a
+  A b.rename/b
+    b/b
+  A c.copy
+    c
+  R b/b
+  $ hg shelve -q -n wibble -m wat a
+
+expect "a" to no longer be present, but status otherwise unchanged
+
+  $ hg status -C
+  A b.rename/b
+    b/b
+  A c.copy
+    c
+  R b/b
+  $ hg shelve -l --stat
+  wibble          [*]    wat (glob)
+   a/a |  1 +
+   1 files changed, 1 insertions(+), 0 deletions(-)
+
+and now "a/a" should reappear
+
+  $ hg unshelve -q wibble
+  $ hg status -C
+  M a/a
+  A b.rename/b
+    b/b
+  A c.copy
+    c
+  R b/b
+
+cause unshelving to result in a merge with 'a' conflicting
+
+  $ hg shelve -q
+  $ echo c>>a/a
+  $ hg commit -m second
+  $ hg tip --template '{files}\n'
+  a/a
+
+add an unrelated change that should be preserved
+
+  $ mkdir foo
+  $ echo foo > foo/foo
+  $ hg add foo/foo
+
+force a conflicted merge to occur
+
+  $ hg unshelve
+  unshelving change 'default'
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 3 changes to 8 files (+1 heads)
+  merging a/a
+  warning: conflicts during merge.
+  merging a/a incomplete! (edit conflicts, then use 'hg resolve --mark')
+  2 files updated, 0 files merged, 1 files removed, 1 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
+  unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
+  [1]
+
+ensure that we have a merge with unresolved conflicts
+
+  $ hg heads -q
+  3:7ec047b69dc0
+  2:ceefc37abe1e
+  $ hg parents -q
+  2:ceefc37abe1e
+  3:7ec047b69dc0
+  $ hg status
+  M a/a
+  M b.rename/b
+  M c.copy
+  A foo/foo
+  R b/b
+  ? a/a.orig
+  $ hg diff
+  diff --git a/a/a b/a/a
+  --- a/a/a
+  +++ b/a/a
+  @@ -1,2 +1,6 @@
+   a
+  +<<<<<<< local
+   c
+  +=======
+  +a
+  +>>>>>>> other
+  diff --git a/b.rename/b b/b.rename/b
+  --- /dev/null
+  +++ b/b.rename/b
+  @@ -0,0 +1,1 @@
+  +b
+  diff --git a/b/b b/b/b
+  deleted file mode 100644
+  --- a/b/b
+  +++ /dev/null
+  @@ -1,1 +0,0 @@
+  -b
+  diff --git a/c.copy b/c.copy
+  --- /dev/null
+  +++ b/c.copy
+  @@ -0,0 +1,1 @@
+  +c
+  diff --git a/foo/foo b/foo/foo
+  new file mode 100644
+  --- /dev/null
+  +++ b/foo/foo
+  @@ -0,0 +1,1 @@
+  +foo
+  $ hg resolve -l
+  U a/a
+
+  $ hg shelve
+  abort: unshelve already in progress
+  (use 'hg unshelve --continue' or 'hg unshelve --abort')
+  [255]
+
+abort the unshelve and be happy
+
+  $ hg status
+  M a/a
+  M b.rename/b
+  M c.copy
+  A foo/foo
+  R b/b
+  ? a/a.orig
+  $ hg unshelve -a
+  unshelve of 'default' aborted
+  $ hg heads -q
+  2:ceefc37abe1e
+  $ hg parents
+  changeset:   2:ceefc37abe1e
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     second
+  
+  $ hg resolve -l
+  $ hg status
+  A foo/foo
+  ? a/a.orig
+
+try to continue with no unshelve underway
+
+  $ hg unshelve -c
+  abort: no unshelve operation underway
+  [255]
+  $ hg status
+  A foo/foo
+  ? a/a.orig
+
+redo the unshelve to get a conflict
+
+  $ hg unshelve -q
+  warning: conflicts during merge.
+  merging a/a incomplete! (edit conflicts, then use 'hg resolve --mark')
+  unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
+  [1]
+
+attempt to continue
+
+  $ hg unshelve -c
+  abort: unresolved conflicts, can't continue
+  (see 'hg resolve', then 'hg unshelve --continue')
+  [255]
+
+  $ hg revert -r . a/a
+  $ hg resolve -m a/a
+
+  $ hg unshelve -c
+  unshelve of 'default' complete
+
+ensure the repo is as we hope
+
+  $ hg parents
+  changeset:   2:ceefc37abe1e
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     second
+  
+  $ hg heads -q
+  2:ceefc37abe1e
+
+  $ hg status -C
+  M a/a
+  M b.rename/b
+    b/b
+  M c.copy
+    c
+  A foo/foo
+  R b/b
+  ? a/a.orig
+
+there should be no shelves left
+
+  $ hg shelve -l
+
+  $ hg commit -m whee a/a
+
+#if execbit
+
+ensure that metadata-only changes are shelved
+
+  $ chmod +x a/a
+  $ hg shelve -q -n execbit a/a
+  $ hg status a/a
+  $ hg unshelve -q execbit
+  $ hg status a/a
+  M a/a
+  $ hg revert a/a
+
+#endif
+
+#if symlink
+
+  $ rm a/a
+  $ ln -s foo a/a
+  $ hg shelve -q -n symlink a/a
+  $ hg status a/a
+  $ hg unshelve -q symlink
+  $ hg status a/a
+  M a/a
+  $ hg revert a/a
+
+#endif
+
+set up another conflict between a commit and a shelved change
+
+  $ hg revert -q -C -a
+  $ echo a >> a/a
+  $ hg shelve -q
+  $ echo x >> a/a
+  $ hg ci -m 'create conflict'
+  $ hg add foo/foo
+
+if we resolve a conflict while unshelving, the unshelve should succeed
+
+  $ HGMERGE=true hg unshelve
+  unshelving change 'default'
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 6 files (+1 heads)
+  merging a/a
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  $ hg parents -q
+  4:be7e79683c99
+  $ hg shelve -l
+  $ hg status
+  M a/a
+  A foo/foo
+  $ cat a/a
+  a
+  c
+  x
+
+test keep and cleanup
+
+  $ hg shelve
+  shelved from default (be7e7968): create conflict
+  shelved as default
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg shelve --list
+  default         [*]    shelved from default (be7e7968): create conflict (glob)
+  $ hg unshelve --keep
+  unshelving change 'default'
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 7 files
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg shelve --list
+  default         [*]    shelved from default (be7e7968): create conflict (glob)
+  $ hg shelve --cleanup
+  $ hg shelve --list