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view hgext/uncommit.py @ 35976:48a3a9283f09
sshpeer: initial definition and implementation of new SSH protocol
The existing SSH protocol has several design flaws. Future commits
will elaborate on these flaws as new features are introduced
to combat these flaws. For now, hopefully you can take me for my
word that a ground up rewrite of the SSH protocol is needed.
This commit lays the foundation for a new SSH protocol by defining
a mechanism to upgrade the SSH transport channel away from the
default (version 1) protocol to something modern (which we'll call
"version 2" for now).
This upgrade process is detailed in the internals documentation
for the wire protocol. The gist of it is the client sends a
request line preceding the "hello" command/line which basically
says "I'm requesting an upgrade: here's what I support." If the
server recognizes that line, it processes the upgrade request and
the transport channel is switched to use the new version of the
protocol. If not, it sends an empty response, which is how all
Mercurial SSH servers from the beginning of time reacted to unknown
commands. The upgrade request is effectively ignored and the client
continues to use the existing version of the protocol as if nothing
happened.
The new version of the SSH protocol is completely identical to
version 1 aside from the upgrade dance and the bytes that follow.
The immediate bytes that follow the protocol switch are defined to
be a length framed "capabilities: " line containing the remote's
advertised capabilities. In reality, this looks very similar to
what the "hello" response would look like. But it will evolve
quickly.
The methodology by which the protocol will evolve is important.
I'm not going to introduce the new protocol all at once. That would
likely lead to endless bike shedding and forward progress would
stall. Instead, I intend to tricle out new features and diversions
from the existing protocol in small, incremental changes.
To support the gradual evolution of the protocol, the on-the-wire
advertised protocol name contains an "exp" to denote "experimental"
and a 4 digit field to capture the sub-version of the protocol.
Whenever we make a BC change to the wire protocol, we can increment
this version and lock out all older clients because it will appear
as a completely different protocol version. This means we can incur
as many breaking changes as we want. We don't have to commit to
supporting any one feature or idea for a long period of time. We
can even evolve the handshake mechanism, because that is defined
as being an implementation detail of the negotiated protocol version!
Hopefully this lowers the barrier to accepting changes to the
protocol and for experimenting with "radical" ideas during its
development.
In core, sshpeer received most of the attention. We haven't even
implemented the server bits for the new protocol in core yet.
Instead, we add very primitive support to our test server, mainly
just to exercise the added code paths in sshpeer.
Differential Revision: https://phab.mercurial-scm.org/D2061
# no-check-commit because of required foo_bar naming
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Tue, 06 Feb 2018 11:08:36 -0800 |
parents | f9a82b9b2c36 |
children | 3d0178bf1039 |
line wrap: on
line source
# uncommit - undo the actions of a commit # # Copyright 2011 Peter Arrenbrecht <peter.arrenbrecht@gmail.com> # Logilab SA <contact@logilab.fr> # Pierre-Yves David <pierre-yves.david@ens-lyon.org> # Patrick Mezard <patrick@mezard.eu> # Copyright 2016 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. """uncommit part or all of a local changeset (EXPERIMENTAL) This command undoes the effect of a local commit, returning the affected files to their uncommitted state. This means that files modified, added or removed in the changeset will be left unchanged, and so will remain modified, added and removed in the working directory. """ from __future__ import absolute_import from mercurial.i18n import _ from mercurial import ( cmdutil, commands, context, copies, error, node, obsutil, pycompat, registrar, rewriteutil, scmutil, ) cmdtable = {} command = registrar.command(cmdtable) configtable = {} configitem = registrar.configitem(configtable) configitem('experimental', 'uncommitondirtywdir', default=False, ) # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should # be specifying the version(s) of Mercurial they are tested with, or # leave the attribute unspecified. testedwith = 'ships-with-hg-core' def _commitfiltered(repo, ctx, match, allowempty): """Recommit ctx with changed files not in match. Return the new node identifier, or None if nothing changed. """ base = ctx.p1() # ctx initialfiles = set(ctx.files()) exclude = set(f for f in initialfiles if match(f)) # No files matched commit, so nothing excluded if not exclude: return None files = (initialfiles - exclude) # return the p1 so that we don't create an obsmarker later if not files and not allowempty: return ctx.parents()[0].node() # Filter copies copied = copies.pathcopies(base, ctx) copied = dict((dst, src) for dst, src in copied.iteritems() if dst in files) def filectxfn(repo, memctx, path, contentctx=ctx, redirect=()): if path not in contentctx: return None fctx = contentctx[path] mctx = context.memfilectx(repo, memctx, fctx.path(), fctx.data(), fctx.islink(), fctx.isexec(), copied=copied.get(path)) return mctx new = context.memctx(repo, parents=[base.node(), node.nullid], text=ctx.description(), files=files, filectxfn=filectxfn, user=ctx.user(), date=ctx.date(), extra=ctx.extra()) # phase handling commitphase = ctx.phase() overrides = {('phases', 'new-commit'): commitphase} with repo.ui.configoverride(overrides, 'uncommit'): newid = repo.commitctx(new) return newid def _fixdirstate(repo, oldctx, newctx, status): """ fix the dirstate after switching the working directory from oldctx to newctx which can be result of either unamend or uncommit. """ ds = repo.dirstate copies = dict(ds.copies()) s = status for f in s.modified: if ds[f] == 'r': # modified + removed -> removed continue ds.normallookup(f) for f in s.added: if ds[f] == 'r': # added + removed -> unknown ds.drop(f) elif ds[f] != 'a': ds.add(f) for f in s.removed: if ds[f] == 'a': # removed + added -> normal ds.normallookup(f) elif ds[f] != 'r': ds.remove(f) # Merge old parent and old working dir copies oldcopies = {} for f in (s.modified + s.added): src = oldctx[f].renamed() if src: oldcopies[f] = src[0] oldcopies.update(copies) copies = dict((dst, oldcopies.get(src, src)) for dst, src in oldcopies.iteritems()) # Adjust the dirstate copies for dst, src in copies.iteritems(): if (src not in newctx or dst in newctx or ds[dst] != 'a'): src = None ds.copy(src, dst) @command('uncommit', [('', 'keep', False, _('allow an empty commit after uncommiting')), ] + commands.walkopts, _('[OPTION]... [FILE]...')) def uncommit(ui, repo, *pats, **opts): """uncommit part or all of a local changeset This command undoes the effect of a local commit, returning the affected files to their uncommitted state. This means that files modified or deleted in the changeset will be left unchanged, and so will remain modified in the working directory. """ opts = pycompat.byteskwargs(opts) with repo.wlock(), repo.lock(): if not pats and not repo.ui.configbool('experimental', 'uncommitondirtywdir'): cmdutil.bailifchanged(repo) old = repo['.'] rewriteutil.precheck(repo, [old.rev()], 'uncommit') if len(old.parents()) > 1: raise error.Abort(_("cannot uncommit merge changeset")) with repo.transaction('uncommit'): match = scmutil.match(old, pats, opts) newid = _commitfiltered(repo, old, match, opts.get('keep')) if newid is None: ui.status(_("nothing to uncommit\n")) return 1 mapping = {} if newid != old.p1().node(): # Move local changes on filtered changeset mapping[old.node()] = (newid,) else: # Fully removed the old commit mapping[old.node()] = () scmutil.cleanupnodes(repo, mapping, 'uncommit') with repo.dirstate.parentchange(): repo.dirstate.setparents(newid, node.nullid) s = repo.status(old.p1(), old, match=match) _fixdirstate(repo, old, repo[newid], s) def predecessormarkers(ctx): """yields the obsolete markers marking the given changeset as a successor""" for data in ctx.repo().obsstore.predecessors.get(ctx.node(), ()): yield obsutil.marker(ctx.repo(), data) @command('^unamend', []) def unamend(ui, repo, **opts): """undo the most recent amend operation on a current changeset This command will roll back to the previous version of a changeset, leaving working directory in state in which it was before running `hg amend` (e.g. files modified as part of an amend will be marked as modified `hg status`) """ unfi = repo.unfiltered() with repo.wlock(), repo.lock(), repo.transaction('unamend'): # identify the commit from which to unamend curctx = repo['.'] rewriteutil.precheck(repo, [curctx.rev()], 'unamend') # identify the commit to which to unamend markers = list(predecessormarkers(curctx)) if len(markers) != 1: e = _("changeset must have one predecessor, found %i predecessors") raise error.Abort(e % len(markers)) prednode = markers[0].prednode() predctx = unfi[prednode] # add an extra so that we get a new hash # note: allowing unamend to undo an unamend is an intentional feature extras = predctx.extra() extras['unamend_source'] = curctx.hex() def filectxfn(repo, ctx_, path): try: return predctx.filectx(path) except KeyError: return None # Make a new commit same as predctx newctx = context.memctx(repo, parents=(predctx.p1(), predctx.p2()), text=predctx.description(), files=predctx.files(), filectxfn=filectxfn, user=predctx.user(), date=predctx.date(), extra=extras) # phase handling commitphase = curctx.phase() overrides = {('phases', 'new-commit'): commitphase} with repo.ui.configoverride(overrides, 'uncommit'): newprednode = repo.commitctx(newctx) newpredctx = repo[newprednode] dirstate = repo.dirstate with dirstate.parentchange(): dirstate.setparents(newprednode, node.nullid) s = repo.status(predctx, curctx) _fixdirstate(repo, curctx, newpredctx, s) mapping = {curctx.node(): (newprednode,)} scmutil.cleanupnodes(repo, mapping, 'unamend')