hgext/amend.py

wireprotov2: define and use stream encoders

Now that we have basic support for defining stream encoding, it is
time to start doing something with it.

We define various classes implementing stream encoders/decoders for
the defined encoding profiles. This is relatively straightforward.

We teach the inputstream and outputstream classes how to encode,
decode, and flush data.

We then teach the clientreactor how to filter received data through
the inputstream decoder.

One of the features of the framing format is that streams can span
requests. This is a differentiating feature from say HTTP/2, which
associates streams with requests. By allowing streams to span requests,
we can reuse compression context data across requests/responses. But
in order to do this, we need a mechanism to "flush" the encoder at
logical boundaries so that receivers receive all data where it is
expected. And a "flush" event is distinct from a "finish" event from
the perspective of certain compressors because a "flush" will retain
compression context state whereas a "finish" operation will not. This
is why encoders have both a flush() and a finish() and each uses
specific flushing semantics on the underlying compressor.

The added tests verify various behavior of decoders via clientreactor.
These tests do test some compression behavior via use of outputstream.
But for all intents and purposes, server reactor support for encoding
is not yet implemented.

Differential Revision: https://phab.mercurial-scm.org/D4921

# amend.py - provide the amend command
#
# Copyright 2017 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.
"""provide the amend command (EXPERIMENTAL)

This extension provides an ``amend`` command that is similar to
``commit --amend`` but does not prompt an editor.
"""

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    cmdutil,
    commands,
    error,
    pycompat,
    registrar,
)

# 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'

cmdtable = {}
command = registrar.command(cmdtable)

@command('amend',
    [('A', 'addremove', None,
      _('mark new/missing files as added/removed before committing')),
     ('e', 'edit', None, _('invoke editor on commit messages')),
     ('i', 'interactive', None, _('use interactive mode')),
     ('n', 'note', '', _('store a note on the amend')),
    ] + cmdutil.walkopts + cmdutil.commitopts + cmdutil.commitopts2,
    _('[OPTION]... [FILE]...'),
    inferrepo=True)
def amend(ui, repo, *pats, **opts):
    """amend the working copy parent with all or specified outstanding changes

    Similar to :hg:`commit --amend`, but reuse the commit message without
    invoking editor, unless ``--edit`` was set.

    See :hg:`help commit` for more details.
    """
    opts = pycompat.byteskwargs(opts)
    if len(opts['note']) > 255:
        raise error.Abort(_("cannot store a note of more than 255 bytes"))
    with repo.wlock(), repo.lock():
        if not opts.get('logfile'):
            opts['message'] = opts.get('message') or repo['.'].description()
        opts['amend'] = True
        return commands._docommit(ui, repo, *pats, **pycompat.strkwargs(opts))