view hgext/share.py @ 36367:043e77f3be09

sshpeer: return framed file object when needed

Currently, wireproto.wirepeer has a default implementation of
_submitbatch() and sshv1peer has a very similar implementation.
The main difference is that sshv1peer is aware of the total amount
of bytes it can read whereas the default implementation reads the
stream until no more data is returned. The default implementation
works for HTTP, since there is a known end to HTTP responses (either
Content-Length or 0 sized chunk).

This commit teaches sshv1peer to use our just-introduced "cappedreader"
class for wrapping a file object to limit the number of bytes that
can be read. We do this by introducing an argument to specify whether
the response is framed. If set, we returned a cappedreader instance
instead of the raw pipe.

_call() always has framed responses. So we set this argument
unconditionally and then .read() the entirety of the result.
Strictly speaking, we don't need to use cappedreader in this case
and can inline frame decoding/read logic. But I like when things
are consistent. The overhead should be negligible.

_callstream() and _callcompressable() are special: whether framing
is used depends on the specific command. So, we define a set
of commands that have framed response. It currently only
contains "batch."

As a result of this change, the one-off implementation of
_submitbatch() in sshv1peer can be removed since it is now
safe to .read() the response's file object until end of stream.
cappedreader takes care of not overrunning the frame.

Differential Revision: https://phab.mercurial-scm.org/D2380

# Copyright 2006, 2007 Matt Mackall <[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.

'''share a common history between several working directories

Automatic Pooled Storage for Clones
-----------------------------------

When this extension is active, :hg:`clone` can be configured to
automatically share/pool storage across multiple clones. This
mode effectively converts :hg:`clone` to :hg:`clone` + :hg:`share`.
The benefit of using this mode is the automatic management of
store paths and intelligent pooling of related repositories.

The following ``share.`` config options influence this feature:

``share.pool``
    Filesystem path where shared repository data will be stored. When
    defined, :hg:`clone` will automatically use shared repository
    storage instead of creating a store inside each clone.

``share.poolnaming``
    How directory names in ``share.pool`` are constructed.

    "identity" means the name is derived from the first changeset in the
    repository. In this mode, different remotes share storage if their
    root/initial changeset is identical. In this mode, the local shared
    repository is an aggregate of all encountered remote repositories.

    "remote" means the name is derived from the source repository's
    path or URL. In this mode, storage is only shared if the path or URL
    requested in the :hg:`clone` command matches exactly to a repository
    that was cloned before.

    The default naming mode is "identity".
'''

from __future__ import absolute_import

import errno
from mercurial.i18n import _
from mercurial import (
    bookmarks,
    commands,
    error,
    extensions,
    hg,
    registrar,
    txnutil,
    util,
)

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

@command('share',
    [('U', 'noupdate', None, _('do not create a working directory')),
     ('B', 'bookmarks', None, _('also share bookmarks')),
     ('', 'relative', None, _('point to source using a relative path '
                              '(EXPERIMENTAL)')),
    ],
    _('[-U] [-B] SOURCE [DEST]'),
    norepo=True)
def share(ui, source, dest=None, noupdate=False, bookmarks=False,
          relative=False):
    """create a new shared repository

    Initialize a new repository and working directory that shares its
    history (and optionally bookmarks) with another repository.

    .. note::

       using rollback or extensions that destroy/modify history (mq,
       rebase, etc.) can cause considerable confusion with shared
       clones. In particular, if two shared clones are both updated to
       the same changeset, and one of them destroys that changeset
       with rollback, the other clone will suddenly stop working: all
       operations will fail with "abort: working directory has unknown
       parent". The only known workaround is to use debugsetparents on
       the broken clone to reset it to a changeset that still exists.
    """

    hg.share(ui, source, dest=dest, update=not noupdate,
             bookmarks=bookmarks, relative=relative)
    return 0

@command('unshare', [], '')
def unshare(ui, repo):
    """convert a shared repository to a normal one

    Copy the store data to the repo and remove the sharedpath data.
    """

    if not repo.shared():
        raise error.Abort(_("this is not a shared repo"))

    hg.unshare(ui, repo)

# Wrap clone command to pass auto share options.
def clone(orig, ui, source, *args, **opts):
    pool = ui.config('share', 'pool')
    if pool:
        pool = util.expandpath(pool)

    opts[r'shareopts'] = {
        'pool': pool,
        'mode': ui.config('share', 'poolnaming'),
    }

    return orig(ui, source, *args, **opts)

def extsetup(ui):
    extensions.wrapfunction(bookmarks, '_getbkfile', getbkfile)
    extensions.wrapfunction(bookmarks.bmstore, '_recordchange', recordchange)
    extensions.wrapfunction(bookmarks.bmstore, '_writerepo', writerepo)
    extensions.wrapcommand(commands.table, 'clone', clone)

def _hassharedbookmarks(repo):
    """Returns whether this repo has shared bookmarks"""
    try:
        shared = repo.vfs.read('shared').splitlines()
    except IOError as inst:
        if inst.errno != errno.ENOENT:
            raise
        return False
    return hg.sharedbookmarks in shared

def getbkfile(orig, repo):
    if _hassharedbookmarks(repo):
        srcrepo = hg.sharedreposource(repo)
        if srcrepo is not None:
            # just orig(srcrepo) doesn't work as expected, because
            # HG_PENDING refers repo.root.
            try:
                fp, pending = txnutil.trypending(repo.root, repo.vfs,
                                                 'bookmarks')
                if pending:
                    # only in this case, bookmark information in repo
                    # is up-to-date.
                    return fp
                fp.close()
            except IOError as inst:
                if inst.errno != errno.ENOENT:
                    raise

            # otherwise, we should read bookmarks from srcrepo,
            # because .hg/bookmarks in srcrepo might be already
            # changed via another sharing repo
            repo = srcrepo

            # TODO: Pending changes in repo are still invisible in
            # srcrepo, because bookmarks.pending is written only into repo.
            # See also https://www.mercurial-scm.org/wiki/SharedRepository
    return orig(repo)

def recordchange(orig, self, tr):
    # Continue with write to local bookmarks file as usual
    orig(self, tr)

    if _hassharedbookmarks(self._repo):
        srcrepo = hg.sharedreposource(self._repo)
        if srcrepo is not None:
            category = 'share-bookmarks'
            tr.addpostclose(category, lambda tr: self._writerepo(srcrepo))

def writerepo(orig, self, repo):
    # First write local bookmarks file in case we ever unshare
    orig(self, repo)

    if _hassharedbookmarks(self._repo):
        srcrepo = hg.sharedreposource(self._repo)
        if srcrepo is not None:
            orig(self, srcrepo)