mercurial/exchangev2.py

exchangev2: fetch and apply bookmarks

This is pretty similar to phases data. We collect bookmarks data
as we process records. Then at the end we make a call to the
bookmarks subsystem to reflect the remote's bookmarks.

Like phases, the code for handling bookmarks is vastly simpler
than the previous wire protocol code because the server always
transfers the full set of bookmarks when bookmarks are requested.
We don't have to keep track of whether we requested bookmarks or
not.

Differential Revision: https://phab.mercurial-scm.org/D4486

# exchangev2.py - repository exchange for wire protocol version 2
#
# Copyright 2018 Gregory Szorc <[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 __future__ import absolute_import

import weakref

from .i18n import _
from .node import (
    nullid,
    short,
)
from . import (
    bookmarks,
    mdiff,
    phases,
    pycompat,
    setdiscovery,
)

def pull(pullop):
    """Pull using wire protocol version 2."""
    repo = pullop.repo
    remote = pullop.remote
    tr = pullop.trmanager.transaction()

    # Figure out what needs to be fetched.
    common, fetch, remoteheads = _pullchangesetdiscovery(
        repo, remote, pullop.heads, abortwhenunrelated=pullop.force)

    # And fetch the data.
    pullheads = pullop.heads or remoteheads
    csetres = _fetchchangesets(repo, tr, remote, common, fetch, pullheads)

    # New revisions are written to the changelog. But all other updates
    # are deferred. Do those now.

    # Ensure all new changesets are draft by default. If the repo is
    # publishing, the phase will be adjusted by the loop below.
    if csetres['added']:
        phases.registernew(repo, tr, phases.draft, csetres['added'])

    # And adjust the phase of all changesets accordingly.
    for phase in phases.phasenames:
        if phase == b'secret' or not csetres['nodesbyphase'][phase]:
            continue

        phases.advanceboundary(repo, tr, phases.phasenames.index(phase),
                               csetres['nodesbyphase'][phase])

    # Write bookmark updates.
    bookmarks.updatefromremote(repo.ui, repo, csetres['bookmarks'],
                               remote.url(), pullop.gettransaction,
                               explicit=pullop.explicitbookmarks)

def _pullchangesetdiscovery(repo, remote, heads, abortwhenunrelated=True):
    """Determine which changesets need to be pulled."""

    if heads:
        knownnode = repo.changelog.hasnode
        if all(knownnode(head) for head in heads):
            return heads, False, heads

    # TODO wire protocol version 2 is capable of more efficient discovery
    # than setdiscovery. Consider implementing something better.
    common, fetch, remoteheads = setdiscovery.findcommonheads(
        repo.ui, repo, remote, abortwhenunrelated=abortwhenunrelated)

    common = set(common)
    remoteheads = set(remoteheads)

    # If a remote head is filtered locally, put it back in the common set.
    # See the comment in exchange._pulldiscoverychangegroup() for more.

    if fetch and remoteheads:
        nodemap = repo.unfiltered().changelog.nodemap

        common |= {head for head in remoteheads if head in nodemap}

        if set(remoteheads).issubset(common):
            fetch = []

    common.discard(nullid)

    return common, fetch, remoteheads

def _fetchchangesets(repo, tr, remote, common, fetch, remoteheads):
    # TODO consider adding a step here where we obtain the DAG shape first
    # (or ask the server to slice changesets into chunks for us) so that
    # we can perform multiple fetches in batches. This will facilitate
    # resuming interrupted clones, higher server-side cache hit rates due
    # to smaller segments, etc.
    with remote.commandexecutor() as e:
        objs = e.callcommand(b'changesetdata', {
            b'noderange': [sorted(common), sorted(remoteheads)],
            b'fields': {b'bookmarks', b'parents', b'phase', b'revision'},
        }).result()

        # The context manager waits on all response data when exiting. So
        # we need to remain in the context manager in order to stream data.
        return _processchangesetdata(repo, tr, objs)

def _processchangesetdata(repo, tr, objs):
    repo.hook('prechangegroup', throw=True,
              **pycompat.strkwargs(tr.hookargs))

    urepo = repo.unfiltered()
    cl = urepo.changelog

    cl.delayupdate(tr)

    # The first emitted object is a header describing the data that
    # follows.
    meta = next(objs)

    progress = repo.ui.makeprogress(_('changesets'),
                                    unit=_('chunks'),
                                    total=meta.get(b'totalitems'))

    def linkrev(node):
        repo.ui.debug('add changeset %s\n' % short(node))
        # Linkrev for changelog is always self.
        return len(cl)

    def onchangeset(cl, node):
        progress.increment()

    nodesbyphase = {phase: set() for phase in phases.phasenames}
    remotebookmarks = {}

    # addgroup() expects a 7-tuple describing revisions. This normalizes
    # the wire data to that format.
    #
    # This loop also aggregates non-revision metadata, such as phase
    # data.
    def iterrevisions():
        for cset in objs:
            node = cset[b'node']

            if b'phase' in cset:
                nodesbyphase[cset[b'phase']].add(node)

            for mark in cset.get(b'bookmarks', []):
                remotebookmarks[mark] = node

            # Some entries might only be metadata only updates.
            if b'revisionsize' not in cset:
                continue

            data = next(objs)

            yield (
                node,
                cset[b'parents'][0],
                cset[b'parents'][1],
                # Linknode is always itself for changesets.
                cset[b'node'],
                # We always send full revisions. So delta base is not set.
                nullid,
                mdiff.trivialdiffheader(len(data)) + data,
                # Flags not yet supported.
                0,
            )

    added = cl.addgroup(iterrevisions(), linkrev, weakref.proxy(tr),
                        addrevisioncb=onchangeset)

    progress.complete()

    return {
        'added': added,
        'nodesbyphase': nodesbyphase,
        'bookmarks': remotebookmarks,
    }