# exchangev2.py - repository exchange for wire protocol version 2

#

# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>

#

# 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 collections

import weakref

from .i18n import _

from .node import (

    nullid,

    short,

)

from . import (

    bookmarks,

    error,

    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)

    manres = _fetchmanifests(repo, tr, remote, csetres['manifestnodes'])

    # Find all file nodes referenced by added manifests and fetch those

    # revisions.

                         manres['linkrevs'])

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'revisions': [{

                b'type': b'changesetdagrange',

                b'roots': sorted(common),

                b'heads': 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'))

    manifestnodes = {}

    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()

        revision = cl.changelogrevision(node)

        # We need to preserve the mapping of changelog revision to node

        # so we can set the linkrev accordingly when manifests are added.

        manifestnodes[cl.rev(node)] = revision.manifest

    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

            # TODO add mechanism for extensions to examine records so they

            # can siphon off custom data fields.

            extrafields = {}

            for field, size in cset.get(b'fieldsfollowing', []):

                extrafields[field] = next(objs)

            # Some entries might only be metadata only updates.

            if b'revision' not in extrafields:

                continue

            data = extrafields[b'revision']

            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,

        'manifestnodes': manifestnodes,

    }

def _fetchmanifests(repo, tr, remote, manifestnodes):

    rootmanifest = repo.manifestlog.getstorage(b'')

    # Some manifests can be shared between changesets. Filter out revisions

    # we already know about.

    fetchnodes = []

    linkrevs = {}

    seen = set()

    for clrev, node in sorted(manifestnodes.iteritems()):

        if node in seen:

            continue

        try:

            rootmanifest.rev(node)

        except error.LookupError:

            fetchnodes.append(node)

            linkrevs[node] = clrev

        seen.add(node)

    # TODO handle tree manifests

    # addgroup() expects 7-tuple describing revisions. This normalizes

    # the wire data to that format.

    def iterrevisions(objs, progress):

        for manifest in objs:

            node = manifest[b'node']

            extrafields = {}

            for field, size in manifest.get(b'fieldsfollowing', []):

                extrafields[field] = next(objs)

            if b'delta' in extrafields:

                basenode = manifest[b'deltabasenode']

                delta = extrafields[b'delta']

            elif b'revision' in extrafields:

                basenode = nullid

                revision = extrafields[b'revision']

                delta = mdiff.trivialdiffheader(len(revision)) + revision

            else:

                continue

            yield (

                node,

                manifest[b'parents'][0],

                manifest[b'parents'][1],

                # The value passed in is passed to the lookup function passed

                # to addgroup(). We already have a map of manifest node to

                # changelog revision number. So we just pass in the

                # manifest node here and use linkrevs.__getitem__ as the

                # resolution function.

                node,

                basenode,

                delta,

                # Flags not yet supported.

                0

            )

            progress.increment()

    progress = repo.ui.makeprogress(_('manifests'), unit=_('chunks'),

                                    total=len(fetchnodes))

    commandmeta = remote.apidescriptor[b'commands'][b'manifestdata']

    batchsize = commandmeta.get(b'recommendedbatchsize', 10000)

    # TODO make size configurable on client?

    # We send commands 1 at a time to the remote. This is not the most

    # efficient because we incur a round trip at the end of each batch.

    # However, the existing frame-based reactor keeps consuming server

    # data in the background. And this results in response data buffering

    # in memory. This can consume gigabytes of memory.

    # TODO send multiple commands in a request once background buffering

    # issues are resolved.

    added = []

    for i in pycompat.xrange(0, len(fetchnodes), batchsize):

        batch = [node for node in fetchnodes[i:i + batchsize]]

        if not batch:

            continue

        with remote.commandexecutor() as e:

            objs = e.callcommand(b'manifestdata', {

                b'tree': b'',

                b'nodes': batch,

                b'fields': {b'parents', b'revision'},

                b'haveparents': True,

            }).result()

            # Chomp off header object.

            next(objs)

            added.extend(rootmanifest.addgroup(

                iterrevisions(objs, progress),

                linkrevs.__getitem__,

                weakref.proxy(tr)))

    progress.complete()

    return {

        'added': added,

        'linkrevs': linkrevs,

    }

    """Determine what file nodes are relevant given a set of manifest nodes.

    Returns a dict mapping file paths to dicts of file node to first manifest

    node.

    """

    ml = repo.manifestlog

    fnodes = collections.defaultdict(dict)

    progress = repo.ui.makeprogress(

        _('scanning manifests'), total=len(manifestnodes))

    with progress:

        for manifestnode in manifestnodes:

            m = ml.get(b'', manifestnode)

            # TODO this will pull in unwanted nodes because it takes the storage

            # delta into consideration. What we really want is something that

            # takes the delta between the manifest's parents. And ideally we

            # would ignore file nodes that are known locally. For now, ignore

            # both these limitations. This will result in incremental fetches

            # requesting data we already have. So this is far from ideal.

            md = m.readfast()

            for path, fnode in md.items():

            progress.increment()

    return fnodes

def _fetchfiles(repo, tr, remote, fnodes, linkrevs):

    """Fetch file data from explicit file revisions."""

    def iterrevisions(objs, progress):

        for filerevision in objs:

            node = filerevision[b'node']

            extrafields = {}

            for field, size in filerevision.get(b'fieldsfollowing', []):

                extrafields[field] = next(objs)

            if b'delta' in extrafields:

                basenode = filerevision[b'deltabasenode']

                delta = extrafields[b'delta']

            elif b'revision' in extrafields:

                basenode = nullid

                revision = extrafields[b'revision']

                delta = mdiff.trivialdiffheader(len(revision)) + revision

            else:

                continue

            yield (

                node,

                filerevision[b'parents'][0],

                filerevision[b'parents'][1],

                node,

                basenode,

                delta,

                # Flags not yet supported.

                0,