view mercurial/filelog.py @ 39646:9c2c77c73f23

wireprotov2: define and implement "changesetdata" command

This commit introduces the "changesetdata" wire protocol command.
The role of the command is to expose data associated with changelog
revisions, including the raw revision data itself.

This command is the first piece of a new clone/pull strategy that
is built on top of domain-specific commands for data retrieval.
Instead of a monolithic "getbundle" command that transfers all of the
things, we'll be introducing commands for fetching specific pieces
of data.

Since the changeset is the fundamental unit from which we derive
pointers to other data (manifests, file nodes, etc), it makes sense
to start reimplementing pull with this data.

The command accepts as arguments a set of root and head revisions
defining the changesets that should be fetched as well as an explicit
list of nodes. By default, the command returns only the node values:
the client must explicitly request additional fields be added to the
response. Current supported fields are the list of parent nodes and
the revision fulltext.

My plan is to eventually add support for transferring other data
associated with changesets, including phases, bookmarks, obsolescence
markers, etc. Since the response format is CBOR, we'll be able to add
this data into the response object relatively easily (it should be
as simple as adding a key in a map).

The documentation captures a number of TODO items. Some of these may
require BC breaking changes. That's fine: wire protocol v2 is still
highly experimental.

Differential Revision: https://phab.mercurial-scm.org/D4481

# filelog.py - file history class for mercurial
#
# Copyright 2005-2007 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.

from __future__ import absolute_import

from . import (
    error,
    repository,
    revlog,
)
from .utils import (
    interfaceutil,
)

@interfaceutil.implementer(repository.ifilestorage)
class filelog(object):
    def __init__(self, opener, path):
        self._revlog = revlog.revlog(opener,
                                     '/'.join(('data', path + '.i')),
                                     censorable=True)
        # full name of the user visible file, relative to the repository root
        self.filename = path
        self.index = self._revlog.index
        self.version = self._revlog.version
        self._generaldelta = self._revlog._generaldelta

    def __len__(self):
        return len(self._revlog)

    def __iter__(self):
        return self._revlog.__iter__()

    def revs(self, start=0, stop=None):
        return self._revlog.revs(start=start, stop=stop)

    def parents(self, node):
        return self._revlog.parents(node)

    def parentrevs(self, rev):
        return self._revlog.parentrevs(rev)

    def rev(self, node):
        return self._revlog.rev(node)

    def node(self, rev):
        return self._revlog.node(rev)

    def lookup(self, node):
        return self._revlog.lookup(node)

    def linkrev(self, rev):
        return self._revlog.linkrev(rev)

    def flags(self, rev):
        return self._revlog.flags(rev)

    def commonancestorsheads(self, node1, node2):
        return self._revlog.commonancestorsheads(node1, node2)

    def descendants(self, revs):
        return self._revlog.descendants(revs)

    def headrevs(self):
        return self._revlog.headrevs()

    def heads(self, start=None, stop=None):
        return self._revlog.heads(start, stop)

    def children(self, node):
        return self._revlog.children(node)

    def deltaparent(self, rev):
        return self._revlog.deltaparent(rev)

    def iscensored(self, rev):
        return self._revlog.iscensored(rev)

    def rawsize(self, rev):
        return self._revlog.rawsize(rev)

    def checkhash(self, text, node, p1=None, p2=None, rev=None):
        return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)

    def revision(self, node, _df=None, raw=False):
        return self._revlog.revision(node, _df=_df, raw=raw)

    def revdiff(self, rev1, rev2):
        return self._revlog.revdiff(rev1, rev2)

    def emitrevisiondeltas(self, requests):
        return self._revlog.emitrevisiondeltas(requests)

    def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
                    node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
                    cachedelta=None):
        return self._revlog.addrevision(revisiondata, transaction, linkrev,
                                    p1, p2, node=node, flags=flags,
                                    cachedelta=cachedelta)

    def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
        return self._revlog.addgroup(deltas, linkmapper, transaction,
                                 addrevisioncb=addrevisioncb)

    def getstrippoint(self, minlink):
        return self._revlog.getstrippoint(minlink)

    def strip(self, minlink, transaction):
        return self._revlog.strip(minlink, transaction)

    def files(self):
        return self._revlog.files()

    def checksize(self):
        return self._revlog.checksize()

    def read(self, node):
        t = self.revision(node)
        if not t.startswith('\1\n'):
            return t
        s = t.index('\1\n', 2)
        return t[s + 2:]

    def add(self, text, meta, transaction, link, p1=None, p2=None):
        if meta or text.startswith('\1\n'):
            text = revlog.packmeta(meta, text)
        return self.addrevision(text, transaction, link, p1, p2)

    def renamed(self, node):
        if self.parents(node)[0] != revlog.nullid:
            return False
        t = self.revision(node)
        m = revlog.parsemeta(t)[0]
        # copy and copyrev occur in pairs. In rare cases due to bugs,
        # one can occur without the other.
        if m and "copy" in m and "copyrev" in m:
            return (m["copy"], revlog.bin(m["copyrev"]))
        return False

    def size(self, rev):
        """return the size of a given revision"""

        # for revisions with renames, we have to go the slow way
        node = self.node(rev)
        if self.renamed(node):
            return len(self.read(node))
        if self.iscensored(rev):
            return 0

        # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
        return self._revlog.size(rev)

    def cmp(self, node, text):
        """compare text with a given file revision

        returns True if text is different than what is stored.
        """

        t = text
        if text.startswith('\1\n'):
            t = '\1\n\1\n' + text

        samehashes = not self._revlog.cmp(node, t)
        if samehashes:
            return False

        # censored files compare against the empty file
        if self.iscensored(self.rev(node)):
            return text != ''

        # renaming a file produces a different hash, even if the data
        # remains unchanged. Check if it's the case (slow):
        if self.renamed(node):
            t2 = self.read(node)
            return t2 != text

        return True

    @property
    def filename(self):
        return self._revlog.filename

    @filename.setter
    def filename(self, value):
        self._revlog.filename = value

    # TODO these aren't part of the interface and aren't internal methods.
    # Callers should be fixed to not use them.
    @property
    def indexfile(self):
        return self._revlog.indexfile

    @indexfile.setter
    def indexfile(self, value):
        self._revlog.indexfile = value

    @property
    def datafile(self):
        return self._revlog.datafile

    @property
    def opener(self):
        return self._revlog.opener

    def clone(self, tr, destrevlog, **kwargs):
        if not isinstance(destrevlog, filelog):
            raise error.ProgrammingError('expected filelog to clone()')

        return self._revlog.clone(tr, destrevlog._revlog, **kwargs)

    def start(self, rev):
        return self._revlog.start(rev)

    def end(self, rev):
        return self._revlog.end(rev)

    def length(self, rev):
        return self._revlog.length(rev)

    def compress(self, data):
        return self._revlog.compress(data)

    def _addrevision(self, *args, **kwargs):
        return self._revlog._addrevision(*args, **kwargs)