comparison mercurial/changegroup.py @ 38975:87b737b78bd0

changegroup: pass function to resolve delta parents into constructor

Previously, _deltaparent() encapsulated the logic for all 3
delta parent modes of operation. The choice of delta parent
is static for the lifetime of the packer and can be passed into
the packer as a callable. So do that.

Differential Revision: https://phab.mercurial-scm.org/D4132

38974:4f06e0360bad

    # Iterable of chunks holding raw delta data.
    deltachunks = attr.ib()

class cgpacker(object):
    def __init__(self, repo, filematcher, version, allowreorder,
                 useprevdelta, builddeltaheader, manifestsend,
                 bundlecaps=None, ellipses=False,
                 shallow=False, ellipsisroots=None, fullnodes=None):
        """Given a source repo, construct a bundler.

        filematcher is a matcher that matches on files to include in the

        allowreorder controls whether reordering of revisions is allowed.
        This value is used when ``bundle.reorder`` is ``auto`` or isn't
        set.

        useprevdelta controls whether revisions should always delta against
        the previous revision in the changegroup.

        builddeltaheader is a callable that constructs the header for a group
        delta.

        manifestsend is a chunk to send after manifests have been fully emitted.

        """
        assert filematcher
        self._filematcher = filematcher

        self.version = version
        self._useprevdelta = useprevdelta
        self._builddeltaheader = builddeltaheader
        self._manifestsend = manifestsend
        self._ellipses = ellipses

        # Set of capabilities we can use to build the bundle.

                    size += len(chunk)
                    yield chunk
                self._verbosenote(_('%8.i  %s\n') % (size, fname))
        progress.complete()

    def _deltaparent(self, store, rev, p1, p2, prev):
        if self._useprevdelta:
            if not store.candelta(prev, rev):
                raise error.ProgrammingError(
                    'cg1 should not be used in this case')
            return prev

        # Narrow ellipses mode.
        if self._ellipses:
            # TODO: send better deltas when in narrow mode.
            #
            # changegroup.group() loops over revisions to send,
            # including revisions we'll skip. What this means is that
            # `prev` will be a potentially useless delta base for all
            # ellipsis nodes, as the client likely won't have it. In
            # the future we should do bookkeeping about which nodes
            # have been sent to the client, and try to be
            # significantly smarter about delta bases. This is
            # slightly tricky because this same code has to work for
            # all revlogs, and we don't have the linkrev/linknode here.
            return p1

        dp = store.deltaparent(rev)
        if dp == nullrev and store.storedeltachains:
            # Avoid sending full revisions when delta parent is null. Pick prev
            # in that case. It's tempting to pick p1 in this case, as p1 will
            # be smaller in the common case. However, computing a delta against
            # p1 may require resolving the raw text of p1, which could be
            # expensive. The revlog caches should have prev cached, meaning
            # less CPU for changegroup generation. There is likely room to add
            # a flag and/or config option to control this behavior.
            base = prev
        elif dp == nullrev:
            # revlog is configured to use full snapshot for a reason,
            # stick to full snapshot.
            base = nullrev
        elif dp not in (p1, p2, prev):
            # Pick prev when we can't be sure remote has the base revision.
            return prev
        else:
            base = dp

        if base != nullrev and not store.candelta(base, rev):
            base = nullrev

        return base

    def _revchunk(self, store, rev, prev, linknode):
        if self._ellipses:
            fn = self._revisiondeltanarrow
        else:
            fn = self._revisiondeltanormal

            yield x

    def _revisiondeltanormal(self, store, rev, prev, linknode):
        node = store.node(rev)
        p1, p2 = store.parentrevs(rev)
        base = self._deltaparent(store, rev, p1, p2, prev)

        prefix = ''
        if store.iscensored(base) or store.iscensored(rev):
            try:
                delta = store.revision(node, raw=True)

            linknode=linknode,
            flags=flags,
            deltachunks=(diffheader, data),
        )

def _makecg1packer(repo, filematcher, bundlecaps, ellipses=False,
                   shallow=False, ellipsisroots=None, fullnodes=None):
    builddeltaheader = lambda d: _CHANGEGROUPV1_DELTA_HEADER.pack(
        d.node, d.p1node, d.p2node, d.linknode)

    return cgpacker(repo, filematcher, b'01',
                    useprevdelta=True,
                    allowreorder=None,
                    builddeltaheader=builddeltaheader,
                    manifestsend=b'',
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,

    # Since generaldelta is directly supported by cg2, reordering
    # generally doesn't help, so we disable it by default (treating
    # bundle.reorder=auto just like bundle.reorder=False).
    return cgpacker(repo, filematcher, b'02',
                    useprevdelta=False,
                    allowreorder=False,
                    builddeltaheader=builddeltaheader,
                    manifestsend=b'',
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,

def _makecg3packer(repo, filematcher, bundlecaps, ellipses=False,
                   shallow=False, ellipsisroots=None, fullnodes=None):
    builddeltaheader = lambda d: _CHANGEGROUPV3_DELTA_HEADER.pack(
        d.node, d.p1node, d.p2node, d.basenode, d.linknode, d.flags)

    return cgpacker(repo, filematcher, b'03',
                    useprevdelta=False,
                    allowreorder=False,
                    builddeltaheader=builddeltaheader,
                    manifestsend=closechunk(),
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,

38975:87b737b78bd0

    # Iterable of chunks holding raw delta data.
    deltachunks = attr.ib()

class cgpacker(object):
    def __init__(self, repo, filematcher, version, allowreorder,
                 deltaparentfn, builddeltaheader, manifestsend,
                 bundlecaps=None, ellipses=False,
                 shallow=False, ellipsisroots=None, fullnodes=None):
        """Given a source repo, construct a bundler.

        filematcher is a matcher that matches on files to include in the

        allowreorder controls whether reordering of revisions is allowed.
        This value is used when ``bundle.reorder`` is ``auto`` or isn't
        set.

        deltaparentfn is a callable that resolves the delta parent for
        a specific revision.

        builddeltaheader is a callable that constructs the header for a group
        delta.

        manifestsend is a chunk to send after manifests have been fully emitted.

        """
        assert filematcher
        self._filematcher = filematcher

        self.version = version
        self._deltaparentfn = deltaparentfn
        self._builddeltaheader = builddeltaheader
        self._manifestsend = manifestsend
        self._ellipses = ellipses

        # Set of capabilities we can use to build the bundle.

                    size += len(chunk)
                    yield chunk
                self._verbosenote(_('%8.i  %s\n') % (size, fname))
        progress.complete()

    def _revchunk(self, store, rev, prev, linknode):
        if self._ellipses:
            fn = self._revisiondeltanarrow
        else:
            fn = self._revisiondeltanormal

            yield x

    def _revisiondeltanormal(self, store, rev, prev, linknode):
        node = store.node(rev)
        p1, p2 = store.parentrevs(rev)
        base = self._deltaparentfn(store, rev, p1, p2, prev)

        prefix = ''
        if store.iscensored(base) or store.iscensored(rev):
            try:
                delta = store.revision(node, raw=True)

            linknode=linknode,
            flags=flags,
            deltachunks=(diffheader, data),
        )

def _deltaparentprev(store, rev, p1, p2, prev):
    """Resolve a delta parent to the previous revision.

    Used for version 1 changegroups, which don't support generaldelta.
    """
    return prev

def _deltaparentgeneraldelta(store, rev, p1, p2, prev):
    """Resolve a delta parent when general deltas are supported."""
    dp = store.deltaparent(rev)
    if dp == nullrev and store.storedeltachains:
        # Avoid sending full revisions when delta parent is null. Pick prev
        # in that case. It's tempting to pick p1 in this case, as p1 will
        # be smaller in the common case. However, computing a delta against
        # p1 may require resolving the raw text of p1, which could be
        # expensive. The revlog caches should have prev cached, meaning
        # less CPU for changegroup generation. There is likely room to add
        # a flag and/or config option to control this behavior.
        base = prev
    elif dp == nullrev:
        # revlog is configured to use full snapshot for a reason,
        # stick to full snapshot.
        base = nullrev
    elif dp not in (p1, p2, prev):
        # Pick prev when we can't be sure remote has the base revision.
        return prev
    else:
        base = dp

    if base != nullrev and not store.candelta(base, rev):
        base = nullrev

    return base

def _deltaparentellipses(store, rev, p1, p2, prev):
    """Resolve a delta parent when in ellipses mode."""
    # TODO: send better deltas when in narrow mode.
    #
    # changegroup.group() loops over revisions to send,
    # including revisions we'll skip. What this means is that
    # `prev` will be a potentially useless delta base for all
    # ellipsis nodes, as the client likely won't have it. In
    # the future we should do bookkeeping about which nodes
    # have been sent to the client, and try to be
    # significantly smarter about delta bases. This is
    # slightly tricky because this same code has to work for
    # all revlogs, and we don't have the linkrev/linknode here.
    return p1

def _makecg1packer(repo, filematcher, bundlecaps, ellipses=False,
                   shallow=False, ellipsisroots=None, fullnodes=None):
    builddeltaheader = lambda d: _CHANGEGROUPV1_DELTA_HEADER.pack(
        d.node, d.p1node, d.p2node, d.linknode)

    return cgpacker(repo, filematcher, b'01',
                    deltaparentfn=_deltaparentprev,
                    allowreorder=None,
                    builddeltaheader=builddeltaheader,
                    manifestsend=b'',
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,

    # Since generaldelta is directly supported by cg2, reordering
    # generally doesn't help, so we disable it by default (treating
    # bundle.reorder=auto just like bundle.reorder=False).
    return cgpacker(repo, filematcher, b'02',
                    deltaparentfn=_deltaparentgeneraldelta,
                    allowreorder=False,
                    builddeltaheader=builddeltaheader,
                    manifestsend=b'',
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,

def _makecg3packer(repo, filematcher, bundlecaps, ellipses=False,
                   shallow=False, ellipsisroots=None, fullnodes=None):
    builddeltaheader = lambda d: _CHANGEGROUPV3_DELTA_HEADER.pack(
        d.node, d.p1node, d.p2node, d.basenode, d.linknode, d.flags)

    deltaparentfn = (_deltaparentellipses if ellipses
                     else _deltaparentgeneraldelta)

    return cgpacker(repo, filematcher, b'03',
                    deltaparentfn=deltaparentfn,
                    allowreorder=False,
                    builddeltaheader=builddeltaheader,
                    manifestsend=closechunk(),
                    bundlecaps=bundlecaps,
                    ellipses=ellipses,