widening: duplicate generateellipsesbundle2() for widening

The widening and the non-widening code are quite different. It will be
clearer to have them as sepearate functions. To start with, I've just
copied it exactly, so it's clearer over the next few patches how
they're different.

The new function should gradually become more similar to
bundle2.widen_bundle(), and should perhaps eventually be merged with
that function. However, I've left it in narrowbundle2.py for now since
it still depends on constants like _KILLNODESIGNAL there.

Differential Revision: https://phab.mercurial-scm.org/D7092

hgext/narrow/narrowbundle2.py

@@ -184,6 +184,105 b' def generateellipsesbundle2('
             part.addparam(b'treemanifest', b'1')
 
 
+def generate_ellipses_bundle2_for_widening(
+    bundler,
+    repo,
+    oldinclude,
+    oldexclude,
+    newinclude,
+    newexclude,
+    version,
+    common,
+    heads,
+    known,
+    depth,
+):
+    newmatch = narrowspec.match(
+        repo.root, include=newinclude, exclude=newexclude
+    )
+    if depth is not None:
+        depth = int(depth)
+        if depth < 1:
+            raise error.Abort(_(b'depth must be positive, got %d') % depth)
+
+    heads = set(heads or repo.heads())
+    common = set(common or [nullid])
+    if known and (oldinclude != newinclude or oldexclude != newexclude):
+        # Steps:
+        # 1. Send kill for "$known & ::common"
+        #
+        # 2. Send changegroup for ::common
+        #
+        # 3. Proceed.
+        #
+        # In the future, we can send kills for only the specific
+        # nodes we know should go away or change shape, and then
+        # send a data stream that tells the client something like this:
+        #
+        # a) apply this changegroup
+        # b) apply nodes XXX, YYY, ZZZ that you already have
+        # c) goto a
+        #
+        # until they've built up the full new state.
+        # Convert to revnums and intersect with "common". The client should
+        # have made it a subset of "common" already, but let's be safe.
+        known = set(repo.revs(b"%ln & ::%ln", known, common))
+        # TODO: we could send only roots() of this set, and the
+        # list of nodes in common, and the client could work out
+        # what to strip, instead of us explicitly sending every
+        # single node.
+        deadrevs = known
+
+        def genkills():
+            for r in deadrevs:
+                yield _KILLNODESIGNAL
+                yield repo.changelog.node(r)
+            yield _DONESIGNAL
+
+        bundler.newpart(_CHANGESPECPART, data=genkills())
+        newvisit, newfull, newellipsis = exchange._computeellipsis(
+            repo, set(), common, known, newmatch
+        )
+        if newvisit:
+            packer = changegroup.getbundler(
+                version,
+                repo,
+                matcher=newmatch,
+                ellipses=True,
+                shallow=depth is not None,
+                ellipsisroots=newellipsis,
+                fullnodes=newfull,
+            )
+            cgdata = packer.generate(common, newvisit, False, b'narrow_widen')
+
+            part = bundler.newpart(b'changegroup', data=cgdata)
+            part.addparam(b'version', version)
+            if b'treemanifest' in repo.requirements:
+                part.addparam(b'treemanifest', b'1')
+
+    visitnodes, relevant_nodes, ellipsisroots = exchange._computeellipsis(
+        repo, common, heads, set(), newmatch, depth=depth
+    )
+
+    repo.ui.debug(b'Found %d relevant revs\n' % len(relevant_nodes))
+    if visitnodes:
+        packer = changegroup.getbundler(
+            version,
+            repo,
+            matcher=newmatch,
+            ellipses=True,
+            shallow=depth is not None,
+            ellipsisroots=ellipsisroots,
+            fullnodes=relevant_nodes,
+        )
+        cgdata = packer.generate(common, visitnodes, False, b'narrow_widen')
+
+        part = bundler.newpart(b'changegroup', data=cgdata)
+        part.addparam(b'version', version)
+        if b'treemanifest' in repo.requirements:
+            part.addparam(b'treemanifest', b'1')
+
+
 @bundle2.parthandler(_SPECPART, (_SPECPART_INCLUDE, _SPECPART_EXCLUDE))
 def _handlechangespec_2(op, inpart):
     # XXX: This bundle2 handling is buggy and should be removed after hg5.2 is

hgext/narrow/narrowwirepeer.py

@@ -120,7 +120,7 b' def narrow_widen('
                 ellipses,
             )
         else:
-            narrowbundle2.generateellipsesbundle2(
+            narrowbundle2.generate_ellipses_bundle2_for_widening(
                 bundler,
                 repo,
                 oldincludes,