outgoing: rework the handling of the `missingroots` case to be faster

The previous implementation was slow, to the point it was taking a significant
amount of `hg bundle --type none-streamv2` call. We rework the code to compute
the same value much faster, making the operation disappear from the `hg bundle
--type none-streamv2` profile. Someone would remark that producing a streamclone
does not requires an `outgoing` object. However that is a matter for another
day. There is other user of `missingroots` (non stream `hg bundle` call for
example), and they will also benefit from this rework.

We implement an old TODO in the process, directly computing the missing and
common attribute as we have most element at hand already.

### benchmark.name                = hg.command.bundle
  # bin-env-vars.hg.flavor        = default
  # bin-env-vars.hg.py-re2-module = default
  # benchmark.variants.revs       = all
  # benchmark.variants.type       = none-streamv2
 ## data-env-vars.name            = heptapod-public-2024-03-25-zstd-sparse-revlog
before: 7.750458
after:  6.665565  (-14.00%, -1.08)
 ## data-env-vars.name            = mercurial-public-2024-03-22-zstd-sparse-revlog
before: 0.700229
after:  0.496050  (-29.16%, -0.20)
 ## data-env-vars.name            = mozilla-try-2023-03-22-zstd-sparse-revlog
before: 346.508952
after:  316.749699  (-8.59%, -29.76)
 ## data-env-vars.name            = pypy-2024-03-22-zstd-sparse-revlog
before: 3.401700
after:  2.915810  (-14.28%, -0.49)
 ## data-env-vars.name            = tryton-public-2024-03-22-zstd-sparse-revlog
before: 1.870798
after:  1.461583  (-21.87%, -0.41)



note: this whole `missingroots` of outgoing has a limited number of callers and
could likely be replace by something simpler (like taking an explicit
"missing_revs" set for example). However this is a wider change and we focus on
a small impact, quick rework that does not change the API for now.

mercurial/discovery.py

@@ -1,624 +1,646 b''
 # discovery.py - protocol changeset discovery functions
 #
 # Copyright 2010 Olivia 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.
 
 
 import functools
 
 from .i18n import _
 from .node import (
     hex,
     short,
 )
 
 from . import (
     bookmarks,
     branchmap,
     error,
+    node as nodemod,
     obsolete,
     phases,
     pycompat,
     scmutil,
     setdiscovery,
     treediscovery,
     util,
 )
 
 
 def findcommonincoming(repo, remote, heads=None, force=False, ancestorsof=None):
     """Return a tuple (common, anyincoming, heads) used to identify the common
     subset of nodes between repo and remote.
 
     "common" is a list of (at least) the heads of the common subset.
     "anyincoming" is testable as a boolean indicating if any nodes are missing
       locally. If remote does not support getbundle, this actually is a list of
       roots of the nodes that would be incoming, to be supplied to
       changegroupsubset. No code except for pull should be relying on this fact
       any longer.
     "heads" is either the supplied heads, or else the remote's heads.
     "ancestorsof" if not None, restrict the discovery to a subset defined by
       these nodes. Changeset outside of this set won't be considered (but may
       still appear in "common").
 
     If you pass heads and they are all known locally, the response lists just
     these heads in "common" and in "heads".
 
     Please use findcommonoutgoing to compute the set of outgoing nodes to give
     extensions a good hook into outgoing.
     """
 
     if not remote.capable(b'getbundle'):
         return treediscovery.findcommonincoming(repo, remote, heads, force)
 
     if heads:
         knownnode = repo.changelog.hasnode  # no nodemap until it is filtered
         if all(knownnode(h) for h in heads):
             return (heads, False, heads)
 
     res = setdiscovery.findcommonheads(
         repo.ui,
         repo,
         remote,
         abortwhenunrelated=not force,
         ancestorsof=ancestorsof,
     )
     common, anyinc, srvheads = res
     if heads and not anyinc:
         # server could be lying on the advertised heads
         has_node = repo.changelog.hasnode
         anyinc = any(not has_node(n) for n in heads)
     return (list(common), anyinc, heads or list(srvheads))
 
 
 class outgoing:
     """Represents the result of a findcommonoutgoing() call.
 
     Members:
 
       ancestorsof is a list of the nodes whose ancestors are included in the
       outgoing operation.
 
       missing is a list of those ancestors of ancestorsof that are present in
       local but not in remote.
 
       common is a set containing revs common between the local and the remote
       repository (at least all of those that are ancestors of ancestorsof).
 
       commonheads is the list of heads of common.
 
       excluded is the list of missing changeset that shouldn't be sent
       remotely.
 
     Some members are computed on demand from the heads, unless provided upfront
     by discovery."""
 
     def __init__(
         self, repo, commonheads=None, ancestorsof=None, missingroots=None
     ):
-        # at least one of them must not be set
-        assert None in (commonheads, missingroots)
+        # at most one of them must not be set
+        if commonheads is not None and missingroots is not None:
+            m = 'commonheads and missingroots arguments are mutually exclusive'
+            raise error.ProgrammingError(m)
         cl = repo.changelog
+        missing = None
+        common = None
         if ancestorsof is None:
             ancestorsof = cl.heads()
         if missingroots:
             # TODO remove call to nodesbetween.
-            # TODO populate attributes on outgoing instance instead of setting
-            # discbases.
-            csets, roots, heads = cl.nodesbetween(missingroots, ancestorsof)
-            included = set(csets)
-            discbases = []
-            for n in csets:
-                discbases.extend([p for p in cl.parents(n) if p != repo.nullid])
-            ancestorsof = heads
-            commonheads = [n for n in discbases if n not in included]
+            missing_rev = repo.revs('%ln::%ln', missingroots, ancestorsof)
+            unfi = repo.unfiltered()
+            ucl = unfi.changelog
+            to_node = ucl.node
+            ancestorsof = [to_node(r) for r in ucl.headrevs(missing_rev)]
+            parent_revs = ucl.parentrevs
+            common_legs = set()
+            for r in missing_rev:
+                p1, p2 = parent_revs(r)
+                if p1 not in missing_rev:
+                    common_legs.add(p1)
+                if p2 not in missing_rev:
+                    common_legs.add(p2)
+            common_legs.discard(nodemod.nullrev)
+            if not common_legs:
+                commonheads = [repo.nullid]
+                common = set()
+            else:
+                commonheads_revs = unfi.revs(
+                    'heads(%ld::%ld)',
+                    common_legs,
+                    common_legs,
+                )
+                commonheads = [to_node(r) for r in commonheads_revs]
+                common = ucl.ancestors(commonheads_revs, inclusive=True)
+            missing = [to_node(r) for r in missing_rev]
         elif not commonheads:
             commonheads = [repo.nullid]
         self.commonheads = commonheads
         self.ancestorsof = ancestorsof
         self._revlog = cl
-        self._common = None
-        self._missing = None
+        self._common = common
+        self._missing = missing
         self.excluded = []
 
     def _computecommonmissing(self):
         sets = self._revlog.findcommonmissing(
             self.commonheads, self.ancestorsof
         )
         self._common, self._missing = sets
 
     @util.propertycache
     def common(self):
         if self._common is None:
             self._computecommonmissing()
         return self._common
 
     @util.propertycache
     def missing(self):
         if self._missing is None:
             self._computecommonmissing()
         return self._missing
 
 
 def findcommonoutgoing(
     repo, other, onlyheads=None, force=False, commoninc=None, portable=False
 ):
     """Return an outgoing instance to identify the nodes present in repo but
     not in other.
 
     If onlyheads is given, only nodes ancestral to nodes in onlyheads
     (inclusive) are included. If you already know the local repo's heads,
     passing them in onlyheads is faster than letting them be recomputed here.
 
     If commoninc is given, it must be the result of a prior call to
     findcommonincoming(repo, other, force) to avoid recomputing it here.
 
     If portable is given, compute more conservative common and ancestorsof,
     to make bundles created from the instance more portable."""
     # declare an empty outgoing object to be filled later
     og = outgoing(repo, None, None)
 
     # get common set if not provided
     if commoninc is None:
         commoninc = findcommonincoming(
             repo, other, force=force, ancestorsof=onlyheads
         )
     og.commonheads, _any, _hds = commoninc
 
     # compute outgoing
     mayexclude = phases.hassecret(repo) or repo.obsstore
     if not mayexclude:
         og.ancestorsof = onlyheads or repo.heads()
     elif onlyheads is None:
         # use visible heads as it should be cached
         og.ancestorsof = repo.filtered(b"served").heads()
         og.excluded = [ctx.node() for ctx in repo.set(b'secret() or extinct()')]
     else:
         # compute common, missing and exclude secret stuff
         sets = repo.changelog.findcommonmissing(og.commonheads, onlyheads)
         og._common, allmissing = sets
         og._missing = missing = []
         og.excluded = excluded = []
         for node in allmissing:
             ctx = repo[node]
             if ctx.phase() >= phases.secret or ctx.extinct():
                 excluded.append(node)
             else:
                 missing.append(node)
         if len(missing) == len(allmissing):
             ancestorsof = onlyheads
         else:  # update missing heads
             to_rev = repo.changelog.index.rev
             to_node = repo.changelog.node
             excluded_revs = [to_rev(r) for r in excluded]
             onlyheads_revs = [to_rev(r) for r in onlyheads]
             new_heads = phases.new_heads(repo, onlyheads_revs, excluded_revs)
             ancestorsof = [to_node(r) for r in new_heads]
         og.ancestorsof = ancestorsof
     if portable:
         # recompute common and ancestorsof as if -r<rev> had been given for
         # each head of missing, and --base <rev> for each head of the proper
         # ancestors of missing
         og._computecommonmissing()
         cl = repo.changelog
         missingrevs = {cl.rev(n) for n in og._missing}
         og._common = set(cl.ancestors(missingrevs)) - missingrevs
         commonheads = set(og.commonheads)
         og.ancestorsof = [h for h in og.ancestorsof if h not in commonheads]
 
     return og
 
 
 def _headssummary(pushop):
     """compute a summary of branch and heads status before and after push
 
     return {'branch': ([remoteheads], [newheads],
                        [unsyncedheads], [discardedheads])} mapping
 
     - branch: the branch name,
     - remoteheads: the list of remote heads known locally
                    None if the branch is new,
     - newheads: the new remote heads (known locally) with outgoing pushed,
     - unsyncedheads: the list of remote heads unknown locally,
     - discardedheads: the list of heads made obsolete by the push.
     """
     repo = pushop.repo.unfiltered()
     remote = pushop.remote
     outgoing = pushop.outgoing
     cl = repo.changelog
     headssum = {}
     missingctx = set()
     # A. Create set of branches involved in the push.
     branches = set()
     for n in outgoing.missing:
         ctx = repo[n]
         missingctx.add(ctx)
         branches.add(ctx.branch())
 
     with remote.commandexecutor() as e:
         remotemap = e.callcommand(b'branchmap', {}).result()
 
     knownnode = cl.hasnode  # do not use nodemap until it is filtered
     # A. register remote heads of branches which are in outgoing set
     for branch, heads in remotemap.items():
         # don't add head info about branches which we don't have locally
         if branch not in branches:
             continue
         known = []
         unsynced = []
         for h in heads:
             if knownnode(h):
                 known.append(h)
             else:
                 unsynced.append(h)
         headssum[branch] = (known, list(known), unsynced)
 
     # B. add new branch data
     for branch in branches:
         if branch not in headssum:
             headssum[branch] = (None, [], [])
 
     # C. Update newmap with outgoing changes.
     # This will possibly add new heads and remove existing ones.
     newmap = branchmap.remotebranchcache(
         repo,
         (
             (branch, heads[1])
             for branch, heads in headssum.items()
             if heads[0] is not None
         ),
     )
     newmap.update(repo, (ctx.rev() for ctx in missingctx))
     for branch, newheads in newmap.items():
         headssum[branch][1][:] = newheads
     for branch, items in headssum.items():
         for l in items:
             if l is not None:
                 l.sort()
         headssum[branch] = items + ([],)
 
     # If there are no obsstore, no post processing are needed.
     if repo.obsstore:
         torev = repo.changelog.rev
         futureheads = {torev(h) for h in outgoing.ancestorsof}
         futureheads |= {torev(h) for h in outgoing.commonheads}
         allfuturecommon = repo.changelog.ancestors(futureheads, inclusive=True)
         for branch, heads in sorted(pycompat.iteritems(headssum)):
             remoteheads, newheads, unsyncedheads, placeholder = heads
             result = _postprocessobsolete(pushop, allfuturecommon, newheads)
             headssum[branch] = (
                 remoteheads,
                 sorted(result[0]),
                 unsyncedheads,
                 sorted(result[1]),
             )
     return headssum
 
 
 def _oldheadssummary(repo, remoteheads, outgoing, inc=False):
     """Compute branchmapsummary for repo without branchmap support"""
 
     # 1-4b. old servers: Check for new topological heads.
     # Construct {old,new}map with branch = None (topological branch).
     # (code based on update)
     knownnode = repo.changelog.hasnode  # no nodemap until it is filtered
     oldheads = sorted(h for h in remoteheads if knownnode(h))
     # all nodes in outgoing.missing are children of either:
     # - an element of oldheads
     # - another element of outgoing.missing
     # - nullrev
     # This explains why the new head are very simple to compute.
     r = repo.set(b'heads(%ln + %ln)', oldheads, outgoing.missing)
     newheads = sorted(c.node() for c in r)
     # set some unsynced head to issue the "unsynced changes" warning
     if inc:
         unsynced = [None]
     else:
         unsynced = []
     return {None: (oldheads, newheads, unsynced, [])}
 
 
 def _nowarnheads(pushop):
     # Compute newly pushed bookmarks. We don't warn about bookmarked heads.
     repo = pushop.repo.unfiltered()
     remote = pushop.remote
     localbookmarks = repo._bookmarks
 
     with remote.commandexecutor() as e:
         remotebookmarks = e.callcommand(
             b'listkeys',
             {
                 b'namespace': b'bookmarks',
             },
         ).result()
 
     bookmarkedheads = set()
 
     # internal config: bookmarks.pushing
     newbookmarks = [
         localbookmarks.expandname(b)
         for b in pushop.ui.configlist(b'bookmarks', b'pushing')
     ]
 
     for bm in localbookmarks:
         rnode = remotebookmarks.get(bm)
         if rnode and rnode in repo:
             lctx, rctx = repo[localbookmarks[bm]], repo[rnode]
             if bookmarks.validdest(repo, rctx, lctx):
                 bookmarkedheads.add(lctx.node())
         else:
             if bm in newbookmarks and bm not in remotebookmarks:
                 bookmarkedheads.add(localbookmarks[bm])
 
     return bookmarkedheads
 
 
 def checkheads(pushop):
     """Check that a push won't add any outgoing head
 
     raise StateError error and display ui message as needed.
     """
 
     repo = pushop.repo.unfiltered()
     remote = pushop.remote
     outgoing = pushop.outgoing
     remoteheads = pushop.remoteheads
     newbranch = pushop.newbranch
     inc = bool(pushop.incoming)
 
     # Check for each named branch if we're creating new remote heads.
     # To be a remote head after push, node must be either:
     # - unknown locally
     # - a local outgoing head descended from update
     # - a remote head that's known locally and not
     #   ancestral to an outgoing head
     if remoteheads == [repo.nullid]:
         # remote is empty, nothing to check.
         return
 
     if remote.capable(b'branchmap'):
         headssum = _headssummary(pushop)
     else:
         headssum = _oldheadssummary(repo, remoteheads, outgoing, inc)
     pushop.pushbranchmap = headssum
     newbranches = [
         branch for branch, heads in headssum.items() if heads[0] is None
     ]
     # 1. Check for new branches on the remote.
     if newbranches and not newbranch:  # new branch requires --new-branch
         branchnames = b', '.join(sorted(newbranches))
         # Calculate how many of the new branches are closed branches
         closedbranches = set()
         for tag, heads, tip, isclosed in repo.branchmap().iterbranches():
             if isclosed:
                 closedbranches.add(tag)
         closedbranches = closedbranches & set(newbranches)
         if closedbranches:
             errmsg = _(b"push creates new remote branches: %s (%d closed)") % (
                 branchnames,
                 len(closedbranches),
             )
         else:
             errmsg = _(b"push creates new remote branches: %s") % branchnames
         hint = _(b"use 'hg push --new-branch' to create new remote branches")
         raise error.StateError(errmsg, hint=hint)
 
     # 2. Find heads that we need not warn about
     nowarnheads = _nowarnheads(pushop)
 
     # 3. Check for new heads.
     # If there are more heads after the push than before, a suitable
     # error message, depending on unsynced status, is displayed.
     errormsg = None
     for branch, heads in sorted(pycompat.iteritems(headssum)):
         remoteheads, newheads, unsyncedheads, discardedheads = heads
         # add unsynced data
         if remoteheads is None:
             oldhs = set()
         else:
             oldhs = set(remoteheads)
         oldhs.update(unsyncedheads)
         dhs = None  # delta heads, the new heads on branch
         newhs = set(newheads)
         newhs.update(unsyncedheads)
         if unsyncedheads:
             if None in unsyncedheads:
                 # old remote, no heads data
                 heads = None
             else:
                 heads = scmutil.nodesummaries(repo, unsyncedheads)
             if heads is None:
                 repo.ui.status(
                     _(b"remote has heads that are not known locally\n")
                 )
             elif branch is None:
                 repo.ui.status(
                     _(b"remote has heads that are not known locally: %s\n")
                     % heads
                 )
             else:
                 repo.ui.status(
                     _(
                         b"remote has heads on branch '%s' that are "
                         b"not known locally: %s\n"
                     )
                     % (branch, heads)
                 )
         if remoteheads is None:
             if len(newhs) > 1:
                 dhs = list(newhs)
                 if errormsg is None:
                     errormsg = (
                         _(b"push creates new branch '%s' with multiple heads")
                         % branch
                     )
                     hint = _(
                         b"merge or"
                         b" see 'hg help push' for details about"
                         b" pushing new heads"
                     )
         elif len(newhs) > len(oldhs):
             # remove bookmarked or existing remote heads from the new heads list
             dhs = sorted(newhs - nowarnheads - oldhs)
         if dhs:
             if errormsg is None:
                 if branch not in (b'default', None):
                     errormsg = _(
                         b"push creates new remote head %s on branch '%s'"
                     ) % (
                         short(dhs[0]),
                         branch,
                     )
                 elif repo[dhs[0]].bookmarks():
                     errormsg = _(
                         b"push creates new remote head %s "
                         b"with bookmark '%s'"
                     ) % (short(dhs[0]), repo[dhs[0]].bookmarks()[0])
                 else:
                     errormsg = _(b"push creates new remote head %s") % short(
                         dhs[0]
                     )
                 if unsyncedheads:
                     hint = _(
                         b"pull and merge or"
                         b" see 'hg help push' for details about"
                         b" pushing new heads"
                     )
                 else:
                     hint = _(
                         b"merge or"
                         b" see 'hg help push' for details about"
                         b" pushing new heads"
                     )
             if branch is None:
                 repo.ui.note(_(b"new remote heads:\n"))
             else:
                 repo.ui.note(_(b"new remote heads on branch '%s':\n") % branch)
             for h in dhs:
                 repo.ui.note(b" %s\n" % short(h))
     if errormsg:
         raise error.StateError(errormsg, hint=hint)
 
 
 def _postprocessobsolete(pushop, futurecommon, candidate_newhs):
     """post process the list of new heads with obsolescence information
 
     Exists as a sub-function to contain the complexity and allow extensions to
     experiment with smarter logic.
 
     Returns (newheads, discarded_heads) tuple
     """
     # known issue
     #
     # * We "silently" skip processing on all changeset unknown locally
     #
     # * if <nh> is public on the remote, it won't be affected by obsolete
     #     marker and a new is created
 
     # define various utilities and containers
     repo = pushop.repo
     unfi = repo.unfiltered()
     torev = unfi.changelog.index.get_rev
     public = phases.public
     getphase = unfi._phasecache.phase
     ispublic = lambda r: getphase(unfi, r) == public
     ispushed = lambda n: torev(n) in futurecommon
     hasoutmarker = functools.partial(pushingmarkerfor, unfi.obsstore, ispushed)
     successorsmarkers = unfi.obsstore.successors
     newhs = set()  # final set of new heads
     discarded = set()  # new head of fully replaced branch
 
     localcandidate = set()  # candidate heads known locally
     unknownheads = set()  # candidate heads unknown locally
     for h in candidate_newhs:
         if h in unfi:
             localcandidate.add(h)
         else:
             if successorsmarkers.get(h) is not None:
                 msg = (
                     b'checkheads: remote head unknown locally has'
                     b' local marker: %s\n'
                 )
                 repo.ui.debug(msg % hex(h))
             unknownheads.add(h)
 
     # fast path the simple case
     if len(localcandidate) == 1:
         return unknownheads | set(candidate_newhs), set()
 
     obsrevs = obsolete.getrevs(unfi, b'obsolete')
     futurenonobsolete = frozenset(futurecommon) - obsrevs
 
     # actually process branch replacement
     while localcandidate:
         nh = localcandidate.pop()
         r = torev(nh)
         current_branch = unfi[nh].branch()
         # run this check early to skip the evaluation of the whole branch
         if ispublic(r) or r not in obsrevs:
             newhs.add(nh)
             continue
 
         # Get all revs/nodes on the branch exclusive to this head
         # (already filtered heads are "ignored"))
         branchrevs = unfi.revs(
             b'only(%n, (%ln+%ln))', nh, localcandidate, newhs
         )
 
         branchnodes = []
         for r in branchrevs:
             c = unfi[r]
             if c.branch() == current_branch:
                 branchnodes.append(c.node())
 
         # The branch won't be hidden on the remote if
         # * any part of it is public,
         # * any part of it is considered part of the result by previous logic,
         # * if we have no markers to push to obsolete it.
         if (
             any(ispublic(r) for r in branchrevs)
             or any(torev(n) in futurenonobsolete for n in branchnodes)
             or any(not hasoutmarker(n) for n in branchnodes)
         ):
             newhs.add(nh)
         else:
             # note: there is a corner case if there is a merge in the branch.
             # we might end up with -more- heads.  However, these heads are not
             # "added" by the push, but more by the "removal" on the remote so I
             # think is a okay to ignore them,
             discarded.add(nh)
     newhs |= unknownheads
     return newhs, discarded
 
 
 def pushingmarkerfor(obsstore, ispushed, node):
     """true if some markers are to be pushed for node
 
     We cannot just look in to the pushed obsmarkers from the pushop because
     discovery might have filtered relevant markers. In addition listing all
     markers relevant to all changesets in the pushed set would be too expensive
     (O(len(repo)))
 
     (note: There are cache opportunity in this function. but it would requires
     a two dimensional stack.)
     """
     successorsmarkers = obsstore.successors
     stack = [node]
     seen = set(stack)
     while stack:
         current = stack.pop()
         if ispushed(current):
             return True
         markers = successorsmarkers.get(current, ())
         # markers fields = ('prec', 'succs', 'flag', 'meta', 'date', 'parents')
         for m in markers:
             nexts = m[1]  # successors
             if not nexts:  # this is a prune marker
                 nexts = m[5] or ()  # parents
             for n in nexts:
                 if n not in seen:
                     seen.add(n)
                     stack.append(n)
     return False