changeset 5926:aca07ac01167

divergence-resolution: use last evolution date to choose p1 when merging

Before this patch, we choose the minimum revision as p1 while merging the
two divergent csets which had a drawback that if independent user resolve
the same divergence, their final resolved cset would have different hashes
(because of 'divergence_source_local' and 'divergence_source_other' extras).

Now, we decide the p1 on the basis of which of the two divergent cset
was rewritten more recently. This new logic removes the "different hash"
problem.

To save us from big output changes in the tests due to this change, I also
added the second factor i.e revision_number while sorting the csets wrt dates
(as date is same for all the csets in tests) to fallback to the old way of
picking the revision i.e choosing the minimum rev number.

And to demonstrate that now divergence resolution is independent of which
side user run the `hg evolve --content-div` resolved cset id won't change,
I have added a separate test file.
Flag --config devel.default-date='...' is being used here to record a
custom date in the obsmarkers.

--- a/CHANGELOG	Mon May 17 19:23:09 2021 +0800
+++ b/CHANGELOG	Wed Mar 03 12:40:59 2021 +0530
@@ -5,6 +5,8 @@
 --------------------
 
   * next: add an --abort flag
+  * evolve: use a more stable criteria for picking p1 when solving
+            content-divergence (most recent evolution will be used).
 
 10.3.1 -- 2021-04-25
 --------------------

--- a/hgext3rd/evolve/evolvecmd.py	Mon May 17 19:23:09 2021 +0800
+++ b/hgext3rd/evolve/evolvecmd.py	Wed Mar 03 12:40:59 2021 +0530
@@ -1114,8 +1114,8 @@
     return revs
 
 def _dedupedivergents(repo, revs):
-    """Dedupe the divergents revs in revs to get one from each group with the
-    lowest revision numbers
+    """Dedupe the divergents revs in revs to get one from each group which
+    will be used as p1 while merging the divergent csets
     """
     repo = repo.unfiltered()
     res = set()
@@ -1127,10 +1127,42 @@
         divergent = repo[rev]
         base, others = divergentdata(divergent)
         othersrevs = [o.rev() for o in others]
-        res.add(min([divergent.rev()] + othersrevs))
-        discarded.update(othersrevs)
+        all_divergents = othersrevs + [divergent.rev()]
+        pick, discard = _pick_latest_divergent(repo, all_divergents)
+        res.add(pick)
+        discarded.update(discard)
     return res
 
+def _pick_latest_divergent(repo, divergent_revs):
+    """On the basis of evolution date, pick out the latest evolved revision
+    from all the `divergent_revs` (which are divergent with each other)
+
+    Return a tuple (latest_evolved, others)
+    """
+    mapping = []
+    for rev in divergent_revs:
+        led = latest_evolution_date(repo, repo[rev])
+        # For purpose of comparing, from `led` which is (unixtime, offset)
+        # we only need `unixtime`.
+        mapping.append((led[0], rev))
+    # Sorting by negating the `rev` in key func, to fallback to the old way
+    # of selecting revision, in case when `led` is same while comparing.
+    # Old way: was to select the one with minimum revision number
+    mapping = sorted(mapping, key=lambda v: (v[0], -v[1]))
+    latest_evolved = mapping[-1][1]
+    others = mapping[:-1]
+    others = [val[1] for val in others[:]]
+    return latest_evolved, others
+
+def latest_evolution_date(repo, ctx):
+    """Return latest evolution date of a changeset `ctx`"""
+    node = ctx.node()
+    pred = list(obsutil.closestpredecessors(repo, node))
+    pred.append(node)
+    markers = obsutil.getmarkers(repo, nodes=pred, exclusive=True)
+    markers_dates = (m.date() for m in markers)
+    return max(markers_dates)
+
 def divergentdata(ctx):
     """return base, other part of a conflict
 

--- a/tests/test-check-sdist.t	Mon May 17 19:23:09 2021 +0800
+++ b/tests/test-check-sdist.t	Wed Mar 03 12:40:59 2021 +0530
@@ -35,7 +35,7 @@
 
   $ tar -tzf hg-evolve-*.tar.gz | sed 's|^hg-evolve-[^/]*/||' | sort > files
   $ wc -l files
-  349 files
+  350 files
   $ fgrep debian files
   tests/test-check-debian.t
   $ fgrep __init__.py files

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-evolve-content-divergent-user-independent-resolution.t	Wed Mar 03 12:40:59 2021 +0530
@@ -0,0 +1,127 @@
+=====================================
+Testing content-divergence resolution
+=====================================
+
+Independent rewrites of same changeset can lead to content-divergence. In most
+common cases, it can occur when multiple users rewrite the same changeset
+independently and push it.
+
+This test aims to check that the resolution of content-divergent changesets is
+independent of the user resolving the divergence. In other words, the two users
+resolving the same divergence should end up with the same result.
+
+Setup
+-----
+  $ . $TESTDIR/testlib/content-divergence-util.sh
+  $ setuprepos user-independent-resolution
+  creating test repo for test case user-independent-resolution
+  - upstream
+  - local
+  - other
+  cd into `local` and proceed with env setup
+
+initial
+
+  $ cd upstream
+  $ mkcommit A0
+
+  $ cd ../local
+  $ hg pull -uq
+  $ hg amend -m "A1" --config devel.default-date='172800 19800'
+
+  $ cd ../other
+  $ hg pull -uq
+  $ hg amend -d '2 0' --config devel.default-date='86400 7200'
+  $ hg push -q
+
+  $ cd ../local
+  $ hg push -q
+  2 new content-divergent changesets
+  $ hg pull -q
+  2 new content-divergent changesets
+
+'local' amended desc, 'other' amended date
+------------------------------------------
+  $ hg log -G
+  *  3:1a0af03d20ad (draft): A0 [content-divergent]
+  |
+  | @  2:0d8c87cec5fc (draft): A1 [content-divergent]
+  |/
+  o  0:a9bdc8b26820 (public): O
+  
+  $ hg evolve --content-div
+  merge:[2] A1
+  with: [3] A0
+  base: [1] A0
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  working directory is now at 276e2aee8fe1
+  $ hg log -G
+  @  4:276e2aee8fe1 (draft): A1
+  |
+  o  0:a9bdc8b26820 (public): O
+  
+  $ hg evolve -l
+
+'local' amended date, 'other' amended desc
+------------------------------------------
+  $ cd ../other
+  $ hg pull -q
+  2 new content-divergent changesets
+  $ hg log -G
+  *  3:0d8c87cec5fc (draft): A1 [content-divergent]
+  |
+  | @  2:1a0af03d20ad (draft): A0 [content-divergent]
+  |/
+  o  0:a9bdc8b26820 (public): O
+  
+  $ hg evolve --content-div
+  merge:[3] A1
+  with: [2] A0
+  base: [1] A0
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  working directory is now at 276e2aee8fe1
+
+  $ hg log -G
+  @  4:276e2aee8fe1 (draft): A1
+  |
+  o  0:a9bdc8b26820 (public): O
+  
+  $ hg evolve -l
+
+both users can push/pull without any issue
+------------------------------------------
+
+  $ hg push
+  pushing to $TESTTMP/user-independent-resolution/upstream
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 1 files (+1 heads)
+  2 new obsolescence markers
+  obsoleted 2 changesets
+  $ hg pull ../local
+  pulling from ../local
+  searching for changes
+  no changes found
+  $ hg debugobsolete -r tip
+  0d8c87cec5fc1540b7c0324332375d530856fb56 276e2aee8fe1d3aae5e21dfee47be818fba8d7fc 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '32', 'operation': 'evolve', 'user': 'test'}
+  1a0af03d20ad8b4e3a99d30620c8734efe076900 276e2aee8fe1d3aae5e21dfee47be818fba8d7fc 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '1', 'operation': 'evolve', 'user': 'test'}
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0d8c87cec5fc1540b7c0324332375d530856fb56 0 (Fri Jan 02 18:30:00 1970 -0530) {'ef1': '1', 'operation': 'amend', 'user': 'test'}
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f 1a0af03d20ad8b4e3a99d30620c8734efe076900 0 (Thu Jan 01 22:00:00 1970 -0200) {'ef1': '32', 'operation': 'amend', 'user': 'test'}
+
+  $ cd ../local
+  $ hg push
+  pushing to $TESTTMP/user-independent-resolution/upstream
+  searching for changes
+  no changes found
+  [1]
+  $ hg pull ../other
+  pulling from ../other
+  searching for changes
+  no changes found
+  $ hg debugobsolete -r tip
+  0d8c87cec5fc1540b7c0324332375d530856fb56 276e2aee8fe1d3aae5e21dfee47be818fba8d7fc 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '32', 'operation': 'evolve', 'user': 'test'}
+  1a0af03d20ad8b4e3a99d30620c8734efe076900 276e2aee8fe1d3aae5e21dfee47be818fba8d7fc 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '1', 'operation': 'evolve', 'user': 'test'}
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0d8c87cec5fc1540b7c0324332375d530856fb56 0 (Fri Jan 02 18:30:00 1970 -0530) {'ef1': '1', 'operation': 'amend', 'user': 'test'}
+  28b51eb45704506b5c603decd6bf7ac5e0f6a52f 1a0af03d20ad8b4e3a99d30620c8734efe076900 0 (Thu Jan 01 22:00:00 1970 -0200) {'ef1': '32', 'operation': 'amend', 'user': 'test'}