--- a/CHANGELOG	Sat Dec 09 22:37:10 2017 +0100
+++ b/CHANGELOG	Sat Dec 09 22:49:07 2017 +0100
@@ -7,6 +7,8 @@
   * verbosity: respect --quiet for prev, next and summary
   * note: add a `-n/--note` flag to all history rewritting commands
   * obslog: shows the obsmarkers notes
+  * obsdiscover: Improved stable range slice for the experimental obshashrange
+                 (client and server need to upgrade to this version)
 
 topic (0.6.0)
 

--- a/hgext3rd/evolve/stablerange.py	Sat Dec 09 22:37:10 2017 +0100
+++ b/hgext3rd/evolve/stablerange.py	Sat Dec 09 22:49:07 2017 +0100
@@ -247,7 +247,11 @@
 
         # search for range defining the lower set of revision
         #
-        # we walk the lower set 
+        # we walk the lower set from the top following the stable order of the
+        # current "head" of the lower range.
+        #
+        # As soon as the revision in the lowerset diverges from the one in the
+        # range being generated, we emit the range and start a new one.
         result = []
         lowerrevs = self.revsfromrange(repo, rangeid)[:(slicepoint - index)]
         head = None
@@ -581,45 +585,15 @@
             parents = self._parents
             bheads = set(bottomrevs)
             du = bheads.difference_update
-            reachableroots = repo.changelog.reachableroots
-            minrev = min(bottomrevs)
             for r in bottomrevs:
                 du(parents(r, parentrevs))
-            for h in bheads:
-                # reachable roots is fast because is C
-                #
-                # It is worth noting that will use this kind of filtering from
-                # "h" multiple time in a warming run. So using "ancestors" and
-                # caching that should be faster. But python code filtering on
-                # the ancestors end up being slower.
-                hrevs = reachableroots(minrev, [h], bottomrevs, True)
-                start = self.depthrev(repo, h) - len(hrevs)
-                entry = (h, start)
-                result.append(entry)
-
-            # Talking about python code being slow, the following code is an
-            # alternative implementation.
-            #
-            # It complexity is better since is does a single traversal on the
-            # bottomset. However since it is all python it end up being
-            # slower.
-            # I'm keeping it here as an inspiration for a future C version
-            # branches = []
-            # for current in reversed(bottomrevs):
-            #     ps = parents(current, parentrevs)
-            #     found = False
-            #     for brevs, bexpect in branches:
-            #         if current in bexpect:
-            #             found = True
-            #             brevs.append(current)
-            #             bexpect.discard(current)
-            #             bexpect.update(ps)
-            #     if not found:
-            #         branches.append(([current], set(ps)))
-            # for revs, __ in reversed(branches):
-            #     head = revs[0]
-            #     index = self.depthrev(repo, head) - len(revs)
-            #     result.append((head, index))
+            seen = 0
+            for r in bottomrevs:
+                seen += 1
+                # XXX bheads might not be a good enough criteria
+                if r in bheads:
+                    result.append((r, self.depthrev(repo, r) - seen))
+                    seen = 0
 
         # top part is trivial
         top = (rangeid[0], globalindex)

--- a/tests/test-stablerange.t	Sat Dec 09 22:37:10 2017 +0100
+++ b/tests/test-stablerange.t	Sat Dec 09 22:49:07 2017 +0100
@@ -449,15 +449,14 @@
 We are still able to reuse one of the branch however
 
   $ hg debugstablerange --verify --verbose --subranges --rev merge
-  8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), 8aca7f8c9bd2-8 (10, 11, 3)
+  8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), 8aca7f8c9bd2-8 (10, 11, 3)
   bebd167eb94d-0 (4, 5, 5) [complete] - 2dc09a01254d-0 (3, 4, 4), bebd167eb94d-4 (4, 5, 1)
   2dc09a01254d-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2dc09a01254d-2 (3, 4, 2)
-  42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
+  42b07e8da27d-1 (7, 4, 3) [complete] - de561312eff4-1 (5, 2, 1), 42b07e8da27d-2 (7, 4, 2)
   8aca7f8c9bd2-8 (10, 11, 3) [complete] - f4b7da68b467-4 (9, 6, 2), 8aca7f8c9bd2-10 (10, 11, 1)
   2dc09a01254d-2 (3, 4, 2) [complete] - 01241442b3c2-2 (2, 3, 1), 2dc09a01254d-3 (3, 4, 1)
   42b07e8da27d-2 (7, 4, 2) [complete] - b9bc20507e0b-2 (6, 3, 1), 42b07e8da27d-3 (7, 4, 1)
   66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-  de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
   f4b7da68b467-4 (9, 6, 2) [complete] - 857477a9aebb-4 (8, 5, 1), f4b7da68b467-5 (9, 6, 1)
   01241442b3c2-2 (2, 3, 1) [leaf] - 
   1ea73414a91b-0 (0, 1, 1) [leaf] - 
@@ -474,16 +473,15 @@
   $ diff -u left.range merge.range
   --- left.range	* (glob)
   +++ merge.range	* (glob)
-  @@ -1,9 +1,21 @@
-  +8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), 8aca7f8c9bd2-8 (10, 11, 3)
+  @@ -1,9 +1,20 @@
+  +8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), 8aca7f8c9bd2-8 (10, 11, 3)
    bebd167eb94d-0 (4, 5, 5) [complete] - 2dc09a01254d-0 (3, 4, 4), bebd167eb94d-4 (4, 5, 1)
    2dc09a01254d-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2dc09a01254d-2 (3, 4, 2)
-  +42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
+  +42b07e8da27d-1 (7, 4, 3) [complete] - de561312eff4-1 (5, 2, 1), 42b07e8da27d-2 (7, 4, 2)
   +8aca7f8c9bd2-8 (10, 11, 3) [complete] - f4b7da68b467-4 (9, 6, 2), 8aca7f8c9bd2-10 (10, 11, 1)
    2dc09a01254d-2 (3, 4, 2) [complete] - 01241442b3c2-2 (2, 3, 1), 2dc09a01254d-3 (3, 4, 1)
   +42b07e8da27d-2 (7, 4, 2) [complete] - b9bc20507e0b-2 (6, 3, 1), 42b07e8da27d-3 (7, 4, 1)
    66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-  +de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
   +f4b7da68b467-4 (9, 6, 2) [complete] - 857477a9aebb-4 (8, 5, 1), f4b7da68b467-5 (9, 6, 1)
    01241442b3c2-2 (2, 3, 1) [leaf] - 
    1ea73414a91b-0 (0, 1, 1) [leaf] - 
@@ -500,17 +498,18 @@
   $ diff -u right.range merge.range
   --- right.range	* (glob)
   +++ merge.range	* (glob)
-  @@ -1,11 +1,21 @@
+  @@ -1,11 +1,20 @@
   -f4b7da68b467-0 (9, 6, 6) [complete] - 42b07e8da27d-0 (7, 4, 4), f4b7da68b467-4 (9, 6, 2)
-  +8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), 8aca7f8c9bd2-8 (10, 11, 3)
+  -42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
+  +8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), 8aca7f8c9bd2-8 (10, 11, 3)
   +bebd167eb94d-0 (4, 5, 5) [complete] - 2dc09a01254d-0 (3, 4, 4), bebd167eb94d-4 (4, 5, 1)
   +2dc09a01254d-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2dc09a01254d-2 (3, 4, 2)
-   42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
+  +42b07e8da27d-1 (7, 4, 3) [complete] - de561312eff4-1 (5, 2, 1), 42b07e8da27d-2 (7, 4, 2)
   +8aca7f8c9bd2-8 (10, 11, 3) [complete] - f4b7da68b467-4 (9, 6, 2), 8aca7f8c9bd2-10 (10, 11, 1)
   +2dc09a01254d-2 (3, 4, 2) [complete] - 01241442b3c2-2 (2, 3, 1), 2dc09a01254d-3 (3, 4, 1)
    42b07e8da27d-2 (7, 4, 2) [complete] - b9bc20507e0b-2 (6, 3, 1), 42b07e8da27d-3 (7, 4, 1)
+  -de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
   +66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-   de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
    f4b7da68b467-4 (9, 6, 2) [complete] - 857477a9aebb-4 (8, 5, 1), f4b7da68b467-5 (9, 6, 1)
   +01241442b3c2-2 (2, 3, 1) [leaf] - 
    1ea73414a91b-0 (0, 1, 1) [leaf] - 
@@ -528,17 +527,16 @@
 Range above the merge, reuse subrange from the merge
 
   $ hg debugstablerange --verify --verbose --subranges --rev tip
-  e6b8d5b46647-0 (12, 13, 13) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), e6b8d5b46647-8 (12, 13, 5)
+  e6b8d5b46647-0 (12, 13, 13) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), e6b8d5b46647-8 (12, 13, 5)
   bebd167eb94d-0 (4, 5, 5) [complete] - 2dc09a01254d-0 (3, 4, 4), bebd167eb94d-4 (4, 5, 1)
   e6b8d5b46647-8 (12, 13, 5) [complete] - 485383494a89-8 (11, 12, 4), e6b8d5b46647-12 (12, 13, 1)
   2dc09a01254d-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2dc09a01254d-2 (3, 4, 2)
-  42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
   485383494a89-8 (11, 12, 4) [complete] - f4b7da68b467-4 (9, 6, 2), 485383494a89-10 (11, 12, 2)
+  42b07e8da27d-1 (7, 4, 3) [complete] - de561312eff4-1 (5, 2, 1), 42b07e8da27d-2 (7, 4, 2)
   2dc09a01254d-2 (3, 4, 2) [complete] - 01241442b3c2-2 (2, 3, 1), 2dc09a01254d-3 (3, 4, 1)
   42b07e8da27d-2 (7, 4, 2) [complete] - b9bc20507e0b-2 (6, 3, 1), 42b07e8da27d-3 (7, 4, 1)
   485383494a89-10 (11, 12, 2) [complete] - 8aca7f8c9bd2-10 (10, 11, 1), 485383494a89-11 (11, 12, 1)
   66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-  de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
   f4b7da68b467-4 (9, 6, 2) [complete] - 857477a9aebb-4 (8, 5, 1), f4b7da68b467-5 (9, 6, 1)
   01241442b3c2-2 (2, 3, 1) [leaf] - 
   1ea73414a91b-0 (0, 1, 1) [leaf] - 
@@ -557,22 +555,21 @@
   $ diff -u merge.range tip.range
   --- merge.range	* (glob)
   +++ tip.range	* (glob)
-  @@ -1,10 +1,12 @@
-  -8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), 8aca7f8c9bd2-8 (10, 11, 3)
-  +e6b8d5b46647-0 (12, 13, 13) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-0 (7, 4, 4), e6b8d5b46647-8 (12, 13, 5)
+  @@ -1,20 +1,24 @@
+  -8aca7f8c9bd2-0 (10, 11, 11) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), 8aca7f8c9bd2-8 (10, 11, 3)
+  +e6b8d5b46647-0 (12, 13, 13) [complete] - bebd167eb94d-0 (4, 5, 5), 42b07e8da27d-1 (7, 4, 3), e6b8d5b46647-8 (12, 13, 5)
    bebd167eb94d-0 (4, 5, 5) [complete] - 2dc09a01254d-0 (3, 4, 4), bebd167eb94d-4 (4, 5, 1)
   +e6b8d5b46647-8 (12, 13, 5) [complete] - 485383494a89-8 (11, 12, 4), e6b8d5b46647-12 (12, 13, 1)
    2dc09a01254d-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2dc09a01254d-2 (3, 4, 2)
-   42b07e8da27d-0 (7, 4, 4) [complete] - de561312eff4-0 (5, 2, 2), 42b07e8da27d-2 (7, 4, 2)
+  +485383494a89-8 (11, 12, 4) [complete] - f4b7da68b467-4 (9, 6, 2), 485383494a89-10 (11, 12, 2)
+   42b07e8da27d-1 (7, 4, 3) [complete] - de561312eff4-1 (5, 2, 1), 42b07e8da27d-2 (7, 4, 2)
   -8aca7f8c9bd2-8 (10, 11, 3) [complete] - f4b7da68b467-4 (9, 6, 2), 8aca7f8c9bd2-10 (10, 11, 1)
-  +485383494a89-8 (11, 12, 4) [complete] - f4b7da68b467-4 (9, 6, 2), 485383494a89-10 (11, 12, 2)
    2dc09a01254d-2 (3, 4, 2) [complete] - 01241442b3c2-2 (2, 3, 1), 2dc09a01254d-3 (3, 4, 1)
    42b07e8da27d-2 (7, 4, 2) [complete] - b9bc20507e0b-2 (6, 3, 1), 42b07e8da27d-3 (7, 4, 1)
   +485383494a89-10 (11, 12, 2) [complete] - 8aca7f8c9bd2-10 (10, 11, 1), 485383494a89-11 (11, 12, 1)
    66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-   de561312eff4-0 (5, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), de561312eff4-1 (5, 2, 1)
    f4b7da68b467-4 (9, 6, 2) [complete] - 857477a9aebb-4 (8, 5, 1), f4b7da68b467-5 (9, 6, 1)
-  @@ -12,10 +14,12 @@
+   01241442b3c2-2 (2, 3, 1) [leaf] - 
    1ea73414a91b-0 (0, 1, 1) [leaf] - 
    2dc09a01254d-3 (3, 4, 1) [leaf] - 
    42b07e8da27d-3 (7, 4, 1) [leaf] - 
@@ -664,7 +661,7 @@
   b4594d867745-0 (13, 6, 6) [complete] - 2b6d669947cd-0 (3, 4, 4), b4594d867745-4 (13, 6, 2)
   e46a4836065c-0 (12, 6, 6) [complete] - 2b6d669947cd-0 (3, 4, 4), e46a4836065c-4 (12, 6, 2)
   2702dd0c91e7-0 (6, 5, 5) [complete] - f0f3ef9a6cd5-0 (5, 4, 4), 2702dd0c91e7-4 (6, 5, 1)
-  1d8d22637c2d-4 (15, 8, 4) [complete] - 4c748ffd1a46-2 (4, 3, 1), 43227190fef8-4 (14, 5, 1), 1d8d22637c2d-6 (15, 8, 2)
+  1d8d22637c2d-4 (15, 8, 4) [complete] - 43227190fef8-4 (14, 5, 1), 4c748ffd1a46-2 (4, 3, 1), 1d8d22637c2d-6 (15, 8, 2)
   2b6d669947cd-0 (3, 4, 4) [complete] - 66f7d451a68b-0 (1, 2, 2), 2b6d669947cd-2 (3, 4, 2)
   f0f3ef9a6cd5-0 (5, 4, 4) [complete] - fa942426a6fd-0 (2, 2, 2), f0f3ef9a6cd5-2 (5, 4, 2)
   dcbb326fdec2-4 (9, 7, 3) [complete] - d62d843c9a01-4 (8, 6, 2), dcbb326fdec2-6 (9, 7, 1)
@@ -723,10 +720,9 @@
   36315563e2fa 3
   f37e476fba9a 5
   $ hg debugstablerange --verify --verbose --subranges --rev 'head()'
-  f37e476fba9a-0 (4, 5, 5) [complete] - 66f7d451a68b-0 (1, 2, 2), 36315563e2fa-0 (3, 3, 3), f37e476fba9a-4 (4, 5, 1)
-  36315563e2fa-0 (3, 3, 3) [complete] - fa942426a6fd-0 (2, 2, 2), 36315563e2fa-2 (3, 3, 1)
+  f37e476fba9a-0 (4, 5, 5) [complete] - 66f7d451a68b-0 (1, 2, 2), 36315563e2fa-1 (3, 3, 2), f37e476fba9a-4 (4, 5, 1)
+  36315563e2fa-1 (3, 3, 2) [complete] - fa942426a6fd-1 (2, 2, 1), 36315563e2fa-2 (3, 3, 1)
   66f7d451a68b-0 (1, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), 66f7d451a68b-1 (1, 2, 1)
-  fa942426a6fd-0 (2, 2, 2) [complete] - 1ea73414a91b-0 (0, 1, 1), fa942426a6fd-1 (2, 2, 1)
   1ea73414a91b-0 (0, 1, 1) [leaf] - 
   36315563e2fa-2 (3, 3, 1) [leaf] - 
   66f7d451a68b-1 (1, 2, 1) [leaf] -