[PATCH 10 of 11] graft: enable rotated-DAG copy tracing (issue4028)

Gábor Stefanik gabor.stefanik at nng.com
Tue Oct 4 10:39:53 EDT 2016


# HG changeset patch
# User Gábor Stefanik <gabor.stefanik at nng.com>
# Date 1475512693 -7200
#      Mon Oct 03 18:38:13 2016 +0200
# Node ID 9e59cd55604c5e30b38c66c502c8c982c01a4a01
# Parent  5977d6569b2e22487134af7be281e5d60cc987f5
graft: enable rotated-DAG copy tracing (issue4028)

Graft performs a merge in a rotated DAG (with a false common ancestor), which
must be taken into account when tracking copies. Find the real common ancestor
in this case, and track copies between the real and false common ancestors in
reverse.

Using this change, when grafting a commit with a change to a file moved earlier
on the graft's source branch, the change is merged as expected into the original
(unmoved) file, rather than recreating it under its new name.
It should also eventually make it possible to support cross-branch updates that
preserve changes in a dirty working copy.

diff -r 5977d6569b2e -r 9e59cd55604c mercurial/copies.py
--- a/mercurial/copies.py	Tue Oct 04 12:51:54 2016 +0200
+++ b/mercurial/copies.py	Mon Oct 03 18:38:13 2016 +0200
@@ -321,7 +321,23 @@
     if repo.ui.configbool('experimental', 'disablecopytrace'):
         return {}, {}, {}, {}
 
-    dirtyc1 = False # dummy bool for later use
+    # In certain scenarios (e.g. graft, update or rebase), ca can be overridden
+    # We still need to know a real common ancestor in this case
+    # We can't just compute _c1.ancestor(_c2) and compare it to ca, because
+    # there can be multiple common ancestors, e.g. in case of bidmerge.
+    # Because our caller may not know if the revision passed in lieu of the CA
+    # is a genuine common ancestor or not without explicitly checking it, it's
+    # better to determine that here.
+    tca = ca
+    # ca.descendant(wc) and ca.descendant(ca) are False, work around that
+    _c1 = c1.p1() if c1.rev() is None else c1
+    _c2 = c2.p1() if c2.rev() is None else c2
+    dirtyc1 = not (ca == _c1 or ca.descendant(_c1))
+    dirtyc2 = not (ca == _c2 or ca.descendant(_c2))
+    graft = dirtyc1 or dirtyc2
+    if graft:
+        tca = _c1.ancestor(_c2)
+
     limit = _findlimit(repo, c1.rev(), c2.rev())
     if limit is None:
         # no common ancestor, no copies
@@ -331,6 +347,7 @@
     m1 = c1.manifest()
     m2 = c2.manifest()
     ma = ca.manifest()
+    mta = tca.manifest()
 
     # see _checkcopies documentation below for these dicts
     copy1, copy2 = {}, {}
@@ -340,18 +357,26 @@
     diverge, incompletediverge = {}, {}
 
     # find interesting file sets from manifests
+    if graft:
+        repo.ui.debug("  computing unmatched files in rotated DAG\n")
     addedinm1 = m1.filesnotin(ma)
     addedinm2 = m2.filesnotin(ma)
     u1r, u2r = _computenonoverlap(repo, c1, c2, addedinm1, addedinm2)
-    u1u, u2u = u1r, u2r
+    if not graft:
+        u1u, u2u = u1r, u2r
+    else: # need to recompute this for directory move handling when grafting
+        repo.ui.debug("  computing unmatched files in unrotated DAG\n")
+        u1u, u2u = _computenonoverlap(repo, c1, c2, m1.filesnotin(mta),
+                                                  m2.filesnotin(mta))
+
     bothnew = sorted(addedinm1 & addedinm2)
 
     for f in u1u:
-        _checkcopies(c1, f, m1, m2, ca, ca, False, limit, diverge, copy1,
+        _checkcopies(c1, f, m1, m2, ca, tca, dirtyc1, limit, diverge, copy1,
                      fullcopy1, incomplete1, incompletediverge)
 
     for f in u2u:
-        _checkcopies(c2, f, m2, m1, ca, ca, False, limit, diverge, copy2,
+        _checkcopies(c2, f, m2, m1, ca, tca, dirtyc2, limit, diverge, copy2,
                      fullcopy2, incomplete2, incompletediverge)
 
     copy = dict(copy1.items() + copy2.items())
@@ -401,9 +426,9 @@
     # reset incomplete dicts for bothdiverge generation
     incomplete1, incomplete2, incompletediverge = {}, {}, {}
     for f in bothnew:
-        _checkcopies(c1, f, m1, m2, ca, ca, False, limit, bothdiverge, _copy,
+        _checkcopies(c1, f, m1, m2, ca, tca, dirtyc1, limit, bothdiverge, _copy,
                      _fullcopy, incomplete1, incompletediverge)
-        _checkcopies(c2, f, m2, m1, ca, ca, False, limit, bothdiverge, _copy,
+        _checkcopies(c2, f, m2, m1, ca, tca, dirtyc2, limit, bothdiverge, _copy,
                      _fullcopy, incomplete2, incompletediverge)
     if dirtyc1:
         assert incomplete2 == {}
diff -r 5977d6569b2e -r 9e59cd55604c tests/test-graft.t
--- a/tests/test-graft.t	Tue Oct 04 12:51:54 2016 +0200
+++ b/tests/test-graft.t	Mon Oct 03 18:38:13 2016 +0200
@@ -179,6 +179,13 @@
   committing changelog
   grafting 5:97f8bfe72746 "5"
     searching for copies back to rev 1
+    computing unmatched files in rotated DAG
+    computing unmatched files in unrotated DAG
+    unmatched files in other:
+     c
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'c' -> dst: 'b' *
+    checking for directory renames
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 6b9e5368ca4e+, remote: 97f8bfe72746
@@ -193,6 +200,13 @@
   scanning for duplicate grafts
   grafting 4:9c233e8e184d "4"
     searching for copies back to rev 1
+    computing unmatched files in rotated DAG
+    computing unmatched files in unrotated DAG
+    unmatched files in other:
+     c
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'c' -> dst: 'b' *
+    checking for directory renames
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 1905859650ec+, remote: 9c233e8e184d
@@ -842,3 +856,431 @@
   |/
   o  0
   
+Graft from behind a move or rename
+==================================
+
+NOTE: This is affected by issue5343, and will need updating when it's fixed
+
+Possible cases during a regular graft (when ca is between cta and c2):
+
+name | c1<-cta | cta<->ca | ca->c2
+A.0  |         |          |
+A.1  |    X    |          |
+A.2  |         |     X    |
+A.3  |         |          |   X
+A.4  |    X    |     X    |
+A.5  |    X    |          |   X
+A.6  |         |     X    |   X
+A.7  |    X    |     X    |   X
+
+A.0 is trivial, and doesn't need copy tracking.
+For A.1, a forward rename is recorded in the c1 pass, to be followed later.
+In A.2, the rename is recorded in the c2 pass and followed backwards.
+A.3 is recorded in the c2 pass as a forward rename to be duplicated on target.
+In A.4, both passes of checkcopies record incomplete renames, which are
+then joined in mergecopies to record a rename to be followed.
+In A.5 and A.7, the c1 pass records an incomplete rename, while the c2 pass
+records an incomplete divergence. The incomplete rename is then joined to the
+appropriate side of the incomplete divergence, and the result is recorded as a
+divergence. The code doesn't distinguish at all between these two cases, since
+the end result of them is the same: an incomplete divergence joined with an
+incomplete rename into a divergence.
+Finally, A.6 records a divergence entirely in the c2 pass.
+
+A.4 has a degenerate case a<-b<-a->a, where checkcopies isn't needed at all.
+A.5 has a special case a<-b<-b->a, which is treated like a<-b->a in a merge.
+A.6 has a special case a<-a<-b->a. Here, checkcopies will find a spurious
+incomplete divergence, which is in fact complete. This is handled later in
+mergecopies.
+A.7 has 4 special cases: a<-b<-a->b (the "ping-pong" case), a<-b<-c->b,
+a<-b<-a->c and a<-b<-c->a. Of these, only the "ping-pong" case is interesting,
+the others are fairly trivial (a<-b<-c->b and a<-b<-a->c proceed like the base
+case, a<-b<-c->a is treated the same as a<-b<-b->a).
+
+f5a therefore tests the "ping-pong" rename case, where a file is renamed to the
+same name on both branches, then the rename is backed out on one branch, and
+the backout is grafted to the other branch. This creates a challenging rename
+sequence of a<-b<-a->b in the graft target, topological CA, graft CA and graft
+source, respectively. Since rename detection will run on the c1 side for such a
+sequence (as for technical reasons, we split the c1 and c2 sides not at the
+graft CA, but rather at the topological CA), it will pick up a false rename,
+and cause a spurious merge conflict. This false rename is always exactly the
+reverse of the true rename that would be detected on the c2 side, so we can
+correct for it by detecting this condition and reversing as necessary.
+
+First, set up the repository with commits to be grafted
+
+  $ hg init ../graftmove
+  $ cd ../graftmove
+  $ echo c1a > f1a
+  $ echo c2a > f2a
+  $ echo c3a > f3a
+  $ echo c4a > f4a
+  $ echo c5a > f5a
+  $ hg ci -qAm a
+  $ hg mv f1a f1b
+  $ hg mv f3a f3b
+  $ hg mv f5a f5b
+  $ hg ci -qAm b
+  $ echo c1c > f1b
+  $ hg mv f2a f2c
+  $ hg mv f5b f5a
+  $ echo c5c > f5a
+  $ hg ci -qAm c
+  $ hg mv f3b f3d
+  $ echo c4d > f4a
+  $ hg ci -qAm d
+  $ hg log -G
+  @  changeset:   3:aa2584f6dee9
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     d
+  |
+  o  changeset:   2:c8d3926d7649
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     c
+  |
+  o  changeset:   1:7e9aff31b586
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     b
+  |
+  o  changeset:   0:3340a7726e9e
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     a
+  
+
+Test the cases A.2 (f1x), A.3 (f2x) and a special case of A.6 (f5x) where the
+two renames actually converge to the same name (thus no actual divergence).
+
+  $ hg up -q 0 # commit "a"
+  $ hg graft -r 2
+  grafting 2:c8d3926d7649 "c"
+  merging f1a and f1b to f1a
+  merging f5a
+  warning: can't find ancestor for 'f5a' copied from 'f5b'!
+  $ hg status --change .
+  M f1a
+  M f5a
+  A f2c
+  R f2a
+  $ hg cat f1a
+  c1c
+  $ hg cat f1b
+  f1b: no such file in rev 68af396ea7bf
+  [1]
+
+Test the cases A.0 (f4x) and A.6 (f3x)
+
+  $ hg graft -r 3
+  grafting 3:aa2584f6dee9 "d"
+  note: possible conflict - f3b was renamed multiple times to:
+   f3d
+   f3a
+  warning: can't find ancestor for 'f3d' copied from 'f3b'!
+
+Set up the repository for some further tests
+
+  $ hg up -q 0
+  $ hg mv f1a f1e
+  $ echo c2e > f2a
+  $ hg mv f3a f3e
+  $ hg mv f4a f4e
+  $ hg mv f5a f5b
+  $ hg ci -qAm e
+  $ hg log -G
+  @  changeset:   6:52db7f4dcf33
+  |  tag:         tip
+  |  parent:      0:3340a7726e9e
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     e
+  |
+  | o  changeset:   5:29f6ffdbca28
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     d
+  | |
+  | o  changeset:   4:68af396ea7bf
+  |/   parent:      0:3340a7726e9e
+  |    user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     c
+  |
+  | o  changeset:   3:aa2584f6dee9
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     d
+  | |
+  | o  changeset:   2:c8d3926d7649
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     c
+  | |
+  | o  changeset:   1:7e9aff31b586
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     b
+  |
+  o  changeset:   0:3340a7726e9e
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     a
+  
+
+Test the cases A.4 (f1x), the "ping-pong" special case of A.7 (f5x),
+and A.3 with a local content change to be preserved (f2x).
+
+  $ hg graft -r 2
+  grafting 2:c8d3926d7649 "c"
+  merging f1e and f1b to f1e
+  merging f2a and f2c to f2c
+  merging f5b and f5a to f5a
+
+Test the cases A.1 (f4x) and A.7 (f3x).
+
+  $ hg graft -r 3
+  grafting 3:aa2584f6dee9 "d"
+  note: possible conflict - f3b was renamed multiple times to:
+   f3e
+   f3d
+  merging f4e and f4a to f4e
+  warning: can't find ancestor for 'f3d' copied from 'f3b'!
+
+Check the results of the grafts tested
+
+  $ hg log -CGv --patch --git
+  @  changeset:   8:4c243d7a2f50
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f3d f4e
+  |  description:
+  |  d
+  |
+  |
+  |  diff --git a/f3d b/f3d
+  |  new file mode 100644
+  |  --- /dev/null
+  |  +++ b/f3d
+  |  @@ -0,0 +1,1 @@
+  |  +c3a
+  |  diff --git a/f4e b/f4e
+  |  --- a/f4e
+  |  +++ b/f4e
+  |  @@ -1,1 +1,1 @@
+  |  -c4a
+  |  +c4d
+  |
+  o  changeset:   7:9b7ee4960a74
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f1e f2a f2c f5a f5b
+  |  copies:      f2c (f2a) f5a (f5b)
+  |  description:
+  |  c
+  |
+  |
+  |  diff --git a/f1e b/f1e
+  |  --- a/f1e
+  |  +++ b/f1e
+  |  @@ -1,1 +1,1 @@
+  |  -c1a
+  |  +c1c
+  |  diff --git a/f2a b/f2c
+  |  rename from f2a
+  |  rename to f2c
+  |  diff --git a/f5b b/f5a
+  |  rename from f5b
+  |  rename to f5a
+  |  --- a/f5b
+  |  +++ b/f5a
+  |  @@ -1,1 +1,1 @@
+  |  -c5a
+  |  +c5c
+  |
+  o  changeset:   6:52db7f4dcf33
+  |  parent:      0:3340a7726e9e
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f1a f1e f2a f3a f3e f4a f4e f5a f5b
+  |  copies:      f1e (f1a) f3e (f3a) f4e (f4a) f5b (f5a)
+  |  description:
+  |  e
+  |
+  |
+  |  diff --git a/f1a b/f1e
+  |  rename from f1a
+  |  rename to f1e
+  |  diff --git a/f2a b/f2a
+  |  --- a/f2a
+  |  +++ b/f2a
+  |  @@ -1,1 +1,1 @@
+  |  -c2a
+  |  +c2e
+  |  diff --git a/f3a b/f3e
+  |  rename from f3a
+  |  rename to f3e
+  |  diff --git a/f4a b/f4e
+  |  rename from f4a
+  |  rename to f4e
+  |  diff --git a/f5a b/f5b
+  |  rename from f5a
+  |  rename to f5b
+  |
+  | o  changeset:   5:29f6ffdbca28
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f3d f4a
+  | |  description:
+  | |  d
+  | |
+  | |
+  | |  diff --git a/f3d b/f3d
+  | |  new file mode 100644
+  | |  --- /dev/null
+  | |  +++ b/f3d
+  | |  @@ -0,0 +1,1 @@
+  | |  +c3a
+  | |  diff --git a/f4a b/f4a
+  | |  --- a/f4a
+  | |  +++ b/f4a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c4a
+  | |  +c4d
+  | |
+  | o  changeset:   4:68af396ea7bf
+  |/   parent:      0:3340a7726e9e
+  |    user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    files:       f1a f2a f2c f5a
+  |    copies:      f2c (f2a)
+  |    description:
+  |    c
+  |
+  |
+  |    diff --git a/f1a b/f1a
+  |    --- a/f1a
+  |    +++ b/f1a
+  |    @@ -1,1 +1,1 @@
+  |    -c1a
+  |    +c1c
+  |    diff --git a/f2a b/f2c
+  |    rename from f2a
+  |    rename to f2c
+  |    diff --git a/f5a b/f5a
+  |    --- a/f5a
+  |    +++ b/f5a
+  |    @@ -1,1 +1,1 @@
+  |    -c5a
+  |    +c5c
+  |
+  | o  changeset:   3:aa2584f6dee9
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f3b f3d f4a
+  | |  copies:      f3d (f3b)
+  | |  description:
+  | |  d
+  | |
+  | |
+  | |  diff --git a/f3b b/f3d
+  | |  rename from f3b
+  | |  rename to f3d
+  | |  diff --git a/f4a b/f4a
+  | |  --- a/f4a
+  | |  +++ b/f4a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c4a
+  | |  +c4d
+  | |
+  | o  changeset:   2:c8d3926d7649
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f1b f2a f2c f5a f5b
+  | |  copies:      f2c (f2a) f5a (f5b)
+  | |  description:
+  | |  c
+  | |
+  | |
+  | |  diff --git a/f1b b/f1b
+  | |  --- a/f1b
+  | |  +++ b/f1b
+  | |  @@ -1,1 +1,1 @@
+  | |  -c1a
+  | |  +c1c
+  | |  diff --git a/f2a b/f2c
+  | |  rename from f2a
+  | |  rename to f2c
+  | |  diff --git a/f5b b/f5a
+  | |  rename from f5b
+  | |  rename to f5a
+  | |  --- a/f5b
+  | |  +++ b/f5a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c5a
+  | |  +c5c
+  | |
+  | o  changeset:   1:7e9aff31b586
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    files:       f1a f1b f3a f3b f5a f5b
+  |    copies:      f1b (f1a) f3b (f3a) f5b (f5a)
+  |    description:
+  |    b
+  |
+  |
+  |    diff --git a/f1a b/f1b
+  |    rename from f1a
+  |    rename to f1b
+  |    diff --git a/f3a b/f3b
+  |    rename from f3a
+  |    rename to f3b
+  |    diff --git a/f5a b/f5b
+  |    rename from f5a
+  |    rename to f5b
+  |
+  o  changeset:   0:3340a7726e9e
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     files:       f1a f2a f3a f4a f5a
+     description:
+     a
+  
+  
+     diff --git a/f1a b/f1a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f1a
+     @@ -0,0 +1,1 @@
+     +c1a
+     diff --git a/f2a b/f2a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f2a
+     @@ -0,0 +1,1 @@
+     +c2a
+     diff --git a/f3a b/f3a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f3a
+     @@ -0,0 +1,1 @@
+     +c3a
+     diff --git a/f4a b/f4a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f4a
+     @@ -0,0 +1,1 @@
+     +c4a
+     diff --git a/f5a b/f5a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f5a
+     @@ -0,0 +1,1 @@
+     +c5a
+  
+  $ hg cat f2c
+  c2e
diff -r 5977d6569b2e -r 9e59cd55604c tests/test-rebase-conflicts.t
--- a/tests/test-rebase-conflicts.t	Tue Oct 04 12:51:54 2016 +0200
+++ b/tests/test-rebase-conflicts.t	Mon Oct 03 18:38:13 2016 +0200
@@ -238,6 +238,10 @@
    merge against 9:e31216eec445
      detach base 8:8e4e2c1a07ae
     searching for copies back to rev 3
+    computing unmatched files in rotated DAG
+    computing unmatched files in unrotated DAG
+    unmatched files in other:
+     f2.txt
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 8e4e2c1a07ae, local: 4bc80088dc6b+, remote: e31216eec445
@@ -255,6 +259,10 @@
    merge against 10:2f2496ddf49d
      detach base 9:e31216eec445
     searching for copies back to rev 3
+    computing unmatched files in rotated DAG
+    computing unmatched files in unrotated DAG
+    unmatched files in other:
+     f2.txt
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: e31216eec445, local: 19c888675e13+, remote: 2f2496ddf49d


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