view tests/test-rebase-rename.t @ 42743:8c9a6adec67a

rust-discovery: using the children cache in add_missing

The DAG range computation often needs to get back to very old
revisions, and turns out to be disproportionately long, given
that the end goal is to remove the descendents of the given
missing revisons from the undecided set.

The fast iteration capabilities available in the Rust case make
it possible to avoid the DAG range entirely, at the cost of
precomputing the children cache, and to simply iterate on
children of the given missing revisions.

This is a case where staying on the same side of the interface
between the two languages has clear benefits.

On discoveries with initial undecided sets
small enough to bypass sampling entirely, the total cost of
computing the children cache and the subsequent iteration
becomes better than the Python + C counterpart, which relies on
reachableroots2.

For example, on a repo with more than one million revisions with
an initial undecided set of 11 elements, we get these figures:

Rust version with simple iteration
  addcommons: 57.287us
  first undecided computation: 184.278334ms
  first children cache computation: 131.056us
  addmissings iteration: 42.766us
  first addinfo total: 185.24 ms

Python + C version
  first addcommons: 0.29 ms
  addcommons 0.21 ms
  first undecided computation 191.35 ms
  addmissings 45.75 ms
  first addinfo total: 237.77 ms

On discoveries with large undecided sets, the initial price paid
makes the first addinfo slower than the Python + C version,
but that's more than compensated by the gain in sampling and
subsequent iterations.
Here's an extreme example with an undecided set of a million revisions:

Rust version:
  first undecided computation: 293.842629ms
  first children cache computation: 407.911297ms
  addmissings iteration: 34.312869ms
  first addinfo total: 776.02 ms
  taking initial sample
  query 2: sampling time: 1318.38 ms
  query 2; still undecided: 1005013, sample size is: 200
  addmissings: 143.062us

Python + C version:
  first undecided computation 298.13 ms
  addmissings 80.13 ms
  first addinfo total: 399.62 ms
  taking initial sample
  query 2: sampling time: 3957.23 ms
  query 2; still undecided: 1005013, sample size is: 200
  addmissings 52.88 ms

Differential Revision: https://phab.mercurial-scm.org/D6428

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > 
  > [alias]
  > tlog  = log --template "{rev}: {node|short} '{desc}' {branches}\n"
  > tglog = tlog --graph
  > EOF


  $ hg init a
  $ cd a

  $ mkdir d
  $ echo a > a
  $ hg ci -Am A
  adding a

  $ echo b > d/b
  $ hg ci -Am B
  adding d/b

  $ hg mv d d-renamed
  moving d/b to d-renamed/b
  $ hg ci -m 'rename B'

  $ hg up -q -C 1

  $ hg mv a a-renamed
  $ echo x > d/x
  $ hg add d/x

  $ hg ci -m 'rename A'
  created new head

  $ hg tglog
  @  3: 73a3ee40125d 'rename A'
  |
  | o  2: 220d0626d185 'rename B'
  |/
  o  1: 3ab5da9a5c01 'B'
  |
  o  0: 1994f17a630e 'A'
  

Rename is tracked:

  $ hg tlog -p --git -r tip
  3: 73a3ee40125d 'rename A' 
  diff --git a/a b/a-renamed
  rename from a
  rename to a-renamed
  diff --git a/d/x b/d/x
  new file mode 100644
  --- /dev/null
  +++ b/d/x
  @@ -0,0 +1,1 @@
  +x
  
Rebase the revision containing the rename:

  $ hg rebase -s 3 -d 2
  rebasing 3:73a3ee40125d "rename A" (tip)
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/73a3ee40125d-1d78ebcf-rebase.hg

  $ hg tglog
  @  3: 032a9b75e83b 'rename A'
  |
  o  2: 220d0626d185 'rename B'
  |
  o  1: 3ab5da9a5c01 'B'
  |
  o  0: 1994f17a630e 'A'
  

Rename is not lost:

  $ hg tlog -p --git -r tip
  3: 032a9b75e83b 'rename A' 
  diff --git a/a b/a-renamed
  rename from a
  rename to a-renamed
  diff --git a/d-renamed/x b/d-renamed/x
  new file mode 100644
  --- /dev/null
  +++ b/d-renamed/x
  @@ -0,0 +1,1 @@
  +x
  

Rebased revision does not contain information about b (issue3739)

  $ hg log -r 3 --debug
  changeset:   3:032a9b75e83bff1dcfb6cbfa4ef50a704bf1b569
  tag:         tip
  phase:       draft
  parent:      2:220d0626d185f372d9d8f69d9c73b0811d7725f7
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    3:035d66b27a1b06b2d12b46d41a39adb7a200c370
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files+:      a-renamed d-renamed/x
  files-:      a
  extra:       branch=default
  extra:       rebase_source=73a3ee40125d6f0f347082e5831ceccb3f005f8a
  description:
  rename A
  
  

  $ cd ..


  $ hg init b
  $ cd b

  $ echo a > a
  $ hg ci -Am A
  adding a

  $ echo b > b
  $ hg ci -Am B
  adding b

  $ hg cp b b-copied
  $ hg ci -Am 'copy B'

  $ hg up -q -C 1

  $ hg cp a a-copied
  $ hg ci -m 'copy A'
  created new head

  $ hg tglog
  @  3: 0a8162ff18a8 'copy A'
  |
  | o  2: 39e588434882 'copy B'
  |/
  o  1: 6c81ed0049f8 'B'
  |
  o  0: 1994f17a630e 'A'
  
Copy is tracked:

  $ hg tlog -p --git -r tip
  3: 0a8162ff18a8 'copy A' 
  diff --git a/a b/a-copied
  copy from a
  copy to a-copied
  
Rebase the revision containing the copy:

  $ hg rebase -s 3 -d 2
  rebasing 3:0a8162ff18a8 "copy A" (tip)
  saved backup bundle to $TESTTMP/b/.hg/strip-backup/0a8162ff18a8-dd06302a-rebase.hg

  $ hg tglog
  @  3: 98f6e6dbf45a 'copy A'
  |
  o  2: 39e588434882 'copy B'
  |
  o  1: 6c81ed0049f8 'B'
  |
  o  0: 1994f17a630e 'A'
  

Copy is not lost:

  $ hg tlog -p --git -r tip
  3: 98f6e6dbf45a 'copy A' 
  diff --git a/a b/a-copied
  copy from a
  copy to a-copied
  

Rebased revision does not contain information about b (issue3739)

  $ hg log -r 3 --debug
  changeset:   3:98f6e6dbf45ab54079c2237fbd11066a5c41a11d
  tag:         tip
  phase:       draft
  parent:      2:39e588434882ff77d01229d169cdc77f29e8855e
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    3:2232f329d66fffe3930d43479ae624f66322b04d
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files+:      a-copied
  extra:       branch=default
  extra:       rebase_source=0a8162ff18a8900df8df8ef7ac0046955205613e
  description:
  copy A
  
  

  $ cd ..


Test rebase across repeating renames:

  $ hg init repo

  $ cd repo

  $ echo testing > file1.txt
  $ hg add file1.txt
  $ hg ci -m "Adding file1"

  $ hg rename file1.txt file2.txt
  $ hg ci -m "Rename file1 to file2"

  $ echo Unrelated change > unrelated.txt
  $ hg add unrelated.txt
  $ hg ci -m "Unrelated change"

  $ hg rename file2.txt file1.txt
  $ hg ci -m "Rename file2 back to file1"

  $ hg update -r -2
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo Another unrelated change >> unrelated.txt
  $ hg ci -m "Another unrelated change"
  created new head

  $ hg tglog
  @  4: b918d683b091 'Another unrelated change'
  |
  | o  3: 1ac17e43d8aa 'Rename file2 back to file1'
  |/
  o  2: 480101d66d8d 'Unrelated change'
  |
  o  1: be44c61debd2 'Rename file1 to file2'
  |
  o  0: 8ce9a346991d 'Adding file1'
  

  $ hg rebase -s 4 -d 3
  rebasing 4:b918d683b091 "Another unrelated change" (tip)
  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/b918d683b091-3024bc57-rebase.hg

  $ hg diff --stat -c .
   unrelated.txt |  1 +
   1 files changed, 1 insertions(+), 0 deletions(-)

  $ cd ..

Verify that copies get preserved (issue4192).
  $ hg init copy-gets-preserved
  $ cd copy-gets-preserved

  $ echo a > a
  $ hg add a
  $ hg commit --message "File a created"
  $ hg copy a b
  $ echo b > b
  $ hg commit --message "File b created as copy of a and modified"
  $ hg copy b c
  $ echo c > c
  $ hg commit --message "File c created as copy of b and modified"
  $ hg copy c d
  $ echo d > d
  $ hg commit --message "File d created as copy of c and modified"

Note that there are four entries in the log for d
  $ hg tglog --follow d
  @  3: 421b7e82bb85 'File d created as copy of c and modified'
  |
  o  2: 327f772bc074 'File c created as copy of b and modified'
  |
  o  1: 79d255d24ad2 'File b created as copy of a and modified'
  |
  o  0: b220cd6d2326 'File a created'
  
Update back to before we performed copies, and inject an unrelated change.
  $ hg update 0
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved

  $ echo unrelated > unrelated
  $ hg add unrelated
  $ hg commit --message "Unrelated file created"
  created new head
  $ hg update 4
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

Rebase the copies on top of the unrelated change.
  $ hg rebase --source 1 --dest 4
  rebasing 1:79d255d24ad2 "File b created as copy of a and modified"
  rebasing 2:327f772bc074 "File c created as copy of b and modified"
  rebasing 3:421b7e82bb85 "File d created as copy of c and modified"
  saved backup bundle to $TESTTMP/copy-gets-preserved/.hg/strip-backup/79d255d24ad2-a2265555-rebase.hg
  $ hg update 4
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

There should still be four entries in the log for d
  $ hg tglog --follow d
  @  4: dbb9ba033561 'File d created as copy of c and modified'
  |
  o  3: af74b229bc02 'File c created as copy of b and modified'
  |
  o  2: 68bf06433839 'File b created as copy of a and modified'
  :
  o  0: b220cd6d2326 'File a created'
  
Same steps as above, but with --collapse on rebase to make sure the
copy records collapse correctly.
  $ hg co 1
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ echo more >> unrelated
  $ hg ci -m 'unrelated commit is unrelated'
  created new head
  $ hg rebase -s 2 --dest 5 --collapse
  rebasing 2:68bf06433839 "File b created as copy of a and modified"
  rebasing 3:af74b229bc02 "File c created as copy of b and modified"
  merging b and c to c
  rebasing 4:dbb9ba033561 "File d created as copy of c and modified"
  merging c and d to d
  saved backup bundle to $TESTTMP/copy-gets-preserved/.hg/strip-backup/68bf06433839-dde37595-rebase.hg
  $ hg co tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

This should show both revision 3 and 0 since 'd' was transitively a
copy of 'a'.

  $ hg tglog --follow d
  @  3: 5a46b94210e5 'Collapsed revision
  :  * File b created as copy of a and modified
  :  * File c created as copy of b and modified
  :  * File d created as copy of c and modified'
  o  0: b220cd6d2326 'File a created'
  

  $ cd ..