view tests/test-bookmarks-merge.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

# init

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m'a'
  $ echo b > b
  $ hg add b
  $ hg commit -m'b'
  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c > c
  $ hg add c
  $ hg commit -m'c'
  created new head

# test merging of diverged bookmarks
  $ hg bookmark -r 1 "c@diverge"
  $ hg bookmark -r 1 b
  $ hg bookmark c
  $ hg bookmarks
     b                         1:d2ae7f538514
   * c                         2:d36c0562f908
     c@diverge                 1:d2ae7f538514
  $ hg merge "c@diverge"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m'merge'
  $ hg bookmarks
     b                         1:d2ae7f538514
   * c                         3:b8f96cf4688b

  $ hg up -C 3
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark c)
  $ echo d > d
  $ hg add d
  $ hg commit -m'd'

  $ hg up -C 3
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo e > e
  $ hg add e
  $ hg commit -m'e'
  created new head
  $ hg up -C 5
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg bookmark e
  $ hg bookmarks
     b                         1:d2ae7f538514
     c                         3:b8f96cf4688b
   * e                         5:26bee9c5bcf3

# the picked side is bookmarked

  $ hg up -C 4
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark e)
  $ hg merge
  abort: heads are bookmarked - please merge with an explicit rev
  (run 'hg heads' to see all heads)
  [255]

# our revision is bookmarked

  $ hg up -C e
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (activating bookmark e)
  $ hg merge
  abort: no matching bookmark to merge - please merge with an explicit rev or bookmark
  (run 'hg heads' to see all heads)
  [255]

# merge bookmark heads

  $ hg up -C 4
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark e)
  $ echo f > f
  $ hg commit -Am "f"
  adding f
  $ hg bookmarks -r 4 "e@diverged"
  $ hg up -q -C "e@diverged"
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg parents
  changeset:   4:a0546fcfe0fb
  bookmark:    e@diverged
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     d
  
  changeset:   5:26bee9c5bcf3
  bookmark:    e
  parent:      3:b8f96cf4688b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     e
  
  $ hg up -C e
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (activating bookmark e)
  $ hg bookmarks
     b                         1:d2ae7f538514
     c                         3:b8f96cf4688b
   * e                         5:26bee9c5bcf3
     e@diverged                4:a0546fcfe0fb
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m'merge'
  $ hg bookmarks
     b                         1:d2ae7f538514
     c                         3:b8f96cf4688b
   * e                         7:ca784329f0ba

# test warning when all heads are inactive bookmarks

  $ hg up -C 6
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark e)
  $ echo g > g
  $ hg commit -Am 'g'
  adding g
  $ hg bookmark -i g
  $ hg bookmarks
     b                         1:d2ae7f538514
     c                         3:b8f96cf4688b
     e                         7:ca784329f0ba
     g                         8:04dd21731d95
  $ hg heads
  changeset:   8:04dd21731d95
  bookmark:    g
  tag:         tip
  parent:      6:be381d1126a0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     g
  
  changeset:   7:ca784329f0ba
  bookmark:    e
  parent:      5:26bee9c5bcf3
  parent:      4:a0546fcfe0fb
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     merge
  
  $ hg merge
  abort: heads are bookmarked - please merge with an explicit rev
  (run 'hg heads' to see all heads)
  [255]