view tests/test-mq-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

Setup extension:

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [mq]
  > git = keep
  > EOF

Test merge with mq changeset as the second parent:

  $ hg init m
  $ cd m
  $ touch a b c
  $ hg add a
  $ hg commit -m a
  $ hg add b
  $ hg qnew -d "0 0" b
  $ hg update 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg add c
  $ hg commit -m c
  created new head
  $ 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
  abort: cannot commit over an applied mq patch
  [255]
  $ cd ..

Issue529: mq aborts when merging patch deleting files

  $ checkundo()
  > {
  >     if [ -f .hg/store/undo ]; then
  >         echo ".hg/store/undo still exists"
  >     fi
  > }

Commit two dummy files in "init" changeset:

  $ hg init t
  $ cd t
  $ echo a > a
  $ echo b > b
  $ hg ci -Am init
  adding a
  adding b
  $ hg tag -l init

Create a patch removing a:

  $ hg qnew rm_a
  $ hg rm a
  $ hg qrefresh -m "rm a"

Save the patch queue so we can merge it later:

  $ hg qsave -c -e
  copy $TESTTMP/t/.hg/patches to $TESTTMP/t/.hg/patches.1
  $ checkundo

Update b and commit in an "update" changeset:

  $ hg up -C init
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b >> b
  $ hg st
  M b
  $ hg ci -m update
  created new head

# Here, qpush used to abort with :
# The system cannot find the file specified => a
  $ hg manifest
  a
  b

  $ hg qpush -a -m
  merging with queue at: $TESTTMP/t/.hg/patches.1
  applying rm_a
  now at: rm_a

  $ checkundo
  $ hg manifest
  b

Ensure status is correct after merge:

  $ hg qpop -a
  popping rm_a
  popping .hg.patches.merge.marker
  patch queue now empty

  $ cd ..

Classic MQ merge sequence *with an explicit named queue*:

  $ hg init t2
  $ cd t2
  $ echo '[diff]' > .hg/hgrc
  $ echo 'nodates = 1' >> .hg/hgrc
  $ echo a > a
  $ hg ci -Am init
  adding a
  $ echo b > a
  $ hg ci -m changea
  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg cp a aa
  $ echo c >> a
  $ hg qnew --git -f -e patcha
  $ echo d >> a
  $ hg qnew -d '0 0' -f -e patcha2

Create the reference queue:

  $ hg qsave -c -e -n refqueue
  copy $TESTTMP/t2/.hg/patches to $TESTTMP/t2/.hg/refqueue
  $ hg up -C 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

Merge:

  $ HGMERGE=internal:other hg qpush -a -m -n refqueue
  merging with queue at: $TESTTMP/t2/.hg/refqueue
  applying patcha
  patching file a
  Hunk #1 succeeded at 2 with fuzz 1 (offset 0 lines).
  fuzz found when applying patch, stopping
  patch didn't work out, merging patcha
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  0 files updated, 2 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  applying patcha2
  now at: patcha2

Check patcha is still a git patch:

  $ cat .hg/patches/patcha
  # HG changeset patch
  # Parent  d3873e73d99ef67873dac33fbcc66268d5d2b6f4
  
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,1 +1,2 @@
  -b
  +a
  +c
  diff --git a/a b/aa
  copy from a
  copy to aa
  --- a/a
  +++ b/aa
  @@ -1,1 +1,1 @@
  -b
  +a

Check patcha2 is still a regular patch:

  $ cat .hg/patches/patcha2
  # HG changeset patch
  # Date 0 0
  # Parent  ???????????????????????????????????????? (glob)
  
  diff -r ???????????? -r ???????????? a (glob)
  --- a/a
  +++ b/a
  @@ -1,2 +1,3 @@
   a
   c
  +d

  $ cd ..