view tests/test-origbackup-conflict.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

Set up repo

  $ cat << EOF >> $HGRCPATH
  > [ui]
  > origbackuppath=.hg/origbackups
  > [merge]
  > checkunknown=warn
  > EOF
  $ hg init repo
  $ cd repo
  $ echo base > base
  $ hg add base
  $ hg commit -m "base"

Make a dir named b that contains a file, and a file named d

  $ mkdir -p b
  $ echo c1 > b/c
  $ echo d1 > d
  $ hg add b/c d
  $ hg commit -m "c1"
  $ hg bookmark c1

Peform an update that causes b/c to be backed up

  $ hg up -q 0
  $ mkdir -p b
  $ echo c2 > b/c
  $ hg up --verbose c1
  resolving manifests
  b/c: replacing untracked file
  getting b/c
  creating directory: $TESTTMP/repo/.hg/origbackups/b
  getting d
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark c1)
  $ test -f .hg/origbackups/b/c

Make files named b and d

  $ hg up -q 0
  $ echo b1 > b
  $ echo d2 > d
  $ hg add b d
  $ hg commit -m b1
  created new head
  $ hg bookmark b1

Perform an update that causes b to be backed up - it should replace the backup b dir

  $ hg up -q 0
  $ echo b2 > b
  $ hg up --verbose b1
  resolving manifests
  b: replacing untracked file
  getting b
  removing conflicting directory: $TESTTMP/repo/.hg/origbackups/b
  getting d
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark b1)
  $ test -f .hg/origbackups/b

Perform an update the causes b/c to be backed up again - it should replace the backup b file

  $ hg up -q 0
  $ mkdir b
  $ echo c3 > b/c
  $ hg up --verbose c1
  resolving manifests
  b/c: replacing untracked file
  getting b/c
  creating directory: $TESTTMP/repo/.hg/origbackups/b
  removing conflicting file: $TESTTMP/repo/.hg/origbackups/b
  getting d
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark c1)
  $ test -d .hg/origbackups/b

Cause two symlinks to be backed up that points to a valid location from the backup dir

  $ hg up -q 0
  $ mkdir ../sym-link-target
#if symlink
  $ ln -s ../../../sym-link-target b
  $ ln -s ../../../sym-link-target d
#else
  $ touch b d
#endif
  $ hg up b1
  b: replacing untracked file
  d: replacing untracked file
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark b1)
#if symlink
  $ readlink.py .hg/origbackups/b
  .hg/origbackups/b -> ../../../sym-link-target
#endif

Perform an update that causes b/c and d to be backed up again - b/c should not go into the target dir

  $ hg up -q 0
  $ mkdir b
  $ echo c4 > b/c
  $ echo d3 > d
  $ hg up --verbose c1
  resolving manifests
  b/c: replacing untracked file
  d: replacing untracked file
  getting b/c
  creating directory: $TESTTMP/repo/.hg/origbackups/b
  removing conflicting file: $TESTTMP/repo/.hg/origbackups/b
  getting d
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark c1)
  $ cat .hg/origbackups/b/c
  c4
  $ cat .hg/origbackups/d
  d3
  $ ls ../sym-link-target

Incorrectly configure origbackuppath to be under a file

  $ echo data > .hg/badorigbackups
  $ hg up -q 0
  $ mkdir b
  $ echo c5 > b/c
  $ hg up --verbose c1 --config ui.origbackuppath=.hg/badorigbackups
  resolving manifests
  b/c: replacing untracked file
  getting b/c
  creating directory: $TESTTMP/repo/.hg/badorigbackups/b
  removing conflicting file: $TESTTMP/repo/.hg/badorigbackups
  getting d
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark c1)
  $ ls .hg/badorigbackups/b
  c