view tests/test-import-merge.t @ 44363:f7459da77f23

nodemap: introduce an option to use mmap to read the nodemap mapping

The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.

This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).

Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:

Before:

 * do not use the persistent nodemap
 * use the CPython implementation of the index for nodemap
 * use mmapping of the changelog index

After:

 * use the MixedIndex Rust code, with the NodeTree object for nodemap access
   (still in review)
 * use the persistent nodemap data from disk
 * access the persistent nodemap data through mmap
 * use mmapping of the changelog index

The persistent nodemap greatly speed up  most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.

Here are some numbers (in seconds) for the reference copy of mozilla-try:

Revset            Before   After     abs-change speedup

-10000:           0.004622 0.005532   0.000910  ×   0.83
-10:              0.000050 0.000132   0.000082  ×   0.37
tip               0.000052 0.000085   0.000033  ×   0.61
0 + (-10000:)     0.028222 0.005337  -0.022885  ×   5.29
0                 0.023521 0.000084  -0.023437  × 280.01
(-10000:) + 0     0.235539 0.005308  -0.230231  ×  44.37
(-10:) + :9       0.232883 0.000180  -0.232703  ×1293.79
(-10000:) + (:99) 0.238735 0.005358  -0.233377  ×  44.55
:99 + (-10000:)   0.317942 0.005593  -0.312349  ×  56.84
:9 + (-10:)       0.313372 0.000179  -0.313193  ×1750.68
:9                0.316450 0.000143  -0.316307  ×2212.93


On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.

Here are some numbers (in seconds) for the reference copy of mercurial:

Revset            Before   After     abs-change speedup
-10:              0.000065 0.000097   0.000032  × 0.67
tip               0.000063 0.000078   0.000015  × 0.80
0                 0.000561 0.000079  -0.000482  × 7.10
-10000:           0.004609 0.003648  -0.000961  × 1.26
0 + (-10000:)     0.005023 0.003715  -0.001307  × 1.35
(-10:) + :9       0.002187 0.000108  -0.002079  ×20.25
(-10000:) + 0     0.006252 0.003716  -0.002536  × 1.68
(-10000:) + (:99) 0.006367 0.003707  -0.002660  × 1.71
:9 + (-10:)       0.003846 0.000110  -0.003736  ×34.96
:9                0.003854 0.000099  -0.003755  ×38.92
:99 + (-10000:)   0.007644 0.003778  -0.003866  × 2.02

Differential Revision: https://phab.mercurial-scm.org/D7894

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ tipparents() {
  > hg parents --template "{rev}:{node|short} {desc|firstline}\n" -r tip
  > }

Test import and merge diffs

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg ci -m changea
  $ echo c > c
  $ hg ci -Am addc
  adding c
  $ hg up 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b > b
  $ hg ci -Am addb
  adding b
  created new head
  $ hg up 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m merge
  $ hg export . > ../merge.diff
  $ grep -v '^merge$' ../merge.diff > ../merge.nomsg.diff
  $ cd ..
  $ hg clone -r2 repo repo2
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files
  new changesets 07f494440405:890ecaa90481
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo2
  $ hg pull -r3 ../repo
  pulling from ../repo
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 102a90ea7b4a
  (run 'hg heads' to see heads, 'hg merge' to merge)

Test without --exact and diff.p1 == workingdir.p1

  $ hg up 1
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cat > $TESTTMP/editor.sh <<EOF
  > env | grep HGEDITFORM
  > echo merge > \$1
  > EOF
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg import --edit ../merge.nomsg.diff
  applying ../merge.nomsg.diff
  HGEDITFORM=import.normal.merge
  $ tipparents
  1:540395c44225 changea
  3:102a90ea7b4a addb
  $ hg strip --no-backup tip
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Test without --exact and diff.p1 != workingdir.p1

  $ hg up 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import ../merge.diff
  applying ../merge.diff
  warning: import the patch as a normal revision
  (use --exact to import the patch as a merge)
  $ tipparents
  2:890ecaa90481 addc
  $ hg strip --no-backup tip
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Test with --exact

  $ hg import --exact ../merge.diff
  applying ../merge.diff
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ tipparents
  1:540395c44225 changea
  3:102a90ea7b4a addb
  $ hg strip --no-backup tip
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Test with --bypass and diff.p1 == workingdir.p1

  $ hg up 1
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass ../merge.diff
  applying ../merge.diff
  $ tipparents
  1:540395c44225 changea
  3:102a90ea7b4a addb
  $ hg strip --no-backup tip

Test with --bypass and diff.p1 != workingdir.p1

  $ hg up 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass ../merge.diff
  applying ../merge.diff
  warning: import the patch as a normal revision
  (use --exact to import the patch as a merge)
  $ tipparents
  2:890ecaa90481 addc
  $ hg strip --no-backup tip

Test with --bypass and --exact

  $ hg import --bypass --exact ../merge.diff
  applying ../merge.diff
  $ tipparents
  1:540395c44225 changea
  3:102a90ea7b4a addb
  $ hg strip --no-backup tip

  $ cd ..

Test that --exact on a bad header doesn't corrupt the repo (issue3616)

  $ hg init repo3
  $ cd repo3
  $ echo a>a
  $ hg ci -Aqm0
  $ echo a>>a
  $ hg ci -m1
  $ echo a>>a
  $ hg ci -m2
  $ echo a>a
  $ echo b>>a
  $ echo a>>a
  $ hg ci -m3
  $ hg export 2 | head -7 > ../a.patch
  $ hg export tip > out
  >>> apatch = open("../a.patch", "ab")
  >>> apatch.write(b"".join(open("out", 'rb').readlines()[7:])) and None

  $ cd ..
  $ hg clone -qr0 repo3 repo3-clone
  $ cd repo3-clone
  $ hg pull -qr1 ../repo3

  $ hg import --exact ../a.patch
  applying ../a.patch
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  patching file a
  Hunk #1 succeeded at 1 with fuzz 1 (offset -1 lines).
  transaction abort!
  rollback completed
  abort: patch is damaged or loses information
  [255]
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files