view tests/test-absorb-rename.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

  $ cat >> $HGRCPATH << EOF
  > [diff]
  > git=1
  > [extensions]
  > absorb=
  > EOF

  $ sedi() { # workaround check-code
  > pattern="$1"
  > shift
  > for i in "$@"; do
  >     sed "$pattern" "$i" > "$i".tmp
  >     mv "$i".tmp "$i"
  > done
  > }

rename a to b, then b to a

  $ hg init repo1
  $ cd repo1

  $ echo 1 > a
  $ hg ci -A a -m 1
  $ hg mv a b
  $ echo 2 >> b
  $ hg ci -m 2
  $ hg mv b a
  $ echo 3 >> a
  $ hg ci -m 3

  $ hg annotate -ncf a
  0 eff892de26ec a: 1
  1 bf56e1f4f857 b: 2
  2 0b888b00216c a: 3

  $ sedi 's/$/a/' a
  $ hg absorb -apq
  showing changes for a
          @@ -0,3 +0,3 @@
  eff892d -1
  bf56e1f -2
  0b888b0 -3
  eff892d +1a
  bf56e1f +2a
  0b888b0 +3a
  
  3 changesets affected
  0b888b0 3
  bf56e1f 2
  eff892d 1

  $ hg status

  $ hg annotate -ncf a
  0 5d1c5620e6f2 a: 1a
  1 9a14ffe67ae9 b: 2a
  2 9191d121a268 a: 3a

when the first changeset is public

  $ hg phase --public -r 0

  $ sedi 's/a/A/' a

  $ hg absorb -apq
  showing changes for a
          @@ -0,3 +0,3 @@
          -1a
  9a14ffe -2a
  9191d12 -3a
          +1A
  9a14ffe +2A
  9191d12 +3A
  
  2 changesets affected
  9191d12 3
  9a14ffe 2

  $ hg diff
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,3 +1,3 @@
  -1a
  +1A
   2A
   3A

copy a to b

  $ cd ..
  $ hg init repo2
  $ cd repo2

  $ echo 1 > a
  $ hg ci -A a -m 1
  $ hg cp a b
  $ echo 2 >> b
  $ hg ci -m 2

  $ hg log -T '{rev}:{node|short} {desc}\n'
  1:17b72129ab68 2
  0:eff892de26ec 1

  $ sedi 's/$/a/' a
  $ sedi 's/$/b/' b

  $ hg absorb -apq
  showing changes for a
          @@ -0,1 +0,1 @@
  eff892d -1
  eff892d +1a
  showing changes for b
          @@ -0,2 +0,2 @@
          -1
  17b7212 -2
          +1b
  17b7212 +2b
  
  2 changesets affected
  17b7212 2
  eff892d 1

  $ hg diff
  diff --git a/b b/b
  --- a/b
  +++ b/b
  @@ -1,2 +1,2 @@
  -1
  +1b
   2b

copy b to a

  $ cd ..
  $ hg init repo3
  $ cd repo3

  $ echo 1 > b
  $ hg ci -A b -m 1
  $ hg cp b a
  $ echo 2 >> a
  $ hg ci -m 2

  $ hg log -T '{rev}:{node|short} {desc}\n'
  1:e62c256d8b24 2
  0:55105f940d5c 1

  $ sedi 's/$/a/' a
  $ sedi 's/$/a/' b

  $ hg absorb -apq
  showing changes for a
          @@ -0,2 +0,2 @@
          -1
  e62c256 -2
          +1a
  e62c256 +2a
  showing changes for b
          @@ -0,1 +0,1 @@
  55105f9 -1
  55105f9 +1a
  
  2 changesets affected
  e62c256 2
  55105f9 1

  $ hg diff
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,2 +1,2 @@
  -1
  +1a
   2a

"move" b to both a and c, follow a - sorted alphabetically

  $ cd ..
  $ hg init repo4
  $ cd repo4

  $ echo 1 > b
  $ hg ci -A b -m 1
  $ hg cp b a
  $ hg cp b c
  $ hg rm b
  $ echo 2 >> a
  $ echo 3 >> c
  $ hg commit -m cp

  $ hg log -T '{rev}:{node|short} {desc}\n'
  1:366daad8e679 cp
  0:55105f940d5c 1

  $ sedi 's/$/a/' a
  $ sedi 's/$/c/' c

  $ hg absorb -apq
  showing changes for a
          @@ -0,2 +0,2 @@
  55105f9 -1
  366daad -2
  55105f9 +1a
  366daad +2a
  showing changes for c
          @@ -0,2 +0,2 @@
          -1
  366daad -3
          +1c
  366daad +3c
  
  2 changesets affected
  366daad cp
  55105f9 1

  $ hg log -G -p -T '{rev}:{node|short} {desc}\n'
  @  1:70606019f91b cp
  |  diff --git a/b b/a
  |  rename from b
  |  rename to a
  |  --- a/b
  |  +++ b/a
  |  @@ -1,1 +1,2 @@
  |   1a
  |  +2a
  |  diff --git a/b b/c
  |  copy from b
  |  copy to c
  |  --- a/b
  |  +++ b/c
  |  @@ -1,1 +1,2 @@
  |  -1a
  |  +1
  |  +3c
  |
  o  0:bfb67c3539c1 1
     diff --git a/b b/b
     new file mode 100644
     --- /dev/null
     +++ b/b
     @@ -0,0 +1,1 @@
     +1a
  
run absorb again would apply the change to c

  $ hg absorb -apq
  showing changes for c
          @@ -0,1 +0,1 @@
  7060601 -1
  7060601 +1c
  
  1 changesets affected
  7060601 cp

  $ hg log -G -p -T '{rev}:{node|short} {desc}\n'
  @  1:8bd536cce368 cp
  |  diff --git a/b b/a
  |  rename from b
  |  rename to a
  |  --- a/b
  |  +++ b/a
  |  @@ -1,1 +1,2 @@
  |   1a
  |  +2a
  |  diff --git a/b b/c
  |  copy from b
  |  copy to c
  |  --- a/b
  |  +++ b/c
  |  @@ -1,1 +1,2 @@
  |  -1a
  |  +1c
  |  +3c
  |
  o  0:bfb67c3539c1 1
     diff --git a/b b/b
     new file mode 100644
     --- /dev/null
     +++ b/b
     @@ -0,0 +1,1 @@
     +1a
  
"move" b to a, c and d, follow d if a gets renamed to e, and c is deleted

  $ cd ..
  $ hg init repo5
  $ cd repo5

  $ echo 1 > b
  $ hg ci -A b -m 1
  $ hg cp b a
  $ hg cp b c
  $ hg cp b d
  $ hg rm b
  $ echo 2 >> a
  $ echo 3 >> c
  $ echo 4 >> d
  $ hg commit -m cp
  $ hg mv a e
  $ hg rm c
  $ hg commit -m mv

  $ hg log -T '{rev}:{node|short} {desc}\n'
  2:49911557c471 mv
  1:7bc3d43ede83 cp
  0:55105f940d5c 1

  $ sedi 's/$/e/' e
  $ sedi 's/$/d/' d

  $ hg absorb -apq
  showing changes for d
          @@ -0,2 +0,2 @@
  55105f9 -1
  7bc3d43 -4
  55105f9 +1d
  7bc3d43 +4d
  showing changes for e
          @@ -0,2 +0,2 @@
          -1
  7bc3d43 -2
          +1e
  7bc3d43 +2e
  
  2 changesets affected
  7bc3d43 cp
  55105f9 1

  $ hg diff
  diff --git a/e b/e
  --- a/e
  +++ b/e
  @@ -1,2 +1,2 @@
  -1
  +1e
   2e

  $ hg log -G -p -T '{rev}:{node|short} {desc}\n'
  @  2:34be9b0c786e mv
  |  diff --git a/c b/c
  |  deleted file mode 100644
  |  --- a/c
  |  +++ /dev/null
  |  @@ -1,2 +0,0 @@
  |  -1
  |  -3
  |  diff --git a/a b/e
  |  rename from a
  |  rename to e
  |
  o  1:13e56db5948d cp
  |  diff --git a/b b/a
  |  rename from b
  |  rename to a
  |  --- a/b
  |  +++ b/a
  |  @@ -1,1 +1,2 @@
  |  -1d
  |  +1
  |  +2e
  |  diff --git a/b b/c
  |  copy from b
  |  copy to c
  |  --- a/b
  |  +++ b/c
  |  @@ -1,1 +1,2 @@
  |  -1d
  |  +1
  |  +3
  |  diff --git a/b b/d
  |  copy from b
  |  copy to d
  |  --- a/b
  |  +++ b/d
  |  @@ -1,1 +1,2 @@
  |   1d
  |  +4d
  |
  o  0:0037613a5dc6 1
     diff --git a/b b/b
     new file mode 100644
     --- /dev/null
     +++ b/b
     @@ -0,0 +1,1 @@
     +1d