view tests/test-branch-option.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

test branch selection options

  $ hg init branch
  $ cd branch
  $ hg branch a
  marked working directory as branch a
  (branches are permanent and global, did you want a bookmark?)
  $ echo a > foo
  $ hg ci -d '0 0' -Ama
  adding foo
  $ echo a2 > foo
  $ hg ci -d '0 0' -ma2
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch c
  marked working directory as branch c
  $ echo c > foo
  $ hg ci -d '0 0' -mc
  $ hg tag -l z
  $ cd ..
  $ hg clone -r 0 branch branch2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 5b65ba7c951d
  updating to branch a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd branch2
  $ hg up 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch b
  marked working directory as branch b
  $ echo b > foo
  $ hg ci -d '0 0' -mb
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --encoding utf-8 branch æ
  marked working directory as branch \xc3\xa6 (esc)
  $ echo ae1 > foo
  $ hg ci -d '0 0' -mae1
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --encoding utf-8 branch -f æ
  marked working directory as branch \xc3\xa6 (esc)
  $ echo ae2 > foo
  $ hg ci -d '0 0' -mae2
  created new head
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch -f b
  marked working directory as branch b
  $ echo b2 > foo
  $ hg ci -d '0 0' -mb2
  created new head

unknown branch and fallback

  $ hg in -qbz
  abort: unknown branch 'z'!
  [255]
  $ hg in -q ../branch#z
  2:f25d57ab0566
  $ hg out -qbz
  abort: unknown branch 'z'!
  [255]

in rev c branch a

  $ hg in -qr c ../branch#a
  1:dd6e60a716c6
  2:f25d57ab0566
  $ hg in -qr c -b a
  1:dd6e60a716c6
  2:f25d57ab0566

out branch .

  $ hg out -q ../branch#.
  1:b84708d77ab7
  4:65511d0e2b55
  $ hg out -q -b .
  1:b84708d77ab7
  4:65511d0e2b55

out branch . non-ascii

  $ hg --encoding utf-8 up æ
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --encoding latin1 out -q ../branch#.
  2:df5a44224d4e
  3:4f4a5125ca10
  $ hg --encoding latin1 out -q -b .
  2:df5a44224d4e
  3:4f4a5125ca10

clone branch b

  $ cd ..
  $ hg clone branch2#b branch3
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files (+1 heads)
  new changesets 5b65ba7c951d:65511d0e2b55
  updating to branch b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -q -R branch3 heads b
  2:65511d0e2b55
  1:b84708d77ab7
  $ hg -q -R branch3 parents
  2:65511d0e2b55
  $ rm -rf branch3

clone rev a branch b

  $ hg clone -r a branch2#b branch3
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files (+1 heads)
  new changesets 5b65ba7c951d:65511d0e2b55
  updating to branch a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -q -R branch3 heads b
  2:65511d0e2b55
  1:b84708d77ab7
  $ hg -q -R branch3 parents
  0:5b65ba7c951d
  $ rm -rf branch3