view tests/test-histedit-merge-tools.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 histedit extension: Merge tools
====================================

Initialization
---------------

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > logt = log --template '{rev}:{node|short} {desc|firstline}\n'
  > [extensions]
  > histedit=
  > mockmakedate = $TESTDIR/mockmakedate.py
  > [ui]
  > pre-merge-tool-output-template='pre-merge message for {node}\n'
  > EOF

Merge conflict
--------------

  $ hg init r
  $ cd r
  $ echo foo > file
  $ hg add file
  $ hg ci -m "First" -d "1 0"
  $ echo bar > file
  $ hg ci -m "Second" -d "2 0"

  $ hg logt --graph
  @  1:2aa920f62fb9 Second
  |
  o  0:7181f42b8fca First
  

Invert the order of the commits, but fail the merge.
  $ hg histedit --config ui.merge=false --commands - 2>&1 <<EOF | fixbundle
  > pick 2aa920f62fb9 Second
  > pick 7181f42b8fca First
  > EOF
  merging file
  pre-merge message for b90fa2e91a6d11013945a5f684be45b84a8ca6ec
  merging file failed!
  Fix up the change (pick 7181f42b8fca)
  (hg histedit --continue to resume)

  $ hg histedit --abort | fixbundle
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Invert the order of the commits, and pretend the merge succeeded.
  $ hg histedit --config ui.merge=true --commands - 2>&1 <<EOF | fixbundle
  > pick 2aa920f62fb9 Second
  > pick 7181f42b8fca First
  > EOF
  merging file
  pre-merge message for b90fa2e91a6d11013945a5f684be45b84a8ca6ec
  7181f42b8fca: skipping changeset (no changes)