view tests/test-remotefilelog-log.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

#require no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > x
  $ hg commit -qAm x
  $ mkdir dir
  $ echo y > dir/y
  $ hg commit -qAm y

  $ cd ..

Shallow clone from full

  $ hgcloneshallow ssh://user@dummy/master shallow --noupdate
  streaming all changes
  2 files to transfer, 473 bytes of data
  transferred 473 bytes in * seconds (*/sec) (glob)
  searching for changes
  no changes found
  $ cd shallow
  $ cat .hg/requires
  dotencode
  exp-remotefilelog-repo-req-1
  fncache
  generaldelta
  revlogv1
  sparserevlog
  store

  $ hg update
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)

Log on a file without -f

  $ hg log dir/y
  warning: file log can be slow on large repos - use -f to speed it up
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
Log on a file with -f

  $ hg log -f dir/y
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
Log on a file with kind in path
  $ hg log -r "filelog('path:dir/y')"
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
Log on multiple files with -f

  $ hg log -f dir/y x
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
  changeset:   0:b292c1e3311f
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     x
  
Log on a directory

  $ hg log dir
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
Log on a file from inside a directory

  $ cd dir
  $ hg log y
  warning: file log can be slow on large repos - use -f to speed it up
  changeset:   1:2e73264fab97
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     y
  
Log on a file via -fr
  $ cd ..
  $ hg log -fr tip dir/ --template '{rev}\n'
  1

Trace renames
  $ hg mv x z
  $ hg commit -m move
  $ hg log -f z -T '{desc} {file_copies}\n' -G
  @  move z (x)
  :
  o  x
  

Verify remotefilelog handles rename metadata stripping when comparing file sizes
  $ hg debugrebuilddirstate
  $ hg status