view tests/test-convert-darcs.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 darcs

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert=" >> $HGRCPATH
  $ DARCS_EMAIL='[e-mail]'; export DARCS_EMAIL

initialize darcs repo

  $ mkdir darcs-repo
  $ cd darcs-repo
  $ darcs init -q
  $ echo a > a
  $ darcs record -a -l -m p0
  Finished recording patch 'p0'
  $ cd ..

branch and update

  $ darcs get -q darcs-repo darcs-clone >/dev/null
  $ cd darcs-clone
  $ echo c >> a
  $ echo c > c
  $ darcs record -a -l -m p1.1
  Finished recording patch 'p1.1'
  $ cd ..

skip if we can't import elementtree

  $ if hg convert darcs-repo darcs-dummy 2>&1 | grep ElementTree > /dev/null; then
  >     echo 'skipped: missing feature: elementtree module'
  >     exit 80
  > fi

update source

  $ cd darcs-repo
  $ echo b >> a
  $ echo b > b
  $ darcs record -a -l -m p1.2
  Finished recording patch 'p1.2'

  $ darcs pull -q -a --no-set-default ../darcs-clone
  Backing up ./a(*) (glob)
  We have conflicts in the following files:
  ./a
   (?)
  $ sleep 1
  $ echo e > a
  $ echo f > f
  $ mkdir dir
  $ echo d > dir/d
  $ echo d > dir/d2
  $ darcs record -a -l -m p2
  Finished recording patch 'p2'

test file and directory move

  $ darcs mv -q f ff

Test remove + move

  $ darcs remove -q dir/d2
  $ rm dir/d2
  $ darcs mv -q dir dir2
  $ darcs record -a -l -m p3
  Finished recording patch 'p3'

The converter does not currently handle patch conflicts very well.
When they occur, it reverts *all* changes and moves forward,
letting the conflict resolving patch fix collisions.
Unfortunately, non-conflicting changes, like the addition of the
"c" file in p1.1 patch are reverted too.
Just to say that manifest not listing "c" here is a bug.

  $ cd ..
  $ hg convert darcs-repo darcs-repo-hg
  initializing destination darcs-repo-hg repository
  scanning source...
  sorting...
  converting...
  4 p0
  3 p1.2
  2 p1.1
  1 p2
  0 p3
  $ hg log -R darcs-repo-hg -g --template '{rev} "{desc|firstline}" ({author}) files: {files}\n' "$@"
  4 "p3" ([e-mail]) files: dir/d dir/d2 dir2/d f ff
  3 "p2" ([e-mail]) files: a dir/d dir/d2 f
  2 "p1.1" ([e-mail]) files: 
  1 "p1.2" ([e-mail]) files: a b
  0 "p0" ([e-mail]) files: a

  $ hg up -q -R darcs-repo-hg
  $ hg -R darcs-repo-hg manifest --debug
  7225b30cdf38257d5cc7780772c051b6f33e6d6b 644   a
  1e88685f5ddec574a34c70af492f95b6debc8741 644   b
  37406831adc447ec2385014019599dfec953c806 644   dir2/d
  b783a337463792a5c7d548ad85a7d3253c16ba8c 644   ff

#if no-outer-repo

try converting darcs1 repository

  $ hg clone -q "$TESTDIR/bundles/darcs1.hg" darcs
  $ hg convert -s darcs darcs/darcs1 2>&1 | grep darcs-1.0
  darcs-1.0 repository format is unsupported, please upgrade

#endif