view tests/test-patchbomb-bookmark.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

Create @ bookmark as main reference

  $ hg init repo
  $ cd repo
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "patchbomb=" >> $HGRCPATH
  $ hg book @

Create a dummy revision that must never be exported

  $ echo no > no
  $ hg ci -Amno -d '6 0'
  adding no

Create a feature and use -B

  $ hg book booktest
  $ echo first > a
  $ hg ci -Amfirst -d '7 0'
  adding a
  $ echo second > b
  $ hg ci -Amsecond -d '8 0'
  adding b
  $ hg email --date '1981-1-1 0:1' -n -t foo -s bookmark -B booktest
  From [test]: test
  this patch series consists of 2 patches.
  
  
  Write the introductory message for the patch series.
  
  Cc: 
  
  displaying [PATCH 0 of 2] bookmark ...
  MIME-Version: 1.0
  Content-Type: text/plain; charset="us-ascii"
  Content-Transfer-Encoding: 7bit
  Subject: [PATCH 0 of 2] bookmark
  Message-Id: <patchbomb.347155260@test-hostname>
  User-Agent: Mercurial-patchbomb/* (glob)
  Date: Thu, 01 Jan 1981 00:01:00 +0000
  From: test
  To: foo
  
  
  displaying [PATCH 1 of 2] first ...
  MIME-Version: 1.0
  Content-Type: text/plain; charset="us-ascii"
  Content-Transfer-Encoding: 7bit
  Subject: [PATCH 1 of 2] first
  X-Mercurial-Node: accde9b8b6dce861c185d0825c1affc09a79cb26
  X-Mercurial-Series-Index: 1
  X-Mercurial-Series-Total: 2
  Message-Id: <accde9b8b6dce861c185.347155261@test-hostname>
  X-Mercurial-Series-Id: <accde9b8b6dce861c185.347155261@test-hostname>
  In-Reply-To: <patchbomb.347155260@test-hostname>
  References: <patchbomb.347155260@test-hostname>
  User-Agent: Mercurial-patchbomb/* (glob)
  Date: Thu, 01 Jan 1981 00:01:01 +0000
  From: test
  To: foo
  
  # HG changeset patch
  # User test
  # Date 7 0
  #      Thu Jan 01 00:00:07 1970 +0000
  # Node ID accde9b8b6dce861c185d0825c1affc09a79cb26
  # Parent  043bd3889e5aaf7d88fe3713cf425f782ad2fb71
  first
  
  diff -r 043bd3889e5a -r accde9b8b6dc a
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:07 1970 +0000
  @@ -0,0 +1,1 @@
  +first
  
  displaying [PATCH 2 of 2] second ...
  MIME-Version: 1.0
  Content-Type: text/plain; charset="us-ascii"
  Content-Transfer-Encoding: 7bit
  Subject: [PATCH 2 of 2] second
  X-Mercurial-Node: 417defd1559c396ba06a44dce8dc1c2d2d653f3f
  X-Mercurial-Series-Index: 2
  X-Mercurial-Series-Total: 2
  Message-Id: <417defd1559c396ba06a.347155262@test-hostname>
  X-Mercurial-Series-Id: <accde9b8b6dce861c185.347155261@test-hostname>
  In-Reply-To: <patchbomb.347155260@test-hostname>
  References: <patchbomb.347155260@test-hostname>
  User-Agent: Mercurial-patchbomb/* (glob)
  Date: Thu, 01 Jan 1981 00:01:02 +0000
  From: test
  To: foo
  
  # HG changeset patch
  # User test
  # Date 8 0
  #      Thu Jan 01 00:00:08 1970 +0000
  # Node ID 417defd1559c396ba06a44dce8dc1c2d2d653f3f
  # Parent  accde9b8b6dce861c185d0825c1affc09a79cb26
  second
  
  diff -r accde9b8b6dc -r 417defd1559c b
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/b	Thu Jan 01 00:00:08 1970 +0000
  @@ -0,0 +1,1 @@
  +second
  
Do the same and combine with -o only one must be exported

  $ cd ..
  $ hg clone repo repo2
  updating to bookmark @
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo
  $ hg up @
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  (activating bookmark @)
  $ hg book outgoing
  $ echo 1 > x
  $ hg ci -Am1 -d '8 0'
  adding x
  created new head
  $ hg push ../repo2 -B outgoing
  pushing to ../repo2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  exporting bookmark outgoing
  $ echo 2 > y
  $ hg ci -Am2 -d '9 0'
  adding y
  $ hg email --date '1982-1-1 0:1' -n -t foo -s bookmark -B outgoing -o ../repo2
  comparing with ../repo2
  From [test]: test
  this patch series consists of 1 patches.
  
  Cc: 
  
  displaying [PATCH] bookmark ...
  MIME-Version: 1.0
  Content-Type: text/plain; charset="us-ascii"
  Content-Transfer-Encoding: 7bit
  Subject: [PATCH] bookmark
  X-Mercurial-Node: 8dab2639fd35f1e337ad866c372a5c44f1064e3c
  X-Mercurial-Series-Index: 1
  X-Mercurial-Series-Total: 1
  Message-Id: <8dab2639fd35f1e337ad.378691260@test-hostname>
  X-Mercurial-Series-Id: <8dab2639fd35f1e337ad.378691260@test-hostname>
  User-Agent: Mercurial-patchbomb/* (glob)
  Date: Fri, 01 Jan 1982 00:01:00 +0000
  From: test
  To: foo
  
  # HG changeset patch
  # User test
  # Date 9 0
  #      Thu Jan 01 00:00:09 1970 +0000
  # Node ID 8dab2639fd35f1e337ad866c372a5c44f1064e3c
  # Parent  0b24b8316483bf30bfc3e4d4168e922b169dbe66
  2
  
  diff -r 0b24b8316483 -r 8dab2639fd35 y
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/y	Thu Jan 01 00:00:09 1970 +0000
  @@ -0,0 +1,1 @@
  +2