view tests/test-bookmarks-corner-case.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 corner case around bookmark
================================

This test file is meant to gather test around bookmark that are specific
 enough to not find a place elsewhere.

Test bookmark/changelog race condition
======================================

The data from the bookmark file are filtered to only contains bookmark with
node known to the changelog. If the cache invalidation between these two bits
goes wrong, bookmark can be dropped.

global setup
------------

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > ssh = "$PYTHON" "$TESTDIR/dummyssh"
  > [server]
  > concurrent-push-mode=check-related
  > EOF

Setup
-----

initial repository setup

  $ hg init bookrace-server
  $ cd bookrace-server
  $ echo a > a
  $ hg add a
  $ hg commit -m root
  $ echo a >> a
  $ hg bookmark book-A
  $ hg commit -m A0
  $ hg up 'desc(root)'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark book-A)
  $ echo b > b
  $ hg add b
  $ hg bookmark book-B
  $ hg commit -m B0
  created new head
  $ hg up null
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  (leaving bookmark book-B)
  $ hg phase --public --rev 'all()'
  $ hg log -G
  o  changeset:   2:c79985706978
  |  bookmark:    book-B
  |  tag:         tip
  |  parent:      0:6569b5a81c7e
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     B0
  |
  | o  changeset:   1:39c28d785860
  |/   bookmark:    book-A
  |    user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     A0
  |
  o  changeset:   0:6569b5a81c7e
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     root
  
  $ hg book
     book-A                    1:39c28d785860
     book-B                    2:c79985706978
  $ cd ..

Add new changeset on each bookmark in distinct clones

  $ hg clone ssh://user@dummy/bookrace-server client-A
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  new changesets 6569b5a81c7e:c79985706978
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R client-A update book-A
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (activating bookmark book-A)
  $ echo a >> client-A/a
  $ hg -R client-A commit -m A1
  $ hg clone ssh://user@dummy/bookrace-server client-B
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  new changesets 6569b5a81c7e:c79985706978
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R client-B update book-B
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark book-B)
  $ echo b >> client-B/b
  $ hg -R client-B commit -m B1

extension to reproduce the race
-------------------------------

If two process are pushing we want to make sure the following happens:

* process A read changelog
* process B to its full push
* process A read bookmarks
* process A proceed with rest of the push

We build a server side extension for this purpose

  $ cat > bookrace.py << EOF
  > import atexit
  > import os
  > import time
  > from mercurial import bookmarks, error, extensions
  > 
  > def wait(repo):
  >     if not os.path.exists('push-A-started'):
  >         assert repo._currentlock(repo._lockref) is None
  >         assert repo._currentlock(repo._wlockref) is None
  >         repo.ui.status(b'setting raced push up\n')
  >         with open('push-A-started', 'w'):
  >             pass
  >     clock = 300
  >     while not os.path.exists('push-B-done'):
  >         clock -= 1
  >         if clock <= 0:
  >             raise error.Abort("race scenario timed out")
  >         time.sleep(0.1)
  > 
  > def reposetup(ui, repo):
  >     class racedrepo(repo.__class__):
  >         @property
  >         def _bookmarks(self):
  >             wait(self)
  >             return super(racedrepo, self)._bookmarks
  >     repo.__class__ = racedrepo
  > 
  > def e():
  >     with open('push-A-done', 'w'):
  >         pass
  > atexit.register(e)
  > EOF

Actual test
-----------

Start the raced push.

  $ cat >> bookrace-server/.hg/hgrc << EOF
  > [extensions]
  > bookrace=$TESTTMP/bookrace.py
  > EOF
  $ hg push -R client-A -r book-A >push-output.txt 2>&1 &

Wait up to 30 seconds for that push to start.

  $ clock=30
  $ while [ ! -f push-A-started ] && [ $clock -gt 0 ] ; do
  >    clock=`expr $clock - 1`
  >    sleep 1
  > done

Do the other push.

  $ cat >> bookrace-server/.hg/hgrc << EOF
  > [extensions]
  > bookrace=!
  > EOF

  $ hg push -R client-B -r book-B
  pushing to ssh://user@dummy/bookrace-server
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  updating bookmark book-B

Signal the raced put that we are done (it waits up to 30 seconds).

  $ touch push-B-done

Wait for the raced push to finish (with the remaning of the initial 30 seconds).

  $ while [ ! -f push-A-done ] && [ $clock -gt 0 ] ; do
  >    clock=`expr $clock - 1`
  >    sleep 1
  > done

Check raced push output.

  $ cat push-output.txt
  pushing to ssh://user@dummy/bookrace-server
  searching for changes
  remote: setting raced push up
  remote has heads on branch 'default' that are not known locally: f26c3b5167d1
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  updating bookmark book-A

Check result of the push.

  $ hg -R bookrace-server log -G
  o  changeset:   4:9ce3b28c16de
  |  bookmark:    book-A
  |  tag:         tip
  |  parent:      1:39c28d785860
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     A1
  |
  | o  changeset:   3:f26c3b5167d1
  | |  bookmark:    book-B
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     B1
  | |
  | o  changeset:   2:c79985706978
  | |  parent:      0:6569b5a81c7e
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     B0
  | |
  o |  changeset:   1:39c28d785860
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     A0
  |
  o  changeset:   0:6569b5a81c7e
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     root
  
  $ hg -R bookrace-server book
     book-A                    4:9ce3b28c16de
     book-B                    3:f26c3b5167d1