bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
#require serve
Test raw style of hgweb
$ hg init test
$ cd test
$ mkdir sub
$ cat >'sub/some text%.txt' <<ENDSOME
> This is just some random text
> that will go inside the file and take a few lines.
> It is very boring to read, but computers don't
> care about things like that.
> ENDSOME
$ hg add 'sub/some text%.txt'
$ hg commit -d "1 0" -m "Just some text"
$ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid
$ cat hg.pid >> $DAEMON_PIDS
$ (get-with-headers.py localhost:$HGPORT 'raw-file/bf0ff59095c9/sub/some%20text%25.txt' content-type content-length content-disposition) >getoutput.txt
$ killdaemons.py hg.pid
$ cat getoutput.txt
200 Script output follows
content-type: application/binary
content-length: 157
content-disposition: inline; filename="some text%.txt"
This is just some random text
that will go inside the file and take a few lines.
It is very boring to read, but computers don't
care about things like that.
$ cat access.log error.log
$LOCALIP - - [$LOGDATE$] "GET /raw-file/bf0ff59095c9/sub/some%20text%25.txt HTTP/1.1" 200 - (glob)
$ rm access.log error.log
$ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid \
> --config web.guessmime=True
$ cat hg.pid >> $DAEMON_PIDS
$ (get-with-headers.py localhost:$HGPORT 'raw-file/bf0ff59095c9/sub/some%20text%25.txt' content-type content-length content-disposition) >getoutput.txt
$ killdaemons.py hg.pid
$ cat getoutput.txt
200 Script output follows
content-type: text/plain; charset="ascii"
content-length: 157
content-disposition: inline; filename="some text%.txt"
This is just some random text
that will go inside the file and take a few lines.
It is very boring to read, but computers don't
care about things like that.
$ cat access.log error.log
$LOCALIP - - [$LOGDATE$] "GET /raw-file/bf0ff59095c9/sub/some%20text%25.txt HTTP/1.1" 200 - (glob)
>>> with open('sub/binary.bin', 'wb') as fp:
... fp.write(b'Binary\0file') and None
$ hg ci -Aqm "add binary file" sub/
$ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid \
> --config web.guessmime=True
$ cat hg.pid >> $DAEMON_PIDS
$ (get-with-headers.py localhost:$HGPORT 'annotate/tip/sub/binary.bin' content-type content-length content-disposition) >getoutput.txt
$ cat getoutput.txt
200 Script output follows
content-type: text/html; charset=ascii
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US">
<head>
<link rel="icon" href="/static/hgicon.png" type="image/png" />
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="/static/style-paper.css" type="text/css" />
<script type="text/javascript" src="/static/mercurial.js"></script>
<title>$TESTTMP/test: sub/binary.bin annotate</title> (glob)
</head>
<body>
<div class="container">
<div class="menu">
<div class="logo">
<a href="https://mercurial-scm.org/">
<img src="/static/hglogo.png" alt="mercurial" /></a>
</div>
<ul>
<li><a href="/shortlog/tip">log</a></li>
<li><a href="/graph/tip">graph</a></li>
<li><a href="/tags">tags</a></li>
<li><a href="/bookmarks">bookmarks</a></li>
<li><a href="/branches">branches</a></li>
</ul>
<ul>
<li><a href="/rev/tip">changeset</a></li>
<li><a href="/file/tip/sub/">browse</a></li>
</ul>
<ul>
<li><a href="/file/tip/sub/binary.bin">file</a></li>
<li><a href="/file/tip/sub/binary.bin">latest</a></li>
<li><a href="/diff/tip/sub/binary.bin">diff</a></li>
<li><a href="/comparison/tip/sub/binary.bin">comparison</a></li>
<li class="active">annotate</li>
<li><a href="/log/tip/sub/binary.bin">file log</a></li>
<li><a href="/raw-file/tip/sub/binary.bin">raw</a></li>
</ul>
<ul>
<li><a href="/help">help</a></li>
</ul>
</div>
<div class="main">
<h2 class="breadcrumb"><a href="/">Mercurial</a> </h2>
<h3>
annotate sub/binary.bin @ 1:<a href="/rev/7dc31308464a">7dc31308464a</a>
<span class="phase">draft</span> <span class="branchhead">default</span> <span class="tag">tip</span>
</h3>
<form class="search" action="/log">
<p><input name="rev" id="search1" type="text" size="30" value="" /></p>
<div id="hint">Find changesets by keywords (author, files, the commit message), revision
number or hash, or <a href="/help/revsets">revset expression</a>.</div>
</form>
<div class="description">add binary file</div>
<table id="changesetEntry">
<tr>
<th class="author">author</th>
<td class="author">test</td>
</tr>
<tr>
<th class="date">date</th>
<td class="date age">Thu, 01 Jan 1970 00:00:00 +0000</td>
</tr>
<tr>
<th class="author">parents</th>
<td class="author"></td>
</tr>
<tr>
<th class="author">children</th>
<td class="author"></td>
</tr>
</table>
<form id="diffopts-form"
data-ignorews="0"
data-ignorewsamount="0"
data-ignorewseol="0"
data-ignoreblanklines="0">
<span>Ignore whitespace changes - </span>
<span>Everywhere:</span>
<input id="ignorews-checkbox" type="checkbox" />
<span>Within whitespace:</span>
<input id="ignorewsamount-checkbox" type="checkbox" />
<span>At end of lines:</span>
<input id="ignorewseol-checkbox" type="checkbox" />
</form>
<script type="text/javascript">
renderDiffOptsForm();
</script>
<div class="overflow">
<table class="bigtable">
<thead>
<tr>
<th class="annotate">rev</th>
<th class="line"> line source</th>
</tr>
</thead>
<tbody class="stripes2 sourcelines"
data-logurl="/log/tip/sub/binary.bin"
data-selectabletag="TR"
data-ishead="1">
<tr id="l1" class="thisrev">
<td class="annotate parity0">
<a href="/annotate/7dc31308464a/sub/binary.bin#l1">
1
</a>
<div class="annotate-info">
<div>
<a href="/annotate/7dc31308464a/sub/binary.bin#l1">
7dc31308464a</a>
add binary file
</div>
<div><em>test</em></div>
<div>parents: </div>
<a href="/diff/7dc31308464a/sub/binary.bin">diff</a>
<a href="/rev/7dc31308464a">changeset</a>
</div>
</td>
<td class="source followlines-btn-parent"><a href="#l1"> 1</a> (binary:application/octet-stream)</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<script type="text/javascript" src="/static/followlines.js"></script>
</body>
</html>
$ (get-with-headers.py localhost:$HGPORT 'comparison/tip/sub/binary.bin' content-type content-length content-disposition) >getoutput.txt
$ (get-with-headers.py localhost:$HGPORT 'file/tip/sub/binary.bin' content-type content-length content-disposition) >getoutput.txt
$ (get-with-headers.py localhost:$HGPORT 'static/hgicon.png' content-type content-length content-disposition) >getoutput.txt
$ killdaemons.py hg.pid
$ cat access.log error.log
$LOCALIP - - [$LOGDATE$] "GET /raw-file/bf0ff59095c9/sub/some%20text%25.txt HTTP/1.1" 200 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /annotate/tip/sub/binary.bin HTTP/1.1" 200 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /comparison/tip/sub/binary.bin HTTP/1.1" 200 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /file/tip/sub/binary.bin HTTP/1.1" 200 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /static/hgicon.png HTTP/1.1" 200 - (glob)
$ cd ..