<!--{
	"Title": "Using Mercurial Queues with Codereview"
}-->

<h2 id="Introduction">Introduction</h2>

<p>
The Mercurial Queues extension (<code>mq</code>) provides a mechanism for
managing patches on top of a Mercurial repository and is described in detail
in Chapters
<a href="http://hgbook.red-bean.com/read/managing-change-with-mercurial-queues.html">12</a>
and <a href="http://hgbook.red-bean.com/read/advanced-uses-of-mercurial-queues.html">13</a>
of <a href="http://hgbook.red-bean.com/read/">Mercurial: The Definitive Guide</a>.
This document explains how to use <code>mq</code> in conjunction
with the <code>codereview</code> Mercurial extension described in the
instructions for <a href="contribute.html">contributing to the Go project</a>.
It assumes you have read those instructions.
</p>

<h2>Configuration</h2>

<p>
To enable <code>mq</code> edit either <code>$HOME/.hgrc</code> (to enable it
for all of your repositories) or <code>$GOROOT/.hg/hgrc</code> (to enable it for the
repository at <code>$GOROOT</code>) to add:</p>

<pre>
[extensions]
mq=
</pre>

<p>
Since pulling, pushing, updating and committing while <code>mq</code> patches
are applied can damage your repository or a remote one, add these lines to
prevent that case: 
</p>

<pre>
[hooks]
# Prevent "hg pull" if MQ patches are applied.
prechangegroup.mq-no-pull = ! hg qtop > /dev/null 2>&amp;1
# Prevent "hg push" if MQ patches are applied.
preoutgoing.mq-no-push = ! hg qtop > /dev/null 2>&amp;1
# Prevent "hg update" if MQ patches are applied.
preupdate.mq-no-update = ! hg qtop > /dev/null 2>&amp;1
</pre>

<h2>Making a change</h2>

<p>
The entire checked-out tree is writable and you can use <code>mq</code>,
as documented in Chapter
<a href="http://hgbook.red-bean.com/read/managing-change-with-mercurial-queues.html">12</a>
of "The Guide",
to implement your change as a single patch or a series of patches.

</p>

<p>When you are ready to send a change out for review, run</p>

<pre>
$ hg change
</pre>

<p>from any directory in your Go repository with all of the <code>mq</code> patches relevant to your
change applied and then proceed as instructed in <a href="contribute.html">contributing
to the Go project</a>.
</p>

<p>
The change number reported by <code>hg change</code>, preceded by a <code>+</code>,
can be used as an <code>mq</code> patch guard to assist in controlling which patches
are applied as described in Chapter
<a href="http://hgbook.red-bean.com/read/advanced-uses-of-mercurial-queues.html">13</a>
of "The Guide".
For example, the command:
</p>

<pre>
for p in $(hg qapplied); do hg qguard $p +99999; done
</pre>

<p>
will apply the guard <code>+99999</code> guard to all currently applied <code>mq</code>
patches.
</p>

<h2>Synchronizing your client</h2>

<p>While you were working, others might have submitted changes
to the repository and, as explained in <a href="contribute.html">contributing
to the Go project</a>, it is necessary to synchronize your repository using
<code>hg sync</code>before sending your change list for review.
Because <code>hg sync</code> runs <code>hg pull -u</code>,
you should not run <code>hg sync</code> while <code>mq</code> patches are
applied. Instead
pop all your patches before running <code>hg sync</code> and reapply them after
it has completed.
</p>

<p>
When reapplying the patches, you may need to resolve conflicts
as described in <a href="contribute.html">contributing to the Go project</a>.
</p>

<h2>Mailing the change for review</h2>

<p>
You should have all of the <code>mq</code> patches relevant to your
change applied when you run <code>hg mail</code>.

<h2>Submitting the change after the review</h2>

If you are a committer, you should have all of the <code>mq</code> patches relevant to your
change applied when you run <code>hg commit</code>.