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go/doc/go1.15.html
Changkun Ou 2e8dbae85c sync: add new Map method LoadAndDelete
This CL implements a LoadAndDelete method in sync.Map. Benchmark:

name                                              time/op
LoadAndDeleteBalanced/*sync_test.RWMutexMap-12    98.8ns ± 1%
LoadAndDeleteBalanced/*sync.Map-12                10.3ns ±11%
LoadAndDeleteUnique/*sync_test.RWMutexMap-12      99.2ns ± 2%
LoadAndDeleteUnique/*sync.Map-12                  6.63ns ±10%
LoadAndDeleteCollision/*sync_test.DeepCopyMap-12   140ns ± 0%
LoadAndDeleteCollision/*sync_test.RWMutexMap-12   75.2ns ± 2%
LoadAndDeleteCollision/*sync.Map-12               5.21ns ± 5%

In addition, Delete is bounded and more efficient if many collisions:

DeleteCollision/*sync_test.DeepCopyMap-12   120ns ± 2%   125ns ± 1%   +3.80%  (p=0.000 n=10+9)
DeleteCollision/*sync_test.RWMutexMap-12   73.5ns ± 3%  79.5ns ± 1%   +8.03%  (p=0.000 n=10+9)
DeleteCollision/*sync.Map-12               97.8ns ± 3%   5.9ns ± 4%  -94.00%  (p=0.000 n=10+10)

Fixes #33762

Change-Id: Ic8469a7861d27ab0edeface0078aad8af9b26c2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/205899
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-02-25 14:31:55 +00:00

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<!--{
"Title": "Go 1.15 Release Notes",
"Path": "/doc/go1.15"
}-->
<!--
NOTE: In this document and others in this directory, the convention is to
set fixed-width phrases with non-fixed-width spaces, as in
<code>hello</code> <code>world</code>.
Do not send CLs removing the interior tags from such phrases.
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<style>
main ul li { margin: 0.5em 0; }
</style>
<h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.15</h2>
<p>
<strong>
Go 1.15 is not yet released. These are work-in-progress
release notes. Go 1.15 is expected to be released in August 2020.
</strong>
</p>
<h2 id="language">Changes to the language</h2>
<p>
TODO
</p>
<h2 id="ports">Ports</h2>
<p>
TODO
</p>
<h2 id="tools">Tools</h2>
<p>
TODO
</p>
<h3 id="go-command">Go command</h3>
<p>
TODO
</p>
<h2 id="runtime">Runtime</h2>
<p>
TODO
</p>
<h2 id="library">Core library</h2>
<p>
TODO
</p>
<dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt>
<dd>
<p><!-- golang.org/issue/28135 -->
The <code>testing.T</code> type now has a <code>Deadline</code> method
that reports the time at which the test binary will have exceeded its
timeout.
</p>
</dl><!-- testing -->
<h3 id="minor_library_changes">Minor changes to the library</h3>
<p>
As always, there are various minor changes and updates to the library,
made with the Go 1 <a href="/doc/go1compat">promise of compatibility</a>
in mind.
</p>
<p>
TODO
</p>
<dl id="sync"><dt><a href="/pkg/sync/">sync</a></dt>
<dd>
<p><!-- golang.org/issue/33762 -->
The new method
<a href="/pkg/sync#Map.LoadAndDelete"><code>Map.LoadAndDelete</code></a>
atomically deletes a key and returns the previous value if present.
</p>
<p><!-- CL 205899 -->
The method
<a href="/pkg/sync#Map.Delete"><code>Map.Delete</code></a>
is more efficient.
</p>
</dl><!-- sync -->
<dl id="time"><dt><a href="/pkg/time/">time</a></dt>
<dd>
<p><!-- golang.org/issue/33184 -->
The new method
<a href="/pkg/time#Ticker.Reset"><code>Ticker.Reset</code></a>
supports changing the duration of a ticker.
</p>
</dd>
</dl><!-- time -->