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Clarify reading op non-atomically

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This commit is contained in:
Eli Bendersky 2019-09-05 13:26:08 -07:00
parent ef8f0e3831
commit b70c15adaa
3 changed files with 28 additions and 6 deletions
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6
examples/atomic-counters/atomic-counters.go
View File

@ -42,5 +42,11 @@ func main() {
// Wait until all the goroutines are done.
wg.Wait()
// It's safe to access `ops` now because we know
// no other goroutine is writing to it. Reading
// atomics safely while they are being updated is
// also possible, using functions like
// `atomic.LoadUint64`.
fmt.Println("ops:", ops)
}

4
examples/atomic-counters/atomic-counters.hash
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@ -1,2 +1,2 @@
103c9b7d036e3a5c14dc481755b78b10dc9f894e
GRkVf6J1--B
8ebec0be3b167021c96b8b497d0e8c0a2ea99385
F2pJfduyQiA

24
public/atomic-counters generated
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@ -46,7 +46,7 @@ counters</em> accessed by multiple goroutines.</p>
</td>
<td class="code leading">
<a href="http://play.golang.org/p/GRkVf6J1--B"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<a href="http://play.golang.org/p/F2pJfduyQiA"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
@ -162,10 +162,26 @@ address of our <code>ops</code> counter with the
<p>Wait until all the goroutines are done.</p>
</td>
<td class="code">
<td class="code leading">
<div class="highlight"><pre> <span class="nx">wg</span><span class="p">.</span><span class="nx">Wait</span><span class="p">()</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;ops:&quot;</span><span class="p">,</span> <span class="nx">ops</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>It&rsquo;s safe to access <code>ops</code> now because we know
no other goroutine is writing to it. Reading
atomics safely while they are being updated is
also possible, using functions like
<code>atomic.LoadUint64</code>.</p>
</td>
<td class="code">
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;ops:&quot;</span><span class="p">,</span> <span class="nx">ops</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
@ -220,7 +236,7 @@ state.</p>
</div>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"sync\"\u000A \"sync/atomic\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' var ops uint64\u000A');codeLines.push(' var wg sync.WaitGroup\u000A');codeLines.push(' for i := 0; i \x3C 50; i++ {\u000A wg.Add(1)\u000A');codeLines.push(' go func() {\u000A for c := 0; c \x3C 1000; c++ {\u000A');codeLines.push(' atomic.AddUint64(&ops, 1)\u000A }\u000A wg.Done()\u000A }()\u000A }\u000A');codeLines.push(' wg.Wait()\u000A fmt.Println(\"ops:\", ops)\u000A}\u000A');codeLines.push('');codeLines.push('');
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"sync\"\u000A \"sync/atomic\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' var ops uint64\u000A');codeLines.push(' var wg sync.WaitGroup\u000A');codeLines.push(' for i := 0; i \x3C 50; i++ {\u000A wg.Add(1)\u000A');codeLines.push(' go func() {\u000A for c := 0; c \x3C 1000; c++ {\u000A');codeLines.push(' atomic.AddUint64(&ops, 1)\u000A }\u000A wg.Done()\u000A }()\u000A }\u000A');codeLines.push(' wg.Wait()\u000A');codeLines.push(' fmt.Println(\"ops:\", ops)\u000A}\u000A');codeLines.push('');codeLines.push('');
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