Oleg Butuzov 646c8b39da bugfix (mmcgrana/gobyexample#294) sha1 sum calculator
This bugfix implements correct way to calculate source sha1 hash, before it will changed,
by propagation of unchanged sources.

This commit will also include regenerated static files and *.hash files.
2019-10-22 14:27:02 +03:00

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<!DOCTYPE html>
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<title>Go by Example: Tickers</title>
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onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'timers';
}
if (e.key == "ArrowRight") {
window.location.href = 'worker-pools';
}
}
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<div class="example" id="tickers">
<h2><a href="./">Go by Example</a>: Tickers</h2>
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<p><a href="timers">Timers</a> are for when you want to do
something once in the future - <em>tickers</em> are for when
you want to do something repeatedly at regular
intervals. Here&rsquo;s an example of a ticker that ticks
periodically until we stop it.</p>
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<a href="http://play.golang.org/p/gs6zoJP-Pl9"><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>
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<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
<span class="s">&quot;fmt&quot;</span>
<span class="s">&quot;time&quot;</span>
<span class="p">)</span>
</pre></div>
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
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<td class="docs">
<p>Tickers use a similar mechanism to timers: a
channel that is sent values. Here we&rsquo;ll use the
<code>select</code> builtin on the channel to await the
values as they arrive every 500ms.</p>
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<td class="code leading">
<div class="highlight"><pre> <span class="nx">ticker</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">NewTicker</span><span class="p">(</span><span class="mi">500</span> <span class="o">*</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span><span class="p">)</span>
<span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">)</span>
</pre></div>
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<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
<span class="k">for</span> <span class="p">{</span>
<span class="k">select</span> <span class="p">{</span>
<span class="k">case</span> <span class="o">&lt;-</span><span class="nx">done</span><span class="p">:</span>
<span class="k">return</span>
<span class="k">case</span> <span class="nx">t</span> <span class="o">:=</span> <span class="o">&lt;-</span><span class="nx">ticker</span><span class="p">.</span><span class="nx">C</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;Tick at&quot;</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}()</span>
</pre></div>
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<td class="docs">
<p>Tickers can be stopped like timers. Once a ticker
is stopped it won&rsquo;t receive any more values on its
channel. We&rsquo;ll stop ours after 1600ms.</p>
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<td class="code">
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="mi">1600</span> <span class="o">*</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span><span class="p">)</span>
<span class="nx">ticker</span><span class="p">.</span><span class="nx">Stop</span><span class="p">()</span>
<span class="nx">done</span> <span class="o">&lt;-</span> <span class="kc">true</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;Ticker stopped&quot;</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
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<p>When we run this program the ticker should tick 3 times
before we stop it.</p>
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<td class="code">
<div class="highlight"><pre><span class="gp">$</span> go run tickers.go
<span class="go">Tick at 2012-09-23 11:29:56.487625 -0700 PDT</span>
<span class="go">Tick at 2012-09-23 11:29:56.988063 -0700 PDT</span>
<span class="go">Tick at 2012-09-23 11:29:57.488076 -0700 PDT</span>
<span class="go">Ticker stopped</span>
</pre></div>
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<p class="next">
Next example: <a href="worker-pools">Worker Pools</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/tickers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
</div>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"time\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' ticker := time.NewTicker(500 * time.Millisecond)\u000A done := make(chan bool)\u000A');codeLines.push(' go func() {\u000A for {\u000A select {\u000A case \x3C-done:\u000A return\u000A case t := \x3C-ticker.C:\u000A fmt.Println(\"Tick at\", t)\u000A }\u000A }\u000A }()\u000A');codeLines.push(' time.Sleep(1600 * time.Millisecond)\u000A ticker.Stop()\u000A done \x3C- true\u000A fmt.Println(\"Ticker stopped\")\u000A}\u000A');codeLines.push('');
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