195 lines
8.4 KiB
Plaintext
Generated
195 lines
8.4 KiB
Plaintext
Generated
<!DOCTYPE html>
|
||
<html>
|
||
<head>
|
||
<meta charset="utf-8">
|
||
<title>Go в примерах: Select</title>
|
||
<link rel=stylesheet href="site.css">
|
||
</head>
|
||
<script>
|
||
onkeydown = (e) => {
|
||
|
||
if (e.key == "ArrowLeft") {
|
||
window.location.href = 'channel-directions';
|
||
}
|
||
|
||
|
||
if (e.key == "ArrowRight") {
|
||
window.location.href = 'timeouts';
|
||
}
|
||
|
||
}
|
||
</script>
|
||
<body>
|
||
<div class="example" id="select">
|
||
<h2><a href="./">Go в примерах</a>: Select</h2>
|
||
|
||
<table>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>Go’s _select позволяет вам ждать нескольких
|
||
операций на канале. Сочетание горутин и каналов
|
||
с помощью select’а - мощная функция Go.</p>
|
||
|
||
</td>
|
||
<td class="code empty leading">
|
||
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
<a href="http://play.golang.org/p/S6N4SGilqad" target="_blank"><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>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
|
||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||
<span class="s">"fmt"</span>
|
||
<span class="s">"time"</span>
|
||
<span class="p">)</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
|
||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>В нашем примере мы будем выбирать между двумя
|
||
каналами.</p>
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
|
||
<div class="highlight"><pre> <span class="nx">c1</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||
<span class="nx">c2</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>Каждый канал получит значение через некоторое время,
|
||
например, для моделирования блокировки RPC-операций,
|
||
выполняемых в параллельных горутинах.</p>
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
|
||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="mi">1</span> <span class="o">*</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||
<span class="nx">c1</span> <span class="o"><-</span> <span class="s">"one"</span>
|
||
<span class="p">}()</span>
|
||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="mi">2</span> <span class="o">*</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||
<span class="nx">c2</span> <span class="o"><-</span> <span class="s">"two"</span>
|
||
<span class="p">}()</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>Мы будем использовать <code>select</code>, чтобы ожидать
|
||
оба значения одновременно, печатая каждое из
|
||
них по мере поступления.</p>
|
||
|
||
</td>
|
||
<td class="code">
|
||
|
||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">2</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||
<span class="k">select</span> <span class="p">{</span>
|
||
<span class="k">case</span> <span class="nx">msg1</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c1</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">"received"</span><span class="p">,</span> <span class="nx">msg1</span><span class="p">)</span>
|
||
<span class="k">case</span> <span class="nx">msg2</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c2</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">"received"</span><span class="p">,</span> <span class="nx">msg2</span><span class="p">)</span>
|
||
<span class="p">}</span>
|
||
<span class="p">}</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
</table>
|
||
|
||
<table>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>Мы получаем значние <code>"one"</code> и потом <code>"two"</code>, как
|
||
и ожидалось.</p>
|
||
|
||
</td>
|
||
<td class="code leading">
|
||
|
||
<div class="highlight"><pre><span class="gp">$</span> <span class="nb">time</span> go run <span class="k">select</span>.go
|
||
<span class="go">received one</span>
|
||
<span class="go">received two</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
<tr>
|
||
<td class="docs">
|
||
<p>Обратите внимание, что общее время выполнения
|
||
составляет всего ~2 секунды, так как и 1, и 2 секунды
|
||
<code>Sleeps</code> выполняются одновременно.</p>
|
||
|
||
</td>
|
||
<td class="code">
|
||
|
||
<div class="highlight"><pre><span class="go">real 0m2.245s</span>
|
||
</pre></div>
|
||
|
||
</td>
|
||
</tr>
|
||
|
||
</table>
|
||
|
||
|
||
<p class="next">
|
||
Следующий пример: <a href="timeouts">Тайм-ауты (Timeouts)</a>.
|
||
</p>
|
||
|
||
<p class="footer">
|
||
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/select">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||
<br/>
|
||
переведено Nick S. | <a href="https://github.com/badkaktus/gobyexample">исходники</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(' c1 := make(chan string)\u000A c2 := make(chan string)\u000A');codeLines.push(' go func() {\u000A time.Sleep(1 * time.Second)\u000A c1 \x3C- \"one\"\u000A }()\u000A go func() {\u000A time.Sleep(2 * time.Second)\u000A c2 \x3C- \"two\"\u000A }()\u000A');codeLines.push(' for i := 0; i \x3C 2; i++ {\u000A select {\u000A case msg1 := \x3C-c1:\u000A fmt.Println(\"received\", msg1)\u000A case msg2 := \x3C-c2:\u000A fmt.Println(\"received\", msg2)\u000A }\u000A }\u000A}\u000A');codeLines.push('');codeLines.push('');
|
||
</script>
|
||
<script src="site.js" async></script>
|
||
</body>
|
||
</html>
|