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157 lines
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Atomically fetch or generate a cache entry</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.apcu-entry" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">apcu_entry</h1>
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<p class="verinfo">(PECL apcu >= 5.1.0)</p><p class="refpurpose"><span class="refname">apcu_entry</span> — <span class="dc-title">
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Atomically fetch or generate a cache entry
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</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.apcu-entry-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>apcu_entry</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$key</code></span>
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, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$generator</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$ttl</code><span class="initializer"> = 0</span></span>
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] ) : <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span></div>
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<p class="para rdfs-comment">
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Atomically attempts to find <code class="parameter">key</code> in the cache, if it cannot be found <code class="parameter">generator</code>
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is called, passing <code class="parameter">key</code> as the only argument. The return value of the call is then cached with the optionally specified
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<code class="parameter">ttl</code>, and returned.
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<span class="simpara">
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When control enters <span class="function"><strong>apcu_entry()</strong></span> the lock for the cache is acquired exclusively, it is released when control leaves <span class="function"><strong>apcu_entry()</strong></span>:
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In effect, this turns the body of <code class="parameter">generator</code> into a critical section, disallowing two processes from executing the same code paths concurrently.
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In addition, it prohibits the concurrent execution of any other APCu functions, since they will acquire the same lock.
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</span>
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</p></blockquote>
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<div class="warning"><strong class="warning">Warning</strong>
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<p class="simpara">
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The only APCu function that can be called safely by <code class="parameter">generator</code> is <span class="function"><strong>apcu_entry()</strong></span>.
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</p>
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</div>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.apcu-entry-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">key</code></dt>
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<dd>
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<p class="para">
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Identity of cache entry
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</p>
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</dd>
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<dt>
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<code class="parameter">generator</code></dt>
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<dd>
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<p class="para">
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A callable that accepts <code class="parameter">key</code> as the only argument and returns the value to cache.
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</p>
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</dd>
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<dt>
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<code class="parameter">ttl</code></dt>
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<dd>
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<p class="para">
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Time To Live; store <code class="parameter">var</code> in the cache for
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<code class="parameter">ttl</code> seconds. After the
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<code class="parameter">ttl</code> has passed, the stored variable will be
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expunged from the cache (on the next request). If no <code class="parameter">ttl</code>
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is supplied (or if the <code class="parameter">ttl</code> is
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<em>0</em>), the value will persist until it is removed from
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the cache manually, or otherwise fails to exist in the cache (clear,
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restart, etc.).
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.apcu-entry-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns the cached value
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.apcu-entry-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-419">
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<p><strong>Example #1 An <span class="function"><strong>apcu_entry()</strong></span> example</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$config </span><span style="color: #007700">= </span><span style="color: #0000BB">apcu_entry</span><span style="color: #007700">(</span><span style="color: #DD0000">"config"</span><span style="color: #007700">, function(</span><span style="color: #0000BB">$key</span><span style="color: #007700">) {<br /> return [<br /> </span><span style="color: #DD0000">"fruit" </span><span style="color: #007700">=> </span><span style="color: #0000BB">apcu_entry</span><span style="color: #007700">(</span><span style="color: #DD0000">"config.fruit"</span><span style="color: #007700">, function(</span><span style="color: #0000BB">$key</span><span style="color: #007700">){<br /> return [<br /> </span><span style="color: #DD0000">"apples"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"pears"<br /> </span><span style="color: #007700">];<br /> }), <br /> </span><span style="color: #DD0000">"people" </span><span style="color: #007700">=> </span><span style="color: #0000BB">apcu_entry</span><span style="color: #007700">(</span><span style="color: #DD0000">"config.people"</span><span style="color: #007700">, function(</span><span style="color: #0000BB">$key</span><span style="color: #007700">){<br /> return [<br /> </span><span style="color: #DD0000">"bob"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"joe"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"niki"<br /> </span><span style="color: #007700">];<br /> })<br /> ];<br />});<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$config</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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array(2) {
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["fruit"]=>
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array(2) {
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[0]=>
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string(6) "apples"
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[1]=>
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string(5) "pears"
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}
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["people"]=>
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array(3) {
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[0]=>
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string(3) "bob"
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[1]=>
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string(3) "joe"
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[2]=>
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string(4) "niki"
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}
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}
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.apcu-entry-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="apcu_store.html" class="function" rel="rdfs-seeAlso">apcu_store()</a> - Cache a variable in the data store</span></li>
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<li class="member"><span class="function"><a href="apcu_fetch.html" class="function" rel="rdfs-seeAlso">apcu_fetch()</a> - Fetch a stored variable from the cache</span></li>
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<li class="member"><span class="function"><a href="apcu_delete.html" class="function" rel="rdfs-seeAlso">apcu_delete()</a> - Removes a stored variable from the cache</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |