如何使用gettimeofday 函數進行網絡延遲的精準測試？

gitbox 2025-06-30

<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// 本段代碼用於初始化環境，與正文內容無關</span></span><span>

</span><span><span class="hljs-title function_ invoke__">date_default_timezone_set</span></span><span>(</span><span><span class="hljs-string">'UTC'</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"準備進行網絡延遲測試...\n"</span></span><span>;
</span><span><span class="hljs-meta">?></span></span><span>

<hr>

<h1>如何使用 gettimeofday 函數進行網絡延遲的精準測試？</h1>

<p>在網絡編程和性能調優中，測量網絡請求的延遲是一個至關重要的任務。PHP 提供了多個時間函數來輔助這一操作，其中 <code>gettimeofday

由於包含了微秒部分，因此可以用來測量兩個時間點之間非常小的時間差，進而計算操作（如HTTP 請求）的精確耗時。

如何使用gettimeofday 測試網絡延遲

以下是一個簡單的示例，使用gettimeofday來測試訪問某個URL 的延遲：

 &lt;?php
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">get_microtime</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
    </span><span><span class="hljs-variable">$t</span></span><span> = </span><span><span class="hljs-title function_ invoke__">gettimeofday</span></span><span>();
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-variable">$t</span></span><span>[</span><span><span class="hljs-string">'sec'</span></span><span>] + </span><span><span class="hljs-variable">$t</span></span><span>[</span><span><span class="hljs-string">'usec'</span></span><span>] / </span><span><span class="hljs-number">1e6</span></span><span>;
}

</span><span><span class="hljs-variable">$url</span></span><span> = </span><span><span class="hljs-string">"https://www.example.com"</span></span><span>;

</span><span><span class="hljs-comment">// 記錄開始時間</span></span><span>
</span><span><span class="hljs-variable">$start</span></span><span> = </span><span><span class="hljs-title function_ invoke__">get_microtime</span></span><span>();

</span><span><span class="hljs-comment">// 發起網絡請求</span></span><span>
</span><span><span class="hljs-variable">$opts</span></span><span> = </span><span><span class="hljs-keyword">array</span></span><span>(
    </span><span><span class="hljs-string">"http"</span></span><span> => </span><span><span class="hljs-keyword">array</span></span><span>(
        </span><span><span class="hljs-string">"method"</span></span><span> => </span><span><span class="hljs-string">"GET"</span></span><span>,
        </span><span><span class="hljs-string">"timeout"</span></span><span> => </span><span><span class="hljs-number">10</span></span><span>
    )
);
</span><span><span class="hljs-variable">$context</span></span><span> = </span><span><span class="hljs-title function_ invoke__">stream_context_create</span></span><span>(</span><span><span class="hljs-variable">$opts</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">file_get_contents</span></span><span>(</span><span><span class="hljs-variable">$url</span></span><span>, </span><span><span class="hljs-literal">false</span></span><span>, </span><span><span class="hljs-variable">$context</span></span><span>);

</span><span><span class="hljs-comment">// 記錄結束時間</span></span><span>
</span><span><span class="hljs-variable">$end</span></span><span> = </span><span><span class="hljs-title function_ invoke__">get_microtime</span></span><span>();

</span><span><span class="hljs-variable">$latency</span></span><span> = (</span><span><span class="hljs-variable">$end</span></span><span> - </span><span><span class="hljs-variable">$start</span></span><span>) * </span><span><span class="hljs-number">1000</span></span><span>; </span><span><span class="hljs-comment">// 轉換為毫秒</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"訪問 <span class="hljs-subst">$url</span></span></span><span> 的延遲為：" . </span><span><span class="hljs-title function_ invoke__">round</span></span><span>(</span><span><span class="hljs-variable">$latency</span></span><span>, </span><span><span class="hljs-number">2</span></span><span>) . </span><span><span class="hljs-string">" 毫秒\n"</span></span><span>;
?&gt;

該腳本通過gettimeofday計算file_get_contents網絡請求前後的時間差，最終得出一個近似的延遲時間（以毫秒為單位）。

優勢與註意事項

高精度：相比time()函數， gettimeofday提供微秒級的時間測量，精度更高。
平台兼容：在大多數主流操作系統上都支持。
受系統時間影響：雖然是高精度，但如果系統時間發生跳變（如NTP 同步），可能會造成誤差。

結語

gettimeofday是PHP 中少有的高精度計時工具，尤其適合網絡延遲測試或性能評估等對時間要求嚴格的場景。結合合適的上下文控制方式，可以輕鬆實現毫秒甚至微秒級的性能測量，為優化提供數據支持。