模拟flock实现文件锁定_php技巧

主要提供了一种思路。
$lock0和$lock1就是文件锁定的标识符，当文件被某一用户打开的时候，$lock0和$lock1就会产生，当该文件没打开则不存在。
其实最关键就是有个标识符来表示当前这个文件的状态， $lock0和$lock1就是起这样的作用。

<?php   <br><br>// Lock a file, timing out if it takes too long.   <BR>function lock ($lock, $tries) {   <BR>       $lock0 = ".{$lock}0";   <BR>       $lock1 = ".{$lock}1";   <BR>       for ($i=0; $i<$tries; $i++) {   <BR>               if (!is_file($lock0)) {   <BR>                       touch($lock0);   <BR>                       if (!is_file($lock1)) {   <BR>                               touch($lock1);   <BR>                               return 1; <b>/本文来源gao@!dai!ma.com搞$$代^@码5网@</b><strong>搞代gaodaima码</strong>  <BR>                       }   <BR>               }   <BR>               usleep(100);   <BR>       }   <BR>       return 0;   <BR>}   <br><br>// Unlock a file.   <BR>function unlock ($lock) {   <BR>       unlink(".{$lock}1");   <BR>       unlink(".{$lock}0");   <BR>}   <br><br>// Usage example.   <BR>$filename = "somefile";   <BR>$data = "stuff and thingsn";   <BR>$tries = 10;   <BR>if (lock($filename, $tries)) {   <BR>       $h = fopen($filename, "a") or die();   <BR>       fwrite($h, $data);   <BR>       fclose($h);   <BR>       /**   <BR>         * 另外一个进程写文件，检查是否锁定   <BR>       */   <BR>       if (lock($filename, $tries)) {   <BR>               $h2 = fopen($filename, "a") or die();   <BR>               fwrite($h2,'check lock');   <BR>               fclose($h2);   <BR>        }else{   <BR>            //die("Failed to lock $filename after ".($tries*100)." milliseconds!";   <BR>        }   <BR>        unlock($filename);   <BR>} else {   <BR>       //die("Failed to lock $filename after ".($tries*100)." milliseconds!";   <BR>}   <BR>?> <BR>

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