模拟flock实现文件锁定_php技巧

// Lock a file, timing out if it takes too long.  
function lock ($lock, $tries) {  
       $lock0 = ".{$lock}0";  
       $lock1 = ".{$lock}1";  
       for ($i=0; $i               if (!is_file($lock0)) {  
                       touch($lock0);  
                       if (!is_file($lock1)) {  
                               touch($lock1);  
                               return 1;  
                       }  
               }  
               usleep(100);  
       }  
       return 0;  
}  

// Unlock a file.  
function unlock ($lock) {  
       unlink(".{$lock}1");  
       unlink(".{$lock}0");  
}  

// Usage example.  
$filename = "somefile";  
$data = "stuff and thingsn";  
$tries = 10;  
if (lock($filename, $tries)) {  
       $h = fopen($filename, "a") or die();  
       fwrite($h, $data);  
       fclose($h);  
       /**  
         * 另外一个进程写文件，检查是否锁定  
       */  
       if (lock($filename, $tries)) {  
               $h2 = fopen($filename, "a") or die();  
               fwrite($h2,'check lock');  
               fclose($h2);  
        }else{  
            //die("Failed to lock $filename after ".($tries*100)." milliseconds!";  
        }  
        unlock($filename);  
} else {  
       //die("Failed to lock $filename after ".($tries*100)." milliseconds!";  
}  
?>