模拟flock实现文件锁定
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。
复制代码 代码如下:
// 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!";
}
?>

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