关于flock文件锁的阻塞与非阻塞

阻塞模式，程序会一直等待。

<?php
$fp = fopen("lock.txt", "r");
if(flock($fp,LOCK_EX))
{
//code
flock($fp,LOCK_UN);
}
fclose($fp);
?>

非阻塞模式，如果文件被占用直接返回false

<?php
$fp = fopen("lock.txt", "r");
if(flock($fp,LOCK_EX | LOCK_NB))
{
//code
flock($fp,LOCK_UN);
}
else
{
echo "error";
}

fclose($fp);
?>

 阻塞时设置超时时间

if ($fp = fopen($fileName, 'a')) {
    $startTime = microtime();
    do {
        $canWrite = flock($fp, LOCK_EX);
        if (!$canWrite) {
            usleep(round(rand(0, 100) * 1000));
        }
    } while ((!$canWrite) && ((microtime() - $startTime) < 1000));
    if ($canWrite) {
        fwrite($fp, $dataToSave);
    }
    fclose($fp);
}