限制文件读取速度

limit_speed_print_file.php

<?php
function limit_speed_print_file($filename, $limit_rate = 100)
{
    if (file_exists($filename) && is_file($filename)) {
        header('Cache-control: private');
        header('Content-Type: application/octet-stream');
        header('Content-Length: '.get_safe_filesize($filename));
        header('Content-Disposition: attachment; filename='
            .basename($filename));
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Pragma: public');

        $chunk = round($limit_rate * 1024);
        
        $f = fopen($filename, 'rb');
        if ($f === false) {
            print '打开文件失败';
            exit(1);
        }
        while (!feof($f)) {
            print fread($f, $chunk);
            flush();
            sleep(1);
        }
        fclose($f);
    } else {
        die('Error: The file '.$filename.' does not exist!');
    }
}