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CDN分发的PHP算法[关闭]

cdn algorithm php

1

Metalshark · 技术社区 · 16 年前

我包含的CSS文件拉入了其他文件中,因此关联*facepalm*

我们有下面的代码来选择每个文件名的CNAME CDN引用。它每次必须基于给定的文件名返回相同的URL。我们认为这是足够随机的:

<?php

  function cdn_prefix($fileName) {
    $number_of_servers = 4;

    $md5 = md5($fileName);

    $md5 = substr($md5, 0, 4);

    $hash_number = base_convert($md5, 16, 10);

    $server_number = ($hash_number % $number_of_servers) + 1;

    $server_prefix = '//static' . $server_number . '.' . $_SERVER['SERVER_NAME'];

    return $server_prefix . $fileName;
  }

?>

然而,它似乎倾向于数字3:

不管我做什么(salt、不同的基、随机乘法等),headerBg到mainNavPipe的结果(在屏幕截图上)都有相同的数字。

有更好的算法吗?

下面是使用SHA1的相同算法得到的结果

阵列(用于测试)是:

FILES = [
    '/a/files/image/250.jpg',
    '/a/files/image/244.jpg',
    '/a/files/image/247.jpg',
    '/a/css/global/core.css',
    '/a/css/global/print.css',
    '/a/img/global/new_logo.gif',
    '/a/img/global/book-a-free-survey.gif',
    '/a/img/global/make_an_enquiry.gif',
    '/a/img/global/purchase-locks-blue.jpg',
    '/a/files/image/251.jpg',
    '/a/img/global/bg.gif',
    '/a/img/global/headerBg.jpg',
    '/a/img/global/basketBg.gif',
    '/a/img/global/arrow.png',
    '/a/img/global/trolley.gif',
    '/a/img/global/mainNavBg.gif',
    '/a/img/global/mainNavCurrentBg.gif',
    '/a/img/global/mainNavPipe.gif',
    '/a/img/common/sectionNavBg.jpg',
    '/a/img/global/nav_arrow.gif',
    '/a/img/global/footerBg.jpg',
    '/a/img/global/footerCopyrightBg.jpg',
    '/a/img/global/footerLogo.jpg'
]

1 回复 | 直到 7 年前

1

Artefacto 16 年前

function cdn_prefix($fileName) {
    $number_of_servers = 4;
    $md5 = md5($fileName);
    $md5 = substr($md5, 0, 4);
    $hash_number = base_convert($md5, 16, 10);
    $server_number = ($hash_number % $number_of_servers) + 1;
    return $server_number;
}
$arr = array(1=>0, 2=>0, 3=>0, 4=>0,);
for ($i = 1; $i < 200000; $i++) {
    $arr[cdn_prefix("anrg".$i)]++;
}
print_r($arr);

给予:

Array
(
    [1] => 49770
    [2] => 50090
    [3] => 50026
    [4] => 50113
)