1. During the implementation of channel publishing, files to be uploaded to a channel may be too large, resulting in upload failures. For example, Douyin currently limits file size to 128 MB. See Figure 1.
2. However, the current implementation logic first downloads the file over HTTP (absolute_url: the absolute URL of the source resource file) to obtain the file’s relative_path (the relative path of the resource file for channel publishing), and only then can it retrieve the file size. This implementation stage is asynchronous. See Figure 2.
3. We now want to optimize the user experience by detecting the file size based on the HTTP protocol when calling the API (i.e., obtaining the file size without downloading the file).
4. Refer to the filesystem function filesize — Gets file size: https://www.php.net/manual/zh/function.filesize.php . The simplest and most efficient implemention for getting remote filesize. See Figure 3.
5. When executing fopen(), you can use the variable $http_response_header. It contains an array of response headers. Print the variable $http_response_header. See Figure 4.
<?php
function remote_filesize($url) {
static $regex = '/^Content-Length: *+\K\d++$/im';
// 将 $url 指定的名字资源绑定到一个流上，只读方式打开，将文件指针指向文件头
if (!$fp = @fopen($url, 'rb')) {
return false;
}
// 执行 fopen() 时可以使用变量 $http_response_header。 其中包含响应标头的数组。
if (
isset($http_response_header) &&
preg_match($regex, implode("\n", $http_response_header), $matches)
) {
print_r($http_response_header);
return (int)$matches[0];
}
echo 1;
return strlen(stream_get_contents($fp));
}
$startTime = time();
$url = 'https://media.shuijingwanwq.com/2021/07/秦时明月第一集荧惑守心.mp4';
echo remote_filesize($url) . "\n";
$endTime = time();
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>Array
(
[0] => HTTP/1.1 200 OK
[1] => Server: nginx
[2] => Date: Mon, 09 Aug 2021 05:46:41 GMT
[3] => Content-Type: video/mp4
[4] => Content-Length: 143162935
[5] => Last-Modified: Tue, 30 Oct 2018 09:52:18 GMT
[6] => Connection: close
[7] => ETag: "5bd829d2-8887e37"
[8] => Expires: Wed, 08 Sep 2021 05:46:41 GMT
[9] => Cache-Control: max-age=2592000
[10] => Strict-Transport-Security: max-age=15768000
[11] => Accept-Ranges: bytes
)
143162935
Time consumed: 0 seconds
6. If the variable $http_response_header does not exist, use the function stream_get_contents — Reads the remainder of a stream into a string. File size: 1.27 MB. Testing the time consumed: 2 seconds, which is unacceptable. Decided to return false when the variable $http_response_header does not exist. See Figure 5.
<?php
function remote_filesize($url) {
static $regex = '/^Content-Length: *+\K\d++$/im';
// 将 $url 指定的名字资源绑定到一个流上，只读方式打开，将文件指针指向文件头
if (!$fp = @fopen($url, 'rb')) {
return false;
}
// 执行 fopen() 时可以使用变量 $http_response_header。 其中包含响应标头的数组。
/*
if (
isset($http_response_header) &&
preg_match($regex, implode("\n", $http_response_header), $matches)
) {
print_r($http_response_header);
return (int)$matches[0];
}
*/
echo 1;
return strlen(stream_get_contents($fp));
}
$startTime = time();
$url = 'https://media.shuijingwanwq.com/2021/07/兔子、牛、还有一只什么哟？认不出来了.mp4';
echo remote_filesize($url) . "\n";
$endTime = time();
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>1334721
Time consumed: 2 seconds
7. The final code implementation is as follows. See Figure 6.
<?php
function remote_filesize($url) {
static $regex = '/^Content-Length: *+\K\d++$/im';
// 将 $url 指定的名字资源绑定到一个流上，只读方式打开，将文件指针指向文件头
if (!$fp = @fopen($url, 'rb')) {
return 0;
}
// 执行 fopen() 时可以使用变量 $http_response_header。其中包含响应标头的数组。
if (
isset($http_response_header) &&
preg_match($regex, implode("\n", $http_response_header), $matches)
) {
print_r($http_response_header);
return (int)$matches[0];
}
return 0;
}
$startTime = time();
$url = 'https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4';
echo remote_filesize($url) . "\n";
$endTime = time();
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>
8. When calling the API, detecting the file size based on the HTTP protocol (i.e., obtaining the file size without downloading the file) ultimately achieves the expected goal. See Figure 7.
