从 Laravel 存储下载而不将整个文件加载到内存中

Question

I am using Laravel Storage and I want to serve users some (larger than memory limit) files. My code was inspired from a post in SO and it goes like this:

$fs = Storage::getDriver();
$stream = $fs->readStream($file->path);

return response()->stream(
    function() use($stream) {
        fpassthru($stream);
    }, 
    200,
    [
        'Content-Type' => $file->mime,
        'Content-disposition' => 'attachment; filename="'.$file->original_name.'"',
    ]);

Unfourtunately, I run into an error for large files:

[2016-04-21 13:37:13] production.ERROR: exception 'Symfony\Component\Debug\Exception\FatalErrorException' with message 'Allowed memory size of 134217728 bytes exhausted (tried to allocate 201740288 bytes)' in /path/app/Http/Controllers/FileController.php:131
Stack trace:
#0 /path/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/HandleExceptions.php(133): Symfony\Component\Debug\Exception\FatalErrorException->__construct()
#1 /path/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/HandleExceptions.php(118): Illuminate\Foundation\Bootstrap\HandleExceptions->fatalExceptionFromError()
#2 /path/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/HandleExceptions.php(0): Illuminate\Foundation\Bootstrap\HandleExceptions->handleShutdown()
#3 /path/app/Http/Controllers/FileController.php(131): fpassthru()
#4 /path/vendor/symfony/http-foundation/StreamedResponse.php(95): App\Http\Controllers\FileController->App\Http\Controllers\{closure}()
#5 /path/vendor/symfony/http-foundation/StreamedResponse.php(95): call_user_func:{/path/vendor/symfony/http-foundation/StreamedResponse.php:95}()
#6 /path/vendor/symfony/http-foundation/Response.php(370): Symfony\Component\HttpFoundation\StreamedResponse->sendContent()
#7 /path/public/index.php(56): Symfony\Component\HttpFoundation\Response->send()
#8 /path/public/index.php(0): {main}()
#9 {main}  

It seems that it tries to load all of the file into memory. I was expecting that usage of stream and passthru would not do this... Is there something missing in my code? Do I have to somehow specify chunk size or what?

The versions I am using are Laravel 5.1 and PHP 5.6.

Answer 1

It seems that output buffering is still building up a lot in memory.

Try disabling ob before doing the fpassthru:

function() use($stream) {
    while(ob_get_level() > 0) ob_end_flush();
    fpassthru($stream);
},

It could be that there are multiple output buffers active that is why the while is needed.

Answer 2

Instead of loading the whole file into memory at once, try to use fread to read and send it chunk by chunk.

Here is a very good article: http://zinoui.com/blog/download-large-files-with-php

<?php

//disable execution time limit when downloading a big file.
set_time_limit(0);

/** @var \League\Flysystem\Filesystem $fs */
$fs = Storage::disk('local')->getDriver();

$fileName = 'bigfile';

$metaData = $fs->getMetadata($fileName);
$handle = $fs->readStream($fileName);

header('Pragma: public');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Cache-Control: private', false);
header('Content-Transfer-Encoding: binary');
header('Content-Disposition: attachment; filename="' . $metaData['path'] . '";');
header('Content-Type: ' . $metaData['type']);

/*
    I've commented the following line out.
    Because \League\Flysystem\Filesystem uses int for file size
    For file size larger than PHP_INT_MAX (2147483647) bytes
    It may return 0, which results in:

        Content-Length: 0

    and it stops the browser from downloading the file.

    Try to figure out a way to get the file size represented by a string.
    (e.g. using shell command/3rd party plugin?)
*/

//header('Content-Length: ' . $metaData['size']);


$chunkSize = 1024 * 1024;

while (!feof($handle)) {
    $buffer = fread($handle, $chunkSize);
    echo $buffer;
    ob_flush();
    flush();
}

fclose($handle);
exit;
?>

---

Update

A simpler way to do this: just call

if (ob_get_level()) ob_end_clean();

before returning a response.

Credit to @Christiaan

//disable execution time limit when downloading a big file.
set_time_limit(0);

/** @var \League\Flysystem\Filesystem $fs */
$fs = Storage::disk('local')->getDriver();

$fileName = 'bigfile';

$metaData = $fs->getMetadata($fileName);
$stream = $fs->readStream($fileName);

if (ob_get_level()) ob_end_clean();

return response()->stream(
    function () use ($stream) {
        fpassthru($stream);
    },
    200,
    [
        'Content-Type' => $metaData['type'],
        'Content-disposition' => 'attachment; filename="' . $metaData['path'] . '"',
    ]);

Answer 3

X-Send-File .

X-Send-File is an internal directive that has variants for Apache, nginx, and lighthttpd. It allows you to completely skip distributing a file through PHP and is an instruction that tells the webserver what to send as a response instead of the actual response from the FastCGI.

I've dealt with this before on a personal project and if you want to see the sum of my work, you can access it here:
https://github.com/infinity-next/infinity-next/blob/master/app/Http/Controllers/Content/ImageController.php#L250-L450

This deals not only with distributing files, but handling streaming media seeking. You are free to use that code.

Here is the official nginx documentation on X-Send-File .
https://www.nginx.com/resources/wiki/start/topics/examples/xsendfile/

You do have to edit your webserver and mark specific directories as internal for nginx to comply with X-Send-File directives.

I have example configuration for both Apache and nginx for my above code here.
https://github.com/infinity-next/infinity-next/wiki/Installation

This has been tested on high-traffic websites. Do not buffer media through a PHP Daemon unless your site has next to no traffic or you're bleeding resources.

Answer 4

You could try using the StreamedResponse component directly, instead of the Laravel wrapper for it. StreamedResponse

Answer 5

https://www.php.net/readfile

<?php
$file = 'monkey.gif';

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.basename($file).'"');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    readfile($file);
    exit;
}
?>