[12.x] Add concurrency control to Http::pool and Http::batch

[WendellAdriel]

This PR adds the ability to control how many concurrent HTTP requests the Http::pool and Http::batch can make.

Http::pool Example

A new optional param should be passed in the Http::pool call:

$responses = Http::pool(fn (Pool $pool) => [
    $pool->get('http://localhost/first'),
    $pool->get('http://localhost/second'),
    $pool->get('http://localhost/third'),
], 2); // Sets the pool to have at max 2 concurrent HTTP requests

Http::batch Example

A new ->concurrency() method can be called before calling the ->send() or ->defer() methods:

$responses = Http::batch(fn (Batch $batch) => [
    $batch->as('first')->get('http://localhost/first'),
    $batch->as('second')->get('http://localhost/second'),
    $batch->as('third')->get('http://localhost/third'),
])->concurrency(2)->send(); // Sets the batch to have at max 2 concurrent HTTP requests

[taylorotwell]

Nice - thanks!

[jonnywilliamson]

@WendellAdriel Should the ->retry method work in this example:

$responses = Http::batch(fn (Batch $batch) => [
    $batch->as('first')->retry(3)->get('http://localhost/first'),
    $batch->as('second')->get('http://localhost/second'),
    $batch->as('third')->get('http://localhost/third'),
])->concurrency(2)->send();

I might be doing something wrong but I can't get it to retry.

[WendellAdriel]

@jonnywilliamson this weekend I'm busy, but next week I'll check it ASAP to give you some feedback.

[jonnywilliamson]

Actually I think I found a way to test it properly! Thank you for replying.

[WendellAdriel]

@jonnywilliamson did you check if the retry is working as expected?

[jonnywilliamson]

Yes this proves it works!

<?php

use Illuminate\Http\Client\Batch;
use Illuminate\Support\Facades\Http;

it('retries failing requests within a batch while concurrent', function () {
    // 1. Strict Mode: Ensure only faked requests are allowed
    Http::preventStrayRequests();

    // 2. Setup Fakes
    Http::fake([
        // The 'first' URL will fail twice (500), then succeed (200)
        'http://localhost/first' => Http::sequence()
            ->push('Server Error 1', 500)
            ->push('Server Error 2', 500)
            ->push('First Success', 200),

        // All other URLs return a standard 200 OK
        'http://localhost/*' => Http::response('OK', 200),
    ]);

    // 3. Execute Batch
    $responses = Http::batch(fn (Batch $batch) => [
        $batch->as('first')->retry(3)->get('http://localhost/first'),
        $batch->as('second')->get('http://localhost/second'),
        $batch->as('third')->get('http://localhost/third'),
        $batch->as('fourth')->get('http://localhost/forth'),
        $batch->as('fifth')->get('http://localhost/fifth'),
    ])->concurrency(2)->send();

    // 4. Assertions

    // Verify 'first' eventually succeeded and got the correct final response
    expect($responses['first']->successful())->toBeTrue();
    expect($responses['first']->body())->toBe('First Success');

    // Verify all other requests succeeded
    expect($responses['second']->successful())->toBeTrue();
    expect($responses['third']->successful())->toBeTrue();
    expect($responses['fourth']->successful())->toBeTrue();
    expect($responses['fifth']->successful())->toBeTrue();

    // CRITICAL ASSERTION:
    // We expect 7 total requests sent to the "network":
    // - 3 attempts for 'first' (Fail, Fail, Success)
    // - 1 attempt for 'second'
    // - 1 attempt for 'third'
    // - 1 attempt for 'fourth'
    // - 1 attempt for 'fifth'
    // = 7 total
    Http::assertSentCount(7);
});

Thanks!