justblackbird/amphp-priority-emitter

In-memory implementation of async emitter with prioritized messages

0.4.0 2020-08-22 12:19 UTC

Requires

• php: ^7.4
• amphp/amp: ^2.4
• justblackbird/stable-priority-queue: ^0.1.0
• react/promise: ^2

Requires (Dev)

• amphp/phpunit-util: ^1.4
• phpunit/phpunit: ^9.2
• squizlabs/php_codesniffer: ^3.5
• vimeo/psalm: ^3.12

MIT

• Dmitry Simushev

README

In-memory implementation of async emitter with prioritized messages

Why

Implementation of AMP Emitter is backed by a queue. It covers many cases but sometimes a priority queue is needed.

For example, you're building a bot for a social network or a messenger. Assume that the bot can react for users' commands and broadcast information to all its subscribers. These two types of messages have different priorities. Commands' responses must be sent as soon as possible to keep UX responsive but broadcasting messages can wait for a while.

You can build the app around a message bus. There is some code that pushes messages to the bus, and some code that pull them out and transfer to social network API.

You cannot use Emitter shipped with AMP because in such case broadcasting messages will block command ones because there is no way to set priority with AMP Emitter.

This library adds and Emitter with API similar to AMP Emitter but with priority support.

Installation

composer require justblackbird/amphp-priority-emitter

Usage

use Amp\Loop;
use JustBlackBird\AmpPriorityEmitter\Emitter;

// The following example will output:
// - important message
// - message one
// - message two

Loop::run(static function() {
    $emitter = new Emitter();

    $emitter->emit('message one', 0);
    $emitter->emit('message two', 0);
    $emitter->emit('important message', 5);
    $emitter->complete();

    $iterator = $emitter->iterate();
    while(yield $iterator->advance()) {
        echo "- " . $iterator->getCurrent() . "\n";        
    }
});

License

MIT (c) Dmitry Simushev

The implementation is based on AMP Emitter.