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A PHP implementation of QUIC protocol congestion control algorithms, supporting NewReno and BBR algorithms for high-performance network communication.

Features
Installation
Quick Start
Testing
Performance Features
API Documentation
Dependencies
Contributing
License
Development Status

Features

Supported Congestion Control Algorithms

NewReno Algorithm
- Traditional loss-based congestion control
- Slow start and congestion avoidance mechanisms
- Fast retransmit and fast recovery
- Ideal for stable network environments
BBR Algorithm
- Google's model-based congestion control
- Bandwidth estimation and RTT measurement
- Four states: startup, drain, probe_bw, probe_rtt
- Optimized for high-bandwidth networks

Core Components

CongestionControlInterface: Standard interface for congestion control algorithms
CongestionWindow: Congestion window management class
CongestionController: Congestion control coordinator
NewReno: NewReno algorithm implementation
BBR: BBR algorithm implementation

Installation

Requirements

PHP 8.1 or higher
tourze/quic-core package
tourze/quic-recovery package

Using Composer

composer require tourze/quic-congestion

Quick Start

Basic Usage

<?php

use Tourze\QUIC\Congestion\NewReno;
use Tourze\QUIC\Congestion\BBR;
use Tourze\QUIC\Congestion\CongestionController;

// Using NewReno algorithm
$newReno = new NewReno();
$controller = new CongestionController($newReno);

// Sending a packet
$controller->onPacketSent(1, 1200, microtime(true));

// Receiving ACK
$controller->onPacketAcked(1, 1200, $sentTime, microtime(true));

// Check if can send
if ($controller->canSend(1200)) {
    // Can send packet
}

// Switch to BBR algorithm
$bbr = new BBR();
$controller->switchAlgorithm($bbr);

Using BBR Algorithm

<?php

use Tourze\QUIC\Congestion\BBR;

$bbr = new BBR(12000); // Initial congestion window 12KB

// Handle packet acknowledgment
$bbr->onPacketAcked($packetNumber, $bytes, $sentTime, $ackTime);

// Get sending rate
$pacingRate = $bbr->getSendingRate();

// Get detailed statistics
$stats = $bbr->getStats();
echo "Current state: " . $stats['state']; // startup, drain, probe_bw, probe_rtt
echo "Bandwidth estimate: " . $stats['bandwidth_estimate'] . " bytes/s";
echo "Min RTT: " . $stats['min_rtt'] . " seconds";

Congestion Window Management

<?php

use Tourze\QUIC\Congestion\CongestionWindow;

$window = new CongestionWindow();

// Slow start growth
$window->onPacketAcked(1200, true); // In slow start phase

// Congestion avoidance growth
$window->onPacketAcked(1200, false); // In congestion avoidance phase

// Handle packet loss
$window->onPacketLost();

// Get current window size
$size = $window->getWindowSize();

Testing

The package includes comprehensive test coverage with 58 unit tests and 163 assertions covering:

BBR Algorithm Tests (17 tests)

Initial state validation
Packet sending and acknowledgment
RTT measurement and bandwidth estimation
State transition mechanisms
Packet loss handling
Statistics accuracy

NewReno Algorithm Tests (13 tests)

Slow start and congestion avoidance
Fast retransmit and fast recovery
Packet loss detection and window adjustment
Duplicate ACK handling
Timeout retransmission

Congestion Window Tests (11 tests)

Window initialization and growth
Minimum/maximum window limits
Window reduction after packet loss
Statistics collection

Congestion Controller Tests (14 tests)

Algorithm switching functionality
Batch ACK and loss handling
RTT calculation and statistics
Edge case handling
Performance metrics collection

Running Tests

./vendor/bin/phpunit packages/quic-congestion/tests

Performance Features

High-frequency packet processing support
Memory usage optimization with automatic history cleanup
Precise bandwidth and RTT measurement
Configurable algorithm parameters
Detailed performance statistics

API Documentation

CongestionControlInterface

interface CongestionControlInterface
{
    public function onPacketAcked(int $packetNumber, int $bytes, float $sentTime, float $ackTime): void;
    public function onPacketLost(int $packetNumber, int $bytes, float $sentTime, float $lossTime): void;
    public function onPacketSent(int $packetNumber, int $bytes, float $sentTime): void;
    public function getCongestionWindow(): int;
    public function getSlowStartThreshold(): int;
    public function canSend(int $bytes, int $bytesInFlight): bool;
    public function getSendingRate(): ?float;
    public function isInSlowStart(): bool;
    public function reset(): void;
    public function getStats(): array;
    public function getAlgorithmName(): string;
}

Dependencies

tourze/quic-core: QUIC protocol core components
tourze/quic-recovery: Packet loss detection and RTT estimation

Contributing

Please see CONTRIBUTING.md for details on how to contribute to this project.

License

The MIT License (MIT). Please see License File for more information.

Development Status

✅ Complete - All core features implemented and tested

NewReno congestion control algorithm
BBR congestion control algorithm
Congestion window management
Congestion controller coordination
Complete unit test coverage

tourze / quic-congestion

Maintainers

Details