Crate rate_limiter_aimd 

Adaptive concurrency rate limiter using AIMD (Additive Increase Multiplicative Decrease) algorithm

This crate provides middleware for reqwest-based HTTP clients that dynamically adjusts the maximum number of concurrent requests based on observed latency and error rates.

Algorithm Overview

The AIMD algorithm:

1. Additive Increase: For each successful request window, increase the concurrency limit by 1
2. Multiplicative Decrease: When errors exceed threshold, decrease limit by factor (default: 0.9)

Features

• Automatic concurrency tuning based on request latencies
• Configurable EWMA smoothing for latency measurements
• Error rate tracking for backoff decisions
• Reqwest middleware integration

Performance

• Overhead: <1μs per request
• Suitable for high-throughput systems (tested up to 10k req/s)

Safety & Concurrency

• Thread-safe: Uses atomic operations for all shared state
• No unsafe code

Basic Usage

use rate_limiter_aimd::adaptive_concurrency::AdaptiveConcurrencySettings;
use rate_limiter_aimd::reqwest_integration::ReqwestService;
use reqwest::Client;
 
let settings = AdaptiveConcurrencySettings::default();
let client = ReqwestService::new(Client::new(), settings);
// Use client as you would normally with reqwest

Configuration

See adaptive_concurrency::AdaptiveConcurrencySettings for tuning parameters

Metrics

Emits metrics via the InternalEvent trait

Modules

adaptive_concurrency

Limit the max number of requests being concurrently processed.

Macros

assert_downcast_matches

register

registered_event

Macro to take care of some of the repetitive boilerplate in implementing a registered event. See the other events in this module for examples of how to use this.

Type Aliases

Error