aidale-layer

Built-in middleware layers for Aidale (logging, retry, caching, etc.).

Overview

aidale-layer provides composable middleware layers following the AOP (Aspect-Oriented Programming) pattern:

• LoggingLayer: Request/response logging with timing
• RetryLayer: Exponential backoff retry with jitter
• More layers coming soon (caching, rate limiting, etc.)

Available Layers

LoggingLayer

Logs all requests and responses with timing information:

use aidale_layer::LoggingLayer;

let executor = RuntimeExecutor::builder(provider)
    .layer(LoggingLayer::new())
    .finish();

Output example:

[AI Request] model=gpt-3.5-turbo messages=2
[AI Response] duration=1.2s tokens=150

RetryLayer

Automatic retry with exponential backoff:

use aidale_layer::RetryLayer;
use std::time::Duration;

let executor = RuntimeExecutor::builder(provider)
    .layer(RetryLayer::new()
        .with_max_retries(3)
        .with_initial_delay(Duration::from_millis(100))
        .with_max_delay(Duration::from_secs(10)))
    .finish();

Features:

• Configurable max retries
• Exponential backoff with jitter
• Configurable delay bounds
• Only retries on transient errors (5xx, network errors)

Composition

Layers are composed in order from outermost to innermost:

let executor = RuntimeExecutor::builder(provider)
    .layer(LoggingLayer::new())      // Executes first (outer)
    .layer(RetryLayer::new()          // Executes second
        .with_max_retries(3))
    .finish();

Execution flow:

Request  → LoggingLayer → RetryLayer → Provider
Response ← LoggingLayer ← RetryLayer ← Provider

Zero-Cost Abstraction

Layers use compile-time composition with static dispatch:

• No virtual dispatch (no dyn Trait)
• No heap allocation for layer chain
• All composition resolved at compile time
• Type-level recursion for layer nesting

This means zero runtime overhead compared to manual implementation!

Usage

Via the main aidale crate:

[dependencies]
aidale = { version = "0.1", features = ["layers"] }

Directly:

[dependencies]
aidale-layer = "0.1"
aidale-core = "0.1"

Custom Layers

Implement the Layer trait from aidale-core:

use aidale_core::{Layer, Provider, ChatCompletionParams, ChatCompletionResponse};
use async_trait::async_trait;

pub struct MyCustomLayer {
    // Your fields
}

#[async_trait]
impl<P: Provider> Layer<P> for MyCustomLayer {
    async fn call(
        &self,
        provider: &P,
        model: &str,
        params: ChatCompletionParams,
    ) -> Result<ChatCompletionResponse> {
        // Pre-processing
        println!("Before request");

        // Call next layer or provider
        let response = provider.chat_completion(model, params).await?;

        // Post-processing
        println!("After request");

        Ok(response)
    }
}

Planned Layers

• CachingLayer: Response caching with TTL
• RateLimitLayer: Request rate limiting
• CircuitBreakerLayer: Circuit breaker pattern
• MetricsLayer: Prometheus metrics export
• TracingLayer: OpenTelemetry distributed tracing

Related Crates

• aidale-core - Core traits and runtime
• aidale-provider - Provider implementations
• aidale-plugin - Plugin system

License

MIT OR Apache-2.0