Module delay 

Available on crate feature tower-delay only.

Request delay middleware.

Adds configurable delays before HTTP requests — useful for rate limiting, testing under slow network conditions, or just being polite to APIs.

Quick Start

Fixed 1-second delay:

use std::time::Duration;
use wreq::Client;
use wreq_util::middleware::delay::DelayLayer;

let client = Client::builder()
    .layer(DelayLayer::new(Duration::from_secs(1)))
    .build()?;

Random jitter (0.8s ~ 1.2s):

use std::time::Duration;
use wreq::Client;
use wreq_util::middleware::delay::JitterDelayLayer;

let client = Client::builder()
    .layer(JitterDelayLayer::new(Duration::from_secs(1), 0.2))
    .build()?;

Conditional Delays

Use .when() to apply delays only to matching requests:

// Only delay POST requests
DelayLayer::new(Duration::from_secs(1))
    .when(|req: &http::Request<_>| req.method() == http::Method::POST)

// Jitter on specific paths
JitterDelayLayer::new(Duration::from_millis(500), 0.3)
    .when(|req: &http::Request<_>| req.uri().path().starts_with("/api"))

Notes

• Delays are async and won’t block the runtime
• Not a substitute for proper rate limiters — servers can still see timing patterns
• Keep delays short in hot paths

Structs

Delay

A Tower Service that introduces a fixed delay before each request.

DelayLayer

A Tower Layer that introduces a fixed delay before each request.

DelayLayerWith

Conditional delay Layer, applies delay based on a predicate.

DelayWith

A Tower Service that conditionally applies fixed delay based on a predicate.

JitterDelay

A Tower Service that applies jittered delay to requests.

JitterDelayLayer

A Tower Layer that introduces a jittered delay before each request.

JitterDelayLayerWith

Conditional jitter delay Layer, applies delay based on a predicate.

JitterDelayWith

A Tower Service that conditionally applies jittered delay based on a predicate.

ResponseFuture

Response future for Delay.