Struct RateLimiter 

pub struct RateLimiter { /* private fields */ }

NCBI E-utilities rate limits:

• 3 requests per second without API key
• 10 requests per second with API key
• Violations can result in IP blocking

Token bucket rate limiter for NCBI API compliance

Implementations

impl RateLimiter

pub fn new(rate: f64) -> Self

Create a new rate limiter with the specified rate

Arguments

• rate - Maximum requests per second (e.g., 3.0 for NCBI default)

Examples

use pubmed_client::RateLimiter;

// Create rate limiter for NCBI API without key (3 req/sec)
let limiter_default = RateLimiter::new(3.0);

// Create rate limiter for NCBI API with key (10 req/sec)
let limiter_with_key = RateLimiter::new(10.0);

pub fn ncbi_default() -> Self

Create rate limiter for NCBI API without API key (3 requests/second)

pub fn ncbi_with_key() -> Self

Create rate limiter for NCBI API with API key (10 requests/second)

pub async fn acquire(&self) -> Result<()>

Acquire a token, waiting if necessary to respect rate limits

This method implements a token bucket algorithm with the following behavior:

1. Check if tokens are available in the bucket
2. If available, consume one token and return immediately
3. If not available, wait for the appropriate interval
4. Refill the bucket and consume one token

Examples

use pubmed_client::RateLimiter;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let limiter = RateLimiter::ncbi_default();

    // This will respect the 3 req/sec limit
    for i in 0..5 {
        limiter.acquire().await?;
        println!("Making API call {}", i + 1);
        // Make your API call here
    }

    Ok(())
}

pub fn check_available(&self) -> bool

Check if a token is available without blocking

Returns true if a token is available and can be acquired immediately. This method does not consume a token.

pub fn token_count(&self) -> f64

Get current token count (for testing and monitoring)

pub fn rate(&self) -> f64

Get the configured rate limit (requests per second)

Trait Implementations

impl Clone for RateLimiter

fn clone(&self) -> RateLimiter

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.