rate_limiter - [devnet]

use 0x1::timestamp;

Enum Resource RateLimiter

enum RateLimiter has copy, drop, store, key

Variants

TokenBucket

Fields

capacity: u64

current_amount: u64

refill_interval: u64

last_refill_timestamp: u64

fractional_accumulated: u64

Functions

initialize

public fun initialize(capacity: u64, refill_interval: u64): rate_limiter::RateLimiter

Implementation

public fun initialize(capacity: u64, refill_interval: u64): RateLimiter {
    RateLimiter::TokenBucket {
        capacity,
        current_amount: capacity, // Start with a full bucket (full capacity of transactions allowed)
        refill_interval,
        last_refill_timestamp: timestamp::now_seconds(),
        fractional_accumulated: 0, // Start with no fractional accumulated
    }
}

request

public fun request(limiter: &mut rate_limiter::RateLimiter, num_token_requested: u64): bool

Implementation

public fun request(limiter: &mut RateLimiter, num_token_requested: u64): bool {
    refill(limiter);
    if (limiter.current_amount >= num_token_requested) {
        limiter.current_amount = limiter.current_amount - num_token_requested;
        true
    } else {
        false
    }
}

refill

fun refill(limiter: &mut rate_limiter::RateLimiter)

Implementation

fun refill(limiter: &mut RateLimiter) {
    let current_time = timestamp::now_seconds();
    let time_passed = current_time - limiter.last_refill_timestamp;
    // Calculate the full tokens that can be added
    let accumulated_amount = time_passed * limiter.capacity + limiter.fractional_accumulated;
    let new_tokens = accumulated_amount / limiter.refill_interval;
    if (limiter.current_amount + new_tokens >= limiter.capacity) {
        limiter.current_amount = limiter.capacity;
        limiter.fractional_accumulated = 0;
    } else {
        limiter.current_amount = limiter.current_amount + new_tokens;
        // Update the fractional amount accumulated for the next refill cycle
        limiter.fractional_accumulated = accumulated_amount % limiter.refill_interval;
    };
    limiter.last_refill_timestamp = current_time;
}