/**
* Rate limiter utility for HTTP requests
*/
interface RateLimitState {
requests: number[];
windowStart: number;
}
/**
* Simple rate limiter using a sliding window
*/
export class RateLimiter {
private readonly maxRequests: number;
private readonly windowMs: number;
private state: RateLimitState;
/**
* Create a rate limiter
*
* @param maxRequests - Maximum number of requests allowed
* @param windowMs - Time window in milliseconds
*/
constructor(maxRequests: number, windowMs: number) {
this.maxRequests = maxRequests;
this.windowMs = windowMs;
this.state = {
requests: [],
windowStart: Date.now(),
};
}
/**
* Check if a request is allowed and record it if so
*
* @returns true if request is allowed, false otherwise
*/
async check(): Promise<boolean> {
const now = Date.now();
const windowStart = now - this.windowMs;
// Remove requests outside the current window
this.state.requests = this.state.requests.filter(
(timestamp) => timestamp > windowStart
);
// Check if we're at the limit
if (this.state.requests.length >= this.maxRequests) {
return false;
}
// Record this request
this.state.requests.push(now);
return true;
}
/**
* Wait until a request is allowed, then record it
*
* @returns Promise that resolves when request is allowed
*/
async waitForSlot(): Promise<void> {
while (!(await this.check())) {
// Calculate how long to wait
const oldestRequest = this.state.requests[0];
const waitTime = oldestRequest + this.windowMs - Date.now() + 100; // +100ms buffer
if (waitTime > 0) {
await new Promise((resolve) => setTimeout(resolve, waitTime));
}
}
}
/**
* Get current request count in the window
*/
getCurrentCount(): number {
const now = Date.now();
const windowStart = now - this.windowMs;
this.state.requests = this.state.requests.filter(
(timestamp) => timestamp > windowStart
);
return this.state.requests.length;
}
}
