congress-dot-gov/dist/rate-limiter/index.cjs

TypeScript SDK for the Congress.gov API

'use strict';

class AdaptiveRateLimiter {
  config;
  lastRequestTime = 0;
  currentDelay = 0;
  hourStartTime = Date.now();
  constructor(config = {}) {
    this.config = {
      safetyMargin: config.safetyMargin ?? 0.1,
      // 10% safety margin
      minDelay: config.minDelay ?? 50,
      // 50ms minimum
      maxDelay: config.maxDelay ?? 3e4
      // 30 seconds maximum
    };
    this.currentDelay = this.config.minDelay;
  }
  /**
   * Call this before making an API request. It will wait the appropriate
   * amount of time based on current rate limit status.
   * @returns A promise that resolves when the next request can be made
   */
  async waitForNextRequest() {
    const now = Date.now();
    if (now - this.hourStartTime >= 36e5) {
      this.hourStartTime = now;
      this.currentDelay = this.config.minDelay;
    }
    const timeSinceLastRequest = now - this.lastRequestTime;
    const delayNeeded = this.currentDelay - timeSinceLastRequest;
    if (delayNeeded > 0) {
      await this.sleep(delayNeeded);
    }
    this.lastRequestTime = Date.now();
  }
  /**
   * Calculate delay based on amount of time remaining in the hour and number of requests remaining
   * @param rateLimitInfo - The current rate limit info
   * @param currentTime - The current time
   * @returns The delay in milliseconds
   */
  calculateDelay(rateLimitInfo, currentTime) {
    const { limit, remaining } = rateLimitInfo;
    const timeElapsedThisHour = currentTime - this.hourStartTime;
    const timeRemainingInHour = Math.max(100, 36e5 - timeElapsedThisHour);
    const safeRemaining = Math.floor(limit * this.config.safetyMargin);
    if (remaining <= safeRemaining) {
      return this.config.maxDelay;
    }
    const optimalDelay = timeRemainingInHour / remaining;
    const utilizationRatio = 1 - remaining / limit;
    const adaptiveDelay = optimalDelay * utilizationRatio;
    return Math.max(this.config.minDelay, Math.min(this.config.maxDelay, adaptiveDelay));
  }
  sleep(ms) {
    return new Promise((resolve) => setTimeout(resolve, ms));
  }
  updateRateLimitInfo(rateLimitInfo) {
    this.currentDelay = this.calculateDelay(rateLimitInfo, Date.now());
    this.lastRequestTime = Date.now();
  }
}

exports.AdaptiveRateLimiter = AdaptiveRateLimiter;