Jira MCP

/** * Token bucket rate limiter for Jira API requests. * Implements a sliding window rate limiting algorithm. * @module utils/rate-limiter */ import { RateLimitError } from './errors.js'; import { createLogger } from './logger.js'; const logger = createLogger('rate-limiter'); /** * Rate limiter configuration. */ export interface RateLimiterConfig { /** Maximum number of requests per window */ maxRequests: number; /** Window size in milliseconds */ windowMs: number; } /** * Token bucket rate limiter. * Tracks requests within a sliding window and prevents exceeding the limit. */ export class RateLimiter { private readonly maxRequests: number; private readonly windowMs: number; private tokens: number; private lastRefill: number; constructor(config: RateLimiterConfig) { this.maxRequests = config.maxRequests; this.windowMs = config.windowMs; this.tokens = config.maxRequests; this.lastRefill = Date.now(); } /** * Refills tokens based on elapsed time. */ private refill(): void { const now = Date.now(); const elapsed = now - this.lastRefill; const tokensToAdd = (elapsed / this.windowMs) * this.maxRequests; this.tokens = Math.min(this.maxRequests, this.tokens + tokensToAdd); this.lastRefill = now; } /** * Attempts to acquire a token for a request. * @throws {RateLimitError} If rate limit is exceeded */ acquire(): void { this.refill(); if (this.tokens < 1) { const retryAfter = Math.ceil( ((1 - this.tokens) / this.maxRequests) * this.windowMs ); logger.warn('Rate limit exceeded', { tokens: this.tokens, retryAfter, }); throw new RateLimitError( `Rate limit exceeded. Retry after ${retryAfter}ms`, retryAfter ); } this.tokens -= 1; logger.debug('Token acquired', { remainingTokens: this.tokens }); } /** * Checks if a request can be made without blocking. */ canAcquire(): boolean { this.refill(); return this.tokens >= 1; } /** * Gets the number of remaining tokens. */ getRemainingTokens(): number { this.refill(); return Math.floor(this.tokens); } /** * Gets the time until the next token is available. */ getTimeUntilNextToken(): number { this.refill(); if (this.tokens >= 1) { return 0; } return Math.ceil(((1 - this.tokens) / this.maxRequests) * this.windowMs); } /** * Waits until a token is available. */ async waitForToken(): Promise<void> { const waitTime = this.getTimeUntilNextToken(); if (waitTime > 0) { logger.debug('Waiting for rate limit', { waitTime }); await new Promise((resolve) => setTimeout(resolve, waitTime)); } this.acquire(); } } /** * Creates a rate limiter with Jira's default limits. * Jira Cloud has a limit of approximately 100 requests per minute. */ export function createJiraRateLimiter( requestsPerMinute: number = 100 ): RateLimiter { return new RateLimiter({ maxRequests: requestsPerMinute, windowMs: 60000, // 1 minute }); }