Master MCP Server

export type LoadBalancingStrategy = 'round_robin' | 'weighted' | 'health' export interface LoadBalancingInstance { id: string weight?: number healthScore?: number // 0..100; higher is better } export interface LoadBalancerOptions { strategy: LoadBalancingStrategy } export class LoadBalancer { private readonly opts: Required<LoadBalancerOptions> private rrIndex: Map<string, number> = new Map() constructor(options?: Partial<LoadBalancerOptions>) { this.opts = { strategy: options?.strategy ?? 'round_robin' } } select<T extends LoadBalancingInstance>(key: string, instances: T[]): T | undefined { if (!instances.length) return undefined switch (this.opts.strategy) { case 'weighted': return this.selectWeighted(instances) case 'health': return this.selectHealth(instances, key) case 'round_robin': default: return this.selectRoundRobin(key, instances) } } private selectRoundRobin<T extends LoadBalancingInstance>(key: string, instances: T[]): T { const idx = this.rrIndex.get(key) ?? 0 const chosen = instances[idx % instances.length] this.rrIndex.set(key, (idx + 1) % instances.length) return chosen } private selectWeighted<T extends LoadBalancingInstance>(instances: T[]): T { const weights = instances.map((i) => Math.max(1, Math.floor(i.weight ?? 1))) const total = weights.reduce((a, b) => a + b, 0) let r = Math.random() * total for (let i = 0; i < instances.length; i++) { if (r < weights[i]) return instances[i] r -= weights[i] } return instances[0] } private selectHealth<T extends LoadBalancingInstance>(instances: T[], key: string): T { // Choose highest health; tie-break with RR for stability const sorted = [...instances].sort((a, b) => (b.healthScore ?? 0) - (a.healthScore ?? 0)) const topScore = sorted[0].healthScore ?? 0 const top = sorted.filter((i) => (i.healthScore ?? 0) === topScore) if (top.length === 1) return top[0] return this.selectRoundRobin(key + '::health', top) } }