构建分布式锁服务

项目概述

本项目实现一个面向 mutual exclusion 的完整系统，核心要解决的问题是 granting locks with fencing tokens so a stale holder cannot corrupt shared state after a pause。整体由 Lock acquirer、Fence issuer、Lease renewer、Release handler、Watchdog timer 五个模块组成，每个模块单一职责、可独立测试，最后通过集成测试验证端到端正确性。设计上把 a holder that pauses, lets its lease expire, and then writes with a stale token that a fencing-aware resource must reject 作为第一类需求先行处理，而非事后再补。

架构与关键决策

数据模型为 a lock identified by a name, held with a lease and a monotonically increasing fencing token that guards against stale writers。Lock acquirer 定义其余阶段共同依赖的数据形状并在边界处校验输入；Fence issuer 承载 mutual exclusion 的正确性逻辑；Lease renewer 专门处理 a holder that pauses, lets its lease expire, and then writes with a stale token that a fencing-aware resource must reject，在失败路径上给出明确的拒绝、重试或降级策略；Release handler 提供可观测性，每次操作输出带关联 id 的结构化事件；Watchdog timer 在过载时按既定方式降级，避免过载演变为数据损坏。配置与代码分离，使风险变更可经 diff 审阅。

实施与测试

按五个阶段依次实现 Lock acquirer、Fence issuer、Lease renewer、Release handler、Watchdog timer，每阶段配套聚焦单测。集成测试组合各模块并驱动真实 mutual exclusion 场景：先验证正常路径，再刻意触发 a holder that pauses, lets its lease expire, and then writes with a stale token that a fencing-aware resource must reject 并断言系统降级而非损坏。所有依赖均在进程内或被桩替换，用例在 CI 中确定可复现。

限制与后续

• 单区域设计，多区域复制超出范围。
• Lock acquirer 默认进程内，未水平共享。
• 无鉴权层，假定部署在强制身份的边缘之后。

代码示例

# setup for distributed-lock-service
pnpm init
pnpm add redis fastify
pnpm add -D typescript tsx vitest

distributed_lock_service/
├── src/index.ts
├── src/lock-acquirer.ts
├── src/fence-issuer.ts
├── tests/distributed_lock_service.test.ts
└── package.json

// Lock acquirer: mutual exclusion core
export function lockacquirer(input: LockacquirerInput): LockacquirerResult {
  // Build the lock acquirer that anchors mutual exclusion and defines the core data shape.
  return processLockacquirer(input);
}

// Fence issuer — handles mutual exclusion Add the fence issuer so
export class Fenceissuer {
  constructor(private opts: FenceissuerOptions) {}
  async run(ctx: Context): Promise<FenceissuerOutput> {
    return this.execute(ctx);
  }
}

// Lease renewer: mutual exclusion stage
export const leaserenewer = (next: Next) => async (req: Request) => {
  const out = await transform(req);
  return next(out);
};

// Release handler for mutual exclusion
export async function releasehandler(stream: AsyncIterable<Chunk>): Promise<Aggregate> {
  let acc = init();
  for await (const c of stream) acc = merge(acc, c);
  return acc;
}

// Watchdog timer: mutual exclusion finalization
export function watchdogtimer(state: State): Result {
  validate(state);
  return finalize(state);
}

# run the mutual exclusion test suite
pnpm vitest run