update

tests/unit/fs-handler-lock.test.js

@@ -0,0 +1,89 @@
+// src/app.js onFilesChanged —— handler 并发闸（audit P1-4）
+//
+// 背景：原代码
+//   const myToken = ++fsHandlerToken;     // 自增但还没 SET
+//   if (inFlightToken !== 0) { return; }  // 检查还是 0
+//   inFlightToken = myToken;              // 才 SET
+// 两行间是 microtask 窗口：burst 50 events 时多个 callback 排在同一 microtask
+// queue 里，每个都看到 inFlightToken === 0，全部过闸 → handler 并发跑
+// （applyEntries 双跑、scanDir 双发、UI 闪烁）。
+//
+// 修复：抽 makeLock() 工厂 → { tryClaim, release, current }。tryClaim 是同步
+// 「check-and-set」原子操作：if 锁空闲则 SET 并返新 token，否则返 null。
+// 在 callback 入口 tryClaim → null 直接 return → 不再丢事件，统一存到
+// pendingRescanRel（既有逻辑保留）。
+//
+// 测试策略：直接 import 工厂函数，模拟 burst 场景验证「N 次 tryClaim 只有
+// 第一次成功」。
+
+import { describe, it, expect } from 'vitest';
+import { makeLock } from '../../src/fs-handler-lock.js';
+
+describe('fs-handler lock（audit P1-4）', () => {
+  it('初始空闲 → tryClaim 返非零 token，current 反映该 token', () => {
+    const lock = makeLock();
+    const t = lock.tryClaim();
+    expect(t).toBeGreaterThan(0);
+    expect(lock.current()).toBe(t);
+  });
+
+  it('已占用时 tryClaim 返 null，current 不变', () => {
+    const lock = makeLock();
+    const t1 = lock.tryClaim();
+    const t2 = lock.tryClaim();
+    expect(t1).toBeGreaterThan(0);
+    expect(t2).toBe(null);
+    expect(lock.current()).toBe(t1);
+  });
+
+  it('release(token) → 锁重新空闲，tryClaim 能拿到新 token', () => {
+    const lock = makeLock();
+    const t1 = lock.tryClaim();
+    expect(lock.release(t1)).toBe(true);
+    expect(lock.current()).toBe(0);
+    const t2 = lock.tryClaim();
+    expect(t2).toBeGreaterThan(0);
+    expect(t2).not.toBe(t1);
+  });
+
+  it('release(非当前 token) → 返 false，锁不被错误释放', () => {
+    const lock = makeLock();
+    const t1 = lock.tryClaim();
+    expect(lock.release(99999)).toBe(false);
+    expect(lock.current()).toBe(t1);
+  });
+
+  it('burst 50 次 tryClaim → 只有 1 次成功', () => {
+    // 关键测试：模拟 microtask 批量场景
+    const lock = makeLock();
+    const results = Array.from({ length: 50 }, () => lock.tryClaim());
+    const successes = results.filter((r) => r !== null);
+    expect(successes).toHaveLength(1);
+    // 其余 49 次全部 null
+    expect(results.filter((r) => r === null)).toHaveLength(49);
+  });
+
+  it('release → tryClaim → 再 burst：交替可串行化多批事件', () => {
+    const lock = makeLock();
+    for (let batch = 0; batch < 5; batch++) {
+      const t = lock.tryClaim();
+      expect(t).not.toBe(null);
+      // 本批 10 次并发全应被拒
+      for (let i = 0; i < 10; i++) {
+        expect(lock.tryClaim()).toBe(null);
+      }
+      // 释放
+      expect(lock.release(t)).toBe(true);
+    }
+  });
+
+  it('token 自增：每次成功 tryClaim 返的 token 都不同', () => {
+    const lock = makeLock();
+    const t1 = lock.tryClaim();
+    lock.release(t1);
+    const t2 = lock.tryClaim();
+    lock.release(t2);
+    const t3 = lock.tryClaim();
+    expect(new Set([t1, t2, t3]).size).toBe(3);
+  });
+});