fix: bound dedupe cache with MAX_INFLIGHT=200 and 30s TTL

src/lib/api/__tests__/dedupe.test.ts

@@ -0,0 +1,185 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { dedupe, cancelDedupe, clearDedupeCache, buildDedupeKey } from '@/lib/api/dedupe';
+
+function deferred<T = unknown>() {
+  let resolve!: (value: T) => void;
+  let reject!: (reason?: unknown) => void;
+  const promise = new Promise<T>((res, rej) => { resolve = res; reject = rej; });
+  return { promise, resolve, reject };
+}
+
+describe('dedupe (basic behavior)', () => {
+  afterEach(() => {
+    clearDedupeCache();
+  });
+
+  it('deduplicates concurrent requests with the same key', async () => {
+    const d = deferred<string>();
+    const fn = vi.fn().mockReturnValue(d.promise);
+
+    const p1 = dedupe('k', fn);
+    const p2 = dedupe('k', fn);
+
+    d.resolve('ok');
+    await expect(p1).resolves.toBe('ok');
+    await expect(p2).resolves.toBe('ok');
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+
+  it('allows different keys to proceed independently', async () => {
+    const d1 = deferred<string>();
+    const d2 = deferred<string>();
+    const fn = vi.fn()
+      .mockReturnValueOnce(d1.promise)
+      .mockReturnValueOnce(d2.promise);
+
+    const p1 = dedupe('a', fn);
+    const p2 = dedupe('b', fn);
+
+    d1.resolve('a-res');
+    d2.resolve('b-res');
+
+    await expect(p1).resolves.toBe('a-res');
+    await expect(p2).resolves.toBe('b-res');
+    expect(fn).toHaveBeenCalledTimes(2);
+  });
+
+  it('rejects all callers when the factory throws', async () => {
+    const d = deferred<string>();
+    const fn = vi.fn().mockReturnValue(d.promise);
+
+    const p1 = dedupe('err', fn);
+    const p2 = dedupe('err', fn);
+
+    d.reject(new Error('nope'));
+    await expect(p1).rejects.toThrow('nope');
+    await expect(p2).rejects.toThrow('nope');
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+
+  it('allows a subsequent request after the first completes', async () => {
+    const d1 = deferred<string>();
+    const d2 = deferred<string>();
+    const fn = vi.fn()
+      .mockReturnValueOnce(d1.promise)
+      .mockReturnValueOnce(d2.promise);
+
+    const r1 = dedupe('k', fn);
+    d1.resolve('first');
+    await expect(r1).resolves.toBe('first');
+
+    const r2 = dedupe('k', fn);
+    d2.resolve('second');
+    await expect(r2).resolves.toBe('second');
+    expect(fn).toHaveBeenCalledTimes(2);
+  });
+
+  it('buildDedupeKey produces stable keys', () => {
+    expect(buildDedupeKey('GET', '/api/test')).toBe('GET:/api/test');
+    expect(buildDedupeKey('get', '/api/test')).toBe('GET:/api/test');
+    expect(buildDedupeKey('POST', '/api/test', { a: 1 })).toBe('POST:/api/test:{"a":1}');
+  });
+
+  it('cancelDedupe removes an in-flight entry', async () => {
+    const neverSettle = () => new Promise(() => {});
+    dedupe('cancel-me', neverSettle);
+    cancelDedupe('cancel-me');
+
+    const fn = vi.fn().mockResolvedValue('fresh');
+    await expect(dedupe('cancel-me', fn)).resolves.toBe('fresh');
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+});
+
+describe('dedupe (MAX_INFLIGHT limit)', () => {
+  afterEach(() => {
+    clearDedupeCache();
+  });
+
+  it('rejects new entries when the cache is full', async () => {
+    const neverSettle = () => new Promise(() => {});
+
+    for (let i = 0; i < 200; i++) {
+      dedupe(`key-${i}`, neverSettle);
+    }
+
+    await expect(dedupe('overflow', () => Promise.resolve('ok')))
+      .rejects.toThrow('Deduplication cache full');
+  });
+
+  it('accepts a new entry when a slot frees up', async () => {
+    for (let i = 0; i < 199; i++) {
+      dedupe(`pending-${i}`, () => new Promise(() => {}));
+    }
+
+    const fn = vi.fn().mockResolvedValue('done');
+    await expect(dedupe('slot-frees', fn)).resolves.toBe('done');
+
+    await expect(dedupe('last', () => Promise.resolve('ok'))).resolves.toBe('ok');
+  });
+});
+
+describe('dedupe (TTL eviction)', () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    clearDedupeCache();
+  });
+
+  it('evicts entries after the TTL and rejects the promise', async () => {
+    const neverSettle = () => new Promise(() => {});
+    const promise = dedupe('ttl-key', neverSettle);
+
+    vi.advanceTimersByTime(30_000);
+
+    await expect(promise).rejects.toThrow('timed out');
+  });
+
+  it('allows a new request after TTL eviction', async () => {
+    const neverSettle = () => new Promise(() => {});
+    const evicted = dedupe('ttl-key', neverSettle);
+    const evictDone = expect(evicted).rejects.toThrow('timed out');
+
+    vi.advanceTimersByTime(30_000);
+
+    await evictDone;
+
+    const fn = vi.fn().mockResolvedValue('fresh');
+    await expect(dedupe('ttl-key', fn)).resolves.toBe('fresh');
+    expect(fn).toHaveBeenCalledTimes(1);
+  });
+
+  it('clears the timer when the request completes before TTL', async () => {
+    let resolveFn!: (v: string) => void;
+    const fn = vi.fn().mockImplementation(
+      () => new Promise<string>(resolve => { resolveFn = resolve; }),
+    );
+
+    const promise = dedupe('fast-key', fn);
+    resolveFn('fast');
+
+    await Promise.resolve();
+
+    await expect(promise).resolves.toBe('fast');
+
+    vi.advanceTimersByTime(30_000);
+
+    const fn2 = vi.fn().mockResolvedValue('after');
+    await expect(dedupe('fast-key', fn2)).resolves.toBe('after');
+    expect(fn2).toHaveBeenCalledTimes(1);
+  });
+
+  it('evicts multiple entries at their respective TTLs', async () => {
+    const neverSettle = () => new Promise(() => {});
+    const pA = dedupe('a', neverSettle);
+    const pB = dedupe('b', neverSettle);
+
+    vi.advanceTimersByTime(30_000);
+
+    await expect(pA).rejects.toThrow('timed out');
+    await expect(pB).rejects.toThrow('timed out');
+  });
+});

src/lib/api/dedupe.ts

@@ -3,8 +3,14 @@
  *
  * Merges concurrent identical requests so only one network call is made.
  * Subsequent callers receive the same promise as the in-flight request.
+ *
+ * The cache is bounded: at most MAX_INFLIGHT entries can be in-flight at once,
+ * and each entry has a TTL of DEDUPE_TTL_MS after which it is automatically evicted.
  */
 
+const MAX_INFLIGHT = 200;
+const DEDUPE_TTL_MS = 30_000;
+
 type Resolver<T> = {
   resolve: (value: T) => void;
   reject: (reason?: unknown) => void;
@@ -13,6 +19,7 @@ type Resolver<T> = {
 interface InFlight<T> {
   promise: Promise<T>;
   resolvers: Resolver<T>[];
+  timer?: ReturnType<typeof setTimeout>;
 }
 
 const cache = new Map<string, InFlight<unknown>>();
@@ -34,12 +41,18 @@ export function buildDedupeKey(method: string, url: string, body?: unknown): str
  * @param key   - Unique identifier for this request (use buildDedupeKey)
  * @param fn    - Factory that performs the actual request
  */
-export async function dedupe<T>(key: string, fn: () => Promise<T>): Promise<T> {
+export function dedupe<T>(key: string, fn: () => Promise<T>): Promise<T> {
   const existing = cache.get(key) as InFlight<T> | undefined;
   if (existing) {
     return existing.promise;
   }
 
+  if (cache.size >= MAX_INFLIGHT) {
+    return Promise.reject(
+      new Error(`Deduplication cache full (max ${MAX_INFLIGHT} entries)`),
+    );
+  }
+
   let resolve!: (value: T) => void;
   let reject!: (reason?: unknown) => void;
 
@@ -49,26 +62,42 @@ export async function dedupe<T>(key: string, fn: () => Promise<T>): Promise<T> {
   });
 
   const entry: InFlight<T> = { promise, resolvers: [{ resolve, reject }] };
+  entry.timer = setTimeout(() => {
+    cache.delete(key);
+    reject(new Error(`Deduplication entry timed out after ${DEDUPE_TTL_MS}ms`));
+  }, DEDUPE_TTL_MS);
+
   cache.set(key, entry as InFlight<unknown>);
 
-  try {
-    const result = await fn();
-    resolve(result);
-    return result;
-  } catch (err) {
-    reject(err);
-    throw err;
-  } finally {
-    cache.delete(key);
-  }
+  fn()
+    .then((result) => {
+      clearTimeout(entry.timer);
+      resolve(result);
+    })
+    .catch((err) => {
+      clearTimeout(entry.timer);
+      reject(err);
+    })
+    .finally(() => {
+      cache.delete(key);
+    });
+
+  return promise;
 }
 
 /** Remove a specific key from the cache (e.g. on cancellation). */
 export function cancelDedupe(key: string): void {
+  const entry = cache.get(key) as InFlight<unknown> | undefined;
+  if (entry?.timer) {
+    clearTimeout(entry.timer);
+  }
   cache.delete(key);
 }
 
 /** Clear the entire deduplication cache. */
 export function clearDedupeCache(): void {
+  for (const entry of cache.values()) {
+    if (entry.timer) clearTimeout(entry.timer);
+  }
   cache.clear();
 }