fix: 写队列满时 Close 不再与 enqueue 死锁

internal/store/queue_test.go

@@ -289,3 +289,137 @@ ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = excluded.upd
 		}
 	}
 }
+
+// openSmallQueue 用小缓冲队列替换默认队列，便于测满通道时的 Close/Drain。
+func openSmallQueue(t *testing.T, buf int) *DB {
+	t.Helper()
+	dir := t.TempDir()
+	db, err := Open(dir, "FULL")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Queue.Close(); err != nil {
+		t.Fatal(err)
+	}
+	db.Queue = newQueue(db.Write, buf)
+	return db
+}
+
+func TestQueueCloseUnblocksFullChannel(t *testing.T) {
+	t.Parallel()
+	const buf = 4
+	db := openSmallQueue(t, buf)
+	defer func() { _ = db.Close() }()
+	q := db.Queue
+
+	hold := make(chan struct{})
+	blockerStarted := make(chan struct{})
+	blockerErr := make(chan error, 1)
+	go func() {
+		blockerErr <- q.Do(context.Background(), func(tx *sql.Tx) error {
+			close(blockerStarted)
+			<-hold
+			return nil
+		})
+	}()
+	<-blockerStarted
+
+	ctx := context.Background()
+	var fillWG sync.WaitGroup
+	for i := 0; i < buf; i++ {
+		fillWG.Add(1)
+		go func() {
+			defer fillWG.Done()
+			_ = q.Do(ctx, func(tx *sql.Tx) error { return nil })
+		}()
+	}
+	deadline := time.Now().Add(2 * time.Second)
+	for q.Len() < buf+1 && time.Now().Before(deadline) {
+		time.Sleep(2 * time.Millisecond)
+	}
+	if q.Len() < buf+1 {
+		t.Fatalf("channel not full: len=%d", q.Len())
+	}
+
+	blockedErr := make(chan error, 1)
+	go func() {
+		blockedErr <- q.Do(ctx, func(tx *sql.Tx) error { return nil })
+	}()
+	// 等额外 Do 堵在 enqueue（pending 超过通道容量+正在执行的一条）。
+	deadline = time.Now().Add(2 * time.Second)
+	for q.Len() < buf+2 && time.Now().Before(deadline) {
+		time.Sleep(2 * time.Millisecond)
+	}
+
+	closeDone := make(chan error, 1)
+	go func() { closeDone <- q.Close() }()
+
+	select {
+	case err := <-blockedErr:
+		if !errors.Is(err, ErrQueueClosed) {
+			t.Fatalf("blocked Do: %v", err)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("Close did not unblock full-channel enqueue")
+	}
+
+	close(hold)
+	select {
+	case err := <-closeDone:
+		if err != nil {
+			t.Fatal(err)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("Close hung after writer released")
+	}
+	<-blockerErr
+	fillWG.Wait()
+}
+
+func TestQueueDrainTimeoutWhileWriterBlocked(t *testing.T) {
+	t.Parallel()
+	const buf = 4
+	db := openSmallQueue(t, buf)
+	defer func() { _ = db.Close() }()
+	q := db.Queue
+
+	hold := make(chan struct{})
+	started := make(chan struct{})
+	go func() {
+		_ = q.Do(context.Background(), func(tx *sql.Tx) error {
+			close(started)
+			<-hold
+			return nil
+		})
+	}()
+	<-started
+
+	ctx := context.Background()
+	var wg sync.WaitGroup
+	for i := 0; i < buf; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_ = q.Do(ctx, func(tx *sql.Tx) error { return nil })
+		}()
+	}
+	deadline := time.Now().Add(2 * time.Second)
+	for q.Len() < buf+1 && time.Now().Before(deadline) {
+		time.Sleep(2 * time.Millisecond)
+	}
+
+	drainCtx, cancel := context.WithTimeout(context.Background(), 80*time.Millisecond)
+	defer cancel()
+	start := time.Now()
+	err := q.Drain(drainCtx)
+	elapsed := time.Since(start)
+	if !errors.Is(err, context.DeadlineExceeded) {
+		t.Fatalf("Drain err=%v want deadline", err)
+	}
+	if elapsed > 500*time.Millisecond {
+		t.Fatalf("Drain took %s, should return on timeout", elapsed)
+	}
+
+	close(hold)
+	wg.Wait()
+}