fix: 修复无订阅者时消息静默丢失问题，完善测试

- 新增 pending 缓冲区，publish 时若无订阅者则暂存消息
- subscribe 时自动将缓冲消息投入 channel，解决服务重启后恢复任务丢失的问题
- 去除 broadcast 5ms 超时导致的消息丢失
- chan bool 改为 chan struct{}，RWMutex 改为 Mutex
- 新增 broker_test.go，12 个单元测试覆盖核心场景（含 -race）
- 为 client_test.go 中的无限循环 demo 添加 t.Skip()

broker.go

@@ -3,102 +3,66 @@ package queue
 import (
 	"errors"
 	"sync"
-	"time"
 )
 
 type Broker struct {
-	exit         chan bool             // 关闭消息队列通道
-	capacity     int                   // 消息队列的容量
-	topics       map[string][]chan any // key： topic  value ： queue, 一个topic可以有多个订阅者，一个订阅者对应着一个通道
-	sync.RWMutex                       // 同步锁
+	exit     chan struct{}
+	capacity int
+	topics   map[string][]chan any
+	pending  map[string][]any // 订阅前发布的消息缓冲，subscribe 时一次性投递
+	mu       sync.Mutex
 }
 
-// 设置消息容量
-// @description 控制消息队列的大小
 func (b *Broker) setConditions(capacity int) {
+	b.mu.Lock()
 	b.capacity = capacity
+	b.mu.Unlock()
 }
 
-// 关闭消息队列
 func (b *Broker) close() {
 	select {
 	case <-b.exit:
 		return
 	default:
 		close(b.exit)
-		b.Lock()
+		b.mu.Lock()
 		b.topics = make(map[string][]chan any)
-		b.Unlock()
+		b.pending = make(map[string][]any)
+		b.mu.Unlock()
 	}
-	return
 }
 
-// 消息推送
-// @param topic 订阅的主题
-// @param msg 传递的消息
-func (b *Broker) publish(topic string, pub any) error {
+// publish 推送消息；若暂无订阅者则缓冲，等待订阅者注册后投递。
+func (b *Broker) publish(topic string, msg any) error {
 	select {
 	case <-b.exit:
 		return errors.New("broker closed")
 	default:
 	}
 
-	b.RLock()
-	subscribers, ok := b.topics[topic]
-	b.RUnlock()
-	if !ok {
+	b.mu.Lock()
+	subs := b.topics[topic]
+	if len(subs) == 0 {
+		b.pending[topic] = append(b.pending[topic], msg)
+		b.mu.Unlock()
 		return nil
 	}
+	// 持有锁期间只做列表复制，发送在锁外进行，避免阻塞其他 publish
+	chs := make([]chan any, len(subs))
+	copy(chs, subs)
+	b.mu.Unlock()
 
-	b.broadcast(pub, subscribers)
-	return nil
-}
-
-// 消息广播
-// @description 对推送的消息进行广播，保证每一个订阅者都可以收到
-func (b *Broker) broadcast(msg any, subscribers []chan any) {
-	count := len(subscribers)
-	concurrency := 1
-
-	switch {
-	case count > 1000:
-		concurrency = 3
-	case count > 100:
-		concurrency = 2
-	default:
-		concurrency = 1
-	}
-
-	pub := func(start int) {
-		//采用Timer 而不是使用time.After 原因：time.After会产生内存泄漏 在计时器触发之前，垃圾回收器不会回收Timer
-		idleDuration := 5 * time.Millisecond
-		idleTimeout := time.NewTimer(idleDuration)
-		defer idleTimeout.Stop()
-		for j := start; j < count; j += concurrency {
-			if !idleTimeout.Stop() {
+	for _, ch := range chs {
 		select {
-				case <-idleTimeout.C:
-				default:
-				}
-			}
-			idleTimeout.Reset(idleDuration)
-			select {
-			case subscribers[j] <- msg:
-			case <-idleTimeout.C:
+		case ch <- msg:
 		case <-b.exit:
-				return
+			return errors.New("broker closed")
 		}
 	}
-	}
-	for i := 0; i < concurrency; i++ {
-		go pub(i)
-	}
+	return nil
 }
 
-// 消息订阅
-// @description 传入订阅的主题，即可完成订阅
-// @param topic 订阅的主题
-// @return sub 通道用来接收数据
+// subscribe 订阅 topic，返回 channel；同时将该 topic 的缓冲消息立即投入 channel。
 func (b *Broker) subscribe(topic string) (<-chan any, error) {
 	select {
 	case <-b.exit:
@@ -106,16 +70,25 @@ func (b *Broker) subscribe(topic string) (<-chan any, error) {
 	default:
 	}
 
-	ch := make(chan any, b.capacity)
-	b.Lock()
+	b.mu.Lock()
+	capacity := b.capacity
+	if capacity <= 0 {
+		capacity = 10
+	}
+	ch := make(chan any, capacity)
 	b.topics[topic] = append(b.topics[topic], ch)
-	b.Unlock()
+	buffered := b.pending[topic]
+	delete(b.pending, topic)
+	b.mu.Unlock()
+
+	// channel 刚创建必然不满，直接写入不会阻塞
+	for _, msg := range buffered {
+		ch <- msg
+	}
+
 	return ch, nil
 }
 
-// 取消订阅
-// @param topic 订阅的主题
-// @param sub 消息订阅的通道
 func (b *Broker) unsubscribe(topic string, sub <-chan any) error {
 	select {
 	case <-b.exit:
@@ -123,31 +96,25 @@ func (b *Broker) unsubscribe(topic string, sub <-chan any) error {
 	default:
 	}
 
-	b.RLock()
-	subscribers, ok := b.topics[topic]
-	b.RUnlock()
+	b.mu.Lock()
+	defer b.mu.Unlock()
 
-	if !ok {
-		return nil
+	subs := b.topics[topic]
+	newSubs := subs[:0]
+	for _, s := range subs {
+		if s != sub {
+			newSubs = append(newSubs, s)
 		}
-	// delete subscriber
-	b.Lock()
-	var newSubs []chan any
-	for _, subscriber := range subscribers {
-		if subscriber == sub {
-			continue
 	}
-		newSubs = append(newSubs, subscriber)
-	}
-
 	b.topics[topic] = newSubs
-	b.Unlock()
 	return nil
 }
 
 func NewBroker() *Broker {
 	return &Broker{
-		exit:   make(chan bool),
+		exit:     make(chan struct{}),
+		capacity: 10,
 		topics:   make(map[string][]chan any),
+		pending:  make(map[string][]any),
 	}
 }

broker_test.go

@@ -0,0 +1,238 @@
+package queue
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+// recv 从 channel 读取一条消息，超时则返回 nil。
+func recv(ch <-chan any, timeout time.Duration) any {
+	select {
+	case v := <-ch:
+		return v
+	case <-time.After(timeout):
+		return nil
+	}
+}
+
+// TestPublishSubscribe 基本收发
+func TestPublishSubscribe(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	ch, err := b.subscribe("job-a")
+	if err != nil {
+		t.Fatalf("subscribe: %v", err)
+	}
+
+	if err := b.publish("job-a", "hello"); err != nil {
+		t.Fatalf("publish: %v", err)
+	}
+
+	got := recv(ch, time.Second)
+	if got != "hello" {
+		t.Fatalf("want %q, got %v", "hello", got)
+	}
+}
+
+// TestPendingBuffer 先发布再订阅，消息不能丢失（队列核心保证）
+func TestPendingBuffer(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	// 先 publish，此时无订阅者
+	for i := 0; i < 3; i++ {
+		if err := b.publish("job-b", i); err != nil {
+			t.Fatalf("publish %d: %v", i, err)
+		}
+	}
+
+	// 再 subscribe，应收到全部缓冲消息
+	ch, _ := b.subscribe("job-b")
+
+	for want := 0; want < 3; want++ {
+		got := recv(ch, time.Second)
+		if got != want {
+			t.Fatalf("pending msg[%d]: want %d, got %v", want, want, got)
+		}
+	}
+}
+
+// TestPendingThenNormal 缓冲消息先于后续消息到达，顺序正确
+func TestPendingThenNormal(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	b.publish("job-c", "buffered")
+
+	ch, _ := b.subscribe("job-c")
+	b.publish("job-c", "live")
+
+	msgs := []any{recv(ch, time.Second), recv(ch, time.Second)}
+	if msgs[0] != "buffered" || msgs[1] != "live" {
+		t.Fatalf("order wrong: %v", msgs)
+	}
+}
+
+// TestMultipleSubscribers 同一 topic 多个订阅者都能收到消息
+func TestMultipleSubscribers(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	ch1, _ := b.subscribe("broadcast")
+	ch2, _ := b.subscribe("broadcast")
+
+	b.publish("broadcast", "msg")
+
+	if recv(ch1, time.Second) != "msg" {
+		t.Fatal("ch1 did not receive message")
+	}
+	if recv(ch2, time.Second) != "msg" {
+		t.Fatal("ch2 did not receive message")
+	}
+}
+
+// TestUnsubscribe 取消订阅后不再收到消息
+func TestUnsubscribe(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	ch, _ := b.subscribe("job-d")
+	b.unsubscribe("job-d", ch)
+
+	b.publish("job-d", "should not arrive")
+
+	if got := recv(ch, 100*time.Millisecond); got != nil {
+		t.Fatalf("after unsubscribe, still got %v", got)
+	}
+}
+
+// TestClosedPublish 关闭后 publish 返回错误
+func TestClosedPublish(t *testing.T) {
+	b := NewBroker()
+	b.close()
+
+	if err := b.publish("x", "msg"); err == nil {
+		t.Fatal("expected error after close, got nil")
+	}
+}
+
+// TestClosedSubscribe 关闭后 subscribe 返回错误
+func TestClosedSubscribe(t *testing.T) {
+	b := NewBroker()
+	b.close()
+
+	if _, err := b.subscribe("x"); err == nil {
+		t.Fatal("expected error after close, got nil")
+	}
+}
+
+// TestConcurrentPublish 并发发布不丢消息，无 data race
+func TestConcurrentPublish(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+	b.setConditions(100)
+
+	const n = 50
+	ch, _ := b.subscribe("concurrent")
+
+	var wg sync.WaitGroup
+	for i := 0; i < n; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			b.publish("concurrent", i)
+		}(i)
+	}
+	wg.Wait()
+
+	var count int32
+	done := make(chan struct{})
+	go func() {
+		for recv(ch, 200*time.Millisecond) != nil {
+			atomic.AddInt32(&count, 1)
+		}
+		close(done)
+	}()
+	<-done
+
+	if int(count) != n {
+		t.Fatalf("want %d messages, got %d", n, count)
+	}
+}
+
+// TestSetConditions 容量设置生效（channel 满时不丢已缓冲的消息）
+func TestSetConditions(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+	b.setConditions(5)
+
+	ch, _ := b.subscribe("cap-test")
+
+	for i := 0; i < 5; i++ {
+		if err := b.publish("cap-test", i); err != nil {
+			t.Fatalf("publish %d: %v", i, err)
+		}
+	}
+
+	for want := 0; want < 5; want++ {
+		got := recv(ch, time.Second)
+		if got != want {
+			t.Fatalf("msg[%d]: want %d, got %v", want, want, got)
+		}
+	}
+}
+
+// TestClientWrapper Client 封装与 Broker 行为一致
+func TestClientWrapper(t *testing.T) {
+	c := NewClient()
+	defer c.Close()
+	c.SetConditions(10)
+
+	ch, err := c.Subscribe("wrap")
+	if err != nil {
+		t.Fatalf("Subscribe: %v", err)
+	}
+
+	c.Publish("wrap", "ok")
+
+	got := recv(ch, time.Second)
+	if got != "ok" {
+		t.Fatalf("want %q got %v", "ok", got)
+	}
+}
+
+// TestGetPayload GetPayload 在 channel 关闭时返回 nil 而非阻塞
+func TestGetPayload(t *testing.T) {
+	c := NewClient()
+	ch, _ := c.Subscribe("gp")
+	c.Publish("gp", "payload")
+
+	got := c.GetPayload(ch)
+	if got != "payload" {
+		t.Fatalf("want %q got %v", "payload", got)
+	}
+}
+
+// TestPendingBufferMultipleTopics 多个 topic 的缓冲互不干扰
+func TestPendingBufferMultipleTopics(t *testing.T) {
+	b := NewBroker()
+	defer b.close()
+
+	for i := 0; i < 5; i++ {
+		topic := fmt.Sprintf("topic-%d", i)
+		b.publish(topic, i*10)
+	}
+
+	for i := 0; i < 5; i++ {
+		topic := fmt.Sprintf("topic-%d", i)
+		ch, _ := b.subscribe(topic)
+		got := recv(ch, time.Second)
+		if got != i*10 {
+			t.Fatalf("topic-%d: want %d, got %v", i, i*10, got)
+		}
+	}
+}

client_test.go

@@ -10,6 +10,7 @@ const topic = "Golang梦工厂"
 
 // 一个topic 测试
 func TestOnceTopic(t *testing.T) {
+	t.Skip("infinite loop demo, not a unit test")
 	m := NewClient()
 	defer m.Close()
 	m.SetConditions(10)
@@ -24,7 +25,7 @@ func TestOnceTopic(t *testing.T) {
 
 // 定时推送
 func OncePub(c *Client) {
-	t := time.NewTicker(10 * time.Second)
+	t := time.NewTicker(1 * time.Second)
 	defer t.Stop()
 	for {
 		select {
@@ -49,6 +50,7 @@ func OnceSub(m <-chan interface{}, c *Client) {
 
 // 多个topic测试
 func TestManyTopic(t *testing.T) {
+	t.Skip("infinite loop demo, not a unit test")
 	m := NewClient()
 	defer m.Close()
 	m.SetConditions(10)