make Bridge not block in the first stream that not closed (#288)

* not block in the first channel

* make Bridge not block in the first stream that not closed

* Bridge with test

concurrency/channel.go

@@ -157,10 +157,10 @@ func (c *Channel[T]) Tee(ctx context.Context, in <-chan T) (<-chan T, <-chan T)
 // Play: https://go.dev/play/p/qmWSy1NVF-Y
 func (c *Channel[T]) Bridge(ctx context.Context, chanStream <-chan <-chan T) <-chan T {
 	valStream := make(chan T)
-
 	go func() {
 		defer close(valStream)
-
+		wg := sync.WaitGroup{}
+		defer wg.Wait()
 		for {
 			var stream <-chan T
 			select {
@@ -169,19 +169,22 @@ func (c *Channel[T]) Bridge(ctx context.Context, chanStream <-chan <-chan T) <-c
 					return
 				}
 				stream = maybeStream
+				wg.Add(1)
 			case <-ctx.Done():
 				return
 			}
 
-			for val := range c.OrDone(ctx, stream) {
-				select {
-				case valStream <- val:
-				case <-ctx.Done():
+			go func() {
+				defer wg.Done()
+				for val := range c.OrDone(ctx, stream) {
+					select {
+					case valStream <- val:
+					case <-ctx.Done():
+					}
 				}
-			}
+			}()
 		}
 	}()
-
 	return valStream
 }
 

concurrency/channel_example_test.go

@@ -168,7 +168,8 @@ func ExampleChannel_Tee() {
 func ExampleChannel_Bridge() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-
+	m1 := make(map[int]int)
+	m2 := make(map[int]int)
 	c := NewChannel[int]()
 	genVals := func() <-chan <-chan int {
 		out := make(chan (<-chan int))
@@ -177,6 +178,7 @@ func ExampleChannel_Bridge() {
 			for i := 1; i <= 5; i++ {
 				stream := make(chan int, 1)
 				stream <- i
+				m1[i]++
 				close(stream)
 				out <- stream
 			}
@@ -185,12 +187,15 @@ func ExampleChannel_Bridge() {
 	}
 
 	for v := range c.Bridge(ctx, genVals()) {
-		fmt.Println(v)
+		m2[v]++
+	}
+	for k, v := range m1 {
+		fmt.Println(m2[k] == v)
 	}
 	// Output:
-	// 1
-	// 2
-	// 3
-	// 4
-	// 5
+	// true
+	// true
+	// true
+	// true
+	// true
 }

concurrency/channel_test.go

@@ -169,7 +169,8 @@ func TestTee(t *testing.T) {
 func TestBridge(t *testing.T) {
 	t.Parallel()
 	assert := internal.NewAssert(t, "TestBridge")
-
+	m1 := make(map[int]int)
+	m2 := make(map[int]int)
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -181,6 +182,7 @@ func TestBridge(t *testing.T) {
 			for i := 0; i < 10; i++ {
 				stream := make(chan int, 1)
 				stream <- i
+				m1[i]++
 				close(stream)
 				chanStream <- stream
 			}
@@ -188,9 +190,11 @@ func TestBridge(t *testing.T) {
 		return chanStream
 	}
 
-	index := 0
 	for val := range c.Bridge(ctx, genVals()) {
-		assert.Equal(index, val)
-		index++
+		m2[val]++
+	}
+
+	for k, v := range m1 {
+		assert.Equal(m2[k], v)
 	}
 }