直接关闭channel启动所有阻塞的goroutine，更简单暴力

cmd/prometheus/main_test.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"sync"
 	"syscall"
 	"testing"
 	"time"
@@ -39,6 +40,40 @@ var promPath = os.Args[0]
 var promConfig = filepath.Join("..", "..", "documentation", "examples", "prometheus.yml")
 var promData = filepath.Join(os.TempDir(), "data")
 
+//不用向channel中写入数据，直接关闭，触发所有阻塞于此的 <- reloadReady.C都执行而不需要一个一个写数据
+//main.go中reloadReady的使用原理
+func TestReloadReady(t *testing.T) {
+	type closeOnce struct {
+		C     chan struct{}
+		once  sync.Once
+		Close func()
+	}
+	// Wait until the server is ready to handle reloading.
+	reloadReady := &closeOnce{
+		C: make(chan struct{}),
+	}
+	reloadReady.Close = func() {
+		reloadReady.once.Do(func() {
+			close(reloadReady.C)
+		})
+	}
+
+	time.Sleep(5 * time.Second)
+	fmt.Println("trigger exec....")
+	reloadReady.Close()
+	select {
+	case <-reloadReady.C:
+		fmt.Println("first exec....")
+
+	}
+	select {
+	case <-reloadReady.C:
+		fmt.Println("second exec....")
+
+	}
+
+}
+
 func TestMain(m *testing.M) {
 	for i, arg := range os.Args {
 		if arg == "-test.main" {