如何在不发送任何请求的情况下在grpc中检测服务器关闭？

Question

希望客户端不发送任何请求也能检测到服务器关闭，所以我使用了keepalive选项。 但是当我用 ctrl+c 关闭服务器时，客户端的连接状态只是从准备好变为空闲而不是关闭。

import (
    "context"
    "fmt"
    "google.golang.org/grpc"
    "google.golang.org/grpc/connectivity"
    "google.golang.org/grpc/keepalive"
    "log"
    "sync"
    "time"
)
func main() {

    var kap = keepalive.ClientParameters{
        Time:                15 * time.Second, // send pings every 10 seconds if there is no activity
        Timeout:             time.Second,      // wait 1 second for ping ack before considering the connection dead
        PermitWithoutStream: true,             // send pings even without active streams
    }
    conn, err := grpc.Dial(
        "localhost:50051",
        grpc.WithBlock(),
        grpc.WithInsecure(),
        grpc.WithKeepaliveParams(kap),
    )
    if err != nil {
        log.Fatalf("failed to dial: %v", err)
    }
    log.Println(conn.GetState())  
    wg := sync.WaitGroup{}
    wg.Add(1) 
    go func() {
        for {
            log.Println(conn.GetState())
            if conn.WaitForStateChange(context.Background(), conn.GetState()) {
                if conn.GetState() == connectivity.Shutdown {
                    log.Println("connection closed")
                    // TODO:
                    break
                }
            }
        }
        defer wg.Done()
    }()
    // wait
    wg.Wait()
    fmt.Println("gRPC connection closed")
}

我希望客户端在不发送任何请求的情况下能够检测到服务器在grpc流式连接中关闭