关于忽略上下文取消功能的 vert 警告

Question

我正在将超时上下文传递给 Server.Shutdown(http 包)。我看不出我需要调用返回的取消函数，所以我忽略了它。但是当我运行 go vet 时，它说 context.WithTimeout 返回的取消函数应该被调用，而不是被丢弃，以避免上下文泄漏。

如果没有问题，我该如何解决问题或避免 go vet 错误消息？

    go signalShutdown(server, stopCh)

    if err := server.ListenAndServeTLS(cert, key); err != http.ErrServerClosed {
        log.Fatalf("ListenAndServeTLS() error: %v\n", err)
    }
    // Note: exit here does not terminate main()
}

// signalShutdown waits for a notification from the OS that the http server
// should be shutdown, then gracefully stops it.
func signalShutdown(server *http.Server, stopCh <-chan struct{}) {
    const ForceShutdownAfter = 10 // Shutdown context times out after this many seconds

    // Setup chan to receive notification of when server should shut down
    quitCh := make(chan os.Signal, 1)
    signal.Notify(quitCh, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)

    // Wait until we get a notification to stop the server
    select {
    case <-quitCh:
        log.Println("WEB : OS signal received on", server.Addr)
    case <-stopCh:
        log.Println("WEB : Shutdown message received on", server.Addr)
    }

    context, _ := context.WithTimeout(context.Background(), ForceShutdownAfter*time.Second)

    // Tell the server to shutdown but only after blocking new connections and waiting for the
    // existing connections to finish (OR if context expires - see ForceShutdownAfter above)
    if err := server.Shutdown(context); err != nil {
        log.Fatalf("Shutdown() error: %v", err)
    }

    os.Exit(0)
}

Answer 1

... the cancel function returned by context.WithTimeout should be called, not discarded, to avoid a context leak.

How do I fix the problem or avoid the go vet error message, if there is no problem?

通过调用而不丢弃cancel 函数，as documented :

context, cancel := context.WithTimeout(context.Background(), ForceShutdownAfter*time.Second)
defer cancel()