net/http server context object does not cancel on closed connections, need to listen for closenotify

main.go

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"time"

	"golang.org/x/net/context/ctxhttp"
)

func main() {
	http.HandleFunc("/foo", func(w http.ResponseWriter, r *http.Request) {
		cn, ok := w.(http.CloseNotifier)
		if !ok {
			log.Fatal("don't support CloseNotifier")
		}
		select {
		case <-cn.CloseNotify():
			log.Print("server handler returning after close notify")
		case <-r.Context().Done():
			log.Print("server handler returning after cancellation")
		case <-time.After(1 * time.Second):
			log.Print("server handler returning after 1 second")
		}
		fmt.Fprintf(w, "Hello, foo")
	})

	go func() {
		log.Fatal(http.ListenAndServe(":8080", nil))
	}()

	time.Sleep(1 * time.Second)

	// make some client requests
	log.Print("test 1: request with no timeout")
	resp, err := http.Get("http://localhost:8080/foo")
	if err != nil {
		log.Fatalf("unexpected error: %s", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != 200 {
		log.Fatalf("unexpected status code: %d", resp.StatusCode)
	}

	log.Print("test 2: request with a 100ms timeout via context")
	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()
	resp, err = ctxhttp.Get(ctx, http.DefaultClient, "http://localhost:8080/foo")
	if err == nil {
		log.Fatal("expected an error, got nil")
	} else if err.Error() != "context deadline exceeded" {
		log.Fatal("expected a a context deadline exceeded error, got nil")
	}
	log.Print("client is done")
	time.Sleep(1 * time.Second)
}

output:

2016/09/19 23:55:26 test 1: request with no timeout
2016/09/19 23:55:27 server handler returning after 1 second
2016/09/19 23:55:27 test 2: request with a 100ms timeout via context
2016/09/19 23:55:27 server handler returning after close notify
2016/09/19 23:55:27 client is done