net/http: add a Linux-only sendfile test

I remembered that sendfile support was lacking a test.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5652079

diff --git a/src/pkg/net/http/fs_test.go b/src/pkg/net/http/fs_test.go
index 45059fd5f3b84e0eed90871d58c10ac0c4382e19..5878f60887dcf985f48514c637daf68582dc4697 100644 (file)
--- a/src/pkg/net/http/fs_test.go
+++ b/src/pkg/net/http/fs_test.go
@@ -5,14 +5,20 @@
 package http_test
 
 import (
+       "bytes"
        "fmt"
        "io"
        "io/ioutil"
+       "net"
        . "net/http"
        "net/http/httptest"
        "net/url"
        "os"
+       "os/exec"
        "path/filepath"
+       "regexp"
+       "runtime"
+       "strconv"
        "strings"
        "testing"
        "time"
@@ -359,6 +365,68 @@ func TestServeContent(t *testing.T) {
        }
 }
 
+// verifies that sendfile is being used on Linux
+func TestLinuxSendfile(t *testing.T) {
+       if runtime.GOOS != "linux" {
+               t.Logf("skipping; linux-only test")
+               return
+       }
+       _, err := exec.LookPath("strace")
+       if err != nil {
+               t.Logf("skipping; strace not found in path")
+               return
+       }
+
+       ln, err := net.Listen("tcp", "127.0.0.1:0")
+       if err != nil {
+               t.Fatal(err)
+       }
+       lnf, err := ln.(*net.TCPListener).File()
+       if err != nil {
+               t.Fatal(err)
+       }
+       defer ln.Close()
+
+       child := exec.Command(os.Args[0], "-test.run=TestLinuxSendfileChild")
+       child.ExtraFiles = append(child.ExtraFiles, lnf)
+       child.Env = append([]string{"GO_WANT_HELPER_PROCESS=1"}, os.Environ()...)
+
+       err = child.Start()
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       pid := child.Process.Pid
+
+       var buf bytes.Buffer
+       strace := exec.Command("strace", "-f", "-p", strconv.Itoa(pid))
+       strace.Stdout = &buf
+       strace.Stderr = &buf
+       err = strace.Start()
+       if err != nil {
+               t.Logf("skipping; failed to start strace: %v", err)
+               return
+       }
+
+       _, err = Get(fmt.Sprintf("http://%s/", ln.Addr()))
+       if err != nil {
+               t.Errorf("http client error: %v", err)
+               return
+       }
+
+       // Force child to exit cleanly.
+       Get(fmt.Sprintf("http://%s/quit", ln.Addr()))
+       child.Wait()
+       strace.Wait()
+
+       rx := regexp.MustCompile(`sendfile\(\d+,\s*\d+,\s*NULL,\s*\d+\)\s*=\s*\d+\s*\n`)
+       rxResume := regexp.MustCompile(`<\.\.\. sendfile resumed> \)\s*=\s*\d+\s*\n`)
+       out := buf.String()
+       if !rx.MatchString(out) && !rxResume.MatchString(out) {
+               t.Errorf("no sendfile system call found in:\n%s", out)
+       }
+}
+
 func getBody(t *testing.T, testName string, req Request) (*Response, []byte) {
        r, err := DefaultClient.Do(&req)
        if err != nil {
@@ -371,6 +439,30 @@ func getBody(t *testing.T, testName string, req Request) (*Response, []byte) {
        return r, b
 }
 
+// TestLinuxSendfileChild isn't a real test. It's used as a helper process
+// for TestLinuxSendfile.
+func TestLinuxSendfileChild(*testing.T) {
+       if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+               return
+       }
+       defer os.Exit(0)
+       fd3 := os.NewFile(3, "ephemeral-port-listener")
+       ln, err := net.FileListener(fd3)
+       if err != nil {
+               panic(err)
+       }
+       mux := NewServeMux()
+       mux.Handle("/", FileServer(Dir("testdata")))
+       mux.HandleFunc("/quit", func(ResponseWriter, *Request) {
+               os.Exit(0)
+       })
+       s := &Server{Handler: mux}
+       err = s.Serve(ln)
+       if err != nil {
+               panic(err)
+       }
+}
+
 func equal(a, b []byte) bool {
        if len(a) != len(b) {
                return false