proxy: Added TestReverseProxyLargeBody test case

This test ensures that the optimizations in 8048e9c3 are actually effective.

caddyhttp/proxy/proxy_test.go

@@ -954,6 +954,90 @@ func TestReverseProxyRetry(t *testing.T) {
 	}
 }
 
+func TestReverseProxyLargeBody(t *testing.T) {
+	log.SetOutput(ioutil.Discard)
+	defer log.SetOutput(os.Stderr)
+
+	// set up proxy
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		io.Copy(ioutil.Discard, r.Body)
+		r.Body.Close()
+	}))
+	defer backend.Close()
+
+	su, err := NewStaticUpstreams(caddyfile.NewDispenser("Testfile", strings.NewReader(`proxy / `+backend.URL)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p := &Proxy{
+		Next:      httpserver.EmptyNext, // prevents panic in some cases when test fails
+		Upstreams: su,
+	}
+
+	// middle is required to simulate closable downstream request body
+	middle := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, err = p.ServeHTTP(w, r)
+		if err != nil {
+			t.Error(err)
+		}
+	}))
+	defer middle.Close()
+
+	// Our request body will be 100MB
+	bodySize := uint64(100 * 1000 * 1000)
+
+	// We want to see how much memory the proxy module requires for this request.
+	// So lets record the mem stats before we start it.
+	begMemstats := &runtime.MemStats{}
+	runtime.ReadMemStats(begMemstats)
+
+	r, err := http.NewRequest("POST", middle.URL, &noopReader{len: bodySize})
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := http.DefaultTransport.RoundTrip(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+
+	// Finally we need the mem stats after the request is done...
+	endMemstats := &runtime.MemStats{}
+	runtime.ReadMemStats(endMemstats)
+
+	// ...to calculate the total amount of allocated memory during the request.
+	totalAlloc := endMemstats.TotalAlloc - begMemstats.TotalAlloc
+
+	// If that's as much as the size of the body itself it's a serious sign that the
+	// request was not "streamed" to the upstream without buffering it first.
+	if totalAlloc >= bodySize {
+		t.Fatalf("proxy allocated too much memory: %d bytes", totalAlloc)
+	}
+}
+
+type noopReader struct {
+	len uint64
+	pos uint64
+}
+
+var _ io.Reader = &noopReader{}
+
+func (r *noopReader) Read(b []byte) (int, error) {
+	if r.pos >= r.len {
+		return 0, io.EOF
+	}
+	n := int(r.len - r.pos)
+	if n > len(b) {
+		n = len(b)
+	}
+	for i := range b[:n] {
+		b[i] = 0
+	}
+	r.pos += uint64(n)
+	return n, nil
+}
+
 func newFakeUpstream(name string, insecure bool) *fakeUpstream {
 	uri, _ := url.Parse(name)
 	u := &fakeUpstream{
@@ -998,6 +1082,7 @@ func (u *fakeUpstream) Select(r *http.Request) *UpstreamHost {
 func (u *fakeUpstream) AllowedPath(requestPath string) bool { return true }
 func (u *fakeUpstream) GetTryDuration() time.Duration       { return 1 * time.Second }
 func (u *fakeUpstream) GetTryInterval() time.Duration       { return 250 * time.Millisecond }
+func (u *fakeUpstream) GetHostCount() int                   { return 1 }
 
 // newWebSocketTestProxy returns a test proxy that will
 // redirect to the specified backendAddr. The function
@@ -1049,6 +1134,7 @@ func (u *fakeWsUpstream) Select(r *http.Request) *UpstreamHost {
 func (u *fakeWsUpstream) AllowedPath(requestPath string) bool { return true }
 func (u *fakeWsUpstream) GetTryDuration() time.Duration       { return 1 * time.Second }
 func (u *fakeWsUpstream) GetTryInterval() time.Duration       { return 250 * time.Millisecond }
+func (u *fakeWsUpstream) GetHostCount() int                   { return 1 }
 
 // recorderHijacker is a ResponseRecorder that can
 // be hijacked.