Merge pull request #84 from dhontecillas/merge_incomplete_responses_data

Fix #80: Merge incomplete responses data

proxy/merging.go

@@ -78,19 +78,27 @@ func requestPart(ctx context.Context, next Proxy, request *Request, out chan<- *
 }
 
 func combineData(total int, parts []*Response) *Response {
-	composedData := make(map[string]interface{})
-	isComplete := len(parts) == total
-
+	var isComplete bool = len(parts) == total
+	var retResponse *Response = nil
 	for _, part := range parts {
-		if part != nil && part.IsComplete {
-			for k, v := range part.Data {
-				composedData[k] = v
-			}
-			isComplete = isComplete && part.IsComplete
-		} else {
+		if part == nil || part.Data == nil {
 			isComplete = false
+			continue
+		}
+		isComplete = isComplete && part.IsComplete
+		if retResponse == nil {
+			retResponse = part
+			continue
+		}
+		for k, v := range part.Data {
+			retResponse.Data[k] = v
 		}
 	}
 
-	return &Response{Data: composedData, IsComplete: isComplete}
+	if nil == retResponse {
+		// do not allow nil data in the response:
+		return &Response{Data: make(map[string]interface{}, 0), IsComplete: isComplete}
+	}
+	retResponse.IsComplete = isComplete
+	return retResponse
 }

proxy/merging_test.go

@@ -41,6 +41,72 @@ func TestNewMergeDataMiddleware_ok(t *testing.T) {
 	}
 }
 
+func TestNewMergeDataMiddleware_mergeIncompleteResults(t *testing.T) {
+	timeout := 500
+	backend := config.Backend{}
+	endpoint := config.EndpointConfig{
+		Backend: []*config.Backend{&backend, &backend},
+		Timeout: time.Duration(timeout) * time.Millisecond,
+	}
+	mw := NewMergeDataMiddleware(&endpoint)
+	p := mw(
+		dummyProxy(&Response{Data: map[string]interface{}{"supu": 42}, IsComplete: true}),
+		dummyProxy(&Response{Data: map[string]interface{}{"tupu": true}, IsComplete: false}))
+	mustEnd := time.After(time.Duration(2*timeout) * time.Millisecond)
+	out, err := p(context.Background(), &Request{})
+	if err != nil {
+		t.Errorf("The middleware propagated an unexpected error: %s\n", err.Error())
+	}
+	if out == nil {
+		t.Errorf("The proxy returned a null result\n")
+		return
+	}
+	select {
+	case <-mustEnd:
+		t.Errorf("We were expecting a response but we got none\n")
+	default:
+		if len(out.Data) != 2 {
+			t.Errorf("We were expecting incomplete results merged but we got %v!\n", out)
+		}
+		if out.IsComplete {
+			t.Errorf("We were expecting an incomplete response but we got an incompleted one!\n")
+		}
+	}
+}
+
+func TestNewMergeDataMiddleware_mergeEmptyResults(t *testing.T) {
+	timeout := 500
+	backend := config.Backend{}
+	endpoint := config.EndpointConfig{
+		Backend: []*config.Backend{&backend, &backend},
+		Timeout: time.Duration(timeout) * time.Millisecond,
+	}
+	mw := NewMergeDataMiddleware(&endpoint)
+	p := mw(
+		dummyProxy(&Response{Data: nil, IsComplete: false}),
+		dummyProxy(&Response{Data: nil, IsComplete: false}))
+	mustEnd := time.After(time.Duration(2*timeout) * time.Millisecond)
+	out, err := p(context.Background(), &Request{})
+	if err != nil {
+		t.Errorf("The middleware propagated an unexpected error: %s\n", err.Error())
+	}
+	if out == nil {
+		t.Errorf("The proxy returned a null result\n")
+		return
+	}
+	select {
+	case <-mustEnd:
+		t.Errorf("We were expecting a response but we got none\n")
+	default:
+		if len(out.Data) != 0 {
+			t.Errorf("We were expecting empty data but we got %v!\n", out)
+		}
+		if out.IsComplete {
+			t.Errorf("We were expecting an incomplete response but we got an incompleted one!\n")
+		}
+	}
+}
+
 func TestNewMergeDataMiddleware_partialTimeout(t *testing.T) {
 	timeout := 100
 	backend := config.Backend{Timeout: time.Duration(timeout) * time.Millisecond}