From 2f0ddc2dc8607e5c8fdd3b10f5cc1712906b2f48 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Sun, 7 May 2017 21:20:08 +0200
Subject: added stateful encoder

---
 src/hub/src/spreadspace.org/sfive/s5cvt.go        | 24 +++++++++++++++
 src/hub/src/spreadspace.org/sfive/s5cvt_test.go   | 36 +++++++++++++++++++++++
 src/hub/src/spreadspace.org/sfive/s5srvForward.go |  6 ++--
 src/hub/src/spreadspace.org/sfive/s5srvWeb.go     |  8 ++---
 4 files changed, 66 insertions(+), 8 deletions(-)

(limited to 'src/hub')

diff --git a/src/hub/src/spreadspace.org/sfive/s5cvt.go b/src/hub/src/spreadspace.org/sfive/s5cvt.go
index 1a8e1f3..9db899c 100644
--- a/src/hub/src/spreadspace.org/sfive/s5cvt.go
+++ b/src/hub/src/spreadspace.org/sfive/s5cvt.go
@@ -119,6 +119,7 @@ type Encoder interface {
 	Slug() string
 }
 
+// stateless protocol interfaces
 type StatelessEncoder struct {
 	enc *json.Encoder
 }
@@ -136,3 +137,26 @@ func (se *StatelessEncoder) Encode(data DataUpdateFull) error {
 	data.StartTime = data.StartTime.UTC()
 	return se.enc.Encode(data)
 }
+
+// stateful protocol interfaces
+type StatefulEncoder struct {
+	enc *json.Encoder
+	Header
+}
+
+func NewStatefulEncoder(w io.Writer) (Encoder, error) {
+	res := &StatefulEncoder{}
+	res.Version = ProtocolVersion
+	res.enc = json.NewEncoder(w)
+	return res, res.enc.Encode(&res)
+}
+
+func (se *StatefulEncoder) Slug() string {
+	return ""
+}
+
+func (se *StatefulEncoder) Encode(data DataUpdateFull) error {
+	data.Version = 0 // the init message took care of that
+	data.StartTime = data.StartTime.UTC()
+	return se.enc.Encode(data)
+}
diff --git a/src/hub/src/spreadspace.org/sfive/s5cvt_test.go b/src/hub/src/spreadspace.org/sfive/s5cvt_test.go
index 2b102d5..b44c628 100644
--- a/src/hub/src/spreadspace.org/sfive/s5cvt_test.go
+++ b/src/hub/src/spreadspace.org/sfive/s5cvt_test.go
@@ -182,3 +182,39 @@ func TestEncodeStateless(t *testing.T) {
 		t.Fatalf("encoding failed:\n actual: %v\n expected: %v\n", decoded, expected)
 	}
 }
+
+func TestEncodeStateful(t *testing.T) {
+	var td DataUpdateFull
+	td.CopyFromSourceId(&initDataStruct)
+	td.CopyFromUpdate(&updateDataStruct)
+
+	encoded := &bytes.Buffer{}
+	enc, err := NewStatefulEncoder(encoded)
+	if err != nil {
+		t.Fatalf("encoding init message failed: %v", err)
+	}
+	if err := enc.Encode(td); err != nil {
+		t.Fatalf("encoding data message failed: %v", err)
+	}
+
+	// check the slug
+	if enc.Slug() != "" {
+		t.Fatalf("the slug of a stateful encoder should be the empty string")
+	}
+
+	// try to decode encoded message
+	dec, err := NewStatefulDecoder(encoded)
+	if err != nil {
+		t.Fatalf("decoding init message failed: %v", err)
+	}
+	decoded, err := dec.Decode()
+	if err != nil {
+		t.Fatalf("decoding data message failed: %v", err)
+	}
+
+	expected := td
+	expected.Version = ProtocolVersion
+	if !reflect.DeepEqual(decoded, expected) {
+		t.Fatalf("encoding failed:\n actual: %v\n expected: %v\n", decoded, expected)
+	}
+}
diff --git a/src/hub/src/spreadspace.org/sfive/s5srvForward.go b/src/hub/src/spreadspace.org/sfive/s5srvForward.go
index 10e4b9d..e88a79d 100644
--- a/src/hub/src/spreadspace.org/sfive/s5srvForward.go
+++ b/src/hub/src/spreadspace.org/sfive/s5srvForward.go
@@ -107,14 +107,14 @@ tryResync:
 				continue nextBatch
 			}
 
-			// TODO: use StatefulEncoder
+			// TODO: directly write to client body
 			buf := &bytes.Buffer{}
-			if err := json.NewEncoder(buf).Encode(Header{Version: 1}); err != nil {
+			enc, err := NewStatefulEncoder(buf)
+			if err != nil {
 				s5l.Printf("fwd: failed encoding init message: %v\n", err)
 				time.Sleep(500 * time.Millisecond)
 				continue nextBatch
 			}
-			enc := NewStatelessEncoder(buf)
 			for _, upd := range updates {
 				if err := enc.Encode(upd); err != nil {
 					s5l.Printf("fwd: failed encoding updates: %v\n", err)
diff --git a/src/hub/src/spreadspace.org/sfive/s5srvWeb.go b/src/hub/src/spreadspace.org/sfive/s5srvWeb.go
index ee9f131..962187f 100644
--- a/src/hub/src/spreadspace.org/sfive/s5srvWeb.go
+++ b/src/hub/src/spreadspace.org/sfive/s5srvWeb.go
@@ -203,13 +203,11 @@ func webUpdatesGetBulk(srv *Server, w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json") // this is actually multiple json documents...
 	w.WriteHeader(http.StatusOK)
 
-	// TODO: use StatefulEncoder
-	if err := json.NewEncoder(w).Encode(Header{Version: 1}); err != nil {
-		s5l.Printf("Error while sending data: %v", err)
+	encoder, err := NewStatefulEncoder(w)
+	if err != nil {
+		s5l.Printf("Error while sending init: %v", err)
 		return
-		s5l.Printf("fwd: failed encoding init message: %v\n", err)
 	}
-	encoder := NewStatelessEncoder(w)
 	for _, upd := range upds {
 		if err := encoder.Encode(upd); err != nil {
 			s5l.Printf("Error while sending data: %v", err)
-- 
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