tmp

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

metadata/context.go

@@ -124,7 +124,7 @@ func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
 		return NewOutgoingContext(ctx, md)
 	}
 	for k, v := range md {
-		omd.Set(k, v)
+		omd[k] = v
 	}
 	return NewOutgoingContext(ctx, omd)
 }
@@ -140,7 +140,7 @@ func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
 		return NewIncomingContext(ctx, md)
 	}
 	for k, v := range md {
-		omd.Set(k, v)
+		omd[k] = v
 	}
 	return NewIncomingContext(ctx, omd)
 }

metadata/metadata.go

@@ -24,7 +24,7 @@ var (
 // Metadata is our way of representing request headers internally.
 // They're used at the RPC level and translate back and forth
 // from Transport headers.
-type Metadata map[string]string
+type Metadata map[string][]string
 
 type rawMetadata struct {
 	md Metadata
@@ -42,7 +42,7 @@ type Iterator struct {
 }
 
 // Next advance iterator to next element
-func (iter *Iterator) Next(k, v *string) bool {
+func (iter *Iterator) Next(k *string, v *[]string) bool {
 	if iter.cur+1 > iter.cnt {
 		return false
 	}
@@ -64,8 +64,11 @@ func (md Metadata) Iterator() *Iterator {
 	return iter
 }
 
-// Get returns value from metadata by key
-func (md Metadata) Get(key string) (string, bool) {
+// Values returns values from metadata by key
+func (md Metadata) Values(key string) ([]string, bool) {
+	if md == nil {
+		return nil, false
+	}
 	// fast path
 	val, ok := md[key]
 	if !ok {
@@ -75,16 +78,42 @@ func (md Metadata) Get(key string) (string, bool) {
 	return val, ok
 }
 
+// Get returns value from metadata by key
+func (md Metadata) Get(key string) (string, bool) {
+	if md == nil {
+		return "", false
+	}
+	// fast path
+	val, ok := md[key]
+	if !ok {
+		// slow path
+		val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
+	}
+	if len(val) == 0 {
+		return "", false
+	}
+	return val[0], ok
+}
+
 // Set is used to store value in metadata
 func (md Metadata) Set(kv ...string) {
+	if md == nil {
+		return
+	}
 	if len(kv)%2 == 1 {
 		kv = kv[:len(kv)-1]
 	}
 	for idx := 0; idx < len(kv); idx += 2 {
-		md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = kv[idx+1]
+		md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = []string{kv[idx+1]}
 	}
 }
 
+// Add is used to append value in metadata
+func (md Metadata) Add(k string, v string) {
+	kn := textproto.CanonicalMIMEHeaderKey(k)
+	md[kn] = append(md[kn], v)
+}
+
 // Del is used to remove value from metadata
 func (md Metadata) Del(keys ...string) {
 	for _, key := range keys {
@@ -99,7 +128,7 @@ func (md Metadata) Del(keys ...string) {
 func Copy(md Metadata) Metadata {
 	nmd := New(len(md))
 	for key, val := range md {
-		nmd.Set(key, val)
+		nmd[key] = val
 	}
 	return nmd
 }
@@ -114,16 +143,24 @@ func New(size int) Metadata {
 
 // Merge merges metadata to existing metadata, overwriting if specified
 func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
-	var ok bool
 	nmd := Copy(omd)
-	for key, val := range mmd {
-		_, ok = nmd[key]
+	for key, nval := range mmd {
+		oval, ok := nmd[key]
 		switch {
 		case ok && !overwrite:
 			continue
-		case val != "":
-			nmd.Set(key, val)
-		case ok && val == "":
+		case len(nval) == 1 && nval[0] != "":
+			nmd[key] = nval
+		case ok && len(nval) > 1:
+			sort.Strings(nval)
+			sort.Strings(oval)
+			for idx, v := range nval {
+				if oval[idx] != v {
+					oval[idx] = v
+				}
+			}
+			nmd[key] = oval
+		case ok && nval[0] == "":
 			nmd.Del(key)
 		}
 	}

metadata/metadata_test.go

@@ -68,10 +68,10 @@ func TestPassing(t *testing.T) {
 
 func TestMerge(t *testing.T) {
 	omd := Metadata{
-		"key1": "val1",
+		"key1": []string{"val1"},
 	}
 	mmd := Metadata{
-		"key2": "val2",
+		"key2": []string{"val2"},
 	}
 
 	nmd := Merge(omd, mmd, true)
@@ -82,13 +82,14 @@ func TestMerge(t *testing.T) {
 
 func TestIterator(t *testing.T) {
 	md := Metadata{
-		"1Last":   "last",
-		"2First":  "first",
-		"3Second": "second",
+		"1Last":   []string{"last"},
+		"2First":  []string{"first"},
+		"3Second": []string{"second"},
 	}
 
 	iter := md.Iterator()
-	var k, v string
+	var k string
+	var v []string
 
 	for iter.Next(&k, &v) {
 		// fmt.Printf("k: %s, v: %s\n", k, v)
@@ -101,20 +102,20 @@ func TestMedataCanonicalKey(t *testing.T) {
 	v, ok := md.Get("x-request-id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
-	} else if v != "12345" {
+	} else if len(v) != 1 && v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
 
 	v, ok = md.Get("X-Request-Id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
-	} else if v != "12345" {
+	} else if len(v) != 1 && v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
 	v, ok = md.Get("X-Request-ID")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
-	} else if v != "12345" {
+	} else if len(v) != 1 && v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
 }
@@ -135,8 +136,8 @@ func TestMetadataSet(t *testing.T) {
 
 func TestMetadataDelete(t *testing.T) {
 	md := Metadata{
-		"Foo": "bar",
-		"Baz": "empty",
+		"Foo": []string{"bar"},
+		"Baz": []string{"empty"},
 	}
 
 	md.Del("Baz")
@@ -157,14 +158,14 @@ func TestNilContext(t *testing.T) {
 
 func TestMetadataCopy(t *testing.T) {
 	md := Metadata{
-		"Foo": "bar",
-		"Bar": "baz",
+		"Foo": []string{"bar"},
+		"Bar": []string{"baz"},
 	}
 
 	cp := Copy(md)
 
 	for k, v := range md {
-		if cv := cp[k]; cv != v {
+		if cv := cp[k]; len(cv) != len(v) || (cv[0] != v[0] && cv[1] != v[1]) {
 			t.Fatalf("Got %s:%s for %s:%s", k, cv, k, v)
 		}
 	}
@@ -172,7 +173,7 @@ func TestMetadataCopy(t *testing.T) {
 
 func TestMetadataContext(t *testing.T) {
 	md := Metadata{
-		"Foo": "bar",
+		"Foo": []string{"bar"},
 	}
 
 	ctx := NewContext(context.TODO(), md)
@@ -182,7 +183,7 @@ func TestMetadataContext(t *testing.T) {
 		t.Errorf("Unexpected error retrieving metadata, got %t", ok)
 	}
 
-	if emd["Foo"] != md["Foo"] {
+	if len(emd["Foo"]) != len(md["Foo"]) || (emd["Foo"][0] != md["Foo"][0]) {
 		t.Errorf("Expected key: %s val: %s, got key: %s val: %s", "Foo", md["Foo"], "Foo", emd["Foo"])
 	}