Add support for Tag metadata (#1125)

* Add support for tag metadata.

* update ocgrpc and ochttp to use new insert/update/upsert api.
:

* updated existing method optional metadata option.

* make TTLNoPropagation and TTLUnlimitedPropagation a function.

* changed ttl api.

* add test case for multiple TTL metadata.

* add test case and note for update/insert api.

Author: rghetia

tag/map.go

@@ -28,10 +28,15 @@ type Tag struct {
 	Value string
 }
 
+type tagContent struct {
+	value string
+	m     metadatas
+}
+
 // Map is a map of tags. Use New to create a context containing
 // a new Map.
 type Map struct {
-	m map[Key]string
+	m map[Key]tagContent
 }
 
 // Value returns the value for the key if a value for the key exists.
@@ -40,7 +45,7 @@ func (m *Map) Value(k Key) (string, bool) {
 		return "", false
 	}
 	v, ok := m.m[k]
-	return v, ok
+	return v.value, ok
 }
 
 func (m *Map) String() string {
@@ -62,29 +67,29 @@ func (m *Map) String() string {
 	return buffer.String()
 }
 
-func (m *Map) insert(k Key, v string) {
+func (m *Map) insert(k Key, v string, md metadatas) {
 	if _, ok := m.m[k]; ok {
 		return
 	}
-	m.m[k] = v
+	m.m[k] = tagContent{value: v, m: md}
 }
 
-func (m *Map) update(k Key, v string) {
+func (m *Map) update(k Key, v string, md metadatas) {
 	if _, ok := m.m[k]; ok {
-		m.m[k] = v
+		m.m[k] = tagContent{value: v, m: md}
 	}
 }
 
-func (m *Map) upsert(k Key, v string) {
-	m.m[k] = v
+func (m *Map) upsert(k Key, v string, md metadatas) {
+	m.m[k] = tagContent{value: v, m: md}
 }
 
 func (m *Map) delete(k Key) {
 	delete(m.m, k)
 }
 
 func newMap() *Map {
-	return &Map{m: make(map[Key]string)}
+	return &Map{m: make(map[Key]tagContent)}
 }
 
 // Mutator modifies a tag map.
@@ -95,13 +100,17 @@ type Mutator interface {
 // Insert returns a mutator that inserts a
 // value associated with k. If k already exists in the tag map,
 // mutator doesn't update the value.
-func Insert(k Key, v string) Mutator {
+// Metadata applies metadata to the tag. It is optional.
+// Metadatas are applied in the order in which it is provided.
+// If more than one metadata updates the same attribute then
+// the update from the last metadata prevails.
+func Insert(k Key, v string, mds ...Metadata) Mutator {
 	return &mutator{
 		fn: func(m *Map) (*Map, error) {
 			if !checkValue(v) {
 				return nil, errInvalidValue
 			}
-			m.insert(k, v)
+			m.insert(k, v, createMetadatas(mds...))
 			return m, nil
 		},
 	}
@@ -110,13 +119,17 @@ func Insert(k Key, v string) Mutator {
 // Update returns a mutator that updates the
 // value of the tag associated with k with v. If k doesn't
 // exists in the tag map, the mutator doesn't insert the value.
-func Update(k Key, v string) Mutator {
+// Metadata applies metadata to the tag. It is optional.
+// Metadatas are applied in the order in which it is provided.
+// If more than one metadata updates the same attribute then
+// the update from the last metadata prevails.
+func Update(k Key, v string, mds ...Metadata) Mutator {
 	return &mutator{
 		fn: func(m *Map) (*Map, error) {
 			if !checkValue(v) {
 				return nil, errInvalidValue
 			}
-			m.update(k, v)
+			m.update(k, v, createMetadatas(mds...))
 			return m, nil
 		},
 	}
@@ -126,18 +139,37 @@ func Update(k Key, v string) Mutator {
 // value of the tag associated with k with v. It inserts the
 // value if k doesn't exist already. It mutates the value
 // if k already exists.
-func Upsert(k Key, v string) Mutator {
+// Metadata applies metadata to the tag. It is optional.
+// Metadatas are applied in the order in which it is provided.
+// If more than one metadata updates the same attribute then
+// the update from the last metadata prevails.
+func Upsert(k Key, v string, mds ...Metadata) Mutator {
 	return &mutator{
 		fn: func(m *Map) (*Map, error) {
 			if !checkValue(v) {
 				return nil, errInvalidValue
 			}
-			m.upsert(k, v)
+			m.upsert(k, v, createMetadatas(mds...))
 			return m, nil
 		},
 	}
 }
 
+func createMetadatas(mds ...Metadata) metadatas {
+	var metas metadatas
+	if len(mds) > 0 {
+		for _, md := range mds {
+			if md != nil {
+				md(&metas)
+			}
+		}
+	} else {
+		WithTTL(TTLUnlimitedPropagation)(&metas)
+	}
+	return metas
+
+}
+
 // Delete returns a mutator that deletes
 // the value associated with k.
 func Delete(k Key) Mutator {
@@ -160,10 +192,10 @@ func New(ctx context.Context, mutator ...Mutator) (context.Context, error) {
 			if !checkKeyName(k.Name()) {
 				return ctx, fmt.Errorf("key:%q: %v", k, errInvalidKeyName)
 			}
-			if !checkValue(v) {
+			if !checkValue(v.value) {
 				return ctx, fmt.Errorf("key:%q value:%q: %v", k.Name(), v, errInvalidValue)
 			}
-			m.insert(k, v)
+			m.insert(k, v.value, v.m)
 		}
 	}
 	var err error

tag/map_codec.go

@@ -170,9 +170,11 @@ func Encode(m *Map) []byte {
 	}
 	eg.writeByte(byte(tagsVersionID))
 	for k, v := range m.m {
-		eg.writeByte(byte(keyTypeString))
-		eg.writeStringWithVarintLen(k.name)
-		eg.writeBytesWithVarintLen([]byte(v))
+		if v.m.ttl.ttl == valueTTLUnlimitedPropagation {
+			eg.writeByte(byte(keyTypeString))
+			eg.writeStringWithVarintLen(k.name)
+			eg.writeBytesWithVarintLen([]byte(v.value))
+		}
 	}
 	return eg.bytes()
 }
@@ -190,7 +192,7 @@ func Decode(bytes []byte) (*Map, error) {
 
 // DecodeEach decodes the given serialized tag map, calling handler for each
 // tag key and value decoded.
-func DecodeEach(bytes []byte, fn func(key Key, val string)) error {
+func DecodeEach(bytes []byte, fn func(key Key, val string, md metadatas)) error {
 	eg := &encoderGRPC{
 		buf: bytes,
 	}
@@ -228,7 +230,10 @@ func DecodeEach(bytes []byte, fn func(key Key, val string)) error {
 		if !checkValue(val) {
 			return errInvalidValue
 		}
-		fn(key, val)
+		fn(key, val, createMetadatas(WithTTL(TTLUnlimitedPropagation)))
+		if err != nil {
+			return err
+		}
 	}
 	return nil
 }

tag/map_codec_test.go

@@ -91,7 +91,7 @@ func TestEncodeDecode(t *testing.T) {
 
 		got := make([]keyValue, 0)
 		for k, v := range decoded.m {
-			got = append(got, keyValue{k, string(v)})
+			got = append(got, keyValue{k, string(v.value)})
 		}
 		want := tc.pairs