refactor(metadata): convert to array structure

metadata/metadata.go

@@ -5,9 +5,15 @@ import (
 	"github.com/ipld/go-ipld-prime"
 )
 
+// Item is a single link traversed in a repsonse
+type Item struct {
+	Link         ipld.Link
+	BlockPresent bool
+}
+
 // Metadata is information about metadata contained in a response, which can be
 // serialized back and forth to bytes
-type Metadata map[ipld.Link]bool
+type Metadata []Item
 
 // DecodeMetadata assembles metadata from a raw byte array, first deserializing
 // as a node and then assembling into a metadata struct.
@@ -18,12 +24,16 @@ func DecodeMetadata(data []byte, ipldBridge ipldbridge.IPLDBridge) (Metadata, er
 	}
 	decodedData, err := ipldBridge.ExtractData(node, func(simpleNode ipldbridge.SimpleNode) interface{} {
 		iterator := simpleNode.ListIterator()
-		metadata := make(Metadata)
+		var metadata Metadata
+		if simpleNode.Length() != -1 {
+			metadata = make(Metadata, 0, simpleNode.Length())
+		}
+
 		for !iterator.Done() {
 			_, item := iterator.Next()
 			link := item.TraverseField("link").AsLink()
 			blockPresent := item.TraverseField("blockPresent").AsBool()
-			metadata[link] = blockPresent
+			metadata = append(metadata, Item{link, blockPresent})
 		}
 		return metadata
 	})
@@ -37,11 +47,11 @@ func DecodeMetadata(data []byte, ipldBridge ipldbridge.IPLDBridge) (Metadata, er
 func EncodeMetadata(entries Metadata, ipldBridge ipldbridge.IPLDBridge) ([]byte, error) {
 	node, err := ipldBridge.BuildNode(func(nb ipldbridge.NodeBuilder) ipld.Node {
 		return nb.CreateList(func(lb ipldbridge.ListBuilder, nb ipldbridge.NodeBuilder) {
-			for link, blockPresent := range entries {
+			for _, item := range entries {
 				lb.Append(
 					nb.CreateMap(func(mb ipldbridge.MapBuilder, knb ipldbridge.NodeBuilder, vnb ipldbridge.NodeBuilder) {
-						mb.Insert(knb.CreateString("link"), vnb.CreateLink(link))
-						mb.Insert(knb.CreateString("blockPresent"), vnb.CreateBool(blockPresent))
+						mb.Insert(knb.CreateString("link"), vnb.CreateLink(item.Link))
+						mb.Insert(knb.CreateString("blockPresent"), vnb.CreateBool(item.BlockPresent))
 					}),
 				)
 			}

metadata/metadata_test.go

@@ -14,11 +14,11 @@ import (
 
 func TestDecodeEncodeMetadata(t *testing.T) {
 	cids := testutil.GenerateCids(10)
-	initialMetadata := make(Metadata)
+	initialMetadata := make(Metadata, 0, 10)
 	for _, k := range cids {
 		link := cidlink.Link{Cid: k}
 		blockPresent := rand.Int31()%2 == 0
-		initialMetadata[link] = blockPresent
+		initialMetadata = append(initialMetadata, Item{link, blockPresent})
 	}
 	bridge := testbridge.NewMockIPLDBridge()
 	encoded, err := EncodeMetadata(initialMetadata, bridge)

responsemanager/responsebuilder/responsebuilder.go

@@ -33,12 +33,7 @@ func (rb *ResponseBuilder) AddBlock(block blocks.Block) {
 // AddLink adds the given link and whether its block is present
 // to the response for the given request ID.
 func (rb *ResponseBuilder) AddLink(requestID gsmsg.GraphSyncRequestID, link ipld.Link, blockPresent bool) {
-	linksForRequest, ok := rb.outgoingResponses[requestID]
-	if !ok {
-		linksForRequest = make(map[ipld.Link]bool)
-		rb.outgoingResponses[requestID] = linksForRequest
-	}
-	linksForRequest[link] = blockPresent
+	rb.outgoingResponses[requestID] = append(rb.outgoingResponses[requestID], metadata.Item{Link: link, BlockPresent: blockPresent})
 }
 
 // AddCompletedRequest marks the given request as completed in the response,
@@ -49,7 +44,7 @@ func (rb *ResponseBuilder) AddCompletedRequest(requestID gsmsg.GraphSyncRequestI
 	// make sure this completion goes out in next response even if no links are sent
 	_, ok := rb.outgoingResponses[requestID]
 	if !ok {
-		rb.outgoingResponses[requestID] = make(map[ipld.Link]bool)
+		rb.outgoingResponses[requestID] = nil
 	}
 }
 

responsemanager/responsebuilder/responsebuilder_test.go

@@ -35,6 +35,7 @@ func TestMessageBuilding(t *testing.T) {
 
 	rb.AddLink(requestID2, links[1], true)
 	rb.AddLink(requestID2, links[2], true)
+	rb.AddLink(requestID2, links[1], true)
 
 	rb.AddCompletedRequest(requestID2, gsmsg.RequestCompletedFull)
 
@@ -64,9 +65,9 @@ func TestMessageBuilding(t *testing.T) {
 
 	response1Metadata, err := metadata.DecodeMetadata(response1.Extra(), ipldBridge)
 	if err != nil || !reflect.DeepEqual(response1Metadata, metadata.Metadata{
-		links[0]: true,
-		links[1]: false,
-		links[2]: true,
+		metadata.Item{Link: links[0], BlockPresent: true},
+		metadata.Item{Link: links[1], BlockPresent: false},
+		metadata.Item{Link: links[2], BlockPresent: true},
 	}) {
 		t.Fatal("Metadata did not match expected")
 	}
@@ -77,8 +78,9 @@ func TestMessageBuilding(t *testing.T) {
 	}
 	response2Metadata, err := metadata.DecodeMetadata(response2.Extra(), ipldBridge)
 	if err != nil || !reflect.DeepEqual(response2Metadata, metadata.Metadata{
-		links[1]: true,
-		links[2]: true,
+		metadata.Item{Link: links[1], BlockPresent: true},
+		metadata.Item{Link: links[2], BlockPresent: true},
+		metadata.Item{Link: links[1], BlockPresent: true},
 	}) {
 		t.Fatal("Metadata did not match expected")
 	}
@@ -89,8 +91,8 @@ func TestMessageBuilding(t *testing.T) {
 	}
 	response3Metadata, err := metadata.DecodeMetadata(response3.Extra(), ipldBridge)
 	if err != nil || !reflect.DeepEqual(response3Metadata, metadata.Metadata{
-		links[0]: true,
-		links[1]: true,
+		metadata.Item{Link: links[0], BlockPresent: true},
+		metadata.Item{Link: links[1], BlockPresent: true},
 	}) {
 		t.Fatal("Metadata did not match expected")
 	}