feat(responsebuilder): add response builder

add a response builder that collects components of a response and then assembles a completed
response message

responsemanager/responsebuilder/responsebuilder.go

+package responsebuilder
+
+import (
+	"github.com/ipfs/go-block-format"
+	"github.com/ipfs/go-graphsync/ipldbridge"
+	gsmsg "github.com/ipfs/go-graphsync/message"
+	"github.com/ipld/go-ipld-prime"
+)
+
+// ResponseBuilder captures componenst of a response message across multiple
+// requests for a given peer and then generates the corresponding
+// GraphSync message components once responses are ready to send.
+type ResponseBuilder struct {
+	outgoingBlocks     []blocks.Block
+	completedResponses map[gsmsg.GraphSyncRequestID]bool
+	outgoingResponses  map[gsmsg.GraphSyncRequestID]map[ipld.Link]bool
+}
+
+// New generates a new ResponseBuilder.
+func New() *ResponseBuilder {
+	return &ResponseBuilder{
+		completedResponses: make(map[gsmsg.GraphSyncRequestID]bool),
+		outgoingResponses:  make(map[gsmsg.GraphSyncRequestID]map[ipld.Link]bool),
+	}
+}
+
+// AddBlock adds the given block to the response.
+func (rb *ResponseBuilder) AddBlock(block blocks.Block) {
+	rb.outgoingBlocks = append(rb.outgoingBlocks, 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
+}
+
+// AddCompletedRequest marks the given request as completed in the response,
+// as well as whether the graphsync request responded with complete or partial
+// data.
+func (rb *ResponseBuilder) AddCompletedRequest(requestID gsmsg.GraphSyncRequestID, isComplete bool) {
+	rb.completedResponses[requestID] = isComplete
+	// 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)
+	}
+}
+
+// Empty returns true if there is no content to send
+func (rb *ResponseBuilder) Empty() bool {
+	return len(rb.outgoingBlocks) == 0 && len(rb.outgoingResponses) == 0
+}
+
+// Build assembles and encodes response data from the added requests, links, and blocks.
+func (rb *ResponseBuilder) Build(ipldBridge ipldbridge.IPLDBridge) ([]gsmsg.GraphSyncResponse, []blocks.Block, error) {
+	responses := make([]gsmsg.GraphSyncResponse, 0, len(rb.outgoingResponses))
+	for requestID, linkMap := range rb.outgoingResponses {
+		extra, err := makeEncodedData(linkMap, ipldBridge)
+		if err != nil {
+			return nil, nil, err
+		}
+		isFull, isComplete := rb.completedResponses[requestID]
+		responses = append(responses, gsmsg.NewResponse(requestID, responseCode(isFull, isComplete), extra))
+	}
+	return responses, rb.outgoingBlocks, nil
+}
+
+func makeEncodedData(entries map[ipld.Link]bool, 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 {
+				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))
+					}),
+				)
+			}
+		})
+	})
+	if err != nil {
+		return nil, err
+	}
+	return ipldBridge.EncodeNode(node)
+}
+
+func responseCode(isFull bool, isComplete bool) gsmsg.GraphSyncResponseStatusCode {
+	if !isComplete {
+		return gsmsg.PartialResponse
+	}
+	if isFull {
+		return gsmsg.RequestCompletedFull
+	}
+	return gsmsg.RequestCompletedPartial
+}

responsemanager/responsebuilder/responsebuilder_test.go

+package responsebuilder
+
+import (
+	"fmt"
+	"math/rand"
+	"testing"
+
+	"github.com/ipld/go-ipld-prime/fluent"
+
+	gsmsg "github.com/ipfs/go-graphsync/message"
+	"github.com/ipfs/go-graphsync/testbridge"
+	"github.com/ipfs/go-graphsync/testutil"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/linking/cid"
+)
+
+func TestMessageBuilding(t *testing.T) {
+	ipldBridge := testbridge.NewMockIPLDBridge()
+	rb := New()
+	blocks := testutil.GenerateBlocksOfSize(3, 100)
+	links := make([]ipld.Link, 0, len(blocks))
+	for _, block := range blocks {
+		links = append(links, cidlink.Link{Cid: block.Cid()})
+	}
+	requestID1 := gsmsg.GraphSyncRequestID(rand.Int31())
+	requestID2 := gsmsg.GraphSyncRequestID(rand.Int31())
+	requestID3 := gsmsg.GraphSyncRequestID(rand.Int31())
+	requestID4 := gsmsg.GraphSyncRequestID(rand.Int31())
+
+	rb.AddLink(requestID1, links[0], true)
+	rb.AddLink(requestID1, links[1], false)
+	rb.AddLink(requestID1, links[2], true)
+
+	rb.AddCompletedRequest(requestID1, false)
+
+	rb.AddLink(requestID2, links[1], true)
+	rb.AddLink(requestID2, links[2], true)
+
+	rb.AddCompletedRequest(requestID2, true)
+
+	rb.AddLink(requestID3, links[0], true)
+	rb.AddLink(requestID3, links[1], true)
+
+	rb.AddCompletedRequest(requestID4, true)
+
+	for _, block := range blocks {
+		rb.AddBlock(block)
+	}
+
+	responses, sentBlocks, err := rb.Build(ipldBridge)
+
+	if err != nil {
+		t.Fatal("Error building responses")
+	}
+
+	if len(responses) != 4 {
+		t.Fatal("Assembled wrong number of responses")
+	}
+
+	response1, err := findResponseForRequestID(responses, requestID1)
+	if err != nil || response1.Status() != gsmsg.RequestCompletedPartial {
+		t.Fatal("did not generate completed partial response")
+	}
+
+	response1Metadata, err := ipldBridge.DecodeNode(response1.Extra())
+	if err != nil {
+		t.Fatal("unable to read metadata from response")
+	}
+	analyzeMetadata(t, response1Metadata, map[ipld.Link]bool{
+		links[0]: true,
+		links[1]: false,
+		links[2]: true,
+	})
+	response2, err := findResponseForRequestID(responses, requestID2)
+	if err != nil || response2.Status() != gsmsg.RequestCompletedFull {
+		t.Fatal("did not generate completed partial response")
+	}
+	response2Metadata, err := ipldBridge.DecodeNode(response2.Extra())
+	if err != nil {
+		t.Fatal("unable to read metadata from response")
+	}
+	analyzeMetadata(t, response2Metadata, map[ipld.Link]bool{
+		links[1]: true,
+		links[2]: true,
+	})
+
+	response3, err := findResponseForRequestID(responses, requestID3)
+	if err != nil || response3.Status() != gsmsg.PartialResponse {
+		t.Fatal("did not generate completed partial response")
+	}
+	response3Metadata, err := ipldBridge.DecodeNode(response3.Extra())
+	if err != nil {
+		t.Fatal("unable to read metadata from response")
+	}
+	analyzeMetadata(t, response3Metadata, map[ipld.Link]bool{
+		links[0]: true,
+		links[1]: true,
+	})
+
+	response4, err := findResponseForRequestID(responses, requestID4)
+	if err != nil || response4.Status() != gsmsg.RequestCompletedFull {
+		t.Fatal("did not generate completed partial response")
+	}
+
+	if len(sentBlocks) != len(blocks) {
+		t.Fatal("Did not send all blocks")
+	}
+
+	for _, block := range sentBlocks {
+		if !testutil.ContainsBlock(blocks, block) {
+			t.Fatal("Sent incorrect block")
+		}
+	}
+}
+
+func findResponseForRequestID(responses []gsmsg.GraphSyncResponse, requestID gsmsg.GraphSyncRequestID) (gsmsg.GraphSyncResponse, error) {
+	for _, response := range responses {
+		if response.RequestID() == requestID {
+			return response, nil
+		}
+	}
+	return gsmsg.GraphSyncResponse{}, fmt.Errorf("Response Not Found")
+}
+
+func analyzeMetadata(t *testing.T, metadata ipld.Node, expectedMetadata map[ipld.Link]bool) {
+	if metadata.Length() != len(expectedMetadata) {
+		t.Fatal("Wrong amount of metadata on first response")
+	}
+	err := fluent.Recover(func() {
+		safeMetadata := fluent.WrapNode(metadata)
+		for i := 0; i < len(expectedMetadata); i++ {
+			metadatum := safeMetadata.TraverseIndex(i)
+			link := metadatum.TraverseField("link").AsLink()
+			blockPresent := metadatum.TraverseField("blockPresent").AsBool()
+			expectedBlockPresent, ok := expectedMetadata[link]
+			if !ok || expectedBlockPresent != blockPresent {
+				t.Fatal("Metadata did not match expected")
+			}
+		}
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}