fix(requestmanager): make termination predictable

termination from remote peers was not properly handling blocks included up to termination, and could
include unpredictable amounts in the response channel

requestmanager/client.go

@@ -66,6 +66,7 @@ type inProgressRequestStatus struct {
 	inProgressChan   chan graphsync.ResponseProgress
 	inProgressErr    chan error
 	traverser        ipldutil.Traverser
+	traverserCancel  context.CancelFunc
 }
 
 // PeerHandler is an interface that can send requests to peers

requestmanager/server.go

@@ -109,12 +109,17 @@ func (rm *RequestManager) requestTask(requestID graphsync.RequestID) executor.Re
 				LinkBudget: int64(rm.maxLinksPerRequest),
 			}
 		}
+		// the traverser has its own context because we want to fail on block boundaries, in the executor,
+		// and make sure all blocks included up to the termination message
+		// are processed and passed in the response channel
+		ctx, cancel := context.WithCancel(rm.ctx)
+		ipr.traverserCancel = cancel
 		ipr.traverser = ipldutil.TraversalBuilder{
 			Root:     cidlink.Link{Cid: ipr.request.Root()},
 			Selector: ipr.request.Selector(),
 			Visitor: func(tp traversal.Progress, node ipld.Node, tr traversal.VisitReason) error {
 				select {
-				case <-ipr.ctx.Done():
+				case <-ctx.Done():
 				case ipr.inProgressChan <- graphsync.ResponseProgress{
 					Node:      node,
 					Path:      tp.Path,
@@ -126,7 +131,7 @@ func (rm *RequestManager) requestTask(requestID graphsync.RequestID) executor.Re
 			Chooser:    ipr.nodeStyleChooser,
 			LinkSystem: rm.linkSystem,
 			Budget:     budget,
-		}.Start(ipr.ctx)
+		}.Start(ctx)
 	}
 
 	ipr.state = running
@@ -165,6 +170,7 @@ func (rm *RequestManager) terminateRequest(requestID graphsync.RequestID, ipr *i
 	ipr.cancelFn()
 	rm.asyncLoader.CleanupRequest(requestID)
 	if ipr.traverser != nil {
+		ipr.traverserCancel()
 		ipr.traverser.Shutdown(rm.ctx)
 	}
 	// make sure context is not closed before closing channels (could cause send

testutil/testutil.go

@@ -152,10 +152,13 @@ func ReadNResponses(ctx context.Context, t TestingT, responseChan <-chan graphsy
 	var returnedBlocks []graphsync.ResponseProgress
 	for i := 0; i < count; i++ {
 		select {
-		case blk := <-responseChan:
+		case blk, ok := <-responseChan:
+			if !ok {
+				require.FailNowf(t, "Channel closed early", "expected %d messages, got %d", count, len(returnedBlocks))
+			}
 			returnedBlocks = append(returnedBlocks, blk)
 		case <-ctx.Done():
-			t.Fatal("Unable to read enough responses")
+			require.FailNow(t, "Unable to read enough responses")
 		}
 	}
 	return returnedBlocks