From 3a98650951f39a5e67682afe8e79bc1489c97926 Mon Sep 17 00:00:00 2001
From: Brandon Westcott <brandon@quorumcontrol.com>
Date: Mon, 28 Sep 2020 16:43:39 -0400
Subject: [PATCH] add mini cache for resending current round to clients

---
 signer/gossip/node.go | 45 ++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/signer/gossip/node.go b/signer/gossip/node.go
index 39659d85..1c4ce86c 100644
--- a/signer/gossip/node.go
+++ b/signer/gossip/node.go
@@ -75,6 +75,8 @@ type Node struct {
 	startCtx context.Context
 
 	closer io.Closer
+
+	roundRepublishCache *lru.Cache
 }
 
 type NewNodeOptions struct {
@@ -116,6 +118,11 @@ func NewNode(ctx context.Context, opts *NewNodeOptions) (*Node, error) {
 		return nil, fmt.Errorf("error creating cache: %w", err)
 	}
 
+	roundRepublishCache, err := lru.New(3)
+	if err != nil {
+		return nil, fmt.Errorf("error creating cache: %w", err)
+	}
+
 	nodeName := opts.Name
 	if nodeName == "" {
 		nodeName = fmt.Sprintf("node-%d", signerIndex)
@@ -128,18 +135,19 @@ func NewNode(ctx context.Context, opts *NewNodeOptions) (*Node, error) {
 	dagStore := opts.DagStore
 
 	n := &Node{
-		name:        nodeName,
-		p2pNode:     opts.P2PNode,
-		signKey:     opts.SignKey,
-		notaryGroup: opts.NotaryGroup,
-		dagStore:    dagStore,
-		hamtStore:   hamtStore,
-		dataStore:   dataStore,
-		signerIndex: signerIndex,
-		inflight:    cache,
-		mempool:     newMempool(),
-		rootContext: opts.RootActorContext,
-		logger:      logger,
+		name:                nodeName,
+		p2pNode:             opts.P2PNode,
+		signKey:             opts.SignKey,
+		notaryGroup:         opts.NotaryGroup,
+		dagStore:            dagStore,
+		hamtStore:           hamtStore,
+		dataStore:           dataStore,
+		signerIndex:         signerIndex,
+		inflight:            cache,
+		mempool:             newMempool(),
+		rootContext:         opts.RootActorContext,
+		logger:              logger,
+		roundRepublishCache: roundRepublishCache,
 	}
 
 	err = n.initRoundHolder()
@@ -243,7 +251,7 @@ func (n *Node) maybeRepublish(ctx context.Context) {
 
 		if found && previousRound != nil && previousRound.published {
 			n.logger.Debugf("republishing round: %d", previousRound.height)
-			n.publishCompletedRound(ctx, previousRound)
+			n.republishCompletedRound(ctx, previousRound)
 		}
 	}
 }
@@ -451,9 +459,20 @@ func (n *Node) publishCompletedRound(ctx context.Context, round *round) error {
 
 	defer func() { round.published = true }()
 
+	n.roundRepublishCache.Add(round.height, conf.Data())
+
 	return n.pubsub.Publish(n.notaryGroup.ID, conf.Data())
 }
 
+func (n *Node) republishCompletedRound(ctx context.Context, round *round) error {
+	roundConfPayload, ok := n.roundRepublishCache.Peek(round) // Peek acts as FIFO based on insert above
+	if ok {
+		n.logger.Debugf("republishing round confirmed to: %s", n.notaryGroup.ID)
+		return n.pubsub.Publish(n.notaryGroup.ID, roundConfPayload.([]byte))
+	}
+	return n.publishCompletedRound(ctx, round)
+}
+
 func (n *Node) storeCompletedRound(round *types.RoundWrapper) error {
 	heightBytes := make([]byte, binary.MaxVarintLen64)
 	binary.PutUvarint(heightBytes, round.Height())