From a3b09ccda26ab9c1b74153233432d24ddf548b29 Mon Sep 17 00:00:00 2001
From: Dave Collins <davec@conformal.com>
Date: Mon, 10 Sep 2018 04:37:29 -0500
Subject: [PATCH] server: Add infrastruct for immediate inv relay.

This modifies the infrastructure for the server inventory relay to allow
the caller to specify the inventory should be announced immediately
versus using the typical trickle mechanism.

It also updates all callers in the repository and changes the relay of
accepted blocks use the new ability.
---
 blockmanager.go |  4 ++--
 server.go       | 31 ++++++++++++++++++++-----------
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/blockmanager.go b/blockmanager.go
index 6d99e2eb..3e2235cf 100644
--- a/blockmanager.go
+++ b/blockmanager.go
@@ -1927,9 +1927,9 @@ func (b *blockManager) handleNotifyMsg(notification *blockchain.Notification) {
 			}
 		}
 
-		// Generate the inventory vector and relay it.
+		// Generate the inventory vector and relay it immediately.
 		iv := wire.NewInvVect(wire.InvTypeBlock, blockHash)
-		b.server.RelayInventory(iv, block.MsgBlock().Header)
+		b.server.RelayInventory(iv, block.MsgBlock().Header, true)
 
 	// A block has been connected to the main block chain.
 	case blockchain.NTBlockConnected:
diff --git a/server.go b/server.go
index 66c2b745..adeee760 100644
--- a/server.go
+++ b/server.go
@@ -91,10 +91,13 @@ type broadcastInventoryDel *wire.InvVect
 type broadcastPruneInventory struct{}
 
 // relayMsg packages an inventory vector along with the newly discovered
-// inventory so the relay has access to that information.
+// inventory and a flag that determines if the relay should happen immediately
+// (it will be put into a trickle queue if false) so the relay has access to
+// that information.
 type relayMsg struct {
-	invVect *wire.InvVect
-	data    interface{}
+	invVect   *wire.InvVect
+	data      interface{}
+	immediate bool
 }
 
 // updatePeerHeightsMsg is a message sent from the blockmanager to the server
@@ -1124,7 +1127,7 @@ func (s *server) AnnounceNewTransactions(newTxs []*dcrutil.Tx) {
 	for _, tx := range newTxs {
 		// Generate the inventory vector and relay it.
 		iv := wire.NewInvVect(wire.InvTypeTx, tx.Hash())
-		s.RelayInventory(iv, tx)
+		s.RelayInventory(iv, tx, false)
 
 		if s.rpcServer != nil {
 			// Notify websocket clients about mempool transactions.
@@ -1389,10 +1392,16 @@ func (s *server) handleRelayInvMsg(state *peerState, msg relayMsg) {
 			}
 		}
 
-		// Queue the inventory to be relayed with the next batch.
-		// It will be ignored if the peer is already known to
-		// have the inventory.
-		sp.QueueInventory(msg.invVect)
+		// Either queue the inventory to be relayed immediately or with
+		// the next batch depending on the immediate flag.
+		//
+		// It will be ignored in either case if the peer is already
+		// known to have the inventory.
+		if msg.immediate {
+			sp.QueueInventoryImmediate(msg.invVect)
+		} else {
+			sp.QueueInventory(msg.invVect)
+		}
 	})
 }
 
@@ -1780,8 +1789,8 @@ func (s *server) BanPeer(sp *serverPeer) {
 
 // RelayInventory relays the passed inventory vector to all connected peers
 // that are not already known to have it.
-func (s *server) RelayInventory(invVect *wire.InvVect, data interface{}) {
-	s.relayInv <- relayMsg{invVect: invVect, data: data}
+func (s *server) RelayInventory(invVect *wire.InvVect, data interface{}, immediate bool) {
+	s.relayInv <- relayMsg{invVect: invVect, data: data, immediate: immediate}
 }
 
 // BroadcastMessage sends msg to all peers currently connected to the server
@@ -2008,7 +2017,7 @@ out:
 			// yet. We periodically resubmit them until they have.
 			for iv, data := range pendingInvs {
 				ivCopy := iv
-				s.RelayInventory(&ivCopy, data)
+				s.RelayInventory(&ivCopy, data, false)
 			}
 
 			// Process at a random time up to 30mins (in seconds)