From ff87bd912f467e8cd784d3aff152ee8ce141c0b2 Mon Sep 17 00:00:00 2001
From: Tess Rinearson <tess.rinearson@gmail.com>
Date: Fri, 27 Mar 2020 15:08:53 +0100
Subject: [PATCH] mempool: reserve IDs in InitPeer instead of AddPeer

---
 mempool/reactor.go      |  9 +++++++--
 mempool/reactor_test.go | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/mempool/reactor.go b/mempool/reactor.go
index 1ae3592a0..fda12c021 100644
--- a/mempool/reactor.go
+++ b/mempool/reactor.go
@@ -47,7 +47,7 @@ type mempoolIDs struct {
 	activeIDs map[uint16]struct{} // used to check if a given peerID key is used, the value doesn't matter
 }
 
-// Reserve searches for the next unused ID and assignes it to the
+// Reserve searches for the next unused ID and assigns it to the
 // peer.
 func (ids *mempoolIDs) ReserveForPeer(peer p2p.Peer) {
 	ids.mtx.Lock()
@@ -114,6 +114,12 @@ func NewReactor(config *cfg.MempoolConfig, mempool *CListMempool) *Reactor {
 	return memR
 }
 
+// InitPeer implements Reactor by creating a state for the peer.
+func (memR *Reactor) InitPeer(peer p2p.Peer) p2p.Peer {
+	memR.ids.ReserveForPeer(peer)
+	return peer
+}
+
 // SetLogger sets the Logger on the reactor and the underlying mempool.
 func (memR *Reactor) SetLogger(l log.Logger) {
 	memR.Logger = l
@@ -142,7 +148,6 @@ func (memR *Reactor) GetChannels() []*p2p.ChannelDescriptor {
 // AddPeer implements Reactor.
 // It starts a broadcast routine ensuring all txs are forwarded to the given peer.
 func (memR *Reactor) AddPeer(peer p2p.Peer) {
-	memR.ids.ReserveForPeer(peer)
 	go memR.broadcastTxRoutine(peer)
 }
 
diff --git a/mempool/reactor_test.go b/mempool/reactor_test.go
index 27c82f2c4..87da0557d 100644
--- a/mempool/reactor_test.go
+++ b/mempool/reactor_test.go
@@ -223,3 +223,21 @@ func TestMempoolIDsPanicsIfNodeRequestsOvermaxActiveIDs(t *testing.T) {
 		ids.ReserveForPeer(peer)
 	})
 }
+
+func TestDontExhaustMaxActiveIDs(t *testing.T) {
+	config := cfg.TestConfig()
+	const N = 1
+	reactors := makeAndConnectReactors(config, N)
+	defer func() {
+		for _, r := range reactors {
+			r.Stop()
+		}
+	}()
+	reactor := reactors[0]
+
+	for i := 0; i < maxActiveIDs+1; i++ {
+		peer := mock.NewPeer(nil)
+		reactor.Receive(MempoolChannel, peer, []byte{0x1, 0x2, 0x3})
+		reactor.AddPeer(peer)
+	}
+}