From 10ff7bd3425aeb361e8828e6dd161ba007b4119f Mon Sep 17 00:00:00 2001
From: Sean Braithwaite <brapse@gmail.com>
Date: Fri, 19 Jul 2019 02:17:49 +0300
Subject: [PATCH] Peer pruning

---
 blockchain/v2/scheduler.go | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/blockchain/v2/scheduler.go b/blockchain/v2/scheduler.go
index c1d89372..27280747 100644
--- a/blockchain/v2/scheduler.go
+++ b/blockchain/v2/scheduler.go
@@ -380,9 +380,16 @@ func (sc *schedule) selectPeer(peers []*scPeer) *scPeer {
 	return peers[r.Intn(len(peers))]
 }
 
-func (sc *schedule) prunablePeers(time time.Time, minSpeed int) []p2p.ID {
-	// TODO
-	return []p2p.ID{}
+// XXX: this duplicates the logic of peersInactiveSince and peersSlowerThan
+func (sc *schedule) prunablePeers(peerTimout time.Duration, minRecvRate int64, now time.Time) []p2p.ID {
+	prunable := []p2p.ID{}
+	for peerID, peer := range sc.peers {
+		if now.Sub(peer.lastTouched) > peerTimout || peer.lastRate < minRecvRate {
+			prunable = append(prunable, peerID)
+		}
+	}
+
+	return prunable
 }
 
 func (sc *schedule) numBlockInState(targetState blockState) uint32 {
@@ -399,12 +406,16 @@ type Scheduler struct {
 	sc             *schedule
 	targetPending  uint32 // the number of blocks we want in blockStatePending
 	targetReceived uint32 // the number of blocks we want in blockStateReceived
-
+	minRecvRate    int64
+	peerTimeout    time.Duration
 }
 
-func NewScheduler(minHeight int64, targetPending uint32, targetReceived uint32) *Scheduler {
+func NewScheduler(minHeight int64, minRecvRate int64, peerTimeout time.Duration,
+	targetPending uint32, targetReceived uint32) *Scheduler {
 	return &Scheduler{
 		sc:             newSchedule(minHeight),
+		minRecvRate:    minRecvRate,
+		peerTimeout:    peerTimeout,
 		targetPending:  targetPending,
 		targetReceived: targetReceived,
 	}
@@ -499,9 +510,16 @@ func (sdr *Scheduler) handleBlockProcessError(peerID p2p.ID, height int64) Event
 	return Skip{}
 }
 
-func (sdr *Scheduler) handleTimeCheck(peerID p2p.ID, now time.Time) interface{} {
-	// prune peers
-	// TODO
+// XXX: Probably split this into two methods
+// + handlePurgePeers
+// + handleNextSchehedule
+func (sdr *Scheduler) handleTimeCheck(now time.Time) interface{} {
+	prunablePeers := sdr.sc.prunablePeers(sdr.peerTimeout, sdr.minRecvRate, now)
+
+	for _, peerID := range prunablePeers {
+		// XXX: Emit these events
+		_ = sdr.sc.removePeer(peerID)
+	}
 
 	// produce new schedule
 	events := []scBlockRequestMessage{}