From fe12e1509ade0a3a9f78eb4dadb26765d6b87721 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Thu, 7 Jun 2018 17:55:43 -0500
Subject: [PATCH] add a throttle to nodes in the dht. the throttle is gradually
 increased each time the node is pinged. it determines the minimum amount of
 time to wait between using the node in a bootstrapping search

---
 src/yggdrasil/dht.go | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/yggdrasil/dht.go b/src/yggdrasil/dht.go
index e77ab90..95f6bb1 100644
--- a/src/yggdrasil/dht.go
+++ b/src/yggdrasil/dht.go
@@ -36,6 +36,7 @@ type dhtInfo struct {
 	send          time.Time // When we last sent a message
 	recv          time.Time // When we last received a message
 	pings         int       // Decide when to drop
+	throttle      uint8     // Number of seconds to wait before pinging a node to bootstrap buckets, gradually increases up to 1 minute
 }
 
 func (info *dhtInfo) getNodeID() *NodeID {
@@ -116,10 +117,11 @@ func (t *dht) handleRes(res *dhtRes) {
 		return
 	}
 	rinfo := dhtInfo{
-		key:    res.Key,
-		coords: res.Coords,
-		send:   time.Now(), // Technically wrong but should be OK...
-		recv:   time.Now(),
+		key:      res.Key,
+		coords:   res.Coords,
+		send:     time.Now(), // Technically wrong but should be OK...
+		recv:     time.Now(),
+		throttle: 1,
 	}
 	// If they're already in the table, then keep the correct send time
 	bidx, isOK := t.getBucketIndex(rinfo.getNodeID())
@@ -130,11 +132,13 @@ func (t *dht) handleRes(res *dhtRes) {
 	for _, oldinfo := range b.peers {
 		if oldinfo.key == rinfo.key {
 			rinfo.send = oldinfo.send
+			rinfo.throttle += oldinfo.throttle
 		}
 	}
 	for _, oldinfo := range b.other {
 		if oldinfo.key == rinfo.key {
 			rinfo.send = oldinfo.send
+			rinfo.throttle += oldinfo.throttle
 		}
 	}
 	// Insert into table
@@ -231,6 +235,9 @@ func (t *dht) insert(info *dhtInfo, isPeer bool) {
 		// This speeds up bootstrapping
 		info.recv = info.recv.Add(-time.Hour)
 	}
+	if isPeer || info.throttle > 60 {
+		info.throttle = 60
+	}
 	// First drop any existing entry from the bucket
 	b.drop(&info.key)
 	// Now add to the *end* of the bucket
@@ -460,7 +467,7 @@ func (t *dht) doMaintenance() {
 		}
 		target := t.getTarget(t.offset)
 		for _, info := range t.lookup(target, true) {
-			if time.Since(info.recv) > time.Minute {
+			if time.Since(info.recv) > time.Duration(info.throttle)*time.Second {
 				t.addToMill(info, target)
 				t.offset++
 				break