From a7c8be4d69b644dce77b7caa06d40c511a09bbb5 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Thu, 5 Jul 2018 23:07:01 -0500
Subject: [PATCH] base backpressure decisions on queue size in bytes, instead
 of packet counts

---
 src/yggdrasil/switch.go | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/yggdrasil/switch.go b/src/yggdrasil/switch.go
index 5b72620c..e7b25a29 100644
--- a/src/yggdrasil/switch.go
+++ b/src/yggdrasil/switch.go
@@ -595,7 +595,7 @@ type switch_packetInfo struct {
 // Used to keep track of buffered packets
 type switch_buffer struct {
 	packets []switch_packetInfo // Currently buffered packets, which may be dropped if it grows too large
-	count   uint64              // Total queue size, including dropped packets
+	size    uint64              // Total queue size in bytes
 }
 
 func (b *switch_buffer) dropTimedOut() {
@@ -603,8 +603,10 @@ func (b *switch_buffer) dropTimedOut() {
 	const timeout = 25 * time.Millisecond
 	now := time.Now()
 	for len(b.packets) > 0 && now.Sub(b.packets[0].time) > timeout {
-		util_putBytes(b.packets[0].bytes)
-		b.packets = b.packets[1:]
+		var packet switch_packetInfo
+		packet, b.packets = b.packets[0], b.packets[1:]
+		b.size -= uint64(len(packet.bytes))
+		util_putBytes(packet.bytes)
 	}
 }
 
@@ -629,9 +631,9 @@ func (t *switchTable) handleIdle(port switchPort, buffs map[string]switch_buffer
 		buffs[streamID] = buf
 		packet := buf.packets[0]
 		coords := switch_getPacketCoords(packet.bytes)
-		if (bestSize == 0 || buf.count < bestSize) && t.portIsCloser(coords, port) {
+		if (bestSize == 0 || buf.size < bestSize) && t.portIsCloser(coords, port) {
 			best = streamID
-			bestSize = buf.count
+			bestSize = buf.size
 		}
 	}
 	if bestSize != 0 {
@@ -639,7 +641,7 @@ func (t *switchTable) handleIdle(port switchPort, buffs map[string]switch_buffer
 		var packet switch_packetInfo
 		// TODO decide if this should be LIFO or FIFO
 		packet, buf.packets = buf.packets[0], buf.packets[1:]
-		buf.count--
+		buf.size -= uint64(len(packet.bytes))
 		if len(buf.packets) == 0 {
 			delete(buffs, best)
 		} else {
@@ -658,16 +660,16 @@ func (t *switchTable) doWorker() {
 	idle := make(map[switchPort]struct{})   // this is to deduplicate things
 	for {
 		select {
-		case packet := <-t.packetIn:
+		case bytes := <-t.packetIn:
 			// Try to send it somewhere (or drop it if it's corrupt or at a dead end)
-			if !t.handleIn(packet, idle) {
+			if !t.handleIn(bytes, idle) {
 				// There's nobody free to take it right now, so queue it for later
-				streamID := switch_getPacketStreamID(packet)
+				packet := switch_packetInfo{bytes, time.Now()}
+				streamID := switch_getPacketStreamID(packet.bytes)
 				buf := buffs[streamID]
 				buf.dropTimedOut()
-				pinfo := switch_packetInfo{packet, time.Now()}
-				buf.packets = append(buf.packets, pinfo)
-				buf.count++
+				buf.packets = append(buf.packets, packet)
+				buf.size += uint64(len(packet.bytes))
 				buffs[streamID] = buf
 			}
 		case port := <-t.idleIn: