From 7cc96d78ad70d94ff1e7ddc722fd28a3e30c94d7 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sat, 6 Mar 2021 14:09:56 -0500
Subject: [PATCH] Delay packets after switching capacity is reached

---
 .../block/netswitch/SwitchBlockEntity.kt      | 66 +++++++++++++++----
 1 file changed, 54 insertions(+), 12 deletions(-)

diff --git a/src/main/kotlin/net/shadowfacts/phycon/block/netswitch/SwitchBlockEntity.kt b/src/main/kotlin/net/shadowfacts/phycon/block/netswitch/SwitchBlockEntity.kt
index 5f9f3f9..5e4f8d0 100644
--- a/src/main/kotlin/net/shadowfacts/phycon/block/netswitch/SwitchBlockEntity.kt
+++ b/src/main/kotlin/net/shadowfacts/phycon/block/netswitch/SwitchBlockEntity.kt
@@ -3,19 +3,24 @@ package net.shadowfacts.phycon.block.netswitch
 import net.fabricmc.fabric.api.block.entity.BlockEntityClientSerializable
 import net.minecraft.block.BlockState
 import net.minecraft.block.entity.BlockEntity
-import net.minecraft.entity.ItemEntity
+import net.minecraft.item.ItemStack
 import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.ListTag
 import net.minecraft.util.Tickable
 import net.minecraft.util.math.Direction
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.api.Interface
 import net.shadowfacts.phycon.api.frame.EthernetFrame
 import net.shadowfacts.phycon.api.frame.PacketFrame
+import net.shadowfacts.phycon.api.util.IPAddress
 import net.shadowfacts.phycon.api.util.MACAddress
+import net.shadowfacts.phycon.frame.BasePacketFrame
 import net.shadowfacts.phycon.init.PhyBlockEntities
-import net.shadowfacts.phycon.util.NetworkUtil
 import net.shadowfacts.phycon.packet.ItemStackPacket
+import net.shadowfacts.phycon.util.NetworkUtil
 import java.lang.ref.WeakReference
+import java.util.Deque
+import java.util.LinkedList
 
 /**
  * @author shadowfacts
@@ -25,13 +30,14 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 	Tickable {
 
 	companion object {
-		var SWITCHING_CAPACITY = 256 // 256 items/tick
+		var SWITCHING_CAPACITY = 256 // 256 packets/tick
 	}
 
 	val interfaces = Direction.values().map { SwitchInterface(it, WeakReference(this), MACAddress.random()) }
 
 	private val macTable = mutableMapOf<MACAddress, Direction>()
-	private var itemsHandledThisTick = 0
+	private var packetsHandledThisTick = 0
+	private var delayedPackets: Deque<Pair<PacketFrame, SwitchInterface>> = LinkedList()
 
 	fun interfaceForSide(side: Direction): SwitchInterface {
 		return interfaces.find { it.side == side }!!
@@ -40,18 +46,20 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 	private fun handle(frame: EthernetFrame, fromItf: SwitchInterface) {
 		macTable[frame.source] = fromItf.side
 
-		if (frame is PacketFrame && frame.packet is ItemStackPacket) {
-			val packet = frame.packet as ItemStackPacket
-			if (itemsHandledThisTick + packet.stack.count > SWITCHING_CAPACITY) {
-				// todo: calculate entity spawn point by finding non-obstructed location
-				val entity = ItemEntity(world!!, pos.x.toDouble(), pos.y + 1.0, pos.z.toDouble(), packet.stack)
-				world!!.spawnEntity(entity)
+		if (frame is PacketFrame) {
+			if (packetsHandledThisTick > SWITCHING_CAPACITY) {
+				PhysicalConnectivity.NETWORK_LOGGER.debug("{} reached capacity, delaying forwarding {}", this, frame)
+				delayedPackets.addLast(frame to fromItf)
 				return
 			} else {
-				itemsHandledThisTick += packet.stack.count
+				packetsHandledThisTick++
 			}
 		}
 
+		resend(frame, fromItf)
+	}
+
+	private fun resend(frame: EthernetFrame, fromItf: SwitchInterface) {
 		if (frame.destination.type != MACAddress.Type.BROADCAST && macTable.containsKey(frame.destination)) {
 			val dir = macTable[frame.destination]!!
 			PhysicalConnectivity.NETWORK_LOGGER.debug("{} ({}, {}) forwarding {} to side {}", this, fromItf.side, fromItf.macAddress, frame, dir)
@@ -75,11 +83,30 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 	}
 
 	override fun tick() {
-		itemsHandledThisTick = 0
+		packetsHandledThisTick = 0
+
+		while (delayedPackets.isNotEmpty() && packetsHandledThisTick <= SWITCHING_CAPACITY) {
+			val (frame, fromItf) = delayedPackets.pop()
+			resend(frame, fromItf)
+		}
 	}
 
 	override fun toTag(tag: CompoundTag): CompoundTag {
 		tag.putLongArray("InterfaceAddresses", interfaces.map { it.macAddress.address })
+		val list = ListTag()
+		for ((frame, fromItf) in delayedPackets) {
+			val packet = frame.packet
+			if (packet !is ItemStackPacket) continue
+			val compound = CompoundTag()
+			compound.putInt("FromItfSide", fromItf.side.ordinal)
+			compound.putInt("SourceIP", packet.source.address)
+			compound.putInt("DestinationIP", packet.destination.address)
+			compound.putLong("SourceMAC", frame.source.address)
+			compound.putLong("DestinationMAC", frame.destination.address)
+			compound.put("Stack", packet.stack.toTag(CompoundTag()))
+			list.add(compound)
+		}
+		tag.put("DelayedStackPackets", list)
 		return super.toTag(tag)
 	}
 
@@ -88,6 +115,21 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 		tag.getLongArray("InterfaceAddresses")?.forEachIndexed { i, l ->
 			interfaces[i].macAddress = MACAddress(l)
 		}
+		tag.getList("DelayedStackPackets", 10).forEach { it ->
+			val compound = it as CompoundTag
+			val fromItfSide = Direction.values()[compound.getInt("FromItfSide")]
+			val fromItf = interfaces.find { it.side == fromItfSide }!!
+			val sourceIP = IPAddress(compound.getInt("SourceIP"))
+			val destinationIP = IPAddress(compound.getInt("DestinationIP"))
+			val sourceMAC = MACAddress(compound.getLong("SourceMAC"))
+			val destinationMAC = MACAddress(compound.getLong("DestinationMAC"))
+			val stack = ItemStack.fromTag(compound.getCompound("Stack"))
+			if (!stack.isEmpty) {
+				val packet = ItemStackPacket(stack, sourceIP, destinationIP)
+				val frame = BasePacketFrame(packet, sourceMAC, destinationMAC)
+				delayedPackets.addLast(frame to fromItf)
+			}
+		}
 	}
 
 	override fun toClientTag(tag: CompoundTag): CompoundTag {