Improve performance on cable addition and removal from cable network

src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableBlockEntity.kt

@@ -111,11 +111,6 @@ abstract class EnergyCableBlockEntity(type: BlockEntityType<*>, blockPos: BlockP
 				_segment = value
 			}
 
-		fun onInvalidate() {
-			_segment = EnergyCableGraph.Segment(this)
-			updatePoweredState(false)
-		}
-
 		val sides get() = energySides
 
 		override fun onNeighbour(link: Link) {

src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableGraph.kt

@@ -68,7 +68,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		}
 	}
 
-	class SegmentPath(private val a: BlockPos, private val b: BlockPos) {
+	class SegmentPath(val a: EnergyCableBlockEntity.Node, val b: EnergyCableBlockEntity.Node) {
 		val segments = LinkedHashSet<Segment>()
 		val nodes = HashSet<EnergyCableBlockEntity.Node>()
 		var shortCircuit = false
@@ -136,7 +136,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		}
 
 		private val nodes = LinkedHashSet<EnergyCableBlockEntity.Node>()
-		private var paths = ReferenceLinkedOpenHashSet<SegmentPath>()
+		var paths = ReferenceLinkedOpenHashSet<SegmentPath>()
 
 		operator fun contains(node: EnergyCableBlockEntity.Node): Boolean {
 			return node in nodes
@@ -338,6 +338,26 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 			}
 		}
 
+		fun split(): List<Segment> {
+			val result = ArrayList<Segment>()
+			result.add(this)
+
+			for (v in nodes) {
+				val segment = Segment()
+				v._segment = segment
+				segment.nodes.add(v)
+				segment.throughput = v.energyThroughput
+				segment.throughputKnown = true
+				segment.transferredLastTick = transferredLastTick
+				result.add(segment)
+				v.updatePoweredState(false)
+			}
+
+			// mark this segment as dead
+			this.nodes.clear()
+			return result
+		}
+
 		private fun combineInto(segment: Segment) {
 			nodes.forEach { it._segment = segment }
 			segment.nodes.addAll(nodes)
@@ -385,11 +405,6 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		}
 	}
 
-	fun invalidatePathCache() {
-		pathCache.clear()
-		nodes.forEach { it.onInvalidate() }
-	}
-
 	// isn't exactly A*, but greedy algorithm, which searched for locally optimal solutions because they lead to globally optimal ones
 	private fun findPath(a: EnergyCableBlockEntity.Node, b: EnergyCableBlockEntity.Node, existing: Collection<SegmentPath>, threshold: Decimal): SegmentPath? {
 		val seenTop = existing.any { a in it }
@@ -435,7 +450,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 					}
 				}
 
-				val path = SegmentPath(a.blockEntity.blockPos, b.blockEntity.blockPos)
+				val path = SegmentPath(a, b)
 				solution.forEach { it.segment.add(path) }
 				touchedSegments.forEach { it.tryCombine(touchedSegments) }
 
@@ -490,18 +505,29 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		return list.paths
 	}
 
+	fun notifyThroughputsChanged() {
+		pathCache.values.forEach { it.saturated = false }
+	}
+
 	override fun onNodeRemoved(node: EnergyCableBlockEntity.Node) {
 		if (livelyNodes.remove(node)) {
 			check(livelyNodesList.remove(node))
 		}
 
-		invalidatePathCache()
+		node.segment.paths.forEach {
+			pathCache.remove(it.a to it.b)
+			pathCache.remove(it.b to it.a)
+		}
+
+		node.segment.paths = ReferenceLinkedOpenHashSet()
+		node.segment.split()
 	}
 
 	override fun onNodeAdded(node: EnergyCableBlockEntity.Node) {
 		check(livelyNodes.add(node))
 		livelyNodesList.add(node)
-		invalidatePathCache()
+
+		notifyThroughputsChanged()
 	}
 
 	fun receiveEnergy(howMuch: Decimal, simulate: Boolean, fromNode: EnergyCableBlockEntity.Node, fromSide: RelativeSide): Decimal {