Don't subscribe block entity to chunk if syncher has no entries

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

@@ -413,7 +413,6 @@ abstract class MatteryBlockEntity(p_155228_: BlockEntityType<*>, p_155229_: Bloc
 	}
 
 	private var _subCache: ChunkSubscribers? = null
-	private val subscription get() = _subCache ?: subscribe()
 	private var playerListUpdated = false
 
 	private fun unsubscribe() {
@@ -430,7 +429,10 @@ abstract class MatteryBlockEntity(p_155228_: BlockEntityType<*>, p_155229_: Bloc
 		playerListUpdated = false
 	}
 
-	private fun subscribe(): ChunkSubscribers {
+	private fun subscribe() {
+		if (!syncher.hasChildren)
+			return
+
 		val level = level
 		check(level is ServerLevel) { "Invalid realm" }
 		unsubscribe()
@@ -442,7 +444,6 @@ abstract class MatteryBlockEntity(p_155228_: BlockEntityType<*>, p_155229_: Bloc
 		subs.subscribe(this)
 		_subCache = subs
 		playerListUpdated = true
-		return subs
 	}
 
 	private class ChunkSubscribers(level: ServerLevel, val chunkPos: Long) {

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

@@ -21,6 +21,56 @@ import kotlin.collections.HashSet
 import kotlin.collections.LinkedHashSet
 import kotlin.math.ln
 
+private class LinkedPriorityQueue<T : Comparable<T>> {
+	private class Entry<T>(val value: T) {
+		var next: Entry<T>? = null
+	}
+
+	private var head: Entry<T>? = null
+
+	fun isNotEmpty(): Boolean {
+		return head != null
+	}
+
+	fun add(value: T) {
+		if (head == null) {
+			head = Entry(value)
+		} else if (head!!.value >= value) {
+			val entry = Entry(value)
+			entry.next = head
+			head = entry
+		} else {
+			var current = head
+			var previous = current
+
+			while (current != null) {
+				if (current.value >= value) {
+					val entry = Entry(value)
+					entry.next = current
+					previous!!.next = entry
+					return
+				}
+
+				previous = current
+				current = current.next
+			}
+
+			previous!!.next = Entry(value)
+		}
+	}
+
+	fun remove(): T? {
+		val head = head
+
+		if (head != null) {
+			this.head = head.next
+			return head.value
+		}
+
+		return null
+	}
+}
+
 class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableGraph>() {
 	private val livelyNodes = HashSet<EnergyCableBlockEntity.Node>()
 	private val livelyNodesList = ArrayList<EnergyCableBlockEntity.Node>()
@@ -335,10 +385,13 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 					v.segment.transferredLastTick = transferredLastTick
 					v.segment.lastPoweredStatus = lastPoweredStatus
 					v.segment.paths = paths.clone()
+
 					paths.forEach { it.segments.add(v.segment) }
+
 					result.add(v.segment)
 				}
 
+				paths.forEach { it.nodes.addAll(nodes) }
 				return result
 			}
 		}
@@ -418,14 +471,16 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 			return null
 		}
 
-		val openNodes = PriorityQueue<SearchNode>()
+		val openNodes = LinkedPriorityQueue<SearchNode>()
 		val seenNodes = HashSet<EnergyCableBlockEntity.Node>()
 
 		openNodes.add(SearchNode(a, b, null, seenTop))
 
+		val existingNodes = HashSet<EnergyCableBlockEntity.Node>()
+		existing.forEach { existingNodes.addAll(it.nodes) }
+
 		while (openNodes.isNotEmpty()) {
-			val first = openNodes.remove()
-			openNodes.remove(first)
+			val first = openNodes.remove()!!
 
 			if (first.node === b) {
 				// solution found
@@ -463,7 +518,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 			} else {
 				for (neighbour in first.node.neighboursView.values) {
 					if (!seenNodes.add(neighbour) || !neighbour.canTraverse) continue
-					val seen = existing.any { neighbour in it }
+					val seen = neighbour in existingNodes
 					if (seen && neighbour.energyThroughput <= threshold) continue
 					openNodes.add(SearchNode(neighbour, b, first, seen))
 				}

src/main/kotlin/ru/dbotthepony/mc/otm/network/syncher/SynchableGroup.kt

@@ -66,6 +66,9 @@ class SynchableGroup : Observer, ISynchable, Iterable<ISynchable> {
 	override val hasRemotes: Boolean
 		get() = remotes.isNotEmpty()
 
+	val hasChildren: Boolean
+		get() = slots.any { it != null }
+
 	override fun iterator(): Iterator<ISynchable> {
 		return slots.iterator().map { it?.synchable }.filterNotNull()
 	}