Move everything to BESubscribeList (and eliminate old, bugged code)

src/main/kotlin/ru/dbotthepony/mc/otm/block/BatteryBankBlock.kt

@@ -19,6 +19,7 @@ import net.minecraft.world.level.block.Block
 import net.minecraft.world.phys.shapes.CollisionContext
 import net.minecraft.world.phys.shapes.VoxelShape
 import ru.dbotthepony.mc.otm.once
+import ru.dbotthepony.mc.otm.oncePre
 import ru.dbotthepony.mc.otm.registry.MBlockEntities
 import ru.dbotthepony.mc.otm.shapes.BlockShapes
 
@@ -77,7 +78,7 @@ class BatteryBankBlock : RotatableMatteryBlock(), EntityBlock {
 	) {
 		super.neighborChanged(state, level, pos, neighbour, neighbourPos, movedByPiston)
 		val blockEntity = level.getBlockEntity(pos) as? BatteryBankBlockEntity ?: return
-		level.once { blockEntity.checkSurroundings(level) }
+		level.oncePre { blockEntity.checkSurroundings() }
 	}
 
 	companion object {

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

@@ -31,6 +31,7 @@ import ru.dbotthepony.mc.otm.core.*
 import ru.dbotthepony.mc.otm.core.math.Decimal
 import ru.dbotthepony.mc.otm.core.math.unaryMinus
 import ru.dbotthepony.mc.otm.core.nbt.set
+import ru.dbotthepony.mc.otm.core.util.BESubscribeList
 import ru.dbotthepony.mc.otm.menu.BatteryBankMenu
 import ru.dbotthepony.mc.otm.registry.MBlockEntities
 
@@ -263,7 +264,7 @@ class BatteryBankBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Matte
 
 	override fun setLevel(p_155231_: Level) {
 		super.setLevel(p_155231_)
-		tickOnceServer(this::checkSurroundings)
+		checkSurroundings()
 	}
 
 	override fun <T> getCapability(cap: Capability<T>, side: Direction?): LazyOptional<T> {
@@ -294,41 +295,23 @@ class BatteryBankBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Matte
 		return super.getCapability(cap,side)
 	}
 
-	private var consumingCapability = LazyOptional.empty<IEnergyStorage>()
+	private val consumers = object : BESubscribeList<IEnergyStorage>(this@BatteryBankBlockEntity, ForgeCapabilities.ENERGY) {
-
+		override fun test(t: Direction): Boolean {
-	fun checkSurroundings(level: Level) {
+			return -blockState.getValue(RotatableMatteryBlock.FACING) == t
-		if (isRemoved) return
-
-		val tile = level.getBlockEntity(blockPos.offset(blockState.getValue(RotatableMatteryBlock.FACING).normal))
-
-		if (tile == null) {
-			consumingCapability = LazyOptional.empty()
-			return
-		}
-
-		consumingCapability = getAndBind(
-			old = consumingCapability,
-			provider = tile,
-			capability = ForgeCapabilities.ENERGY,
-			side = -blockState.getValue(RotatableMatteryBlock.FACING)
-		) {
-			@Suppress("name_shadowing")
-			val level = this.level
-
-			if (level is ServerLevel && !SERVER_IS_LIVE)
-				checkSurroundings(level)
 		}
 	}
 
+	fun checkSurroundings() = consumers.update((-blockState.getValue(RotatableMatteryBlock.FACING))::equals)
+
 	fun tick() {
 		if (isBlockedByRedstone)
 			return
 
-		consumingCapability.ifPresentK {
+		for (it in consumers) {
 			val (_, maxThroughput) = energy.getDistribution(false)
 
 			if (maxThroughput.isZero)
-				return@ifPresentK
+				continue
 
 			val diff = it.receiveEnergy(maxThroughput, true)
 

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

@@ -29,6 +29,7 @@ import ru.dbotthepony.mc.otm.core.nbt.getByteArrayList
 import ru.dbotthepony.mc.otm.core.nbt.ifHas
 import ru.dbotthepony.mc.otm.core.nbt.map
 import ru.dbotthepony.mc.otm.core.nbt.set
+import ru.dbotthepony.mc.otm.core.util.BESubscribeList
 import ru.dbotthepony.mc.otm.menu.EnergyCounterMenu
 import ru.dbotthepony.mc.otm.registry.MBlockEntities
 import java.lang.ref.WeakReference
@@ -125,8 +126,17 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 	private val energyInput = EnergyCounterCap(true)
 	private val energyOutput = EnergyCounterCap(false)
 
-	private var inputCapability: LazyOptional<out IEnergyStorage> = LazyOptional.empty()
+	private val inputCapability = object : BESubscribeList<IEnergyStorage>(this@EnergyCounterBlockEntity, ForgeCapabilities.ENERGY) {
-	private var outputCapability: LazyOptional<out IEnergyStorage> = LazyOptional.empty()
+		override fun test(t: Direction): Boolean {
+			return t == blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION)
+		}
+	}
+
+	private val outputCapability = object : BESubscribeList<IEnergyStorage>(this@EnergyCounterBlockEntity, ForgeCapabilities.ENERGY) {
+		override fun test(t: Direction): Boolean {
+			return t == -blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION)
+		}
+	}
 
 	override fun setLevel(p_155231_: Level) {
 		super.setLevel(p_155231_)
@@ -137,9 +147,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		override val energyFlow = FlowDirection.input(isInput)
 
 		override fun extractEnergy(howMuch: Decimal, simulate: Boolean): Decimal {
-			if (inputCapability.isPresent) {
+			val it = inputCapability.first
-				val it = inputCapability.resolve().get()
 
+			if (it != null) {
 				val diff: Decimal
 
 				val ioLimit = ioLimit
@@ -162,9 +172,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		}
 
 		override fun receiveEnergy(howMuch: Decimal, simulate: Boolean): Decimal {
-			if (outputCapability.isPresent) {
+			val it = outputCapability.first
-				val it = outputCapability.resolve().get()
 
+			if (it != null) {
 				val diff: Decimal
 
 				val ioLimit = ioLimit
@@ -192,9 +202,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		override var batteryLevel: Decimal
 			get() {
 				if (energyFlow.input) {
-					if (outputCapability.isPresent) {
+					val it = outputCapability.first
-						val it = outputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.batteryLevel
 						}
@@ -202,9 +212,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 						return Decimal(it.energyStored)
 					}
 				} else {
-					if (inputCapability.isPresent) {
+					val it = inputCapability.first
-						val it = inputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.batteryLevel
 						}
@@ -222,9 +232,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		override val maxBatteryLevel: Decimal
 			get() {
 				if (energyFlow.input) {
-					if (outputCapability.isPresent) {
+					val it = outputCapability.first
-						val it = outputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.maxBatteryLevel
 						}
@@ -232,9 +242,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 						return Decimal(it.maxEnergyStored)
 					}
 				} else {
-					if (inputCapability.isPresent) {
+					val it = inputCapability.first
-						val it = inputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.maxBatteryLevel
 						}
@@ -249,9 +259,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		override val missingPower: Decimal
 			get() {
 				if (energyFlow.input) {
-					if (outputCapability.isPresent) {
+					val it = outputCapability.first
-						val it = outputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.missingPower
 						}
@@ -259,9 +269,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 						return Decimal((it.maxEnergyStored - it.energyStored).coerceAtLeast(0))
 					}
 				} else {
-					if (inputCapability.isPresent) {
+					val it = inputCapability.first
-						val it = inputCapability.resolve().get()
 
+					if (it != null) {
 						if (it is IMatteryEnergyStorage) {
 							return it.missingPower
 						}
@@ -326,45 +336,9 @@ class EnergyCounterBlockEntity(p_155229_: BlockPos, p_155230_: BlockState) : Mat
 		}
 	}
 
-	private fun getAndBind(
-		level: Level,
-		old: LazyOptional<out IEnergyStorage>,
-		side: Direction
-	): LazyOptional<out IEnergyStorage> {
-		val ent = level.getBlockEntity(blockPos.offset(side.normal)) ?: return LazyOptional.empty()
-		val resolve = ent.getEnergySided(-side)
-
-		if (resolve !== old) {
-			if (resolve.isPresent) {
-				val weak = WeakReference(this)
-
-				resolve.addListener {
-					if (SERVER_IS_LIVE)
-						weak.get()?.checkSurroundings()
-				}
-			}
-
-			return resolve
-		}
-
-		return old
-	}
-
 	fun checkSurroundings() {
-		val level = level
+		inputCapability.update((blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION))::equals)
-		if (isRemoved || level !is ServerLevel) return
+		outputCapability.update((-blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION))::equals)
-
-		inputCapability = getAndBind(
-			level,
-			inputCapability,
-			blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION)
-		)
-
-		outputCapability = getAndBind(
-			level,
-			outputCapability,
-			-blockState.getValue(EnergyCounterBlock.INPUT_DIRECTION)
-		)
 	}
 
 	override fun <T> getCapability(cap: Capability<T>, side: Direction?): LazyOptional<T> {

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

@@ -98,29 +98,6 @@ abstract class MatteryBlockEntity(p_155228_: BlockEntityType<*>, p_155229_: Bloc
 		level.oncePre { if (!isRemoved) func.invoke(level) }
 	}
 
-	protected fun <T> getAndBind(
-		old: LazyOptional<T>,
-		provider: ICapabilityProvider?,
-		capability: Capability<T>,
-		side: Direction,
-		invalidate: Runnable
-	): LazyOptional<T> {
-		val get = provider?.getCapability(capability, side) ?: LazyOptional.empty()
-
-		if (old !== get) {
-			if (get.isPresent) {
-				val ref = WeakReference(invalidate)
-				get.addListener {
-					ref.get()?.run()
-				}
-			}
-
-			return get.cast()
-		}
-
-		return get.cast()
-	}
-
 	override fun getDisplayName(): Component {
 		return customDisplayName ?: defaultDisplayName
 	}

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

@@ -27,11 +27,11 @@ import ru.dbotthepony.mc.otm.capability.energy.extractEnergyExact
 import ru.dbotthepony.mc.otm.container.ItemFilter
 import ru.dbotthepony.mc.otm.core.*
 import ru.dbotthepony.mc.otm.core.math.Decimal
-import ru.dbotthepony.mc.otm.core.math.plus
 import ru.dbotthepony.mc.otm.core.math.toIntSafe
 import ru.dbotthepony.mc.otm.core.math.unaryMinus
 import ru.dbotthepony.mc.otm.core.nbt.map
 import ru.dbotthepony.mc.otm.core.nbt.set
+import ru.dbotthepony.mc.otm.core.util.BESubscribeList
 import ru.dbotthepony.mc.otm.graph.Graph6Node
 import ru.dbotthepony.mc.otm.graph.GraphNodeListener
 import ru.dbotthepony.mc.otm.graph.storage.BasicStorageGraphNode
@@ -81,12 +81,14 @@ abstract class AbstractStorageImportExport<T>(
 	override fun invalidateCaps() {
 		super.invalidateCaps()
 		cell.invalidate()
+		target.invalidate()
 		valid = false
 	}
 
 	override fun reviveCaps() {
 		super.reviveCaps()
 		cell.revive()
+		target.revive()
 		valid = true
 	}
 
@@ -101,21 +103,22 @@ abstract class AbstractStorageImportExport<T>(
 
 		if (p_155231_ is ServerLevel) {
 			StorageNetworkGraph.discoverFull(this, cell.storageNode)
+			tickOnceServer(this::checkSurroundings)
 		}
-
-		tickOnceServer(this::checkSurroundings)
 	}
 
-	protected var target: LazyOptional<T> = LazyOptional.empty()
 	protected abstract val targetCapability: Capability<T>
 
+	protected val target by lazy {
+		object : BESubscribeList<T>(this@AbstractStorageImportExport, targetCapability) {
+			override fun test(t: Direction): Boolean {
+				return t == -this@AbstractStorageImportExport.blockState.getValue(RotatableMatteryBlock.FACING_FULL)
+			}
+		}
+	}
+
 	fun checkSurroundings() {
-		target = getAndBind(
+		target.update()
-			target,
-			level?.getBlockEntity(blockPos + blockState.getValue(RotatableMatteryBlock.FACING_FULL).normal),
-			targetCapability,
-			-blockState.getValue(RotatableMatteryBlock.FACING_FULL),
-		) { tickOnceServer(this::checkSurroundings) }
 	}
 
 	abstract val filter: ItemFilter
@@ -226,18 +229,18 @@ class StorageImporterBlockEntity(blockPos: BlockPos, blockState: BlockState)
 
 		nextTick--
 
-		if (nextTick <= 0 && target.isPresent && enoughEnergy) {
+		val target = target.firstOrNull()
+
+		if (nextTick <= 0 && target != null && enoughEnergy) {
 			val graph = cell.storageGraph ?: return
 			val items = graph.getVirtualComponent(ITEM_STORAGE)
 
-			val resolved = target.orThrow()
+			if (lastSlot >= target.slots) {
-
-			if (lastSlot >= resolved.slots) {
 				lastSlot = 0
 			}
 
 			val maxMove = energy.extractEnergyExact(ITEM_STORAGE.energyPerOperation, MAX_MOVE_PER_OPERATION, true)
-			var extracted = resolved.extractItem(lastSlot, maxMove, true)
+			var extracted = target.extractItem(lastSlot, maxMove, true)
 
 			if (extracted.isEmpty || !filter.match(extracted)) {
 				lastSlot++
@@ -245,7 +248,7 @@ class StorageImporterBlockEntity(blockPos: BlockPos, blockState: BlockState)
 				val leftOver = items.insertStack(ItemStackWrapper(extracted), true)
 
 				if (leftOver.count.toInt() != extracted.count) {
-					extracted = resolved.extractItem(lastSlot, extracted.count - leftOver.count.toInt(), false)
+					extracted = target.extractItem(lastSlot, extracted.count - leftOver.count.toInt(), false)
 					energy.extractEnergyExact(ITEM_STORAGE.energyPerOperation, extracted.count, false)
 					items.insertStack(ItemStackWrapper(extracted), false)
 				} else {
@@ -335,43 +338,50 @@ class StorageExporterBlockEntity(blockPos: BlockPos, blockState: BlockState) :
 
 		nextTick--
 
-		if (nextTick <= 0 && target.isPresent && enoughEnergy) {
+		val target = target.firstOrNull()
+
+		if (nextTick <= 0 && target != null && enoughEnergy) {
 			val graph = cell.storageGraph ?: return
 			val items = graph.getVirtualComponent(ITEM_STORAGE)
 
-			val resolved = target.orThrow()
+			if (lastSlot >= target.slots) {
-
-			if (lastSlot >= resolved.slots) {
 				lastSlot = 0
 			}
 
 			var hit = false
 
 			for (stack in exportStacks) {
-				if (!resolved.isItemValid(lastSlot, stack.second.item)) {
+				if (!target.isItemValid(lastSlot, stack.second.item)) {
 					continue
 				}
 
-				val exportAmountA = items.extractStack(stack.first, stack.second.count.coerceAtMost(
+				val exportAmountA = items.extractStack(
-					MAX_MOVE_PER_OPERATION
+					stack.first, stack.second.count.coerceAtMost(
-				), true).count
+						MAX_MOVE_PER_OPERATION
+					), true
+				).count
 
 				if (exportAmountA == BigInteger.ZERO) {
 					continue
 				}
 
-				var exportAmount = energy.extractEnergyExact(ITEM_STORAGE.energyPerOperation, exportAmountA, true).toIntSafe()
+				var exportAmount =
+					energy.extractEnergyExact(ITEM_STORAGE.energyPerOperation, exportAmountA, true).toIntSafe()
 
 				if (exportAmount == 0) {
 					break
 				}
 
-				val leftover = resolved.insertItem(lastSlot, stack.second.stack.also { it.count = exportAmount }, true)
+				val leftover = target.insertItem(lastSlot, stack.second.stack.also { it.count = exportAmount }, true)
 
 				if (leftover.count != exportAmount) {
 					hit = true
-					exportAmount = items.extractStack(stack.first, (exportAmount - leftover.count).toBigInteger(), false).count.toInt()
+					exportAmount = items.extractStack(
-					resolved.insertItem(lastSlot, stack.second.stack.also { it.count = exportAmount }, false)
+						stack.first,
+						(exportAmount - leftover.count).toBigInteger(),
+						false
+					).count.toInt()
+					target.insertItem(lastSlot, stack.second.stack.also { it.count = exportAmount }, false)
 					energy.extractEnergyExact(ITEM_STORAGE.energyPerOperation, exportAmount, false)
 					break
 				}

src/main/kotlin/ru/dbotthepony/mc/otm/core/util/BESubscribeList.kt

@@ -2,23 +2,84 @@ package ru.dbotthepony.mc.otm.core.util
 
 import net.minecraft.core.Direction
 import net.minecraft.core.SectionPos
+import net.minecraft.server.level.ServerLevel
 import net.minecraft.world.level.block.entity.BlockEntity
 import net.minecraftforge.common.capabilities.Capability
 import net.minecraftforge.common.util.LazyOptional
+import ru.dbotthepony.mc.otm.SERVER_IS_LIVE
 import ru.dbotthepony.mc.otm.core.collect.WeakHashSet
 import ru.dbotthepony.mc.otm.core.math.plus
+import ru.dbotthepony.mc.otm.core.math.unaryMinus
 import ru.dbotthepony.mc.otm.core.orNull
 import ru.dbotthepony.mc.otm.onceServer
 import java.lang.ref.WeakReference
 import java.util.EnumMap
 import java.util.function.Predicate
 
+private inline val Direction.flag: Int get() = 1 shl (ordinal + 1)
+
+/**
+ * This class allows block entities to track [capability] per block side.
+ *
+ * Allowed sides are governed by [test] method, which is open for override.
+ *
+ * **IMPORTANT:** Once rules behind [test] are changed, you MUST call [validate] or [update] right away, or expect hard to debug bugs.
+ * If rule changes can't be tracked in practical way, then flip on [alwaysValidate], although it will come with performance
+ * penalty (this will cause [iterator] to invoke [validate] on each its invocation).
+ *
+ * Subclasses can also override [subscribe] and [unsubscribe] to more finely track changes in neighbours.
+ *
+ * **THIS CLASS IS COMPLETELY THREAD UNSAFE**, it is assumed you only ever invoke it on server thread,
+ * or, at very least, thread where [ServerLevel] resides.
+ */
 open class BESubscribeList<T>(
 	val block: BlockEntity,
 	val capability: Capability<T>,
+	val alwaysValidate: Boolean = false
 ) : Predicate<Direction>, Iterable<T> {
 	private val knownCaps = WeakHashSet<LazyOptional<T>>()
 	private val trackedCaps = EnumMap<Direction, WeakReference<LazyOptional<T>>>(Direction::class.java)
+	private var updateQueued = false
+	private var firstKey: Direction? = null
+	private var lastDirectionSet = 0
+	private var isWaitingOnChunk = false
+
+	/**
+	 * First valid capability, this is faster than invoking [iterator] and getting first value from it.
+	 */
+	val first: T? get() {
+		return firstLO.orNull()
+	}
+
+	/**
+	 * First valid capability as [LazyOptional], this is faster than invoking [iterator] and getting first value from it.
+	 *
+	 * If required, calls [update]
+	 */
+	val firstLO: LazyOptional<T> get() {
+		if (updateQueued) {
+			update()
+		} else if (alwaysValidate) {
+			validate()
+		}
+
+		for (i in 0 .. 2) {
+			if (firstKey == null) {
+				return LazyOptional.empty()
+			}
+
+			val get = trackedCaps[firstKey]?.get()
+
+			if (get == null || !get.isPresent) {
+				update()
+				continue
+			}
+
+			return get
+		}
+
+		return LazyOptional.empty()
+	}
 
 	var valid = true
 		set(value) {
@@ -48,17 +109,13 @@ open class BESubscribeList<T>(
 		return true
 	}
 
-	fun validate() {
-		val iterator = trackedCaps.iterator()
-
-		for ((k, v) in iterator) {
-			if (v.get() == null || !test(k)) {
-				unsubscribe(k, null)
-			}
-		}
-	}
-
 	override fun iterator(): Iterator<T> {
+		if (updateQueued) {
+			update()
+		} else if (alwaysValidate) {
+			validate()
+		}
+
 		return object : Iterator<T> {
 			val iterator = trackedCaps.iterator()
 			var value: T? = null
@@ -68,9 +125,13 @@ open class BESubscribeList<T>(
 					val (k, v) = iterator.next()
 					value = v.get()?.orNull()
 
-					if (value == null || !test(k)) {
+					if (value == null) {
 						iterator.remove()
 						unsubscribe(k, null)
+					} else if (!test(k)) {
+						iterator.remove()
+						unsubscribe(k, null)
+						updateQueued = true
 					}
 				}
 			}
@@ -93,29 +154,99 @@ open class BESubscribeList<T>(
 		return update(direction::equals)
 	}
 
-	private var updateTick = 0
+	private fun calculateDirectionSet(): Int {
+		var set = 0
+
+		for (value in VALUES)
+			if (test(value))
+				set = set or value.flag
+
+		return set
+	}
 
 	/**
-	 * Updates subscription list, searching for new capabilities or "removing" outdated ones
+	 * Checks for one of these conditions to be true:
+	 * * If [test] was determined to be changed during last time [iterator] was invoked AND tracked capability was filtered out due to [test] returning false
+	 * * Performs a fast bitflag intersection test, by calling [test] on all directions and seeking difference between built set and previous set checked during last [update]
+	 * * Tracked capabilities are checked for validity (if references are still valid)
 	 *
-	 * [predicate] predicate narrows sides-to-check list, not replaces list generated by this class' [test]
+	 * Once *any* of conditions above end up true, [update] is called and nothing else down the list is checked further.
+	 */
+	fun validate() {
+		check(valid) { "Subscription list is marked as invalid" }
+
+		if (updateQueued) {
+			update()
+			return
+		}
+
+		val new = calculateDirectionSet()
+
+		if (new != lastDirectionSet) {
+			val intersect = new and lastDirectionSet
+			val removed = lastDirectionSet and (intersect.inv())
+			val added = new and (intersect.inv())
+
+			for (dir in VALUES) {
+				if (dir.flag and removed != 0) {
+					val value1 = trackedCaps.remove(dir)
+					val value = value1?.get()
+
+					if (value1 != null) {
+						unsubscribe(dir, value)
+					}
+				}
+			}
+
+			if (added != 0) {
+				update { it.flag and added != 0 }
+			}
+
+			lastDirectionSet = new
+			return
+		}
+
+		val iterator = trackedCaps.iterator()
+		var any = 0
+
+		for ((k, v) in iterator) {
+			if (v.get() == null) {
+				unsubscribe(k, null)
+				any = any or k.flag
+			}
+		}
+
+		if (any != 0) {
+			update { it.flag and any != 0 }
+		}
+	}
+
+	/**
+	 * Updates subscription list, searching for new capabilities and "removing" outdated ones.
+	 *
+	 * [predicate] narrows sides-to-check list, not replaces the set generated by this class' [test]
 	 */
 	@JvmOverloads
 	fun update(predicate: Predicate<Direction>? = null) {
-		if (!valid)
+		if (!valid || block.isRemoved)
 			return
 
-		val sorse = block.level?.chunkSource ?: return
+		val level = block.level as? ServerLevel ?: return // don't run on client
+		val sorse = level.chunkSource
 		var waitChunkLoad = false
 
-		updateTick++
+		var stream = Direction.stream()
-		val updateTick = updateTick
-		var stream = Direction.stream().filter(this)
 
 		if (predicate != null) {
 			stream = stream.filter(predicate)
+		} else {
+			updateQueued = false
+			lastDirectionSet = calculateDirectionSet()
 		}
 
+		stream = stream.filter(this)
+		firstKey = null
+
 		for (dir in stream) {
 			val pos = block.blockPos + dir
 			val getChunk = sorse.getChunkNow(SectionPos.blockToSectionCoord(pos.x), SectionPos.blockToSectionCoord(pos.z))
@@ -123,7 +254,7 @@ open class BESubscribeList<T>(
 			if (getChunk == null) {
 				waitChunkLoad = true
 			} else {
-				val cap = getChunk.getBlockEntity(pos)?.getCapability(capability)
+				val cap = getChunk.getBlockEntity(pos)?.getCapability(capability, -dir)
 				val knownCap = trackedCaps[dir]?.get()
 
 				if (cap != null && cap.isPresent) {
@@ -147,6 +278,10 @@ open class BESubscribeList<T>(
 						trackedCaps[dir] = WeakReference(cap)
 						subscribe(dir, cap)
 					}
+
+					if (firstKey == null) {
+						firstKey = dir
+					}
 				} else {
 					trackedCaps.remove(dir)
 					unsubscribe(dir, knownCap)
@@ -154,8 +289,15 @@ open class BESubscribeList<T>(
 			}
 		}
 
-		if (waitChunkLoad) {
+		if (waitChunkLoad && SERVER_IS_LIVE) {
-			onceServer { if (updateTick == this.updateTick) update(predicate) }
+			onceServer { if (isWaitingOnChunk) update() }
+			isWaitingOnChunk = true
+		} else if (predicate == null) {
+			isWaitingOnChunk = false
 		}
 	}
+
+	companion object {
+		private val VALUES = Direction.values()
+	}
 }