Implement multiple-comparator sorted lists for efficiently tracking portals

src/main/kotlin/MultiSortedList.kt

@@ -0,0 +1,100 @@
+import java.util.*
+import kotlin.Comparator
+
+class MultiSortedList<E> constructor(
+    underlying: MutableList<E>,
+    comparator: Comparator<in E>,
+    vararg extraComparators: Comparator<in E>
+): SortedList<E>(underlying, comparator) {
+    companion object {
+        fun <T: Comparable<T>> ofComparable(
+            underlying: MutableList<T> = ArrayList(),
+            comparator: Comparator<in T> = Comparator { a, b -> a.compareTo(b) },
+            vararg extraComparators: Comparator<in T>
+        ) = MultiSortedList(underlying, comparator, *extraComparators)
+    }
+
+    private var extraLists = extraComparators.associateWith { SortedList(underlying.subList(0, underlying.size), it) }
+
+    override fun add(element: E): Boolean {
+        extraLists.values.forEach {
+            it.add(element)
+        }
+
+        return super.add(element)
+    }
+
+    override fun add(index: Int, element: E) {
+        add(element)
+    }
+
+    override fun addAll(elements: Collection<E>): Boolean {
+        for (element in elements)
+            add(element)
+
+        return elements.isNotEmpty()
+    }
+
+    override fun addAll(index: Int, elements: Collection<E>) = addAll(elements)
+    override fun containsAll(elements: Collection<E>): Boolean {
+        for (element in elements)
+            if (!contains(element))
+                return false
+
+        return true
+    }
+
+    override fun remove(element: E): Boolean {
+        if (super.remove(element)) {
+            extraLists.values.forEach {
+                it.remove(element)
+            }
+
+            return true
+        }
+
+        return false
+    }
+
+    override fun removeAt(index: Int) = removeAt(index, comparator)
+
+    override fun removeAll(elements: Collection<E>): Boolean {
+        var result = false
+
+        for (element in elements)
+            result = remove(element) || result
+
+        return result
+    }
+
+    fun removeAt(index: Int, comparator: Comparator<in E>): E {
+        if (comparator == this.comparator) {
+            val result = super.removeAt(index)
+
+            extraLists.values.forEach {
+                it.remove(result)
+            }
+
+            return result
+        } else {
+            val result = extraLists[comparator]!!.removeAt(index)
+
+            extraLists.forEach { (comp, list) -> if (comparator != comp) list.remove(result) }
+            super.remove(result)
+
+            return result
+        }
+    }
+
+    fun get(index: Int, comparator: Comparator<in E>) =
+        if (comparator == this.comparator) this[index]
+        else extraLists[comparator]!![index]
+
+    fun binSearch(element: E, comparator: Comparator<in E>) =
+        if (comparator == this.comparator) binarySearch(element, comparator)
+        else extraLists[comparator]!!.binarySearch(element, comparator)
+
+    fun binSearch(comparator: Comparator<in E>, comparison: (E) -> Int) =
+        if (comparator == this.comparator) binarySearch(comparison = comparison)
+        else extraLists[comparator]!!.binarySearch(comparison = comparison)
+}

src/main/kotlin/Numbers.kt

@@ -1,4 +1,5 @@
 import java.nio.ByteBuffer
+import java.util.*
 
 private val threadLocalBuffer = ThreadLocal.withInitial { ByteBuffer.allocateDirect(9) }
 
@@ -104,3 +105,9 @@ val Char.varIntSize get() = code.varIntSize
 
 fun Float.varIntSize(min: Float, max: Float) = ((this - min)/max).toULong().varIntSize
 fun Double.varIntSize(min: Double, max: Double) = ((this - min)/max).toULong().varIntSize
+
+
+operator fun UUID.plus(value: ULong): UUID {
+    val lsb = leastSignificantBits.toULong() + value
+    return UUID(if (lsb < leastSignificantBits.toULong()) mostSignificantBits + 1L else mostSignificantBits, lsb.toLong())
+}

src/main/kotlin/Portal.kt

@@ -10,7 +10,12 @@ import kotlin.experimental.or
 
 private val PLAYER_COMPARATOR = Comparator<OfflinePlayer> { a, b -> a.uniqueId.compareTo(b.uniqueId) }
 val LOCATION_COMPARATOR = Comparator<Location> { a, b -> a.compareByOrder(b, { world!!.uid }, Location::getBlockX, Location::getBlockY, Location::getBlockZ) }
-val PORTAL_COMPARATOR = Comparator<Portal> { a, b -> a.compareByOrder(b, { world.uid }, Portal::x, Portal::y, Portal::z, Portal::id) }
+
+// An owner cannot place two portals on the same block, implying that this comparator defines a partial order
+val PORTAL_LOCATION_COMPARATOR = Comparator<Portal> { a, b -> a.compareByOrder(b, { world.uid }, Portal::x, Portal::y, Portal::z, { owner.uniqueId }) }
+
+// IDs are unique, so this comparator inherently defines a partial order
+val PORTAL_UID_COMPARATOR = Comparator<Portal> { a, b -> a.id.compareTo(b.id) }
 
 
 private val threadLocalInputBuffer = ThreadLocal.withInitial { ReallocatingBuffer(ByteBuffer.allocate(96)) }
@@ -188,9 +193,9 @@ fun readCompressedPortal(
         },
         if (PortalFlag.LINKED.isFlagSet(flags)) UUID(inputBuffer.long, inputBuffer.long)
         else null,
-        if (PortalFlag.NO_EXCLUSIONS.isFlagSet(flags)) SortedList.create(comparator = PLAYER_COMPARATOR)
+        if (PortalFlag.NO_EXCLUSIONS.isFlagSet(flags)) SortedList(comparator = PLAYER_COMPARATOR)
         else run {
-            val collect = SortedList.create(comparator = PLAYER_COMPARATOR)
+            val collect = SortedList(comparator = PLAYER_COMPARATOR)
             while (inputBuffer.position < dataLen)
                 collect += playerMapper(inputBuffer.packedUInt) ?: continue
             return@run collect

src/main/kotlin/PortalManager.kt

@@ -1,7 +1,10 @@
 import org.bukkit.Location
 import org.bukkit.configuration.ConfigurationSection
 import org.bukkit.event.EventHandler
+import org.bukkit.event.HandlerList
+import org.bukkit.event.Listener
 import org.bukkit.event.player.PlayerMoveEvent
+import org.bukkit.plugin.Plugin
 import java.util.*
 import kotlin.collections.ArrayList
 
@@ -10,10 +13,55 @@ private const val PATH_WORLDS = "worlds"
 private const val PATH_PORTALS = "portals"
 
 
-class PortalManager(private val data: ConfigurationSection, private val config: () -> ConfigurationSection) {
+class PortalManager(private val data: ConfigurationSection, private val config: () -> ConfigurationSection): Listener {
     private val players = PlayerMapper(data, PATH_PLAYERS)
     private val worlds = WorldMapper(data, PATH_WORLDS)
-    private var portals = SortedList.create(comparator = PORTAL_COMPARATOR)
+    private var portals = MultiSortedList(ArrayList(), PORTAL_LOCATION_COMPARATOR, PORTAL_UID_COMPARATOR)
+
+    // Make UUIDs as "sequential" as possible
+    private var nextUUIDUsed = false
+    private var nextUUID = UUID(0, 0)
+        get() {
+            // If currently held value guaranteed to be unused, just return it
+            if (!nextUUIDUsed) {
+                nextUUIDUsed = true
+                return field
+            }
+
+            // Compute next available uuid
+            var lsb = field.leastSignificantBits.toULong()
+            var msb = field.mostSignificantBits.toULong()
+
+            // Start sequential search at the resulting index if it is populated
+            val index = portals.binSearch(PORTAL_UID_COMPARATOR) {
+                compareValues(
+                    { msb } to { it.id.mostSignificantBits.toULong() },
+                    { lsb } to { it.id.leastSignificantBits.toULong() }
+                )
+            }
+
+            if (index >= 0) {
+                // Increment 128-bit value
+                if (++lsb == 0UL)
+                    ++msb
+
+                for (i in index until portals.size) {
+                    val find = portals.get(index, PORTAL_UID_COMPARATOR).id
+
+                    // Found a gap in the UUIDs
+                    if (find.mostSignificantBits.toULong() != msb || find.leastSignificantBits.toULong() != lsb)
+                        break
+                    else if (++lsb == 0UL)
+                        ++msb
+                }
+            }
+
+            // Save result and mark as used
+            field = UUID(msb.toLong(), lsb.toLong())
+            nextUUIDUsed = true
+
+            return field
+        }
 
     fun reload() {
         players.reload()
@@ -21,9 +69,22 @@ class PortalManager(private val data: ConfigurationSection, private val config:
 
         val portalList = ArrayList<Portal>()
         data.getStringList(PATH_PORTALS).forEach {
-            portalList += readCompressedPortal(it, worlds::getValue, players::getValue) ?: return@forEach
+            val portal = readCompressedPortal(it, worlds::getValue, players::getValue) ?: return@forEach
+            portalList += portal
+
+            if (portal.id >= nextUUID)
+                nextUUID = portal.id + 1UL
+        }
+        portals = MultiSortedList(portalList, PORTAL_LOCATION_COMPARATOR, PORTAL_UID_COMPARATOR)
+
+        if(portals.isEmpty()) nextUUID = UUID(0, 0)
+        else {
+            nextUUID = portals.get(0, PORTAL_UID_COMPARATOR).id + 1UL
+
+            // Compute next UUID
+            nextUUID
+            nextUUIDUsed = false
         }
-        portals = SortedList.create(PORTAL_COMPARATOR, portalList)
     }
 
     fun save() {
@@ -32,6 +93,13 @@ class PortalManager(private val data: ConfigurationSection, private val config:
         data.set(PATH_PORTALS, portals.map { it.toCompressedString(worlds::getIndex, players::getIndex) })
     }
 
+    fun onEnable(plugin: Plugin) {
+        plugin.server.pluginManager.registerEvents(this, plugin)
+    }
+
+    fun onDisable() {
+        HandlerList.unregisterAll(this)
+    }
 
     @EventHandler
     fun onPlayerMove(moveEvent: PlayerMoveEvent) {

src/main/kotlin/PortalsPlugin.kt

@@ -10,13 +10,24 @@ class PortalsPlugin: JavaPlugin() {
     override fun onEnable() {
         super.onEnable()
 
+        reloadConfig()
+
+        portalManager.onEnable(this)
+    }
+
+    override fun reloadConfig() {
+        super.reloadConfig()
         saveDefaultConfig()
         data.load()
+
+        portalManager.reload()
     }
 
     override fun onDisable() {
         super.onDisable()
 
+        portalManager.onDisable()
+
         data.save()
         saveConfig()
     }

src/main/kotlin/SortedList.kt

@@ -1,24 +1,15 @@
 import java.util.*
+import kotlin.collections.ArrayList
 
-class SortedList<E> private constructor(
-    private val underlying: MutableList<E>,
-    private val comparator: Comparator<in E>
+open class SortedList<E> constructor(
+    private val underlying: MutableList<E> = ArrayList(),
+    protected val comparator: Comparator<in E>
 ): MutableList<E> by underlying {
-
     companion object {
-        fun <T> create(
-            type: Class<T>,
-            underlying: MutableList<T>,
-            comparator: Comparator<in T>
-        ) = SortedList(Collections.checkedList(underlying, type), comparator)
-
-        inline fun <reified T: Comparable<T>> create(
+        fun <T: Comparable<T>> ofComparable(
             underlying: MutableList<T> = ArrayList(),
             comparator: Comparator<T> = Comparator { a, b -> a.compareTo(b) }
-        ) = create(T::class.java, underlying, comparator)
-
-        inline fun <reified T> create(comparator: Comparator<T>, underlying: MutableList<T> = ArrayList()) =
-            create(T::class.java, underlying, comparator)
+        ) = SortedList(underlying, comparator)
     }
 
     init {
@@ -29,29 +20,23 @@ class SortedList<E> private constructor(
     override fun add(element: E): Boolean {
         val index = underlying.binarySearch(element, comparator)
 
-        if (index < 0)
-            underlying.add(-(index + 1), element)
-        else
-            underlying[index] = element
+        underlying.add(if (index < 0) -(index + 1) else index, element)
 
-        return index < 0
+        return true
     }
 
-    override fun add(index: Int, element: E) =
-        throw UnsupportedOperationException("Cannot insert at index for sorted list")
+    override fun add(index: Int, element: E) {
+        add(element)
+    }
 
     override fun addAll(elements: Collection<E>): Boolean {
-        var result = false
-
         for (element in elements)
-            result = add(element) || result
+            add(element)
 
-        return result
+        return elements.isNotEmpty()
     }
 
-    override fun addAll(index: Int, elements: Collection<E>) =
-        throw UnsupportedOperationException("Cannot insert at index for sorted list")
-
+    override fun addAll(index: Int, elements: Collection<E>) = addAll(elements)
     override fun contains(element: E) = underlying.binarySearch(element, comparator) >= 0
 
     override fun containsAll(elements: Collection<E>): Boolean {
@@ -73,9 +58,7 @@ class SortedList<E> private constructor(
         return false
     }
 
-    override fun removeAt(index: Int) =
-        underlying.removeAt(index)
-
+    override fun removeAt(index: Int) = underlying.removeAt(index)
     override fun removeAll(elements: Collection<E>): Boolean {
         var result = false