Register entities globally

README.md

@@ -12,13 +12,13 @@
 - Players can have items (with metadata) in their inventory
 - Inventories
 - World modifications are sent to players
-- Crafting
 - PlayerInteract events are emitted when blocks are clicked
 - Command framework + permissions
 - Commands can be sent from the console
 - Players can be teleported between worlds
 - Entity AI framework
 - Scoreboards + Teams
+- Crafting
 
 ## Conventions
 

test-plugin/src/main/kotlin/space/uranos/testplugin/anvil/AnvilWorld.kt

@@ -8,7 +8,6 @@ package space.uranos.testplugin.anvil
 import com.google.common.cache.CacheBuilder
 import com.google.common.cache.CacheLoader
 import com.google.common.cache.LoadingCache
-import space.uranos.entity.Entity
 import space.uranos.world.Chunk
 import space.uranos.world.Dimension
 import space.uranos.world.World
@@ -19,7 +18,6 @@ class AnvilWorld(
     override val isFlat: Boolean
 ) : World(UUID.randomUUID()) {
     override val loadedChunks: Map<Chunk.Key, Chunk> get() = chunks.asMap().filter { (_, chunk) -> chunk.loaded }
-    override val entities = emptyList<Entity>()
 
     private val chunks: LoadingCache<Chunk.Key, Chunk> = CacheBuilder.newBuilder()
         .build(object : CacheLoader<Chunk.Key, Chunk>() {
@@ -29,8 +27,4 @@ class AnvilWorld(
         })
 
     override fun getChunk(key: Chunk.Key): Chunk = chunks.get(key)
-
-    override fun spawnEntity(entity: Entity) {
-        TODO("Not yet implemented")
-    }
 }

uranos-api/src/main/kotlin/space/uranos/entity/Entity.kt

@@ -5,15 +5,13 @@
 
 package space.uranos.entity
 
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import space.uranos.Uranos
+import space.uranos.world.World
 import java.util.*
 
 abstract class Entity internal constructor() {
-    /**
-     * An integer unique to this entity which will not be persisted, for example when the entity is serialized.
-     */
-    val uid: Int = Uranos.claimEntityID()
-
     /**
      * The UUID of this entity.
      *
@@ -25,4 +23,28 @@ abstract class Entity internal constructor() {
     open val uuid: UUID = UUID.randomUUID()
 
     abstract val type: EntityType
+
+    private val worldMutex = Mutex()
+    var world: World? = null; private set
+
+    suspend fun setWorld(world: World?) {
+        if (world == this.world) return
+
+        worldMutex.withLock {
+            this.world?.internalEntities?.remove(this)
+            this.world = world
+            world?.internalEntities?.add(this)
+        }
+    }
+
+    /**
+     * Returns [world] if it is not null, otherwise throws [IllegalStateException].
+     */
+    fun getWorldOrFail() = world ?: throw IllegalStateException("This entity has not been spawned")
+
+    /**
+     * An integer unique to this entity which will not be persisted, for example when the entity is serialized.
+     */
+    @Suppress("LeakingThis")
+    val uid: Int = Uranos.registerEntity(this)
 }

uranos-api/src/main/kotlin/space/uranos/player/Player.kt

@@ -14,9 +14,6 @@ import space.uranos.world.World
 import java.util.*
 import kotlin.coroutines.CoroutineContext
 
-/**
- * A **real** player.
- */
 interface Player {
     val coroutineContext: CoroutineContext get() = session.coroutineContext
 
@@ -107,7 +104,7 @@ interface Player {
     var playerListName: TextComponent?
     var compassTarget: VoxelLocation
 
-    val currentlyViewedChunks: List<Chunk>
+    val currentlyViewedChunks: Collection<Chunk>
 
     companion object {
         const val DEFAULT_FIELD_OF_VIEW = 0.1f

uranos-api/src/main/kotlin/space/uranos/server/Server.kt

@@ -8,6 +8,7 @@ package space.uranos.server
 import space.uranos.Registry
 import space.uranos.Scheduler
 import space.uranos.command.Command
+import space.uranos.entity.Entity
 import space.uranos.event.EventBus
 import space.uranos.event.EventHandlerPositionManager
 import space.uranos.logging.Logger
@@ -19,55 +20,66 @@ import space.uranos.recipe.Recipe
 import space.uranos.world.BiomeRegistry
 import space.uranos.world.Dimension
 import java.io.File
+import java.util.*
+import java.util.concurrent.atomic.AtomicInteger
 import kotlin.coroutines.CoroutineContext
 
-interface Server {
-    val eventBus: EventBus
-    val eventHandlerPositions: EventHandlerPositionManager
+abstract class Server {
+    abstract val eventBus: EventBus
+    abstract val eventHandlerPositions: EventHandlerPositionManager
 
     /**
      * [CoroutineContext] confined to the server thread.
      *
      * Is cancelled when the server is shutting down.
      */
-    val coroutineContext: CoroutineContext
+    abstract val coroutineContext: CoroutineContext
 
     /**
      * All sessions connected to the server.
      */
-    val sessions: Collection<Session>
+    abstract val sessions: Collection<Session>
 
     /**
      * All players connected to the server.
      */
-    val players: Collection<Player>
+    abstract val players: Collection<Player>
 
-    val pluginManager: PluginManager
-    val serverDirectory: File
+    abstract val pluginManager: PluginManager
+    abstract val serverDirectory: File
     val cacheDirectory: File get() = serverDirectory.resolve("cache")
 
-    val dimensionRegistry: Registry<Dimension>
-    val recipeRegistry: Registry<Recipe>
-    val commandRegistry: Registry<Command>
-    val biomeRegistry: BiomeRegistry
+    abstract val dimensionRegistry: Registry<Dimension>
+    abstract val recipeRegistry: Registry<Recipe>
+    abstract val commandRegistry: Registry<Command>
+    abstract val biomeRegistry: BiomeRegistry
 
-    val loggingOutputProvider: LoggingOutputProvider
-    val scheduler: Scheduler
+    abstract val loggingOutputProvider: LoggingOutputProvider
+    abstract val scheduler: Scheduler
 
-    val developmentMode: Boolean
-    val minimumLogLevel: Logger.Level
-
-    /**
-     * Returns an unused entity ID.
-     *
-     * **Should not be used by plugins.**
-     */
-    fun claimEntityID(): Int
+    abstract val developmentMode: Boolean
+    abstract val minimumLogLevel: Logger.Level
 
     /**
      * Initiates shutting down the server.
      */
-    fun shutdown()
+    abstract fun shutdown()
+
+    /**
+     * Set of all existing [Entity] instances.
+     *
+     * This is not public because the instances may not be fully initialized as they are added.
+     */
+    protected val entities: MutableSet<Entity> = Collections.newSetFromMap(WeakHashMap())
+    private val nextEntityID = AtomicInteger()
+
+    /**
+     * Returns the UID for [entity].
+     */
+    internal fun registerEntity(entity: Entity): Int {
+        entities.add(entity)
+        return nextEntityID.getAndIncrement()
+    }
 
     companion object {
         const val TICKS_PER_SECOND = 20

uranos-api/src/main/kotlin/space/uranos/util/Clamp.kt

@@ -6,3 +6,7 @@
 package space.uranos.util
 
 fun Int.clamp(range: IntRange) = maxOf(minOf(range.first, range.last), minOf(maxOf(range.first, range.last), this))
+
+fun clampArgument(name: String, range: IntRange, actualValue: Int) {
+    if (!range.contains(actualValue)) throw IllegalArgumentException("$name must be in $range")
+}

uranos-api/src/main/kotlin/space/uranos/world/World.kt

@@ -15,6 +15,7 @@ import space.uranos.util.newSingleThreadDispatcher
 import space.uranos.util.supervisorChild
 import space.uranos.util.untilPossiblyNegative
 import java.util.*
+import java.util.concurrent.CopyOnWriteArraySet
 import kotlin.coroutines.CoroutineContext
 
 /**
@@ -45,9 +46,11 @@ abstract class World(val uuid: UUID) {
     open val seed: Long? = null
 
     /**
-     * All entities in this world. Use [spawnEntity] for spawning new ones.
+     * All entities in this world.
      */
-    abstract val entities: Collection<Entity>
+    internal val internalEntities = CopyOnWriteArraySet<Entity>()
+
+    val entities get() = internalEntities.toList()
 
     abstract fun getChunk(key: Chunk.Key): Chunk
 
@@ -66,7 +69,6 @@ abstract class World(val uuid: UUID) {
      *
      * @param hollow Whether the cube is hollow
      */
-    @OptIn(ExperimentalStdlibApi::class)
     fun getVoxelsInCube(cornerA: VoxelLocation, cornerB: VoxelLocation, hollow: Boolean = false): List<Voxel> {
         fun getList(a: Int, b: Int) =
             if (hollow) listOf(a, b).distinct()
@@ -95,11 +97,6 @@ abstract class World(val uuid: UUID) {
         TODO()
     }
 
-    /**
-     * Spawns [entity][Entity] in this world.
-     */
-    abstract fun spawnEntity(entity: Entity)
-
     suspend fun destroy() = withContext(coroutineContext) {
         // TODO: Move or kick players
         coroutineContext.cancel()

uranos-server/src/main/kotlin/space/uranos/UranosServer.kt

@@ -28,13 +28,12 @@ import space.uranos.world.Dimension
 import java.io.File
 import java.security.KeyPair
 import java.util.concurrent.Executors
-import java.util.concurrent.atomic.AtomicInteger
 import kotlin.coroutines.CoroutineContext
 import kotlin.system.exitProcess
 
 // TODO: Consider using DI because this improves testability
 
-class UranosServer internal constructor() : Server {
+class UranosServer internal constructor() : Server() {
     val logger = Logger("Server")
     private val socketServer = UranosSocketServer(this)
 
@@ -90,9 +89,6 @@ class UranosServer internal constructor() : Server {
     override val eventBus = UranosEventBus(developmentMode)
     override val eventHandlerPositions = UranosEventHandlerPositionManager()
 
-    private val nextEntityID = AtomicInteger()
-    override fun claimEntityID() = nextEntityID.incrementAndGet()
-
     override fun shutdown() {
         runBlocking {
             scheduler.shutdown()

uranos-server/src/main/kotlin/space/uranos/player/UranosPlayer.kt

@@ -10,6 +10,7 @@ import space.uranos.chat.TextComponent
 import space.uranos.net.Session
 import space.uranos.net.packet.play.ChunkDataPacket
 import space.uranos.net.packet.play.ChunkLightDataPacket
+import space.uranos.util.clampArgument
 import space.uranos.world.Chunk
 import space.uranos.world.VoxelLocation
 import space.uranos.world.World
@@ -35,8 +36,8 @@ class UranosPlayer(
 ) : Player {
     override var selectedHotbarSlot = 0
         set(value) {
-            if (value in 0..8) field = value
-            else throw IllegalArgumentException("selectedHotbarSlot must be in 0..8")
+            clampArgument("selectedHotbarSlot", 0..8, value)
+            field = value
         }
 
     init {
@@ -44,7 +45,7 @@ class UranosPlayer(
     }
 
     override var playerListName: TextComponent? = null
-    override var currentlyViewedChunks: List<Chunk> = emptyList()
+    override var currentlyViewedChunks = emptyList<Chunk>()
 
     init {
         updateCurrentlyViewedChunks()