Add an option for EventTargetGroup to be thread-safe

blokk-api/src/main/kotlin/space/blokk/event/EventTargetGroup.kt

@@ -1,9 +1,10 @@
 package space.blokk.event
 
-abstract class EventTargetGroup<T : EventTarget<*>> : Iterable<T> {
-    // TODO: Allow using a different collection implementation (in order to allow concurrency)
-    private val targets: MutableCollection<T> = mutableSetOf()
-    private val listeners = mutableSetOf<Listener>()
+import java.util.concurrent.CopyOnWriteArraySet
+
+abstract class EventTargetGroup<T : EventTarget<*>>(threadSafe: Boolean = false) : Iterable<T> {
+    private val targets: MutableSet<T> = if (threadSafe) CopyOnWriteArraySet() else HashSet()
+    private val listeners: MutableSet<Listener> = if (threadSafe) CopyOnWriteArraySet() else HashSet()
 
     /**
      * Register a listener for all elements in this group.
@@ -11,8 +12,8 @@ abstract class EventTargetGroup<T : EventTarget<*>> : Iterable<T> {
      * because this may lead to strange behaviour.
      */
     fun <T : Listener> registerListener(listener: T): T {
-        targets.forEach { it.eventBus.register(listener) }
         listeners.add(listener)
+        targets.forEach { it.eventBus.register(listener) }
         return listener
     }
 
@@ -28,15 +29,16 @@ abstract class EventTargetGroup<T : EventTarget<*>> : Iterable<T> {
     override fun iterator(): Iterator<T> = targets.iterator()
 
     protected fun addTarget(target: T) {
-        listeners.forEach { target.eventBus.register(it) }
         targets.add(target)
+        listeners.forEach { target.eventBus.register(it) }
     }
 
     protected fun removeTarget(target: T) {
         targets.remove(target)
+        listeners.forEach { target.eventBus.unregister(it) }
     }
 
-    class Public<T : EventTarget<*>> : EventTargetGroup<T>() {
+    class Mutable<T : EventTarget<*>>(threadSafe: Boolean = false) : EventTargetGroup<T>(threadSafe) {
         fun add(target: T) = addTarget(target)
         fun remove(target: T) = removeTarget(target)
     }

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

@@ -31,7 +31,7 @@ abstract class World(val uuid: UUID) {
     /**
      * All entities in this world. Use [spawnEntity] for spawning new ones.
      */
-    abstract val entities: EventTargetGroup.Public<Entity>
+    abstract val entities: EventTargetGroup.Mutable<Entity>
 
     /**
      * All currently loaded chunks of this world.

blokk-server/src/main/kotlin/space/blokk/BlokkServer.kt

@@ -5,10 +5,11 @@ import com.sksamuel.hoplite.ConfigLoader
 import com.sksamuel.hoplite.ConfigSource
 import space.blokk.config.BlokkConfig
 import space.blokk.event.EventBus
+import space.blokk.event.EventTargetGroup
 import space.blokk.logging.BlokkLoggingOutputProvider
 import space.blokk.logging.Logger
 import space.blokk.net.BlokkSocketServer
-import space.blokk.player.PlayerGroup
+import space.blokk.player.Player
 import space.blokk.plugin.BlokkPluginManager
 import space.blokk.server.Server
 import space.blokk.server.event.ServerEvent
@@ -27,7 +28,7 @@ class BlokkServer internal constructor() : Server {
     override val eventBus = EventBus(ServerEvent::class, scope, logger)
 
     override val sessions by socketServer::sessions
-    override val players = PlayerGroup()
+    override val players = EventTargetGroup.Mutable<Player>(true)
     override val pluginManager = BlokkPluginManager(this)
 
     val keyPair: KeyPair

blokk-server/src/main/kotlin/space/blokk/net/BlokkSocketServer.kt

@@ -11,6 +11,7 @@ import io.netty.channel.kqueue.KQueueServerSocketChannel
 import io.netty.channel.nio.NioEventLoopGroup
 import io.netty.channel.socket.nio.NioServerSocketChannel
 import space.blokk.BlokkServer
+import space.blokk.event.EventTargetGroup
 import space.blokk.logging.Logger
 
 class BlokkSocketServer(val server: BlokkServer) {
@@ -31,7 +32,7 @@ class BlokkSocketServer(val server: BlokkServer) {
         .childOption(ChannelOption.TCP_NODELAY, true)
         .childHandler(BlokkChannelInitializer(this))
 
-    internal val sessions = SessionGroup()
+    internal val sessions = EventTargetGroup.Mutable<Session>(true)
 
     fun bind() {
         bootstrap.bind(server.config.host, server.config.port)

blokk-server/src/main/kotlin/space/blokk/net/SessionGroup.kt

@@ -1,8 +0,0 @@
-package space.blokk.net
-
-import space.blokk.event.EventTargetGroup
-
-class SessionGroup : EventTargetGroup<Session>() {
-    fun add(target: Session) = addTarget(target)
-    fun remove(target: Session) = removeTarget(target)
-}

blokk-server/src/main/kotlin/space/blokk/player/PlayerGroup.kt

@@ -1,8 +0,0 @@
-package space.blokk.player
-
-import space.blokk.event.EventTargetGroup
-
-class PlayerGroup : EventTargetGroup<Player>() {
-    fun add(target: Player) = addTarget(target)
-    fun remove(target: Player) = removeTarget(target)
-}