Microdungeon placement now don't hog event loop

src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerChunk.kt

@@ -2,6 +2,7 @@ package ru.dbotthepony.kstarbound.server.world
 
 import it.unimi.dsi.fastutil.objects.ObjectAVLTreeSet
 import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.future.await
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.suspendCancellableCoroutine
@@ -59,6 +60,7 @@ import kotlin.concurrent.withLock
 import kotlin.coroutines.cancellation.CancellationException
 import kotlin.coroutines.resume
 import kotlin.coroutines.resumeWithException
+import kotlin.math.min
 
 class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, ServerChunk>(world, pos) {
 	override var state: ChunkState = ChunkState.FRESH
@@ -758,6 +760,10 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 
 							break
 						}
+
+						// some breathing room for other code, since placement checking is performance intense operation
+						if (!world.isInPreparation && world.clients.isNotEmpty())
+							delay(min(60L, anchor.reader.size.x * anchor.reader.size.y / 100L))
 					}
 				}
 			}

src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorld.kt

@@ -306,8 +306,12 @@ class ServerWorld private constructor(
 		}
 	}
 
+	var isInPreparation = false
+		private set
+
 	private suspend fun prepare0() {
 		try {
+			isInPreparation = true
 			isBusy++
 
 			val random = random(template.seed)
@@ -362,6 +366,7 @@ class ServerWorld private constructor(
 			}
 		} finally {
 			isBusy--
+			isInPreparation = false
 		}
 	}
 

src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt

@@ -352,9 +352,9 @@ class ServerWorldTracker(val world: ServerWorld, val client: ServerConnection, p
 			// instantly added back because new world rejected us
 			world.eventLoop.execute { remove0() }
 
+			scope.cancel()
 			damageTilesQueue.close()
 			modifyTilesQueue.close()
-			scope.cancel()
 		}
 	}