AsyncWorker: Use statics for thread-local worker storage instead of globals

src/pocketmine/scheduler/AsyncWorker.php

@@ -26,6 +26,8 @@ namespace pocketmine\scheduler;
 use pocketmine\Worker;
 
 class AsyncWorker extends Worker{
+	/** @var mixed[] */
+	private static $store = [];
 
 	private $logger;
 	private $id;
@@ -53,9 +55,6 @@ class AsyncWorker extends Worker{
 			ini_set('memory_limit', '-1');
 			$this->logger->debug("No memory limit set");
 		}
-
-		global $store;
-		$store = [];
 	}
 
 	public function getLogger() : \ThreadedLogger{
@@ -73,4 +72,30 @@ class AsyncWorker extends Worker{
 	public function getAsyncWorkerId() : int{
 		return $this->id;
 	}
+
+	/**
+	 * Saves mixed data into the worker's thread-local object store. This can be used to store objects which you
+	 * want to use on this worker thread from multiple AsyncTasks.
+	 *
+	 * @param string $identifier
+	 * @param mixed  $value
+	 */
+	public function saveToThreadStore(string $identifier, $value) : void{
+		self::$store[$identifier] = $value;
+	}
+
+	/**
+	 * Retrieves mixed data from the worker's thread-local object store.
+	 *
+	 * Note that the thread-local object store could be cleared and your data might not exist, so your code should
+	 * account for the possibility that what you're trying to retrieve might not exist.
+	 *
+	 * Objects stored in this storage may ONLY be retrieved while the task is running.
+	 *
+	 * @param string $identifier
+	 * @return mixed
+	 */
+	public function getFromThreadStore(string $identifier){
+		return self::$store[$identifier] ?? null;
+	}
 }