Added capability to dump AsyncWorkers' memory (#1379)

This now actually works with PHP 7.2 + latest pthreads, before it was too unstable.

src/pocketmine/scheduler/AsyncWorker.php

@@ -64,4 +64,8 @@ class AsyncWorker extends Worker{
 	public function getThreadName() : string{
 		return "Asynchronous Worker #" . $this->id;
 	}
+
+	public function getAsyncWorkerId() : int{
+		return $this->id;
+	}
 }

src/pocketmine/scheduler/DumpWorkerMemoryTask.php

@@ -0,0 +1,61 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\scheduler;
+
+use pocketmine\MemoryManager;
+
+/**
+ * Task used to dump memory from AsyncWorkers
+ */
+class DumpWorkerMemoryTask extends AsyncTask{
+	/** @var string */
+	private $outputFolder;
+	/** @var int */
+	private $maxNesting;
+	/** @var int */
+	private $maxStringSize;
+
+	/**
+	 * @param string $outputFolder
+	 * @param int    $maxNesting
+	 * @param int    $maxStringSize
+	 */
+	public function __construct(string $outputFolder, int $maxNesting, int $maxStringSize){
+		$this->outputFolder = $outputFolder;
+		$this->maxNesting = $maxNesting;
+		$this->maxStringSize = $maxStringSize;
+	}
+
+	public function onRun(){
+		global $store;
+
+		MemoryManager::dumpMemory(
+			["worker" => $this->worker, "store" => $store],
+			$this->worker->getClassLoader(),
+			$this->outputFolder . DIRECTORY_SEPARATOR . "AsyncWorker#" . $this->worker->getAsyncWorkerId(),
+			$this->maxNesting,
+			$this->maxStringSize
+		);
+	}
+}