Fix modstore/favourites hang by adding asynchronous lua job support

src/script/lua_api/l_async_events.h

@@ -0,0 +1,228 @@
+/*
+Minetest
+Copyright (C) 2013 sapier, <sapier AT gmx DOT net>
+
+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 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef C_ASYNC_EVENTS_H_
+#define C_ASYNC_EVENTS_H_
+
+#include <vector>
+#include <map>
+#include <unistd.h>
+
+/******************************************************************************/
+/* Includes                                                                   */
+/******************************************************************************/
+#include "jthread/jthread.h"
+#include "jthread/jmutex.h"
+#include "jthread/jsemaphore.h"
+#include "debug.h"
+#include "lua.h"
+
+/******************************************************************************/
+/* Typedefs and macros                                                        */
+/******************************************************************************/
+#define MAINMENU_NUMBER_OF_ASYNC_THREADS                   4
+
+/******************************************************************************/
+/* forward declarations                                                       */
+/******************************************************************************/
+class AsyncEngine;
+
+/******************************************************************************/
+/* declarations                                                               */
+/******************************************************************************/
+
+/** a struct to encapsulate data required to queue a job **/
+struct LuaJobInfo {
+	/** function to be called in async environment **/
+	std::string serializedFunction;
+	/** parameter table to be passed to function **/
+	std::string serializedParams;
+	/** result of function call **/
+	std::string serializedResult;
+	/** jobid used to identify a job and match it to callback **/
+	unsigned int JobId;
+};
+
+/** class encapsulating a asynchronous working environment **/
+class AsyncWorkerThread : public JThread {
+public:
+	/**
+	 * default constructor
+	 * @param pointer to job dispatcher
+	 */
+	AsyncWorkerThread(AsyncEngine* jobdispatcher, unsigned int threadnumber);
+
+	/**
+	 * default destructor
+	 */
+	virtual ~AsyncWorkerThread();
+
+	/**
+	 * thread function
+	 */
+	void* Thread() {
+			ThreadStarted();
+			return worker_thread_wrapper(this);
+	}
+
+	/**
+	 * wait for thread to stop
+	 */
+	void Wait() {
+		while(IsRunning()) {
+			sleep(1);
+		}
+	}
+
+private:
+	/**
+	 * helper function to run a lua script
+	 * @param path of script
+	 */
+	bool runScript(std::string script);
+
+	/**
+	 * main function of thread
+	 */
+	void* worker_thread_main();
+
+	/**
+	 * static wrapper for thread creation
+	 * @param this pointer to the thread to be created
+	 */
+	static void* worker_thread_wrapper(void* thread);
+
+	/**
+	 * pointer to job dispatcher
+	 */
+	AsyncEngine* m_JobDispatcher;
+
+	/**
+	 * the lua stack to run at
+	 */
+	lua_State*   m_LuaStack;
+
+	/**
+	 * lua internal stack number of error handler
+	 */
+	int m_luaerrorhandler;
+
+	/**
+	 * thread number used for debug output
+	 */
+	unsigned int m_threadnum;
+
+};
+
+/** asynchornous thread and job management **/
+class AsyncEngine {
+	friend AsyncWorkerThread;
+public:
+	/**
+	 * default constructor
+	 */
+	AsyncEngine();
+	/**
+	 * default destructor
+	 */
+	~AsyncEngine();
+
+	/**
+	 * register function to be used within engines
+	 * @param name function name to be used within lua environment
+	 * @param fct c-function to be called
+	 */
+	bool registerFunction(const char* name, lua_CFunction fct);
+
+	/**
+	 * create async engine tasks and lock function registration
+	 * @param numengines number of async threads to be started
+	 */
+	void Initialize(unsigned int numengines);
+
+	/**
+	 * queue/run a async job
+	 * @param fct serialized lua function
+	 * @param params serialized parameters
+	 * @return jobid the job is queued
+	 */
+	unsigned int doAsyncJob(std::string fct, std::string params);
+
+	/**
+	 * engine step to process finished jobs
+	 *   the engine step is one way to pass events back, PushFinishedJobs another
+	 * @param L the lua environment to do the step in
+	 */
+	void Step(lua_State *L);
+
+
+	void PushFinishedJobs(lua_State* L);
+
+protected:
+	/**
+	 * Get a Job from queue to be processed
+	 *  this function blocks until a job is ready
+	 * @return a job to be processed
+	 */
+	LuaJobInfo getJob();
+
+	/**
+	 * put a Job result back to result queue
+	 * @param result result of completed job
+	 */
+	void putJobResult(LuaJobInfo result);
+
+	/**
+	 * initialize environment with current registred functions
+	 *  this function adds all functions registred by registerFunction to the
+	 *  passed lua stack
+	 * @param L lua stack to initialize
+	 * @param top stack position
+	 */
+	void PrepareEnvironment(lua_State* L, int top);
+
+private:
+
+	/** variable locking the engine against further modification **/
+	bool m_initDone;
+
+	/** internal store for registred functions **/
+	std::map<std::string,lua_CFunction> m_FunctionList;
+
+	/** internal counter to create job id's **/
+	unsigned int m_JobIdCounter;
+
+	/** mutex to protect job queue **/
+	JMutex m_JobQueueMutex;
+	/** job queue **/
+	std::vector<LuaJobInfo> m_JobQueue;
+
+	/** mutext to protect result queue **/
+	JMutex m_ResultQueueMutex;
+	/** result queue **/
+	std::vector<LuaJobInfo> m_ResultQueue;
+
+	/** list of current worker threads **/
+	std::vector<AsyncWorkerThread*> m_WorkerThreads;
+
+	/** counter semaphore for job dispatching **/
+	JSemaphore m_JobQueueCounter;
+};
+
+#endif /* C_ASYNC_EVENTS_H_ */