anki-3d-engine/anki/core/AsyncLoader.h

#ifndef ANKI_CORE_ASYNC_LOADER_H
#define ANKI_CORE_ASYNC_LOADER_H

#include <list>
#include <string>
#include <boost/thread/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <SDL/SDL.h>


namespace anki {


/// Asynchronous loader
///
/// It creates a thread that loads files on demand. It accepts requests (in the
/// form of a filename of the file to load, a pointer to a function for the way
/// to load the file and a generic pointer for the data to load them to). Its
/// not meant to be destroyed because of a deadlock.
class AsyncLoader
{
public:
	/// Type of the callback function that the async loader wants
	typedef void (*LoadCallback)(const char*, void*);

	/// Default constructor starts the thread
	AsyncLoader()
	{
		start();
	}
	
	/// Do nothing
	~AsyncLoader()
	{}

	/// Tell me what to load, how to load it and where to store it. This
	/// puts a new loading request in the stack
	/// @param filename The file to load
	/// @param loadCallback How to load the file. The function should gets
	/// a filename (const char*) and the storage.
	/// It can throw an exception in case of a loading error
	/// @param storage This points to the storage that the loader will
	/// store the data. The storage should not be destroyed from other
	/// threads
	void load(const char* filename, LoadCallback loadCallback,
		void* storage);

	/// Query the loader and see if its got something
	/// @param[out] filename The file that finished loading
	/// @param[out] storage The data are stored in this buffer
	/// @param[out] ok Its true if the loading of the resource was ok
	/// @return Return true if there is something that finished loading
	bool pollForFinished(std::string& filename, void* storage, bool& ok);

private:
	/// A loading request
	struct Request
	{
		std::string filename;
		LoadCallback loadCallback;
		void* storage;
	};

	/// It contains a few things to identify the response
	struct Response
	{
		std::string filename;
		void* storage;
		bool ok; ///< True if the loading was successful
	};

	std::list<Request> requests;
	std::list<Response> responses;
	boost::mutex mutexReq; ///< Protect the requests container
	boost::mutex mutexResp; ///< Protect the responses container
	boost::thread thread;
	boost::condition_variable condVar;

	/// The thread function. It waits for something in the requests
	/// container
	void workingFunc();
	void start(); ///< Start thread
};


} // end namespace


#endif