haiku/headers/private/media/DormantNodeManager.h

/* 
 * Copyright 2002, Marcus Overhagen. All rights reserved.
 * Distributed under the terms of the MIT License.
 */

#ifndef _DORMANT_NODE_MANAGER_H
#define _DORMANT_NODE_MANAGER_H

#include "TMap.h"

namespace BPrivate {
namespace media {

// To instantiate a dormant node in the current address space, we need to
// either load the add-on from file and create a new BMediaAddOn class and
// cache the BMediaAddOn after that for later reuse, or reuse the cached
// BMediaAddOn if we already have one.
// This is handled by the DormantNodeManager.
//
// GetAddon() will provide a ready to use BMediaAddOn, while
// PutAddonDelayed() will unload it when it's no longer needed,
// but will delay the unloading slightly, because it is called
// from a node destructor of the loaded add-on.

class DormantNodeManager
{
public:
	DormantNodeManager();
	~DormantNodeManager();

	// Be careful, GetAddon and PutAddon[Delayed] must be balanced.
	BMediaAddOn *GetAddon(media_addon_id id);
	void PutAddon(media_addon_id id);
	void PutAddonDelayed(media_addon_id id);

	// For use by media_addon_server only
	media_addon_id RegisterAddon(const char *path);
	void UnregisterAddon(media_addon_id id);
	
	// query the server for the path
	status_t FindAddonPath(BPath *path, media_addon_id id);

private:
	struct loaded_addon_info
	{
		BMediaAddOn *addon;
		image_id image;
		int32 usecount;
	};

	// returns the addon or NULL if it needs to be loaded
	BMediaAddOn *TryGetAddon(media_addon_id id);
	
	// manage loading and unloading add-ons from images
	status_t LoadAddon(BMediaAddOn **newaddon, image_id *newimage, const char *path, media_addon_id id);
	void UnloadAddon(BMediaAddOn *addon, image_id image);
	
private:

	Map<media_addon_id,loaded_addon_info> *fAddonmap;
	BLocker *fLock;
};

}; // namespace media
}; // namespace BPrivate

extern BPrivate::media::DormantNodeManager *_DormantNodeManager;

#endif /* _DORMANT_NODE_MANAGER_H */