OpenFrames::FrameManager Class Reference

This class allows priority access to a ReferenceFrame heirarchy. More...

#include <FrameManager.hpp>

Inheritance diagram for OpenFrames::FrameManager:

Public Types
enum	Priority { LOW_PRIORITY, HIGH_PRIORITY }

Public Member Functions
	FrameManager (ReferenceFrame *frame=NULL)
void	setFrame (ReferenceFrame *frame)
ReferenceFrame *	getFrame ()
osg::Group *	getData ()
int	lock (Priority priority=HIGH_PRIORITY)
int	unlock (Priority priority=HIGH_PRIORITY)
	Users must specify the same priority as they did for lock/trylock.
int	trylock (Priority priority=HIGH_PRIORITY)

Protected Attributes
osg::ref_ptr< ReferenceFrame >	_frame
OpenThreads::Mutex	_mutexData
OpenThreads::Mutex	_mutexNext
OpenThreads::Mutex	_mutexLP

Detailed Description

This class allows priority access to a ReferenceFrame heirarchy.

This class allows multiple clients to synchronize access to a ReferenceFrame heirarchy, but allows high-priority clients access before low-priority clients. This avoids the case where high-fps rendering threads can hog the lock on certain OS's, and significantly delay the user trying to acquire the lock. To use: threads that frequently acquire the lock (e.g. rendering threads) should use low priority, and threads that need to make one-off changes to the scene graph (e.g. the user) should use high priority. NOTE: Implements "triple mutex" approach documented in: https://stackoverflow.com/questions/11666610/how-to-give-priority-to-privileged-thread-in-mutex-locking Approach summary: Data mutex D, Next-access mutex N, low-priority mutex L Low-priority Thread: lock L -> lock N -> lock D -> unlock N -> (...work...) -> unlock D -> unlock L High-priority Thread: lock N -> lock D -> unlock N -> (...work...) -> unlock D.

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The documentation for this class was generated from the following file:

• include/OpenFrames/FrameManager.hpp