RTT::os::Semaphore Class Reference

#include <Semaphore.hpp>

Public Member Functions
	Semaphore (int count)
void	signal ()
bool	trywait ()
int	value ()
void	wait ()
	~Semaphore ()

Private Attributes
rt_sem_t	sem

Detailed Description

An object oriented wrapper around a counting semaphore. It works like a traffic light on which a thread can wait() until the sempahore's value becomes positive, otherwise it blocks. Another thread then needs to signal() the semaphore. One thread which is waiting will then be awakened, if none is waiting, the first thread calling wait() will continue directly (and decrease the value by 1).

Warning

Semaphore instances should only be created in soft realtime, since the initialisation of a semaphore can not be done in hard realtime.

Definition at line 61 of file Semaphore.hpp.

Constructor & Destructor Documentation

RTT::os::Semaphore::Semaphore ( int  count )

inline

Initialize a Semaphore with an initial count.

See also

value() to retrieve the current count.

Definition at line 70 of file Semaphore.hpp.

RTT::os::Semaphore::~Semaphore ( )

inline

Destroy a Semaphore.

Definition at line 78 of file Semaphore.hpp.

Member Function Documentation

void RTT::os::Semaphore::signal ( )

inline

Raise this semaphore and signal one thread waiting on this semaphore.

Definition at line 96 of file Semaphore.hpp.

bool RTT::os::Semaphore::trywait ( )

inline

Try to wait on this semaphore

Returns

true when the locking succeeded ( this->value() was > 0), false otherwise ( this->value() was = 0 )

Definition at line 106 of file Semaphore.hpp.

int RTT::os::Semaphore::value ( )

inline

Return the current count of this semaphore.

Definition at line 117 of file Semaphore.hpp.

void RTT::os::Semaphore::wait ( )

inline

Lower this semaphore and return if value() is non zero. Or wait if value() is zero until a signal occurs.

Definition at line 87 of file Semaphore.hpp.

Member Data Documentation

rt_sem_t RTT::os::Semaphore::sem

private

Definition at line 64 of file Semaphore.hpp.

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

• Semaphore.hpp