RTT::internal::AtomicMWMRQueue< T > Class Template Reference

Create an atomic, non-blocking single ended queue (FIFO) for storing a pointer to T. More...

#include <rtt/internal/AtomicMWMRQueue.hpp>

Inheritance diagram for RTT::internal::AtomicMWMRQueue< T >:

Public Types
typedef AtomicQueue< T >::size_type	size_type

Public Member Functions
	AtomicMWMRQueue (unsigned int size)
	Create an AtomicQueue with queue size size. More...
	~AtomicMWMRQueue ()
bool	isFull () const
	Inspect if the Queue is full. More...
bool	isEmpty () const
	Inspect if the Queue is empty. More...
size_type	capacity () const
	Return the maximum number of items this queue can contain. More...
size_type	size () const
	Return the exact number of elements in the queue. More...
bool	enqueue (const T &value)
	Enqueue an item. More...
bool	dequeue (T &result)
	Dequeue an item. More...
const T	front () const
	Return the next to be read value. More...
void	clear ()
	Clear all contents of the Queue and thus make it empty. More...

Detailed Description

template<class T>
class RTT::internal::AtomicMWMRQueue< T >

Create an atomic, non-blocking single ended queue (FIFO) for storing a pointer to T.

It is a Many Readers, Many Writers implementation based on the atomic Compare And Swap instruction. Any number of threads may access the queue concurrently.

This queue tries to obey strict ordering, but under high contention of reads interfering writes, one or more elements may be dequeued out of order. For this reason, size() is expensive to accurately calculate the size.

Due to the same limitations, it is possible that the full capacity of the queue is not used (simulations show seldomly an off by one element if capacity==10) and that isFull() returns true, while size() < capacity().

Warning

You can not store null pointers.

Parameters

T	The pointer type to be stored in the Queue. Example : AtomicQueue< A* > is a queue of pointers to A.

Definition at line 71 of file AtomicMWMRQueue.hpp.

Member Typedef Documentation

template<class T >

typedef AtomicQueue<T>::size_type RTT::internal::AtomicMWMRQueue< T >::size_type

Definition at line 185 of file AtomicMWMRQueue.hpp.

Constructor & Destructor Documentation

template<class T >

RTT::internal::AtomicMWMRQueue< T >::AtomicMWMRQueue ( unsigned int  size )

inline

Create an AtomicQueue with queue size size.

Parameters

size	The size of the queue, should be 1 or greater.

Definition at line 191 of file AtomicMWMRQueue.hpp.

References RTT::internal::AtomicMWMRQueue< T >::clear().

template<class T >

RTT::internal::AtomicMWMRQueue< T >::~AtomicMWMRQueue ( )

inline

Definition at line 198 of file AtomicMWMRQueue.hpp.

Member Function Documentation

template<class T >

size_type RTT::internal::AtomicMWMRQueue< T >::capacity ( ) const

inlinevirtual

Return the maximum number of items this queue can contain.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 232 of file AtomicMWMRQueue.hpp.

template<class T >

void RTT::internal::AtomicMWMRQueue< T >::clear ( )

inlinevirtual

Clear all contents of the Queue and thus make it empty.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 305 of file AtomicMWMRQueue.hpp.

Referenced by RTT::internal::AtomicMWMRQueue< T >::AtomicMWMRQueue().

template<class T >

bool RTT::internal::AtomicMWMRQueue< T >::dequeue ( T &  result )

inlinevirtual

Dequeue an item.

Parameters

value

The value dequeued.

Returns

false if queue is empty, true if dequeued.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 279 of file AtomicMWMRQueue.hpp.

References RTT::os::CAS().

template<class T >

bool RTT::internal::AtomicMWMRQueue< T >::enqueue ( const T &  value )

inlinevirtual

Enqueue an item.

Parameters

value

The value to enqueue, not zero.

Returns

false if queue is full or value is zero, true if queued.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 259 of file AtomicMWMRQueue.hpp.

References RTT::os::CAS().

template<class T >

const T RTT::internal::AtomicMWMRQueue< T >::front ( ) const

inlinevirtual

Return the next to be read value.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 297 of file AtomicMWMRQueue.hpp.

template<class T >

bool RTT::internal::AtomicMWMRQueue< T >::isEmpty ( ) const

inlinevirtual

Inspect if the Queue is empty.

Returns

true if empty, false otherwise.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 221 of file AtomicMWMRQueue.hpp.

template<class T >

bool RTT::internal::AtomicMWMRQueue< T >::isFull ( ) const

inlinevirtual

Inspect if the Queue is full.

Returns

true if full, false otherwise.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 207 of file AtomicMWMRQueue.hpp.

template<class T >

size_type RTT::internal::AtomicMWMRQueue< T >::size ( ) const

inlinevirtual

Return the exact number of elements in the queue.

This is slow because it scans the whole queue.

Implements RTT::internal::AtomicQueue< T >.

Definition at line 242 of file AtomicMWMRQueue.hpp.

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

• rtt/internal/AtomicMWMRQueue.hpp