Create an atomic, non-blocking single ended queue (FIFO) for storing a pointer to T. More...
#include <rtt/internal/AtomicQueue.hpp>
Public Types | |
| typedef unsigned int | size_type |
Public Member Functions | |
| AtomicQueue (unsigned int size) | |
| Create an AtomicQueue with queue size size. | |
| bool | isFull () const |
| Inspect if the Queue is full. | |
| bool | isEmpty () const |
| Inspect if the Queue is empty. | |
| size_type | capacity () const |
| Return the maximum number of items this queue can contain. | |
| size_type | size () const |
| Return the exact number of elements in the queue. | |
| bool | enqueue (const T &value) |
| Enqueue an item. | |
| bool | dequeue (T &result) |
| Dequeue an item. | |
| const T | front () const |
| Return the next to be read value. | |
| void | clear () |
| Clear all contents of the Queue and thus make it empty. | |
Detailed Description
template<class T>
class RTT::internal::AtomicQueue< 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 70 of file AtomicQueue.hpp.
Constructor & Destructor Documentation
| RTT::internal::AtomicQueue< T >::AtomicQueue | ( | 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 190 of file AtomicQueue.hpp.
References RTT::internal::AtomicQueue< T >::clear().
Member Function Documentation
| bool RTT::internal::AtomicQueue< T >::dequeue | ( | T & | result | ) | [inline] |
Dequeue an item.
- Parameters:
-
value The value dequeued.
- Returns:
- false if queue is empty, true if dequeued.
Definition at line 278 of file AtomicQueue.hpp.
References RTT::os::CAS().
| bool RTT::internal::AtomicQueue< T >::enqueue | ( | const T & | value | ) | [inline] |
Enqueue an item.
- Parameters:
-
value The value to enqueue, not zero.
- Returns:
- false if queue is full or value is zero, true if queued.
Definition at line 258 of file AtomicQueue.hpp.
References RTT::os::CAS().
| bool RTT::internal::AtomicQueue< T >::isEmpty | ( | ) | const [inline] |
Inspect if the Queue is empty.
- Returns:
- true if empty, false otherwise.
Definition at line 220 of file AtomicQueue.hpp.
| bool RTT::internal::AtomicQueue< T >::isFull | ( | ) | const [inline] |
Inspect if the Queue is full.
- Returns:
- true if full, false otherwise.
Definition at line 206 of file AtomicQueue.hpp.
| size_type RTT::internal::AtomicQueue< T >::size | ( | ) | const [inline] |
Return the exact number of elements in the queue.
This is slow because it scans the whole queue.
Definition at line 241 of file AtomicQueue.hpp.
The documentation for this class was generated from the following file:
- rtt/internal/AtomicQueue.hpp
