Queue
The queue folder contains a multi-producer single-consumer queue implementation, which is composed of a non-templated base class and a generic templated class.
This queue will be unique to each cluster in the middleware system, and will be used to store Message objects.
The queue must be declared with a QueueTraits type, which is a templated structure that contains the following members:
T - the type that will be contained in the queue
LockStrategy - a type that will be used to lock a mutex with a RAII pattern.
- MutexType - the underlying mutex type accepted by
QueueMutex. It must be an integral type or a pointer to an integral type.
- MutexType - the underlying mutex type accepted by
ELEMENT_COUNT - the number of elements that the queue can store.
Queue state is initialized by the queue constructor. There is no separate
init call. To write and read from the queue, two nested classes named
Sender and Receiver are provided, each receiving a reference to a queue
object.
To write an element to the queue, call the method write of the Sender nested class.
To read an element from the queue, call peek, and then advance from the Receiver nested class.
The call to advance is needed in order for the queue to advance to the next written element.
Each queue will also contain statistics that are stored in a structure named QueueStats.
Each time a queue will be processed, you can call the queue’s takeSnapshot method to internally update some of these statistics like the maximum fill rate.
Other statistics, such as processed messages or lost messages, are updated during read and write operations.