RWTPCValQueueGuarded< Type > Class Template Reference

First-in-first-out (FIFO) queue that provides producer-consumer synchronization semantics for exchanging guarded values between cooperating threads. More...

#include <rw/itc/RWTPCValQueueGuarded.h>

Inheritance diagram for RWTPCValQueueGuarded< Type >:

Public Member Functions
	RWTPCValQueueGuarded (size_t maxCapacity=0, bool isOpen=true)
	~RWTPCValQueueGuarded (void)
Public Member Functions inherited from RWTPCValBufferBaseGuarded< Type, RWTGuardDecorator< Type > >
virtual	~RWTPCValBufferBaseGuarded (void)
Type	peek (void)
RWWaitStatus	peek (Type &result, unsigned long milliseconds)
Type	read (void)
RWWaitStatus	read (Type &result, unsigned long milliseconds)
bool	tryPeek (Type &value)
bool	tryRead (Type &value)
bool	tryWrite (const Type &value, const RWTFunctor< bool()> &guard)
void	write (const Type &value, const RWTFunctor< bool()> &guard)
RWWaitStatus	write (const Type &value, const RWTFunctor< bool()> &guard, unsigned long milliseconds)
Public Member Functions inherited from RWTPCValBufferBaseDecorated< Type, RWTGuardDecorator< Type > >
virtual	~RWTPCValBufferBaseDecorated (void)
Type	peek (void)
RWWaitStatus	peek (Type &result, unsigned long milliseconds)
Type	read (void)
RWWaitStatus	read (Type &result, unsigned long milliseconds)
bool	tryPeek (Type &result)
bool	tryRead (Type &result)
bool	tryWrite (const Type &value)
void	write (const Type &value)
RWWaitStatus	write (const Type &value, unsigned long milliseconds)

Additional Inherited Members
Protected Member Functions inherited from RWTPCValBufferBase< RWTGuardDecorator< Type > >
virtual	~RWTPCValBufferBase (void)
RWTGuardDecorator< Type >	peek (void)
RWWaitStatus	peek (RWTGuardDecorator< Type > &result, unsigned long milliseconds)
RWTGuardDecorator< Type >	read (void)
RWWaitStatus	read (RWTGuardDecorator< Type > &result, unsigned long milliseconds)
bool	tryPeek (RWTGuardDecorator< Type > &result)
bool	tryRead (RWTGuardDecorator< Type > &result)
bool	tryWrite (const RWTGuardDecorator< Type > &value)
void	write (const RWTGuardDecorator< Type > &value)
RWWaitStatus	write (const RWTGuardDecorator< Type > &value, unsigned long milliseconds)

Detailed Description

template<class Type>
class RWTPCValQueueGuarded< Type >

RWTPCValQueueGuarded<Type> is a first-in-first-out (FIFO) queue that provides producer-consumer synchronization semantics for exchanging guarded values between cooperating threads.

In the producer-consumer synchronization model, reader threads (consumers) are blocked while the queue is empty, and writer threads (producers) are blocked while the queue is full. The queue is considered full when the number of unread entries equals or exceeds some user-specified maximum capacity.

The write operations inherited by this class bind a guard functor to each value prior to storing that value in an internal buffer. A guard functor is used during read operations to determine whether the associated value is currently eligible for retrieval from the buffer.

Example

#include <rw/functor/RWTFunctor.h>
#include <rw/itc/RWTPCValQueueGuardedPrioritized.h>
#include <rw/thread/RWThreadFunction.h>
#include <iostream>

enum Command
{RUN, STOP, PROCESS_HIGH, PROCESS_MED, PROCESS_LOW, EXIT};

RWTPCValQueueGuardedPrioritized<Command>  pcQueue;
bool isRunning = false;

// The guard function
bool canProcess()
{
    return isRunning;
}

void reader(void)
{
    // Get commands from queue, update state,
    // and write to stdout.
    Command command;
    while (EXIT != (command = pcQueue.read())) {
        switch (command) {
            case RUN:
                std::cout << "RUN" << std::endl;
                isRunning = true;
                break;
            case STOP:
                std::cout << "STOP" << std::endl;
                isRunning = false;
                break;
            case PROCESS_HIGH:
                std::cout << "PROCESS_HIGH" << std::endl;
                break;
            case PROCESS_MED:
                std::cout << "PROCESS_MED" << std::endl;
                break;
            case PROCESS_LOW:
                std::cout << "PROCESS_LOW" << std::endl;
                break;
        }
    }
    std::cout << "EXIT" << std::endl;
}

int main()
{
    RWThread thread = RWThreadFunction::make(reader);
    RWTFunctor<bool()> guard = canProcess;

    thread.start();
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(2, PROCESS_MED, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(3, PROCESS_HIGH, guard);
    pcQueue.write(4, RUN);
    pcQueue.write(2, PROCESS_MED, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(3, PROCESS_HIGH, guard);
    pcQueue.write(4, STOP);
    pcQueue.write(3, PROCESS_HIGH, guard);
    pcQueue.write(1, PROCESS_LOW, guard);
    pcQueue.write(4, RUN);
    pcQueue.write(0, EXIT);
    thread.join();
    return 0;
}

OUTPUT:

RUN
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
STOP
RUN
PROCESS
PROCESS
PROCESS
EXIT

Constructor & Destructor Documentation

template<class Type >

RWTPCValQueueGuarded< Type >::RWTPCValQueueGuarded ( size_t  maxCapacity = 0, bool  isOpen = true  )

inline

Constructs a value-based, guarded, producer-consumer queue instance.

The parameter maxCapacity specifies the maximum number of unread entries allowed to accumulate within the queue. Once the number of entries in the queue equals this number, any thread attempting to write an additional entry is blocked until an entry is removed by a read operation, or until the capacity is increased. A capacity of zero, the default, indicates that the queue has no size limit, except as imposed by memory limitations, and that all write operations should complete without blocking.

The parameter isOpen is a bool value that specifies whether the queue should be initialized in the open state, true, the default, or the closed state, false.

template<class Type >

RWTPCValQueueGuarded< Type >::~RWTPCValQueueGuarded ( void  )

inline

Destructor.