RWTPCValQueueGuardedPrioritized<Type>RWTPCValBufferBaseGuardedPrioritized<Type,RWTGuardAndPriorityDecorator<Type>>
None
#include <rw/itc/RWTPCValQueueGuardedPrioritized.h>
RWTPCValQueueGuardedPrioritized<Type> is a first-in-first-out (FIFO) queue that provides producer-consumer synchronization semantics for exchanging guarded and prioritized 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 and priority value to each data value prior to storing that value in an internal buffer. The guard functor is used during read operations to determine whether the associated value is currently eligible for retrieval from the buffer. The priority value is used during write operations to determine a value's insertion point within the queue, such that the set of unread values will be retrieved in priority order when they are eventually read from the queue. A new value is retrieved after any previously inserted values of the same priority, except when the retrieval of the older values is prohibited by their guard functors.
#include <rw/itc/RWTPCValQueueGuardedPrioritized.h>
#include <rw/thread/RWThreadFunction.h> // for RWThreadFunction
#include <rw/functor/functorR0.h> // for RWTFunctorR0<>
#include <iostream.h>
enum Command
{RUN,STOP,PROCESS_HIGH,PROCESS_MED,PROCESS_LOW,EXIT};
RWTPCValQueueGuardedPrioritized<Command> pcQueue;
RWBoolean isRunning = FALSE;
// The guard function
RWBoolean 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: cout<<"RUN"<<endl; isRunning=TRUE; break;
case STOP: cout<<"STOP"<<endl; isRunning=FALSE; break;
case PROCESS_HIGH: cout<<"PROCESS_HIGH"<<endl; break;
case PROCESS_MED: cout<<"PROCESS_MED"<<endl; break;
case PROCESS_LOW: cout<<"PROCESS_LOW"<<endl; break;
}
}
cout<<"EXIT"<<endl;
}
int main()
{
RWThread thread = rwtMakeThreadFunctionG(void,reader);
RWTFunctorR0<RWBoolean> guard =
rwtMakeFunctorR0G(RWBoolean,RWBoolean,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;
}
This code produces the following output:
RUN PROCESS_HIGH PROCESS_MED PROCESS_MED PROCESS_LOW PROCESS_LOW PROCESS_LOW PROCESS_LOW PROCESS_LOW PROCESS_LOW STOP RUN PROCESS_HIGH PROCESS_HIGH PROCESS_LOW EXIT
RWTPCValQueueGuardedPrioritized(size_t maxCapacity=0,
RWBoolean isOpen=TRUE);
Constructs a value-based, guarded, prioritized, 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 an RWBoolean value that specifies whether the queue should be initialized in the open state (TRUE, the default) or the closed state (FALSE).
RWTPCValBufferBaseGuardedPrioritized<...>, RWTPCValStackGuardedPrioritized<Type>
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