Another Asynchronous Example
Example 48 provides another alternative for processing the results of asynchronous operations. In this example, the
RWRunnableServer is replaced by an
RWServerPool, an identification value is added for each operation invocation, and the
RWTIOUTrap processes the results of the operations.
Example 48 – Using an IOU trap to handle results from asynchronous operations
#include <rw/thread/RWRunnableSelf.h>
#include <rw/thread/RWServerPool.h>
#include <rw/thread/RWTRunnableIOUFunction.h>
#include <rw/itc/RWTIOUResult.h>
#include <rw/itc/RWTIOUTrap.h>
#include <iostream>
using namespace std;
class ServiceProvider; // Forward reference for inlines!
class ServiceProvider {
private:
RWServerPool server_;
protected:
int syncService(int opId, int delay) // 1
{
// Do something that takes varying amounts of time
rwSleep(delay);
return opId;
}
public:
ServiceProvider(size_t concurrencyLevel) { // 2
server_ = RWServerPool::make(concurrencyLevel);
server_.start();
}
~ServiceProvider() { // 3
server_.stop();
server_.join();
}
RWTIOUResult<int> asyncService(int opId, int delay) { // 4
RWTRunnableIOUFunction<int> runnable;
runnable = RWTRunnableIOUFunction<int>::make(
rwBind(&ServiceProvider::syncService, this, opId, delay));
server_.enqueue(runnable);
return runnable.result();
}
};
void
main()
{
const size_t concurrency = 5;
const size_t operations = 10;
size_t i;
ServiceProvider provider(concurrency); // 5
RWTIOUTrap<int> trap; // 6
for (i=0; i<operations; i++)
trap.setTrap(provider.asyncService(i,rand()%1000)); // 7
for (i=0; i<operations; i++) {
cout << "Operation ";
cout << trap.getNext(); // 8
cout << " complete!" << endl;
}
}
