Stopping a Poco::Thread for Unit Tests - c++

Question

Problem
I have a UDPlistener application that I need to write a unit test for. This listener continuously listens on a port and is meant to always be running on the product. We use the poco libraries for frameworks not in the standard library.
Now I need to add it to the unit test application.
Curent Solution
I thought it would be easiest to implement Poco::Runnable in a class RunApp that runs the application. Then I can create a new Poco::Thread in my unit test to run the RunApp class.
This works; my listener is running and I can send test messages in the unit test body after the thread is spawned. BUT, I need to stop the listener so other unit tests can run. I added a UDP message that tells the listener to kill itself but this is only used by the unit test and a potential security problem.
Question
Is there a way to force a Poco::Thread to stop? Or I structuring this unit test wrong? I don't want the listener to run during all the other unit tests.

Answer 1

If instead of using a Poco::Thread you use a Poco::Task, you get a thread that can be cancelled. The following sample code (ready to run as-is) should give you an idea:
#include <Poco/Task.h>
#include <Poco/TaskManager.h>
#include <Poco/Thread.h>
#include <string>
#include <iostream>
using namespace std;
class UdpListenerTask : public Poco::Task {
public:
UdpListenerTask(const string& name) : Task(name) { }
void runTask() {
cout << name() << ": starting" << endl;
while (! isCancelled()) {
// Do some work. Cannot block indefinitely, otherwise it
// will never test the isCancelled() condition.
doSomeWork();
}
cout << endl << name() << ": cancelled " << endl;
}
private:
int doSomeWork() {
cout << "*" << flush;
// Simulate some time spent doing work
int i;
for (i = 0; i < INT32_MAX/1000; i++) { }
return i;
}
};
void runUdpProbe() {
// Simulate some time spent running the probe.
Poco::Thread::sleep(1000);
}
int main() {
Poco::TaskManager tm;
UdpListenerTask* st = new UdpListenerTask("task1");
tm.start(st); // tm takes ownership
// Run test 1.
runUdpProbe();
// Test 1 done. Cancel the UDP listener
st->cancel();
// Run all the other tests
// cleanup
tm.joinAll();
return 0;
}
The POCO slides Multithreading give examples of usage of both Poco::Thread and Poco::Task.
As an aside, a unit test should bypass the UDP communication via abstract classes and mock objects; I think this test should be called feature test :-)