ArmarX Threads

ArmarX provides utility methods in order to include different types of threads.

In order to support the inclusion of multiple threads in a single objects, without the neccessity to write additional thread classes the mechanism uses functionoids of class methods. Two types of threads are provided by the ArmarX core: the RunningTask and the PeriodicTask. These can be extended in projects which use the ArmarX core.

The API documentation can be found here: Threads

Using running tasks

The running task executes one thread method once. The task can be started only once.

#include <ArmarXCore/core/Component.h>
#include <ArmarXCore/core/services/tasks/RunningTask.h>
 
namespace armarx
{
    class RunningTaskExample :
        virtual public Component
    {
    public:
        virtual std::string getDefaultName()
        {
            return "RunningTaskExample";
        }
            
        virtual void onInitComponent()
        {
        }
 
        virtual void onConnectComponent()
        {
            // create a running task which uses exampleThreadMethod in this class as thread method
            // namespace needs to be specified with the method name
            exampleTask = new RunningTask<RunningTaskExample>(this, &RunningTaskExample::exampleThreadMethod);
 
            // start the thread
            exampleTask->start();
        }
            
        virtual void onDisconnectComponent()
        {
            // stop the thread and wait for join
            exampleTask->stop();
        }
            
        void exampleThreadMethod()
        {
            // do the work
            printf("Thread method\n");
                
            // shutdown is set if exampleTask->stop() is called.
            // running tasks need to handle the shutdown by themselves.
            // Here it is essentially not necessary but just serves as an example
            while(!exampleTask->isStopped())
            {
                usleep(10);
                // if the sleep time should be synchronized with Simulator time,
                // use TimeUtil::Sleep(IceUtil::Time) or TimeUtil::MSSleep(int) instead
                // Especially this will pause execution when the simulator is paused
                //TimeUtil::MSSleep(1)
            }
        }
 
    private:
        // shared pointer to RunningTask
        RunningTask<RunningTaskExample>::pointer_type exampleTask;
    };
 
}

Using periodic tasks

The periodic task executes one thread method repeatedly using the time period specified in the constructor.

#include <ArmarXCore/core/Component.h>
#include <ArmarXCore/core/services/tasks/PeriodicTask.h>
 
namespace armarx
{
    class PeriodicTaskExample :
        virtual public Component
    {
    public:
        virtual std::string getDefaultName()
        {
            return "PeriodicTaskExample";
        }
            
        virtual void onInitComponent()
        {
        }
 
        virtual void onConnectComponent()
        {
            // create a running task which uses exampleThreadMethod in this class as thread method
            // namespace needs to be specified with the method name
            // will be called every second
            exampleTask = new PeriodicTask<PeriodicTaskExample>(this, &PeriodicTaskExample::exampleThreadMethod, 1000);
 
            // start the thread
            exampleTask->start();
        }
            
        virtual void onDisconnectComponent()
        {
            // stop the thread and wait for join
            exampleTask->stop();
        }
            
        void exampleThreadMethod()
        {
            // do the work
            printf("Thread method\n");
        }
 
    private:
        // shared pointer to PeriodicTask
        PeriodicTask<PeriodicTaskExample>::pointer_type exampleTask;
    };
 
}