handler_example.cpp

#include <shogun/base/init.h>
#include <shogun/base/some.h>
#include <shogun/labels/BinaryLabels.h>
#include <shogun/lib/SGVector.h>
#include <shogun/lib/Signal.h>
#include <shogun/machine/Machine.h>
#include <iostream>
#include <thread>

using namespace shogun;
using namespace std;

// Mock algorithm which implements a fake train_machine method
class MockAlg : public CMachine {

	public:
	MockAlg() : m_counter(0) {}
	~MockAlg() {}

protected:
	
	virtual bool train_machine(CFeatures * feat) {
		cout << "Training machine..." << endl;
		for(; m_counter<10000; m_counter++)
		{
			COMPUTATION_CONTROLLERS
			// We set up a delay to simulate long computation
			this_thread::sleep_for(chrono::milliseconds(1000));
		}			
	}


	// on_next() method which implements a custom behavior.  
	virtual void on_next()
	{
		m_cancel_computation.store(true);
		cout << "We have done " << m_counter << " iterations" << endl;
	}

private:
	int m_counter;

};

int main() {

	init_shogun_with_defaults();

	// Set up binary labels
	int * labs = new int[2];
	labs[0] = -1;
	labs[1] = 1;
    	SGVector<int32_t> labs_v {labs, 2};
	auto train_labs = some<CBinaryLabels>(labs_v);

	// We enable the signal handler. This way when pressing
	// CTRL+C, it will be Shogun handler to catch the SIGINT
	// message.
	get_global_signal()->enable_handler();

	MockAlg a, b;
	a.set_labels(train_labs);
	b.set_labels(train_labs);
	
	// The MockAlg instance is registered into the signal
	// handler by the train() method. The() train method
	// is also responsible for unregistering the algorithm when
	// the training is ended and also to reset all the
	// flags used (so that subsequent calls to the train()
	// method can be done without problems). 
	a.train();
	b.train();

	return 0;
}

result

uriel@uriel:Playground$ ./a.out 
Training machine...
^C
[ShogunSignalHandler] Immediately return to prompt / Prematurely finish computations / Pause current computation / Do nothing (I/C/P/D)? C
[ShogunSignalHandler] Terminating prematurely current algorithm...
We have done 11 iterations
Training machine...
^C
[ShogunSignalHandler] Immediately return to prompt / Prematurely finish computations / Pause current computation / Do nothing (I/C/P/D)? C
[ShogunSignalHandler] Terminating prematurely current algorithm...
We have done 4 iterations
uriel@uriel:Playground$