freeing worker resources

main.cpp

// g++ -std=c++11 main.cpp -lpthread -o main && ./main
#include <iostream>
#include <thread>
#include <atomic>
#include <chrono>

class BackgroundTask {
public:
    BackgroundTask() : done_(false),
        worker_(&BackgroundTask::worker_main, this) {}
    virtual ~BackgroundTask() {}
protected:
    virtual void execute() = 0;
    void join_worker() { done_ = true; worker_.join(); }
private:
    std::thread worker_;
    std::atomic<bool> done_;
    void worker_main() {
        while (1) {
            if (done_) return;
            execute();
        }
    }
};

class Printer : public BackgroundTask {
public:
    Printer() {
        resource_ = new float[1] { 12.34 };
    }
    virtual ~Printer() {
        // need to join worker *before* freeing resource
        // every derived class needs to do this :(
        join_worker();
        delete[] resource_;
    }
    void execute() {
        std::cout << "my resource: " << resource_[0] << std::endl;
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }
private:
    float *resource_;
};

int main(int argc, char *argv[]) {
    Printer p;
    std::this_thread::sleep_for(std::chrono::seconds(3));
    return 0;
}