Waking a boost::sleep timer and reset it to 0 in C++

Question

I require a heartbeat signal every 10 seconds or so. To implement this I have produced a class with the following constructor:

HeartBeat::HeartBeat (int Seconds, MessageQueue * MsgQueue)
{
TimerSeconds = Seconds;
    pQueue = MsgQueue;
    isRunning = true;
    assert(!m_pHBThread);
    m_pHBThread = shared_ptr<thread>(new thread(boost::bind(&HeartBeat::TimerStart,this)));
}

Which calls the following method in a new thread:

void HeartBeat::TimerStart ()
{
while (1)
{
    cout << "heartbeat..." << endl;
    boost::this_thread::sleep(boost::posix_time::seconds (TimerSeconds));
    addHeartBeat();
}
}

This produces a heartbeat with out any issues. However I would like to be able to reset the sleep timer back to zero. Is there a simple way of doing this, or should I use something other than

 boost::this_thread::sleep

for my sleep?

---

OS: Redhat

IDE: Eclipse

Code language: C++

---

EDIT:

I have looked at using

m_pHBThread->interrupt();

And it seems to be what I'm after, so thank you!

Answer 1

This sounds exactly like what asynchronous timer does. Since you're using boost already, perhaps it makes sense to use boost's own async timers in the long run?

#include <iostream>
#include <boost/thread.hpp>
#include <boost/date_time.hpp>
#include <boost/asio.hpp>
boost::posix_time::ptime now()
{
        return boost::posix_time::microsec_clock::local_time();
}
class HeartBeat {
    boost::asio::io_service ios;
    boost::asio::deadline_timer timer;
    boost::posix_time::time_duration TimerSeconds;
    boost::thread thread;
 public:
    HeartBeat(int Seconds) : ios(), timer(ios),
        TimerSeconds(boost::posix_time::seconds(Seconds))
    {
        reset(); // has to start timer before starting the thread
        thread = boost::thread(boost::bind(&boost::asio::io_service::run,
                                           &ios));
    }
    ~HeartBeat() {
        ios.stop();
        thread.join();
    }
    void reset()
    {
        timer.expires_from_now(TimerSeconds);
        timer.async_wait(boost::bind(&HeartBeat::TimerExpired,
                        this, boost::asio::placeholders::error));
    }
    void TimerExpired(const boost::system::error_code& ec)
    {
        if (ec == boost::asio::error::operation_aborted) {
           std::cout << "[" << now() << "] timer was reset" << std::endl;
        } else {
           std::cout << "[" << now() << "] heartbeat..." << std::endl;
           reset();
        }
    }
};
int main()
{
    std::cout << "["  << now() << "] starting up.\n";
    HeartBeat hb(10);
    sleep(15);
    std::cout << "["  << now() << "] Resetting the timer\n";
    hb.reset();
    sleep(15);
}

test run:

~ $ ./test
[2011-Sep-07 12:08:17.348625] starting up.
[2011-Sep-07 12:08:27.348944] heartbeat...
[2011-Sep-07 12:08:32.349002] Resetting the timer
[2011-Sep-07 12:08:32.349108] timer was reset
[2011-Sep-07 12:08:42.349160] heartbeat...

Answer 2

也许您可以使用interrupt（）来执行此操作。

Answer 3

Well, it is not very efficient to launch a new thread every time you have an heart beat... I'd do it instead with a single thread and a sleep inside it. If you need to change the heart beat frequency then you can kill the current thread and start a new one with a new sleep time. You can use the boost::thread and the interrupt signal for this.

EDIT: look here for info on boost threads: boost thread management

if you want to reset the time to zero and execute your code immediately then call it inside the catch for boost::thread_interrupted...

EDIT2: I didn't look properly to the code and I assumed that the common error of launching a new thread for each heart beat was there... sorry, my mistake... I guess I don't like the fact that the thread's name is: TimerStart()
Anyway I think that using the interrupt() and catching it should work if you need to execute the heart beat right away.