How to call a function with multiple threads at regular interal? - c++

Question

I use deadline_timer and pthread_t to call a function at regular interval.
I need return values from pthread so I use thread joinable.
That function takes around 60msec to process.
I like to call that function at every 10 msec with six threads, so that function is processed at every 10msec. Even though I tested here two threads, it is supposed to run six threads at every 10msec interval.
I made the function to be thread safe.
Main.c
int main()
{
io_service io;
deadline_timer t(io);
Wheelchaircontrol w(t);
io.run();
std::cout << "Exit" << endl;
}
W_control class
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <iostream>
using namespace std;
using namespace boost::asio;
static const int NUM_THREADS = 6;
struct Detectdirection {
static void* Tracking_helper(void*) {
return nullptr; // take 60ms in threadsafe manner
}
};
class Wheelchaircontrol {
public:
Wheelchaircontrol(deadline_timer &t_) : t(t_) {
d = new Detectdirection();
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
wait();
}
~Wheelchaircontrol() { delete d; }
void timeout(const boost::system::error_code &e) {
for (int t = 0; t < NUM_THREADS; t++) {
usleep(10000); // 10 msec
switch (t) {
case 0:
rc = pthread_create(&thread[t], &attr, d->Tracking_helper, d);
if (rc) {
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
break;
case 1:
rc = pthread_create(&thread[t], &attr, d->Tracking_helper, d);
if (rc) {
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
break;
} // switch (t)
} // for
for (int t = 0; t < NUM_THREADS; t++) {
switch (t) {
case 0:
rc = pthread_join(thread[t], &ret_status);
if (!rc) {
free(ret_status);
gettimeofday(&tp, NULL);
long int ms = tp.tv_sec * 1000 + tp.tv_usec / 1000;
cout << " time instance from1 " << ms << endl;
}
break;
case 1:
rc = pthread_join(thread[t], &ret_status);
if (!rc) {
free(ret_status);
gettimeofday(&tp, NULL);
long int ms = tp.tv_sec * 1000 + tp.tv_usec / 1000;
cout << " time instance from2 " << ms << endl;
}
break;
} // switch (t)
} // for
wait();
}
void cancel() { t.cancel(); }
void wait() {
t.expires_from_now(boost::posix_time::milliseconds(1)); // 100msec
t.async_wait(boost::bind(&Wheelchaircontrol::timeout, this, boost::asio::placeholders::error));
}
private:
int rc;
deadline_timer &t;
struct timeval tp;
Detectdirection *d; // for direction
// InterfaceUSB *usb;
pthread_t thread[NUM_THREADS];
pthread_attr_t attr;
void *ret_status;
int distance;
bool imturn;
// myMosq *mq;
// int cnt_mqt;
// ofstream out;
};
Tracking_helper is the function to be executed at every 10 msec.
time instance from1 1480056797897
time instance from2 1480056797957
time instance from1 1480056798089
time instance from2 1480056798089
time instance from1 1480056798156
time instance from2 1480056798226
time instance from1 1480056798358
time instance from2 1480056798358
time instance from1 1480056798493
time instance from2 1480056798494
time instance from1 1480056798557
But the time instances are not in equal interval.
Sometime they finish at same time instances.
I like to have all in 10msec interval.