PollThread.cc

Go to the documentation of this file.

#ifndef PLATFORM_APERIOS
#include "PollThread.h"
#include <stdio.h>
#include <errno.h>
#include <signal.h>

//better to put this here instead of the header
using namespace std; 

void PollThread::start() {
  initialPoll=true;
  startTime.Set();
  Thread::start();
}

bool PollThread::poll() {
  unsigned int sleeptime=runloop();
  if(sleeptime==-1U)
    return false;
  period.Set(static_cast<long>(sleeptime));
  return true;
}

void PollThread::interrupted() {
  if(!initialPoll) {
    if(period-startTime.Age()<1L) {
      delay=0L;
    } else {
      while(!(period-startTime.Age()<1L))
        startTime-=period;
      startTime+=period;
      delay=period;
    }
  }
}

void * PollThread::run() {
  timespec sleepSpec,remainSpec;
  TimeET age = startTime.Age();
  if(age<delay) {
    sleepSpec=delay-age;
    while(nanosleep(&sleepSpec,&remainSpec)) {
      if(errno!=EINTR) {
        if(errno==EINVAL)
          std::cerr << "Invalid PollThread periodic sleep time, age=" << startTime.Age() << " period=" << period << ", delay=" << delay << " sleepSpec=" << sleepSpec.tv_sec << ' ' << sleepSpec.tv_nsec << std::endl;
        else
          perror("PollThread::run(): initial nanosleep");
        break;
      }
      testCancel();
      //interrupted() may have changed delay to indicate remaining sleep time
      age = startTime.Age();
      if(delay<1L || delay<age)
        break;
      sleepSpec=delay-age;
    }
  }
  testCancel();
  if(!poll())
    return returnValue;
  initialPoll=false;
  bool wasInterrupted=true; // need to add delay instead of period for the first time, same as if an interrupt occurred
  for(;;) {
    bool noSleep=false;
    if(TimeET(0,0)<period) {
      if(trackPollTime) {
        if(wasInterrupted) {
          if(delay<0L || startTime.Age()<delay) {}
          else
            startTime+=delay;
        } else {
          if(startTime.Age()<period) {}
          else
            startTime+=period;
        }
        //the idea with this part is that if we get behind, (because of poll() taking longer than period)
        // then we want to quick poll again as fast as we can to catch up, but we don't want to backlog
        // such that we'll be quick-calling multiple times once we do catch up
        if(period<startTime.Age()) {
          noSleep=true;
          while(period<startTime.Age())
            startTime+=period;
          startTime-=period; //back off one -- the amount we've overshot counts towards the next period
        }
        age = startTime.Age();
        if(age<period)
          sleepSpec=period-age;
        else
          noSleep=true;
      } else {
        sleepSpec=period;
        startTime.Set();
      }
      wasInterrupted=false;
      while(!noSleep && nanosleep(&sleepSpec,&remainSpec)) {
        wasInterrupted=true;
        if(errno!=EINTR) {
          if(errno==EINVAL)
            std::cerr << "Invalid PollThread periodic sleep time, age=" << startTime.Age() << " period=" << period << ", delay=" << delay << " sleepSpec=" << sleepSpec.tv_sec << ' ' << sleepSpec.tv_nsec << std::endl;
          else
            perror("PollThread::run(): periodic nanosleep");
          break;
        }
        testCancel();
        //interrupted() should have changed delay and/or period to indicate remaining sleep time
        age = startTime.Age();
        if(delay<1L || delay<age)
          break;
        sleepSpec=delay-age;
      }
    } else {
      startTime.Set();
    }
    testCancel();
    if(!poll())
      return returnValue;
  }
  // this return is just to satisfy warnings with silly compiler
  return returnValue; //never happens -- cancel or bad poll would exit
}

//void PollThread::cancelled() {
  //signal handlers are global, not per-thread, so if we reset the handler, then the next interrupt will cause the program to end :(
  //signal(SIGALRM,SIG_DFL);
//}



/*! @file
 * @brief 
 * @author Ethan Tira-Thompson (ejt) (Creator)
 */
#endif