int main() { { struct timeval tv; TimeStampQueue tsq; TimeStamp now; cout << "Start Time: " << now << endl; for(int i=100; i<=900; i+=100) tsq.push( new TimeStamp(6, i MILLISEC) ); tsq.push( new TimeStamp(10, 0) ); tsq.push( new TimeStamp(3, 00 MILLISEC) ); tsq.push( new TimeStamp(14, 950 MILLISEC) ); cout << " Expected time \t Real Time \t Delta \tFlag" << endl; cout << "==========================\t==========================\t=========\t====" << endl; while( 1 ) { now.setNow(); if( ! tsq.empty() ) { // schedule next event tv.tv_sec = tsq.top()->getEpoch() - now.getEpoch(); tv.tv_usec = tsq.top()->getMicroSecond() - now.getMicroSecond(); // adjust for carry if( tv.tv_usec < 0 ) { tv.tv_sec -= 1; tv.tv_usec = 1000000L + tv.tv_usec; } if( tv.tv_sec < 0 ) tv.tv_sec = 0; cout << "wakeup set in " << tv.tv_sec << " seconds " << tv.tv_usec/1000 << " msec" << endl; } else { break; tv.tv_sec = 1; tv.tv_usec = 50 MILLISEC; } select(0, NULL, NULL, NULL, &tv); // used as sleep while( ! tsq.empty() ) { TimeStamp * tstmp = tsq.top(); now.setNow(); long int secdelta = tstmp->getEpoch() - now.getEpoch(); long int usecdelta = tstmp->getMicroSecond() - now.getMicroSecond(); // negative delta if late if( secdelta == 0 ) { if( usecdelta <= 50 MILLISEC && usecdelta >= -50 MILLISEC) // +/-50msec is considered "on-time" { cout << tstmp << "\t" << now << "\t" << secdelta << "." << usecdelta << "\t\t----" << endl; tsq.pop(); delete(tstmp); } else if( usecdelta < -50 MILLISEC ) // late more than 50 msec but less than 1 sec { cout << tstmp << "\t" << now << "\t" << secdelta << "." << usecdelta << "\tlate" << endl; tsq.pop(); delete(tstmp); } else // > 50 msec but < 1sec => reschedule break; } else if ( secdelta < 0 ) // negative seconds means at least one second LATE { cout << tstmp << "\t" << now << "\t" << secdelta << "." << usecdelta << "\tLATE" << endl; tsq.pop(); delete(tstmp); } else break; } } } }