void MemGraph::Timeout()
{
m_timer.start(static_cast<int>(updatePeriod->value()*1000));
const size_t allocated = m_capacity - GetSharedMemory().get_free_memory();
const double ratio = allocated/(double)m_capacity;
graph->AddData(QDateTime::currentDateTime(),ratio);
current->setText(QString::number(allocated / 1024 /1024));
currentPercent->setText(QString::number(static_cast<int>(ratio * 100)));
}
MemGraph::MemGraph(QWidget* /*parent*/):
m_timer(this),
m_capacity(GetSharedMemory().get_size())
{
setupUi(this); // this sets up GUI
// signals/slots mechanism in action
connect(historyLength, SIGNAL(valueChanged(double)), this, SLOT(HistoryChanged(double)) );
connect(updatePeriod, SIGNAL(valueChanged(double)), this, SLOT(PeriodChanged(double)));
connect(verticalScale, SIGNAL(valueChanged(int)), this, SLOT(ScaleChanged(int)));
connect(&m_timer, SIGNAL(timeout()), this, SLOT(Timeout()));
m_timer.setSingleShot(true);
m_timer.start(static_cast<int>(updatePeriod->value()*1000));
graph->SetHistoryLength(static_cast<int>(historyLength->value()*60));
total->setText(QString::number(m_capacity / 1024 / 1024));
}
int initsem(key_t key , int nsems)
{
int i;
semun arg;
semid_ds buf;
sembuf sb;
int semid;
semid = semget(key,nsems , IPC_CREAT | IPC_EXCL | 0666);
printf( "After semget\n");
if(semid >=0)
{
printf("semid > 0\n");
GetAndInitialiseSharedMemory();
printf("After initialising shared memory \n");
// prepare sembuf as it will be passed to semop to initialise the semapores in the semaphore set.
sb.sem_op = 1;
sb.sem_flg = 0;
// arg.val initialaises the semaphore with the number of resouces available
arg.val = 1;
for(sb.sem_num = 0 ; sb.sem_num <nsems ; sb.sem_num ++)
{
if(semop(semid , &sb , 1) == -1)
{
// error in semop ree the semaphore
int e = errno;
semctl(semid , 0 , IPC_RMID); // remove the semphore
errno = e;
return -1;
}
}
}
else if( errno == EEXIST)
{
GetSharedMemory();
// the other process got the seaphore
int ready = 0;
semid = semget(key , nsems , 0);
if(semid < 0)
{
// error
return semid;
}
// wait for other process to initialise semaphore
arg.buf = &buf;
for(int i = 0 ; i< MAX_RETRIES ;i++)
{
semctl(semid , nsems-1 , IPC_STAT , arg);
if( arg.buf -> sem_otime != 0 )
{
ready = 1;
}
else
{
sleep(1);
}
}
if(!ready)
{
errno = ETIME;
return -1;
}
}
else
{
return semid; // error condition
}
return semid;
}
