int manageContextSwitching( RunningState* run_state, Heap* ready_queue,
DeviceSet* device_set, ConfigData* configurations,
ActivityLog* activity_log )
{
// case: we have a process that was running
if( run_state->process_is_running )
{
// move the process to its next task and place the process in
// the back of the ready queue
increment_iterator( &(run_state->currently_running_process.job_list) );
insert_heap( ready_queue, run_state->currently_running_process,
configurations->cpu_scheduler );
run_state->process_is_running = false;
}
// get one from the queue if possible
if( !is_Heap_empty( ready_queue ) )
{
// pop the item out of the queue
run_state->currently_running_process =
remove_PCB_from_Heap( ready_queue );
run_state->process_is_running = true;
}
// case: there are no items to remove from the queue
// leave the run state empty, with no process running
// perform context switches until we get a processor destined
// for the CPU or we are out of processeses to get
while( ( get_listTask( &(run_state->currently_running_process.job_list) ).task_number != PROCESS ) &&
!is_Heap_empty( ready_queue ) )
{
// send the process to the I/O queue it is destined for
sendToIoQueue( &(run_state->currently_running_process), device_set,
activity_log );
// get one from the queue if possible
if( !is_Heap_empty( ready_queue ) )
{
// pop the item out of the queue
run_state->currently_running_process =
remove_PCB_from_Heap( ready_queue );
}
// case: there are no items to remove from the queue
// leave the run state empty, with no process running
}
// now we will either have a process ready for the CPU or all
// processes will be doing their I/O operations
// (or the simulator run will be just about over)
}
void increment()
{
return boost::fusion::for_each(iterators_,
increment_iterator());
}