public void ScheduleFirst(AbstractTask task)
{
lock (syncLock)
{
task.ExecutionState = ExecutionState.Scheduled;
CurrentThreadQueuedTasks.AddFirst(new SchedulePair(task, delegate { return(true); }));
Monitor.PulseAll(syncLock);
}
}
public Future Reschedule(AbstractTask task, Condition condition)
{
lock (syncLock)
{
totalTasks += 1;
if (task.ExecutionState == ExecutionState.Running)
{
Interlocked.Decrement(ref currentRunningProcessCount);
}
task.ExecutionState = ExecutionState.Scheduled;
CurrentThreadQueuedTasks.AddLast(new SchedulePair(task, condition));
Monitor.PulseAll(syncLock);
}
return(task.Completed);
}
/// <summary>
/// This must run under the lock!
/// </summary>
private bool?TryGetTaskToRun(ref AbstractTask task)
{
//this approach gives us an O(1) _removal_ cost from the list
LinkedListNode <SchedulePair> node = CurrentThreadQueuedTasks.First;
while (node != null)
{
SchedulePair pair = node.Value;
if (pair.Condition())
{
task = pair.Task;
CurrentThreadQueuedTasks.Remove(node);
break;
}
pair.CannotRunCount += 1;
//this is probably a process that is waiting for other processes
//move it to the end of the list so we don't have to iterate over it all
//the time
LinkedListNode <SchedulePair> prev = node;
node = node.Next;
if (pair.CannotRunCount == 3 && Status != ScheduleStatus.Idle)
{
pair.CannotRunCount = -1; //give it a bit of a boost for the next time
CurrentThreadQueuedTasks.Remove(prev);
CurrentThreadQueuedTasks.AddLast(prev);
}
}
if (task == null) // no tasks to run in the curren threa, time to steal some work...
{
StealWorkFromAnotherThread();
//nothing runs, and there are no tasks that we _can_ run
// we are either deadlocked or waiting for an external resource
// we will let the idle task decide what to do.
if (currentRunningProcessCount == 0)
{
Status = ScheduleStatus.Idle;
task = idleTask;
return(true);
}
}
return(null);
}
