add pseudocode for the engine

[msc-thesis1617.git] / methods.mtask.tex

diff --git a/methods.mtask.tex b/methods.mtask.tex
index 5b6128d..db31782 100644 (file)
--- a/methods.mtask.tex
+++ b/methods.mtask.tex
@@ -36,11 +36,45 @@ instance isExpr Expr
 \end{lstlisting}
 
 \section{Semantics}
-\gls{mTask} do not behave like functions but more like
-\gls{iTasks}-\glspl{Task}. When an \gls{mTask} is created it returns immediatly
-and the \gls{Task} will be executed sometime in the future. \glspl{Task} can
-run at an interval and they can start other tasks.
-\todo{Meer uitwijden over de mTask semantiek}
+The \gls{C}-backend of the \gls{mTask}-system has an engine that is generated
+alongside the code for the \glspl{Task}. This engine will execute the
+\glspl{mTask} according to certain rules and semantics.
+\glspl{mTask} do not behave like functions but more like
+\gls{iTasks}-\glspl{Task}. An \gls{mTask} is queued when either his timer runs
+out or when it is started by another \gls{mTask}. When an \gls{mTask} is
+queued it does not block the execution but it will return immediately while
+the actual \gls{Task} will be executed some time in the future.
+
+The \gls{iTasks}-backend simulates the \gls{C}-backend and thus uses the same
+semantics. This engine expressed in pseudocode is listed as
+Algorithm~\ref{lst:engine}. All the \glspl{Task} are inspected on their waiting
+time. When the waiting time has not passed the delta is subtracted and they are
+pushed to the end of the queue. When the waiting has has surpassed they are
+executed. When a \gls{mTask} wants to queue another \gls{mTask} it can just
+append it to the queue.
+
+\begin{algorithm}[H]
+       \KwData{\textbf{queue} queue$[]$, \textbf{time} $t, t_p$}
+
+       $t\leftarrow\text{now}()$\;
+       \Begin{
+               \While{true}{
+                       $t_p\leftarrow t$\;
+                       $t\leftarrow\text{now}()$\;
+                       \If{notEmpty$($queue$)$}{
+                               $task\leftarrow \text{queue.pop}()$\;
+                               $task$.wait $-= t-t_p$\;
+                               \eIf{$task.wait>t_0$}{
+                                       queue.append$(task)$\;
+                               }{
+                                       run\_task$(task)$\;
+                               }
+                       }
+               }
+       }
+       \caption{Engine pseudocode for the \gls{C}- and
+               \gls{iTasks}-backends}\label{lst:engine}
+\end{algorithm}
 
 \section{Expressions}
 Expressions in the \gls{mTask}-\gls{EDSL} are divided into two types, namely