X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=methods.mtask.tex;h=a0ec96b536f1590926f3f694bd096f00fad86d41;hb=c4c4901bb58dcf6450dd50010e27be66f80b7a00;hp=db317820b360f8e7c2b87bc974b1488ab1ee27d4;hpb=047ee8a13310ba90d01934827cb17c680b32a4b5;p=msc-thesis1617.git diff --git a/methods.mtask.tex b/methods.mtask.tex index db31782..a0ec96b 100644 --- a/methods.mtask.tex +++ b/methods.mtask.tex @@ -35,47 +35,6 @@ instance isExpr Upd instance isExpr Expr \end{lstlisting} -\section{Semantics} -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 boolean expressions and arithmetic expressions. The class of arithmetic @@ -101,15 +60,16 @@ class boolExpr v where \end{lstlisting} \section{Control flow} -Looping of \glspl{Task} happens because \glspl{Task} are launched at regular -intervals or relaunch themselves. Therefore there is no need for loop control -flow functionality such as \emph{while} or \emph{for} constructions. The main -control flow is the sequence operator and the \emph{if} statement. Both are -shown in Listing~\ref{lst:control}. The first class of \emph{If} statements -describe the regular \emph{if} statement. The expressions given can have any -role. The functional dependency on \CI{s} determines the return type of the -statement. The sequence operator is very straightforward and just ties the two -expressions together in sequence. +Looping of \glspl{Task} happens because \glspl{Task} are executed after waiting +a specified amount of time or when they are launched by another task or even +themselves. Therefore there is no need for loop control flow functionality such +as \emph{while} or \emph{for} constructions. The main control flow is the +sequence operator and the \emph{if} statement. Both are shown in +Listing~\ref{lst:control}. The first class of \emph{If} statements describe the +regular \emph{if} statement. The expressions given can have any role. The +functional dependency on \CI{s} determines the return type of the statement. +The sequence operator is very straightforward and just ties the two expressions +together in sequence. \begin{lstlisting}[% language=Clean,label={lst:control},caption={Control flow operators}] @@ -166,24 +126,79 @@ class sds v where sds :: ((v t Upd)->In t (Main (v c s))) -> (Main (v c s)) | ... \end{lstlisting} +\section{Semantics} +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 $\leftarrow task$.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}-backend}\label{lst:engine} +\end{algorithm} + +To achieve this in the \gls{EDSL} a \gls{Task} clas are added that work in a +similar fashion as the \texttt{sds} class. This class is listed in +Listing~\ref{lst:taskclass}. \glspl{Task} can have an argument and always have +to specify a delay or waiting time. The type signature of the \CI{mtask} is +rather arcane and therefore an example is given. The aforementioned Listing +shows a simple specification containing one task that increments a value +indefinitely every one seconds. + +\begin{lstlisting}[language=Clean,label={lst:taskclass},% + caption={The classes for defining tasks}] +class mtask v a where + task :: (((v delay r) a->v MTask Expr)->In (a->v u p) (Main (v t q))) -> Main (v t q) | ... + +count = task \count = (\n.count (lit 1000) (n +. One)) In {main = count (lit 1000) Zero} +\end{lstlisting} + \section{Example mTask} -\todo{Also explain semantics about running tasks} Some example \glspl{mTask} using almost all of the functionality are shown in Listing~\ref{lst:exmtask}. The \glspl{mTask} shown in the example do not belong to a particular view and therefore are of the type \CI{View t r}. The -\CI{blink} \gls{mTask} show the classic \emph{Arduino} \emph{Hello World!} -application that blinks a certain LED at each interval. The \CI{thermostat} -\gls{mTask} will enable a digital pin powering a cooling fan when the analog +\CI{blink} \gls{mTask} show the classic \gls{Arduino} \emph{Hello World!} +application that blinks a certain LED every second. The \CI{thermostat} +expression will enable a digital pin powering a cooling fan when the analog pin representing a temperature sensor is too high. \CI{thermostat`} shows the -same program but now using the assignment style \gls{GPIO}. +same expression but now using the assignment style \gls{GPIO} technique. \begin{lstlisting}[% language=Clean,label={lst:exmtask},caption={Some example \glspl{mTask}}] -blink :: Main (View Int Stmt) -blink = sds \x=1 In sds \led=LED1 In {main = - IF (x ==. lit 1) (ledOn led) (ledOff led) :. - x =. lit 1 -. x - } +blink = task \blink=(\x. + IF (x ==. lit True) (ledOn led) (ledOff led) :. + blink (lit 1000) (Not x) + In {main=blink (lit 1000) True} thermostat :: Main (View () Stmt) thermostat = {main =