EXERCISE #$2$

An implementation of a circular FIFO queue for multiple producers and consumers are attached in the appendix $($it is the one we designed in our lecture$).$ Regarding the implementation:

Question #$1$: Is it necessary to have "wait $($mutex$)"$ and "signal$($mutex$)"$ in the producer processes? If NO$,$ explain why not. If YES, explain why we need them.

Question #$2$: Is there any merit in using two different "mutex semaphore" $($one for the producers and the other for the consumers$)?$ If yes, describe what is the merit? If not, why not?

Question #$3$: Is the implementation "starvation free" for both producers and consumers? If NO$,$ explain why it is not. If YES, explain why we it is$.$

APPENDIX:

$\backslash$table$[[$#define N $100,//$ the queue size$],[$shared memory int CFQ $[$N$]$;$,\frac{\frac{?}{?}}{?}$ the circular FIFO queue$],[$shared memory int TOP $=0$;$,\frac{\frac{?}{?}}{?}$ pointer to the top of the queue$],[$shared memory int TAIL $=0$;$,\frac{\frac{?}{?}}{?}$ pointer to the tail of the queue$],[,//$ a mutex semaphore$],[$semaphore mutex $=1$;$,//$ a counting semaphore$],[$semaphore empty $=N$;$,/$ counting semaphore$],[$semophore full $=0$;$,]]$

void producer $($void$)$

$1$

int new item; $//$ place holder for a new item to insert

while $($TRUE$)$

I

new item $=$ produce new item $()$; $//$ generate a new item

wait $($empty$)$:

woit $($mutex$)$;

$//$ make sure the queue is NOT full

$//$ I should be the only one

insert$($CFQ$,$ TAIL, new item$)$; $//$ insert the new itern to the queue

TAL$=(TAL+1)\%N$;$\frac{,}{\frac{?}{?}}$ update the Top pointer

signal$($mutex$)$; $,//$ t am done!

signal$($full$)$; full