os_kernel_lab/labcodes/lab7/kern/sync/monitor.c

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2012-08-22 12:32:13 +08:00
#include <stdio.h>
#include <monitor.h>
#include <kmalloc.h>
#include <assert.h>
// Initialize monitor.
void
monitor_init (monitor_t * mtp, size_t num_cv) {
int i;
assert(num_cv>0);
mtp->next_count = 0;
mtp->cv = NULL;
sem_init(&(mtp->mutex), 1); //unlocked
sem_init(&(mtp->next), 0);
mtp->cv =(condvar_t *) kmalloc(sizeof(condvar_t)*num_cv);
assert(mtp->cv!=NULL);
for(i=0; i<num_cv; i++){
mtp->cv[i].count=0;
sem_init(&(mtp->cv[i].sem),0);
mtp->cv[i].owner=mtp;
}
}
// Unlock one of threads waiting on the condition variable.
void
cond_signal (condvar_t *cvp) {
//LAB7 EXERCISE1: YOUR CODE
cprintf("cond_signal begin: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
/*
* cond_signal(cv) {
* if(cv.count>0) {
* mt.next_count ++;
* signal(cv.sem);
* wait(mt.next);
* mt.next_count--;
* }
* }
*/
cprintf("cond_signal end: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
}
// Suspend calling thread on a condition variable waiting for condition Atomically unlocks
// mutex and suspends calling thread on conditional variable after waking up locks mutex. Notice: mp is mutex semaphore for monitor's procedures
void
cond_wait (condvar_t *cvp) {
//LAB7 EXERCISE1: YOUR CODE
cprintf("cond_wait begin: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
/*
* cv.count ++;
* if(mt.next_count>0)
* signal(mt.next)
* else
* signal(mt.mutex);
* wait(cv.sem);
* cv.count --;
*/
cprintf("cond_wait end: cvp %x, cvp->count %d, cvp->owner->next_count %d\n", cvp, cvp->count, cvp->owner->next_count);
}