int sthread_mutex_lock(sthread_mutex_t *mutex)
{
sthread_t ptr_this_thread = sthread_self();
//fighting for the right to modify Q
while(test_and_set(&mutex->M)){}
//after this I am now the only one
//to modify the passed in mutex
//therefore I should go ahead and
//modify the lock and Q if needed
//check if I should go into critical
//section
struct queue *pQ = &mutex->Q;
if(Q_empty(pQ))
{
//lock available
Q_push(pQ, ptr_this_thread);
mutex->M = 0; // I am done with Q; others can come and look / change Q.
return 0; //this_thread will go into critical section
}
else
{
//lock not available
//there are someone or myself before me in the Q
//if it is myself in criticle section
//I shoud not wait for myself to wake myself up
//I will increment counter and keep running in criticle seciton
//else
//someone else is before me in the Q
//either he is sleeping (he is not the 1st)
//or he is in the critical section now (he is the 1st and
//I am the 2nd in Q)
//either way I should go to bed and wait for him to wake me up
if(Q_first(pQ)->ptr_thread == ptr_this_thread)
{
Q_first(pQ)->count++; //Trying to acquire the lock own by myself
//take down this attempt and keep myself in
//criticle section
mutex->M = 0; //I am done with lock; others can now check / modify lock.
}
else
{
Q_push(pQ, ptr_this_thread);
mutex->M = 0;
sthread_suspend(); //Other thread is in criticle section
//I should go to bed and sleep
return 0; //the moment I am woken up will
//return 0 to caller
}
}
}
void LG_topPrint(LGraph lg)
{
unsigned *indegree;
unsigned i,count=0;
DLL_Node* node_ptr;
Queue q;
if(lg.count==0)
return ;
indegree=(unsigned *)malloc(sizeof(unsigned)*lg.count);
for(i=0;i<lg.count;i++)
indegree[i]=lg.in_ptr[i];
Q_init(&q);
for(i=0;i<lg.count;i++)
if(indegree[i]==0)
Q_push(&q,i);
while(!Q_isEmpty(q))
{
Q_getFront(q,&i);
Q_pop(&q);
printf("%c ",lg.d_ptr[i]);
++count;
for(node_ptr=lg.l_ptr[i].head;node_ptr;node_ptr=node_ptr->next)
{
i=node_ptr->data;
if(--indegree[i]==0)
Q_push(&q,i);
}
}
if(count<lg.count)
printf("ͼÖÐÓлØ·£¬ÅÅÐòʧ°Ü\n");
else
printf("\n");
Q_clear(&q);
free(indegree);
}
int sthread_mutex_trylock(sthread_mutex_t *mutex)
{
sthread_t ptr_this_thread = sthread_self();
//fighting for the right to modify Q
while(test_and_set(&mutex->M)){}
//after this I am now the only one
//to modify the passed in mutex
//therefore I should go ahead and
//modify the lock and Q if needed
//check if I should go into critical
//section
struct queue *pQ = &mutex->Q;
if(Q_empty(pQ))
{
//lock available
Q_push(pQ, ptr_this_thread);
mutex->M = 0; // I am done with Q; others can come and look / change Q.
//this_thread will go into critical section
return 0;
}
else
{
//lock not available
if(Q_first(pQ)->ptr_thread == ptr_this_thread)
{
Q_first(pQ)->count++;//Trying to acquire the lock own by myself
//take down this attempt and keep myself in
//criticle section
mutex->M = 0; //I am done with lock; others can now check / modify lock.
}
//do not block caller
//return non-zero indication lock not available
return -1;
}
}
