void *hello(void *t)
{
///int *reps = (int*)t;
int i = 0;
// initialize thread specific data for each thread
int* id = (int*)malloc(sizeof(int));
assert(id);
*id = mythread_self();
mythread_setspecific(id_key, id);
//set name
char* name = (char*)malloc(sizeof(char)*MAX_NAME_LENGTH);
assert(name);
memset(name, '\0', MAX_NAME_LENGTH);
sprintf(name, "worker-%d", mythread_self());
mythread_setspecific(name_key,name);
// user specific data
for (; i < mythread_self(); i++) {
printf("Thread-%d:Hello thread:%d\n", mythread_self(), i);
sleep(1);
mythread_yield();
}
printf("Thread specific data for %d thread is %d and worker name is %s\n", mythread_self(), *((int *)mythread_getspecific(id_key)), (char*)mythread_getspecific(name_key));
return NULL;
}
void *thread_function(void *arg)
{
int rc, i;
mythread_t thread,childthread ;
struct threadValues *value;
value = (struct threadValues *)arg;
thread=mythread_self();
printf("This is thread %d before yielding\n",thread.tid);
for(i=0; i < MAX_KEYS; i++)
{
printf("\nSettig values %d %d for key %d by thread %d", value->v1, value->v2, i, thread.tid);
rc = mythread_setspecific(keys[i], value);
if(rc != 0)
{
printf("\nmythread_setspecific call error for thread = %d", keys[i]);
}
}
rc=mythread_create(&childthread,NULL,&printingfunction,NULL);
rc=mythread_yield();
printf("this is thread %d after yield\n",thread.tid);
//rc = mythread_yield();
getData();
return NULL;
}
int mythread_mutex_lock(mythread_mutex_t *mutex)
{
int lockstatus;
mythread_enter_kernel();
mutex->noofwaitingthreads=mutex->noofwaitingthreads+1;
mythread_leave_kernel();
if(mutex->lockvariable==-1)// if the lock was already destroyed then return the error code
{
return 1; // error code
}
lockstatus=testandtestandset(&(mutex->lockvariable)); // a lockstatus of 0 denotes a successful acquiring of lock
while(lockstatus==1) // if the lock acquiring fails after 100 tries , then the thread is blocked and put in a queue until lock becomes available
{
mythread_enter_kernel();
mutex->noofblockedthreads=mutex->noofblockedthreads+1;
mythread_block((mutex->blocked_threads),0);// actual 0
lockstatus=testandtestandset(&(mutex->lockvariable)); // thread that returns from the block state tries to acquire the lock again
}
mythread_enter_kernel();
mutex->owner_thread=mythread_self();
mythread_leave_kernel();
return lockstatus;
}
void *mythread_getspecific(mythread_key_t key)
{
int i;
struct list_node* start;
mythread_t tcb;
const void *value;
for(i=0; i< tsd_key_counter; i++)
{
if(globalTSD[i].key == key)
{
start = globalTSD[i].ptr;
tcb = mythread_self();
value = search_lnode(start, tcb);
if(value == NULL)
{
write(1,"\nmythread_getspecific - Thread specific data value is not associated with the key",82);
return NULL;
}
//printf("\nmythread_getspecific - Thread specific data value found with this key - %d", ((mythread_t *) value)->tid);
return ((void *)value);
}
}
//if key not found in the global array
write(1, "\nmythread_getspecific - key not found in the global array\n",60);
return NULL;
}
int mythread_leave_kernel(){
mythread_t self = mythread_self();
repeat:
if(self->reschedule == 1){
self->reschedule = 0;
/* Reschedule here*/
if(mythread_readyq()!=NULL && self->attr.attr == 0){
/*The threads time is up and since there's some thread waiting in readyq, it needs to
preempt itself */
mythread_scheduler();
}
else{
/*If Ready queue is empty or time is not up, continue executing
*/
mythread_leave_kernel_nonpreemptive();
}
}
else{
mythread_leave_kernel_nonpreemptive();
}
/* Check again in case of a rescheduling since leaving kernel */
if(self->reschedule == 1){
mythread_enter_kernel();
goto repeat;
}
return 0;
}
void *barrierTest(void* arg){
mythread_enter_kernel();
printf("Going to sleep...%ld\n",mythread_self());
mythread_leave_kernel();
//sleep(5);
mythread_barrier_wait(&mybarrier);
mythread_enter_kernel();
printf("Moving towards new barrier... %ld\n",mythread_self());
mythread_leave_kernel();
mythread_barrier_wait(&mybarrier);
mythread_enter_kernel();
printf("%ld exiting... %ld\n",mythread_self());
mythread_leave_kernel();
mythread_exit(NULL);
}
int mythread_scheduler(){
mythread_t self = mythread_self();
/*Limiting number of priority queues to 10 */
if(self->preemptions < 10){
self->preemptions += 1;
}
self->attr.attr = pow(2,self->preemptions); /*Since preemptions = invocation -1 */
mythread_block(mythread_readyq(),1);
return 0;
}
void* thread_func(void *args) {
int t = 0;
char buf[10];
mythread_t self = mythread_self();
sprintf(buf, "%ld", (long) args);
mythread_mutex_lock(&mutex);
strcat(actualOutput, buf);
mythread_mutex_unlock(&mutex);
}
void getData() {
int i;
mythread_t tcb;
for(i=0; i < MAX_KEYS; i++)
{
struct threadValues *value = mythread_getspecific(keys[i]);
printf("\nmythread_getspecific call for key = %d, values=%d %d\n", keys[i], value->v1, value->v2);
if (value == NULL)
printf("\nmythread_setspecific call error for thread = %d", keys[i]);
tcb = mythread_self();
}
}
/* Thread function */
void *thread_function ()
{
int c = 0;
while (1)
{
if (c < 3000)
{
if (c%2 == 0)
{
int k = 1;
while(k<100000) //While loops to simulate preemptions by making threads run for longer
k++;
c++; // Each thread will update this variable
}
else
{
int k = 1;
while(k<200000) //While loops to simulate preemptions by making threads run for longer
k++;
c++;
}
}
else
break;
}
mythread_enter_kernel();
printf("Thread with tid %ld has been pre-empted: %d times! \n", mythread_self(), mythread_self()->preemptions);
mythread_leave_kernel_nonpreemptive();
}
int mythread_setspecific(mythread_key_t key, const void *value)
{
int i;
lnode* start;
lnode* new_lnode;
int rc;
mythread_t tcb;
for(i=0; i < tsd_key_counter; i++)
{
if((globalTSD[i].key) == key)
{
tcb = mythread_self();
new_lnode = create_lnode(tcb, value);
if(globalTSD[i].ptr == NULL)
{
globalTSD[i].ptr = new_lnode;
rc = 0;
}
else
{
start = globalTSD[i].ptr;
/*passing tcb and value to check if a value already exists for this thread.
*If it does, just change the value in that node and delete the new node
*/
rc = append_lnode(start, new_lnode, /*key,*/ tcb, value);
}
if(rc == 0)
{
//printf("\nmythread_setspecific: value for this thread added successfully with key - %d\n",key);
return 0;
}
else if (rc == 1)
{
/*if the thread specific data value already existed,then it is updated to the new value*/
printf("\nmythread_setspecific: value for this thread updated with key %d\n",key);
return 0;
}
else
{
printf("\nmythread_setspecific - EINVAL: Invalid key. Failed to add with key %d\n",key);
return -1;
}
}
}
write(1,"\nmythread_setspecific - EINVAL: Invalid key\n",45);
return -1;
}
void myhandler(int signal){
mythread_queue_t rq_head,temp, runq_head;
rq_head = *mythread_readyq();
runq_head = *mythread_runq();
temp = runq_head;
mythread_t self = mythread_self();
/*Every thread will set its reschudle flag on receiving a signal*/
self->reschedule = 1;
if(rq_head != NULL){
(self->attr.attr)--;
/*On every signal (SIGALRM/SIGUSR1) the attr which denotes its remaining quanta is decremented
This happens only if there is atleast one thread in readyq.
*/
mythread_enter_kernel();
if(signal == SIGALRM){
do{
if(temp->item != self){
syscall(SYS_tkill, ((mythread_t)(temp->item))->tid, SIGUSR1);
}
temp = temp ->next;
}
while(temp!=runq_head);
}
/*Only one thread will enter the kernel and reschedule the remaining ones which did not enter the kernel.
* While doing so, the thread will set the reschedule flag of these threads to 0
* We need to check this condition before letting the threads enter the scheduler via mythread_leave_kernel()
*/
if(self->reschedule == 0){
mythread_leave_kernel_nonpreemptive();
}
else{
mythread_leave_kernel();
}
}
/*Ready queue is empty so let this thread continue running without any interruptions*/
return;
}
/* Uses dispatcher to yeild the next Ready thread */
int mythread_yield()
{
mythread_t *self_tcb = queue_search_elementbyId(mythread_queue_globalVar, mythread_self().tid);
/* Using yield_futex so that no other thread yields when one thread is yielding */
futex_down(&yield_futex);
if (__dispatch_thread(self_tcb) == -1) {
futex_up(&yield_futex);
return 0;
}
/* Release the yield futex */
futex_up(&yield_futex);
/* Sleep till another process wakes us up */
futex_down(&self_tcb->futex);
return 0;
}
int mythread_mutex_lock (mythread_mutex_t *mutex)
{
// if mutex is not poinitng to anything valid then return EINVAL
if (!mutex)
return EINVAL;
if (mutex->value == -1)
return EINVAL;
int retry = 0;
while (1)
{
mythread_enter_kernel();
// check if lock is available for atmost 50 times
while ((mutex->value == 1) && (retry < RETRY_MAX))
{
retry++;
}
// if we waited for 50 times and lock still not avaialable then break from he loop and block the current thread.
if (retry == RETRY_MAX)
{
break;
}
// if lock is avaialable, grab it atomically using compare and swap function
if (compare_and_swap (&mutex->value, 1, 0)==0)
{
// update the current owner to mutex to current thread
mutex->thread = mythread_self();
mythread_leave_kernel();
return 0; // success
}
} // end of while loop
// if lock is not available after 50 tries, block the current thread.
mythread_block (&mutex->queue, BLOCKED);
return 0; // success
}
int mythread_init_sched(){
/* Set the new_mask for SIGUSR1 and SIGALRM */
mythread_t self = mythread_self();
self->preemptions = 0;
(self->attr).attr = pow(2.0,self->preemptions);
sigemptyset(&new_mask);
sigaddset(&new_mask,SIGUSR1);
sigaddset(&new_mask,SIGALRM);
sigprocmask(SIG_UNBLOCK,&new_mask,&old_mask);
new_action.sa_handler = myhandler;
new_action.sa_mask = new_mask;
new_action.sa_flags = 0;
/* Install signal handler for SIGUSR1 */
if(sigaction(SIGUSR1,&new_action,&old_action)<0){
perror("Error in installing handler for SIGUSR1\n");
return -1;
}
/* Install signal handler for SIGALRM */
if(sigaction(SIGALRM,&new_action,&old_action)<0){
perror("Error in installing handler for SIGUSR1\n");
return -1;
}
if(timer_set == 0){
timer_set = 1;
struct itimerval timer;
struct timeval timerval;
timerval.tv_sec=0;
timerval.tv_usec=10000;
timer.it_interval=timerval;
timer.it_value=timerval;
setitimer(ITIMER_REAL, &timer, NULL);
}
return 0;
}
void * printingfunction (void * argument)
{
mythread_t mythread = mythread_self();
printf("this is printing function %d\n",mythread.tid);
}
