I'm doing some test on how a scheduler schedules a waiting thread and in the process, I want to not let OS to see a waiting thread, so I kill a thread which is waiting on a lock and start it when the lock is released, I think I should save the context of the thread before exiting and restore it when I create it again. Obviously I'm doing something wrong but I can't figure it out. (I'm very new to the subject.)
this is my code so far, it generates segmentation fault with setcontext.
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <ucontext.h>
ucontext_t data;
pthread_t pth;
pthread_mutex_t lock1;
void* wake_up(void* arg) {
printf("going to wake up a thread\n");
setcontext(&data);
}
void MUTEX_UNLOCK(pthread_mutex_t* lock) {
pthread_mutex_unlock(lock);
pthread_create(&pth, NULL, wake_up, NULL);
}
void MUTEX_LOCK(pthread_mutex_t* lock) {
getcontext(&data);
while(1) {
if(pthread_mutex_trylock(lock) == 0) {
printf("got the lock\n");
break;
}
else {
printf("going to exit thread\n");
pthread_exit(NULL);
}
}
}
void* routine1(void* param) {
MUTEX_LOCK(&lock1);
printf("enter any character to continue\n");
getchar();
MUTEX_UNLOCK(&lock1);
}
int main(int argc, char** argv) {
pthread_mutex_init(&lock1, 0);
pthread_t thread1[2];
int i;
for (i = 0; i < 2; i++)
pthread_create(&thread1[i], NULL, routine1, NULL);
while(1);
}
