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#include <stdio.h>
#include <uv.h>
uv_barrier_t blocker;
uv_rwlock_t numlock;
int shared_num;
void reader(void *n)
{
int num = *(int *)n;
int i;
for (i = 0; i < 20; i++) {
uv_rwlock_rdlock(&numlock);
printf("Reader %d: acquired lock\n", num);
printf("Reader %d: shared num = %d\n", num, shared_num);
uv_rwlock_rdunlock(&numlock);
printf("Reader %d: released lock\n", num);
}
uv_barrier_wait(&blocker);
}
void writer(void *n)
{
int num = *(int *)n;
int i;
for (i = 0; i < 20; i++) {
uv_rwlock_wrlock(&numlock);
printf("Writer %d: acquired lock\n", num);
shared_num++;
printf("Writer %d: incremented shared num = %d\n", num, shared_num);
uv_rwlock_wrunlock(&numlock);
printf("Writer %d: released lock\n", num);
}
uv_barrier_wait(&blocker);
}
int main()
{
uv_barrier_init(&blocker, 4);
shared_num = 0;
uv_rwlock_init(&numlock);
uv_thread_t threads[3];
int thread_nums[] = {1, 2, 1};
uv_thread_create(&threads[0], reader, &thread_nums[0]);
uv_thread_create(&threads[1], reader, &thread_nums[1]);
uv_thread_create(&threads[2], writer, &thread_nums[2]);
uv_barrier_wait(&blocker);
uv_barrier_destroy(&blocker);
uv_rwlock_destroy(&numlock);
return 0;
}
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