63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/wait.h>
|
|
#include <pthread.h>
|
|
#include <stdbool.h>
|
|
#include <time.h>
|
|
|
|
struct shared_data {
|
|
pthread_mutex_t mutex;
|
|
int counter;
|
|
};
|
|
|
|
void increment_counter(const char *name, struct shared_data *data) {
|
|
for (int i = 0; i < 10000; i++) {
|
|
if (pthread_mutex_lock(&data->mutex) != 0) {
|
|
perror("pthread_mutex_lock");
|
|
}
|
|
|
|
data->counter++;
|
|
|
|
if (pthread_mutex_unlock(&data->mutex) != 0) {
|
|
perror("pthread_mutex_unlock");
|
|
}
|
|
}
|
|
}
|
|
|
|
int main() {
|
|
struct shared_data *shared_data = mmap(NULL, sizeof(struct shared_data), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
|
|
if (shared_data == NULL) {
|
|
perror("mmap");
|
|
return -1;
|
|
}
|
|
pthread_mutexattr_t mutex_attr;
|
|
pthread_mutexattr_init(&mutex_attr);
|
|
pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
|
|
|
|
if (pthread_mutex_init(&shared_data->mutex, &mutex_attr) < 0) {
|
|
printf("Failed to initialise mutex\n");
|
|
return -1;
|
|
}
|
|
|
|
shared_data->counter = 0;
|
|
|
|
int pid = fork();
|
|
if (pid == 0) {
|
|
srand(time(NULL)+1);
|
|
increment_counter("Child ", shared_data);
|
|
return 0;
|
|
} else {
|
|
srand(time(NULL)+2);
|
|
increment_counter("Parent", shared_data);
|
|
}
|
|
|
|
int child_status;
|
|
waitpid(pid, &child_status, 0);
|
|
|
|
printf("Counter is %d\n", shared_data->counter);
|
|
}
|
|
|