thread_test.c

   1 /*
   2   gcc -Wall -Wextra thread_test.c -g -lpthread
   3  */
   4 #include <pthread.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <errno.h>
   8 #include <stdlib.h>
   9
  10 #define KB(x) (x * 1024)
  11
  12
  13 /* we want to call this func from a thread. */
  14 int worker_func(int x, void* y, int z) {
  15         return z;
  16 }
  17
  18 typedef struct {
  19         pthread_attr_t attr;
  20         pthread_t thread;
  21         int result;
  22         int x;
  23         void* y;
  24         int z;
  25 } worker_func_thread_data;
  26
  27 static void* worker_func_child_thread(void* data) {
  28         worker_func_thread_data *child_thread_data = (worker_func_thread_data*)data;
  29         child_thread_data->result = worker_func(child_thread_data->x, child_thread_data->y, child_thread_data->z);
  30         return NULL;
  31 }
  32
  33 /* returns NULL on success, otherwise error message string
  34  * if an error happens, the pthread_attr_t member of ti gets
  35  * automatically cleaned up. */
  36 static const char* worker_func_thread_launcher(size_t stacksize, worker_func_thread_data** ti, int x, void* y, int z) {
  37         const char* errmsg = NULL;
  38         *ti = calloc(1, sizeof(worker_func_thread_data));
  39         (*ti)->x = x;
  40         (*ti)->y = y;
  41         (*ti)->z = z;
  42
  43         if((errno = pthread_attr_init(&(*ti)->attr))) {
  44                 errmsg = "pthread_attr_init";
  45                 goto ret;
  46         }
  47
  48         if((errno = pthread_attr_setstacksize(&(*ti)->attr, stacksize))) {
  49                 errmsg = "pthread_attr_setstacksize";
  50                 goto pt_err_attr;
  51         }
  52         if((errno = pthread_create(&(*ti)->thread, &(*ti)->attr, worker_func_child_thread, *ti))) {
  53                 errmsg = "pthread_create";
  54                 goto pt_err_attr;
  55         }
  56
  57         ret:
  58         return errmsg;
  59
  60         pt_err_attr:
  61         pthread_attr_destroy(&(*ti)->attr);
  62         goto ret;
  63 }
  64
  65 static const char* worker_func_wait(int* result, worker_func_thread_data** ti) {
  66         const char* errmsg = NULL;
  67
  68         if((errno = pthread_join((*ti)->thread, NULL))) {
  69                 errmsg = "pthread_join";
  70                 pthread_attr_destroy(&(*ti)->attr);
  71                 goto ret;
  72         }
  73         if((errno = pthread_attr_destroy(&(*ti)->attr))) {
  74                 errmsg = "pthread_attr_destroy";
  75         }
  76         *result = (*ti)->result;
  77         ret:
  78         free(*ti);
  79         *ti = NULL;
  80         return errmsg;
  81 }
  82
  83 int main() {
  84         worker_func_thread_data* child;
  85         int result;
  86         const char* errmsg;
  87         if((errmsg = worker_func_thread_launcher(KB(128), &child, 0, NULL, 1))) goto pt_err;
  88         if((errmsg = worker_func_wait(&result, &child))) goto pt_err;
  89
  90         printf("workerfunc returned %d\n", result);
  91
  92         return 0;
  93         pt_err:
  94         perror(errmsg);
  95         return 1;
  96 }