#include <pthread.h>
#include <malloc.h>
#include <stdio.h>
#include <unistd.h>

//dummy structures
typedef int ThrStat;
typedef int ThrBuffer;

//global variables, shared among threads
pthread_key_t thr_stat, thr_buffer;

void *threadf(void *x);
void func();
void free_data(void *x);

int main() {
	pthread_t t1, t2; //memory for handles of created threads

	//main thread – initialization of ‘keys’, basis for thread specific data
	pthread_key_create(&thr_stat, free_data);
	pthread_key_create(&thr_buffer, free_data);
	//initially, value NULL is associated with each key for all threads

	pthread_create(&t1, NULL, threadf, (void *) 1);
	pthread_create(&t2, NULL, threadf, (void *) 2);

	pthread_join(t1, NULL);
	pthread_join(t2, NULL);

	return 0;
}
	
//worker thread - initialization
void *threadf(void *x) {
	ThrStat *stat;
	ThrBuffer *buffer;

	stat = malloc(sizeof(ThrStat));	//stat - local variable
	buffer = malloc(sizeof(ThrBuffer));	//buffer - local variable

	*stat = (int) x;
	*buffer = *stat * 10;

	//associate stat with key thr_stat for current thread only!!!
	pthread_setspecific(thr_stat, stat);
	pthread_setspecific(thr_buffer, buffer);

	usleep(100000);
	func();

	return NULL;
}

//worker thread – in some function
void func() {
	ThrStat *s;
	ThrBuffer *b;

	//get data associated with keys
	s = pthread_getspecific(thr_stat);
	b = pthread_getspecific(thr_buffer);

	//use ‘s’ and ‘b’
	printf("stat=%d, buffer=%d\n", *s, *b);
}

void free_data(void *x) {
	//printf("Releasing data %p\n", x);
	if (x)
		free(x);
}