/* 
	Bow / bow back

	Idea from Java Puzzlers
*/

#include <stdio.h>      // printf
#include <string.h>     // strcpy
#include <pthread.h> 	// pthread_t, pthread_create

struct Friend {
    char name[20];
};

void initFriend(struct Friend* friend, char* name) {
    strcpy(friend->name, name);
}

void bowBack(struct Friend* bowee, struct Friend* bower) {
    printf("%s: I bow back to %s\n", bowee->name, bower->name);
}

void bow(struct Friend* bower, struct Friend* bowee) {
    printf("%s: I bow to %s\n", bower->name, bowee->name);
    bowBack(bowee, bower);
}


int main() {
    struct Friend alphonse;
    initFriend(&alphonse, "Alphonse");
    struct Friend gaston;
    initFriend(&gaston, "Gaston");

    bow(&alphonse, &gaston);
    bow(&gaston, &alphonse);
}

void* bowing(void* p) {
  struct Friend** friends = (struct Friend**)p;
  //  printf("In bowing\n");
  pthread_mutex_lock(&friends[0]->mutex);
  pthread_mutex_lock(&friends[1]->mutex);
  bow(friends[0], friends[1]);
  pthread_mutex_unlock(&friends[0]->mutex);
  pthread_mutex_unlock(&friends[1]->mutex);
}

int main() {
  Friend alphonse;
  initFriend(&alphonse, "Alphonse");
  Friend gaston;
  initFriend(&gaston, "Gaston");
  pthread_t tid1, tid2;

  Friend* ag[] = {&alphonse, &gaston};
  Friend* ga[] = {&gaston, &alphonse};
  pthread_create(&tid1, NULL, bowing, (void*)ag);
  pthread_create(&tid2, NULL, bowing, (void*)ga);
  //  pthread_exit(0);
  pthread_join(tid1, NULL);
  pthread_join(tid2, NULL);
}