/*
Author: Chris Osborn
Class: CSE2431
Assignment: Lab4
Compilation Command: gcc PartA.c -o A -lpthread -lrt
*/

#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>

// Thread routines
void *Thread1();
void *Thread2();
void *Thread3();
void *Thread4();

pthread_t tid[4]; // array of thread IDs
sem_t semaphore1; // sem1
sem_t semaphore2; // sem2
sem_t semaphore3; // sem3
sem_t semaphore4; // sem4

// Only shared variable
int Account[3];

int main()
{
  int i;

  // Initialize accounts
  Account[0] = 100000;
  Account[1] = 100000;
  Account[2] = 100000;

  // Initialize semaphores to 1
  i = sem_init(&semaphore1, 0, 1);
  if(i < 0){exit;}
  i = sem_init(&semaphore2, 0, 1);
  if(i < 0){exit;}
  i = sem_init(&semaphore3, 0, 1);
  if(i < 0){exit;}
  i = sem_init(&semaphore4, 0, 1);
  if(i < 0){exit;}

  // Create threads 1, 2, & 3
  i = pthread_create(&tid[0], NULL, Thread1, NULL);
  if(i < 0){exit;}
  i = pthread_create(&tid[1], NULL, Thread2, NULL);
  if(i < 0){exit;}
  i = pthread_create(&tid[2], NULL, Thread3, NULL);
  if(i < 0){exit;}

  // Wait for Thread2 to finish, then exit
  i = pthread_join(tid[1], NULL);
  if(i < 0){exit;}
  exit;
}

void *Thread1()
{
  int i, internal_reg;

  // Create Thread4
  i = pthread_create(&tid[3], NULL, Thread4, NULL);
  if(i < 0){exit;}

/* here sync with Thread2, Thread3, and Thread4 (4 way) */
  sem_post(&semaphore2);
  sem_post(&semaphore3);
  sem_post(&semaphore4);

  sem_wait(&semaphore1);
  sem_wait(&semaphore1);
  sem_wait(&semaphore1);

  for (i = 0; i < 10000; i++)
    {
      sem_wait(&semaphore1);
      internal_reg = Account[0];
      internal_reg = internal_reg - 200;
      Account[0] = internal_reg;
      /* moving $200 from Account[0] to Account[1] */
      internal_reg = Account [1];
      internal_reg = internal_reg + 200;
      Account[1] = internal_reg;
      sem_post(&semaphore1);

      /* Prints contents of each account and their sum after each 1000 iterations*/
      if (i % 1000 == 0 && i != 0){
	printf("Thread1 #%d - Acc0: %d, Acc1: %d, Acc2: %d, Sum: %d\n", i, Account[0],Account[1],Account[2],Account[0]+Account[1]+Account[2]);
      }
      // Sleep every 3000 iterations
      if(i % 3000 == 0 && i != 0)
	{usleep(200000);}
    }
  sem_post(&semaphore4);
  pthread_exit(NULL);
}

void *Thread2()
{
  int i, internal_reg;

/* here sync with Thread1, Thread3, and Thread4 (4 way) */
  sem_post(&semaphore1);
  sem_post(&semaphore3);
  sem_post(&semaphore4);

  sem_wait(&semaphore2);
  sem_wait(&semaphore2);
  sem_wait(&semaphore2);

  for (i = 0; i < 10000; i++)
    {
      sem_wait(&semaphore1);
      internal_reg = Account[1];
      internal_reg = internal_reg - 200;
      Account[1] = internal_reg;
      /* moving $200 from Account[1] to Account[2] */
      internal_reg = Account [2];
      internal_reg = internal_reg + 200;
      Account[2] = internal_reg;
      sem_post(&semaphore1);

      /* Prints contents of each account and their sum after each 1000 iterations*/
      if (i % 1000 == 0 && i != 0){
	printf("Thread2 #%d - Acc0: %d, Acc1: %d, Acc2: %d, Sum: %d\n", i, Account[0],Account[1],Account[2],Account[0]+Account[1]+Account[2]);
      }
      // Sleep after 2000, 4000, 6000, and 9000 iterations
      if(i == 2000 || i == 4000 || i == 6000 || i == 9000)
	{usleep(200000);}
    }
  sem_post(&semaphore4);
  pthread_exit(NULL);
}

void *Thread3()
{
  int i, internal_reg;

/* here sync with Thread1, Thread2, and Thread4 (4 way) */
  sem_post(&semaphore1);
  sem_post(&semaphore2);
  sem_post(&semaphore4);

  sem_wait(&semaphore3);
  sem_wait(&semaphore3);
  sem_wait(&semaphore3);

  for (i = 0; i < 10000; i++)
    {
      sem_wait(&semaphore1);
      internal_reg = Account[2];
      internal_reg = internal_reg - 200;
      Account[2] = internal_reg;
      /* moving $200 from Account[2] to Account[0] */
      internal_reg = Account [0];
      internal_reg = internal_reg + 200;
      Account[0] = internal_reg;
      sem_post(&semaphore1);

      /* Prints contents of each account and their sum after each 1000 iterations*/
      if (i % 1000 == 0 && i != 0){
	printf("Thread3 #%d - Acc0: %d, Acc1: %d, Acc2: %d, Sum: %d\n", i, Account[0],Account[1],Account[2],Account[0]+Account[1]+Account[2]);
      }
      // Sleep after 2000 and 7500 iterations
      if(i == 2000 || i == 7500)
	{usleep(300000);}
    }
  sem_post(&semaphore4);
  pthread_exit(NULL);
}

void *Thread4()
{
  int i, count = 0;
/* here sync with Thread1, Thread2, and Thread3 (4 way) */
  sem_post(&semaphore1);
  sem_post(&semaphore2);
  sem_post(&semaphore3);

  sem_wait(&semaphore4);
  sem_wait(&semaphore4);
  sem_wait(&semaphore4);

  for(i = 0; i < 50000; i++)
    {
      if(Account[0]+Account[1]+Account[2] != 300000)
	{count++;}
      if(i % 10000 == 0 && i != 0)
	{usleep(50000);}
    }
  // 4 process 1 way sync to ensure Thread4 prints and exits last
  sem_wait(&semaphore4);
  sem_wait(&semaphore4);
  sem_wait(&semaphore4);

  printf("The accounts did not add up to $300,000 %d times out of 50,000.\n", count);
  exit;
}