Starcraft.c

//--------------------------------------------
// NAME: Veselin Dechev
// CLASS: XIA
// NUMBER: 2
// PROBLEM: #3
// FILE NAME: Starcraft.c (unix file name)
// FILE PURPOSE:
// Synchronising threads with mutex.
// Example with workers and one mine like THE GAME Starcraft.
// ...
//--------------------------------------------

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

int NUM_THREADS; //Number of threads

pthread_mutex_t lock; //Mutex
int gold; //Gold in the mine
int* workers_gold; //gold of every worker
int startminerals = 0;
//--------------------------------------------
// FUNCTION: GetGold
// Geting the gold from the mine and allows only one worker to work.
// PARAMETERS:
// ID of the worker
//--------------------------------------------

void* GetGold(void* arg){    //Geting the gold of the mine
    size_t thread_num = (size_t)arg; //get id of the thread
    while(gold>0){ //when there's a gold in mine , loop works
        pthread_mutex_trylock(&lock); //lock mutex
        printf("SCV %zd is mining\n", thread_num);
        if(gold>7){
            gold-=8; //geting the gold
            startminerals = startminerals + 8; //incrments the gold in every worker's inventory

        }

        else{ //if the gold is less than 8 , the worker takes the gold wich lefts.
            startminerals = startminerals + gold;
            gold-=gold;
        }
        printf("SCV %zd is transporting minerals\n", thread_num);
            printf( "SCV %zd delivered minerals to 'Command Center 1' %d\n", thread_num, startminerals);
        printf("Remaining gold: %d\n",gold);
        pthread_mutex_unlock(&lock); //unlock the mutex
        sleep(1); //simulating when the worker works.
    }
}

int main(int argc, char* argv[]){ //main

    if(argc<2){ //if there's no arguments
        gold = 5000;
        NUM_THREADS = 5;
    }
    else{ //reading from argument line
        gold = atoi(argv[1]);
        NUM_THREADS = atoi(argv[2]);
    }

    pthread_t threads[NUM_THREADS]; //creating array from threads
    pthread_mutex_init(&lock, NULL);  //inits the mutex

    size_t i; //counter

    workers_gold = (int*)malloc(NUM_THREADS*sizeof(int)); // allocate memorry for every worker's inventory
    for (i = 0; i< NUM_THREADS; i++){
                workers_gold[i]=0; //every worker's inventory is set to 0;
    }

    for (i = 1; i <= NUM_THREADS; i++) {
        int error = pthread_create(&threads[i], NULL, GetGold, (void*)i); //creating the threads and checks for errors.
        if (error != 0) {
            fprintf(stderr, "Error creating thread %zd: error: %d\n", i, error);
        }
  }

  for (i = 0; i < NUM_THREADS; i++) {
        int error = pthread_join(threads[i], NULL); //joining the threads.
        if (error != 0) {
            fprintf(stderr, "Error joining thread %zd: error: %d\n", i, error);
        }
  }

    pthread_mutex_destroy(&lock); //destroys mutex
  pthread_exit(NULL); //exit from the threads

    return 0; //epic crash!!!
}