Threaded Bank

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <semaphore.h>
#include "myutils.h"

#define NOPERATIONS 1000
#define FILENAME "Bank.dat"
#define NACCOUNTS 10
#define NTHREADS 250
#define INITIAL_ACCOUNT_MONEY 100

int SOLUTION = 0; // La Solution 1 es usando FileLocks y la Solution 2 es con Semáforos.
int fbank; // Archivo Bank.dat

typedef struct account { int ID; double Balance; } Account; // Estructura de nuestra cuenta bancaria.

sem_t* NamedMutex;

void doSomething() { for (int i=0; i < 100000; i++); }

void bankInit(){
    for(int i=0; i<NACCOUNTS; i++) {
        Account CurrentAccount = {.ID = i, .Balance = INITIAL_ACCOUNT_MONEY}; // Iniciamos la cuenta.
        write(fbank, &CurrentAccount, sizeof(Account)); // Escribimos nuestra cuenta en el Bank.dat
    }
}

void fileWithdraw(int accountID, double amount){
    Account tempAccount;
    lseek(fbank, accountID * sizeof(Account), SEEK_SET);
    read(fbank, &tempAccount, sizeof(Account));

    tempAccount.Balance -= amount;

    lseek(fbank, accountID * sizeof(Account), SEEK_SET);
    write(fbank, &tempAccount, sizeof(Account));
}

void fileDeposit(int accountID, double amount){
    Account tempAccount;
    lseek(fbank, accountID * sizeof(Account), SEEK_SET);
    read(fbank, &tempAccount, sizeof(Account));

    tempAccount.Balance += amount;

    lseek(fbank, accountID * sizeof(Account), SEEK_SET);
    write(fbank, &tempAccount, sizeof(Account));
}

bool check(Account* acc, double amount) { return acc->Balance - amount >= 0; }

bool fileCheck(int accountID, double amount){
    Account tempAccount;
    lseek(fbank, accountID * sizeof(Account), SEEK_SET);
    read(fbank, &tempAccount, sizeof(Account));
    return check(&tempAccount, amount);
}

bool withdraw(int accountID, double amount) {
    if(fileCheck(accountID, amount))  {
        fileWithdraw(accountID, amount);
        doSomething();
        return true;
    }
    return false;
}

void deposit(int accountID, double amount) {
    fileDeposit(accountID, amount);
    doSomething();
}

bool transfer1(int fromID, int toID, double amount){
    // Solución usando FileLocks.

    int Lock1, Lock2; // Con esto vamos a evitar posibles Deadlocks.
    if (fromID > toID) {Lock1 = toID * sizeof(Account); Lock2 = fromID * sizeof(Account); }
    else{ Lock1 = fromID * sizeof(Account), Lock2 = toID * sizeof(Account); }

    while(file_lock(fbank, Lock1, sizeof(Account)) < 0);
    while(file_lock(fbank, Lock2, sizeof(Account)) < 0);

    // En este momento, ya hemos hecho el lock de la zona determinada de nuestro archivo.
    // Así que ya podemos hacer la operación de sumar y restar dinero.
    bool isDone = withdraw(fromID, amount);
    if (isDone) { deposit(toID, amount); }

    file_unlock(fbank, Lock1, sizeof(Account));
    file_unlock(fbank, Lock2, sizeof(Account));

    return isDone;
}

bool transfer2(int fromID, int toID, double amount){
    // Solución usando semáforos.

    sem_wait(NamedMutex);

    bool isDone = withdraw(fromID, amount);
    if (isDone) { deposit(toID, amount); }

    sem_post(NamedMutex);

    return isDone;
}

void* tranferThread(){
    fbank = open("Bank.dat",  O_RDWR, 0600);
    int iter = NOPERATIONS/NACCOUNTS;
    int fromID = -1, toID = -1;
    while(iter--) {
        fromID = -1; toID = -1;
        while(fromID == toID) { // Si hemos seleccionado aleatoriamente las mismas cuentas, repetimos el proceso.
            fromID = rand()%NACCOUNTS; toID = rand()%NACCOUNTS;
        }

        double randomAmount = rand()%50+1;
        printf("ID: %d --- %d€ ---> ID: %d \n", fromID, (int) randomAmount, toID);
        if (SOLUTION == 1) transfer1(fromID, toID, randomAmount);
        else if (SOLUTION == 2) transfer2(fromID, toID, randomAmount);

    }
    return NULL;
}

int main(int argc, char* argv[]){
    if (argc > 1) SOLUTION = atoi(argv[1]);
    startTimer(0);
    if (SOLUTION == 1 || SOLUTION == 2){
        pthread_t ThreadsID[NTHREADS];
        fbank = open(FILENAME, O_CREAT | O_RDWR, 0600);
        if (SOLUTION == 2) NamedMutex = sem_open("/NamedMutex", O_CREAT, 0644, 1);
        bankInit();
        printf("----> Initial Bank Total Money: %d€ <----\n", INITIAL_ACCOUNT_MONEY);
        if (SOLUTION == 1){
            for (int i=0; i < NTHREADS; i++){
                int PID = fork();
                if (PID == 0){
                    tranferThread();
                    exit(0);
                }
            }
            while(wait(NULL) > 0);
        }
        else if (SOLUTION == 2){
            for(int i=0; i<NTHREADS; i++) { pthread_create(&ThreadsID[i], NULL, tranferThread, NULL); }
            for(int i=0; i<NTHREADS; i++) { pthread_join(ThreadsID[i], NULL); }
        }

        sem_close(NamedMutex);
        close(fbank);

        printf("Time: %ld ms\n", endTimer(0));
        return 0;
    }
    else return -1;
}