#include
#include
#include
#include

//Max Number of customers
#define MAX 5
//Max number of resources
#define RESOURCES 3

//available resources
int available[RESOURCES];
//maximum demand of customers
int maximum[MAX][RESOURCES];
//allocation of customer
int allocation[MAX][RESOURCES];
//need of customer
int need[MAX][RESOURCES];

pthread_mutex_t mutex;

//Function to check for safe state
int checkSafeState(int allocated[][RESOURCES], int need[][RESOURCES], int available[])
{
int finish[MAX] = {0};
int work[RESOURCES];
int i, j;

// Initializing the work[] array
for (i = 0; i < RESOURCES; i++)
work[i] = available[i];

int count = 0;
while (count < MAX)
{
int safe = 0;
for (i = 0; i < MAX; i++)
{
if (finish[i] == 0)
{
int flag = 0;
for (j = 0; j < RESOURCES; j++)
{
if (need[i][j] > work[j])
flag = 1;
}
if (flag == 0)
{
for (j = 0; j < RESOURCES; j++)
work[j] += allocated[i][j];
safe = 1;
finish[i] = 1;
count++;
}
}
}
if (safe == 0)
return 0;
}
return 1;
}

//Function to request resources
int request_resource(int customer_id, int request[])
{
int i;

//Acquiring the mutex lock
pthread_mutex_lock(&mutex);

//Check if request can be granted
for (i = 0; i < RESOURCES; i++)
{
if (request[i] > need[customer_id][i])
{
printf("Exceeds maximum claim.\n");
pthread_mutex_unlock(&mutex);
return -1;
}
}

for (i = 0; i < RESOURCES; i++)
{
if (request[i] > available[i])
{
printf("Resources not available.\n");
pthread_mutex_unlock(&mutex);
return -1;
}
}

//Decrement available resources and increment allocated resources
for (i = 0; i < RESOURCES; i++)
{
available[i] -= request[i];
allocation[customer_id][i] += request[i];
need[customer_id][i] -= request[i];
}

//Check for safe state
if (checkSafeState(allocation, need, available))
{
printf("Request granted.\n");
pthread_mutex_unlock(&mutex);
return 0;
}
else
{
printf("Request denied. System is not in safe state.\n");
//Rollback changes
for (i = 0; i < RESOURCES; i++)
{
available[i] += request[i];
allocation[customer_id][i] -= request[i];
need[customer_id][i] += request[i];
}
pthread_mutex_unlock(&mutex);
return -1;
}
}

//Function to release resources
int release_resource(int customer_id, int release[])
{
int i;

//Acquiring the mutex lock
pthread_mutex_lock(&mutex);

//Increment available resources and decrement allocated resources
for (i = 0; i < RESOURCES; i++)
{
available[i] += release[i];
allocation[customer_id][i] -= release[i];
need[customer_id][i] += release[i];
}

printf("Resource released.\n");
pthread_mutex_unlock(&mutex);
return 0;
}

//Function to execute threads
void* thread_function(void* arg)
{
int customer_id = (int)arg;
int request[RESOURCES];
int i;

while (1)
{
printf("Customer %d\n", customer_id);
printf("Available resources:");
for (i = 0; i < RESOURCES; i++)
printf(" %d", available[i]);
printf("\n");

//Generate random request
for (i = 0; i < RESOURCES; i++)
request[i] = rand() % (need[customer_id][i] + 1);

printf("Requesting resources:");
for (i = 0; i < RESOURCES; i++)
printf(" %d", request[i]);
printf("\n");

//Request resources
int ret = request_resource(customer_id, request);
if (ret == 0)
{
//Release resources
release_resource(customer_id, request);
}
sleep(1);
}
}

int main(int argc, char** argv)
{
int i, j;

//Initializing mutex
pthread_mutex_init(&mutex, NULL);

//Taking input for available resources
printf("Enter number of available resources for each type:\n");
for (i = 0; i < RESOURCES; i++)
scanf("%d", &available[i]);

//Taking input for maximum demand of customers
printf("\nEnter maximum demand for each customer for each type:\n");
for (i = 0; i < MAX; i++)
for (j = 0; j < RESOURCES; j++)
scanf("%d", &maximum[i][j]);

//Initializing allocated and need matrix
for (i = 0; i < MAX; i++)
for (j = 0; j < RESOURCES; j++)
{
allocation[i][j] = 0;
need[i][j] = maximum[i][j];
}

//Creating customer threads
pthread_t threads[MAX];
for (i = 0; i < MAX; i++)
pthread_create(&threads[i], NULL, thread_function, (void*)i);

//Joining customer threads
for (i = 0; i < MAX; i++)
pthread_join(threads[i], NULL);

//Destroy the mutex
pthread_mutex_destroy(&mutex);
return 0;
}