I am trying to create a program that will add and subtract from a global variable. The add and subtract features will be handled by threads. How do I continuously add/subtract until the global variable has reached some threshold?
Say I have the following code,
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <ctime>
#include <numeric>
#include <cmath>
#include <sstream>
#include <thread>
#include <chrono>
#include <ctime>
#include <mutex>
int GetRandom(int max){
//generate a pseudo-random number with time as the seed
//time as seed will always return a different starting point
srand(time(NULL));
//mod max to ensure we return a number below max
return rand() % max;
}
std::string GetTime(){
auto nowTime = std::chrono::system_clock::now();
std::time_t sleepTime =
std::chrono::system_clock::to_time_t(nowTime);
return std::ctime(&sleepTime);
}
double acctBalance = 10;
// Protects shared data from being accessed at the
// same time
std::mutex acctLock;
void Add(int id,
double adding, int sleep){
int rand = GetRandom(10);
// The exception safe way to protect access
// to code within its scope. The lock is released
// after execution leaves this scope
std::lock_guard<std::mutex> lock(acctLock);
// Blocks access between lock and unlock
// until execution completes
// This isn't good to use however if an error
// occurs between lock and unlock
// acctLock.lock();
std::this_thread::sleep_for(std::chrono::seconds(sleep));
std::cout << id <<
": adding : " <<
rand << " on " <<
GetTime() << ": slept for " << sleep<<"seconds"<< "\n";
if((acctBalance - rand) <= 20){
acctBalance += rand;
std::cout << "New Account Balance is $" <<
acctBalance << "\n";
} else {
std::cout << "Not Enough Money in Account\n";
std::cout << "Current Balance is $" <<
acctBalance << "\n";
}
// acctLock.unlock();
}
void Subtract(int id, double subtract, int sleep){
int rand = GetRandom(10);
// The exception safe way to protect access
// to code within its scope. The lock is released
// after execution leaves this scope
std::lock_guard<std::mutex> lock(acctLock);
// Blocks access between lock and unlock
// until execution completes
// This isn't good to use however if an error
// occurs between lock and unlock
// acctLock.lock();
std::this_thread::sleep_for(std::chrono::seconds(sleep));
std::cout << id <<
" tries to withdrawal $" <<
rand << " on " <<
GetTime() << ": slept for " << sleep<<"seconds"<<"\n";
if((acctBalance - rand) <=20){
acctBalance -= rand;
std::cout << "New Account Balance is $" <<
acctBalance << "\n";
} else {
std::cout << "Not Enough Money in Account\n";
std::cout << "Current Balance is $" <<
acctBalance << "\n";
}
// acctLock.unlock();
}
int main()
{
// We will create a pool of threads that
// will access a bank account in no particular
// order
std::thread threads[2];
int rand = 3;
int x = 10;
threads[0] = std::thread(Add, 0, 15,rand);
threads[1] = std::thread(Subtract, 1, 15,rand);
for(int i = 0; i < 2; ++i){
threads[i].join();
}
return 0;
}
I currently have created 2 threads, 1 for adding, another for subtracting. But my program will only add and subtract from the global variable one time each. I figure I should create a dynamic array of threads that will grow until the acctBalance reaches some number. How would I go about accomplishing this?
