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--- c:c_threads:thread_class [2021/03/05 17:12] – peter
+++ c:c_threads:thread_class [2021/03/05 17:13] (current) – peter
@@ Line 51: / Line 51: @@
 ----
-<code cpp>
-#include <iostream>
-#include <thread>
-#include <vector>
-#include<mutex>
-// Wallet provides a service to add money in a Wallet.
-//
-// The same Wallet object is used between different threads, so a Lock is needed in the addMoney() method of the Wallet.
-//
-// Acquire lock before increment the money of Wallet and release lock before leaving that function.
-//
-// This member function, first acquires a lock then increments the internal money of wallet object by a specified count and then releases the lock.
-class Wallet
-{
-  int mMoney;
-  std::mutex mutex;
-public:
-  Wallet() :mMoney(0){}
-  int getMoney()   {     return mMoney; }
-  void addMoney(int money)
-  {
-    mutex.lock();
-    for(int i = 0; i < money; ++i)
-    {
-      mMoney++;
-    }
-    mutex.unlock();
-  }
-};
-// Five threads will share the same Wallet class object and each thread will add 1000 into the Wallet using the addMoney() member function in parallel.
-//
-// So, if initially the money in the wallet is 0, then then after completion of all the threads, the money in the Wallet should be 5000.
-//
-// Adding a mutex lock guarantees that Money in the Wallet will be 5000 at the end.
-int testMultithreadedWallet()
-{
-  Wallet walletObject;
-  std::vector<std::thread> threads;
-  for(int i = 0; i < 5; ++i) {
-    threads.push_back(std::thread(&Wallet::addMoney, &walletObject, 1000));
-  }
-  for(int i = 0; i < threads.size() ; i++)
-  {
-    threads.at(i).join();
-  }
-  return walletObject.getMoney();
-}
-int main()
-{
-  int val = 0;
-  for(int k = 0; k < 1000; k++)
-  {
-    if((val = testMultithreadedWallet()) != 5000)
-    {
-      std::cout << "Error at count = "<<k<<"  Money in Wallet = "<<val << std::endl;
-      //break;
-    }
-  }
-  return 0;
-}
-</code>
-<WRAP info>
-**NOTE:**  The **mutex** lock in addMoney() makes sure that once one thread finishes the modification of money then only any other thread modifies the money in Wallet.
-</WRAP>