a simple thread example to show thread-safe vector operation

threadexample.cpp

#include <iostream>
#include <concurrent_vector.h>
#include <thread>
#include <algorithm>
#include <cstdlib>
#include <atomic>
#include <vector>
#include <mutex>

int counter = 0;
std::vector<int> vec;
// mutex to lock critical region
std::mutex mylock;

void push2vector() {
	try {
		for (int i = 0; i < 1000000; i++){
			// increment here will generate repeated values in the vector
			//counter++;
			mylock.lock();
			// increment here is thread safe
			counter++;
			// push back to the vector when the mutex is locked
			// using the concurrent vector has the same effect
			vec.push_back(counter);
			mylock.unlock();
		}
	}
	catch (std::exception e) {
		std::cout << "counter = " << counter << std::endl;
		std::cerr << e.what() << std::endl;
	}
	
}

int main() {

	for (int i = 0; i < 10; i++) {
		counter = 0;
		vec.clear();
		std::thread t1(push2vector);
		std::thread t2(push2vector);

		t1.join();
		t2.join();

		std::sort(vec.begin(), vec.end());

		bool repeated = false;
		for (int j = 0; j < vec.size() - 1; j++) {
			repeated |= (vec[j] == vec[j + 1]);

		}

		std::cout << (repeated ? "repeat" : "no repeat") << std::endl;
		/*
		std::for_each(vec.begin(), vec.end(), [](int x){
			std::cout << x << std::endl;
		});
		*/

		system("pause");
	}

	return 0;
}

Ehlenn.

I've tried commenting #include <concurrent_vector.h> and the result seems the same, so what's the use of it?

@keineahnung2345 this example shows how to use std::mutex to create a simple thread-safe vector. The concurrent_vector header is from Intel TBB, which is a thread-safe vector implemented by Intel.