How do C++ functions manage state in concurrent programming?

Common techniques for managing function state in C concurrent programming include: Thread-local storage (TLS) allows each thread to maintain its own independent copy of variables. Atomic variables allow atomic reading and writing of shared variables in a multi-threaded environment. Mutexes ensure state consistency by preventing multiple threads from executing critical sections at the same time.

C functions perform state management in concurrent programming

In multi-threaded programming, concurrent functions often need to manage their own state . To ensure data consistency and correctness, state management is crucial. This article explores common techniques for managing function state in C concurrent programming.

Thread Local Storage (TLS)

TLS allows each thread to have its own independent copy of a variable. This is useful for functions that need to maintain specific state for each thread. Here is an example of using TLS:

#include <thread>

// 定义线程局部变量
thread_local int thread_counter;

// 并发函数
void increment_counter() {
  ++thread_counter;
  std::cout << "Current counter: " << thread_counter << std::endl;
}

int main() {
  // 创建多个线程并执行并发函数
  std::vector<std::thread> threads;
  for (int i = 0; i < 10; ++i) {
    threads.emplace_back(increment_counter);
  }

  // 等待所有线程完成
  for (auto& thread : threads) {
    thread.join();
  }

  return 0;
}

Atomic Variables

Atomic variables allow atomic reading and writing of shared variables in a multi-threaded environment. This prevents race conditions and data corruption of the state. Here's how to use std::atomic atomic variables:

#include <atomic>

// 定义原子变量
std::atomic<int> counter;

// 并发函数
void increment_counter() {
  ++counter;
  std::cout << "Current counter: " << counter << std::endl;
}

int main() {
  // 创建多个线程并执行并发函数
  std::vector<std::thread> threads;
  for (int i = 0; i < 10; ++i) {
    threads.emplace_back(increment_counter);
  }

  // 等待所有线程完成
  for (auto& thread : threads) {
    thread.join();
  }

  return 0;
}

Mutex lock

Mutex locks are used to control access to shared resources. They ensure state consistency by preventing multiple threads from executing critical sections simultaneously. Here's how to use a std::mutex mutex:

#include <mutex>

// 定义互斥锁
std::mutex counter_lock;

// 并发函数
void increment_counter() {
  // 获得锁
  std::lock_guard<std::mutex> lock(counter_lock);

  // 读写共享状态
  ++counter;
  std::cout << "Current counter: " << counter << std::endl;
}

int main() {
  // 创建多个线程并执行并发函数
  std::vector<std::thread> threads;
  for (int i = 0; i < 10; ++i) {
    threads.emplace_back(increment_counter);
  }

  // 等待所有线程完成
  for (auto& thread : threads) {
    thread.join();
  }

  return 0;
}

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