在编写多线程程序时，多个线程同时访问某个共享资源，会导致同步的问题，这篇文章中我们将介绍 C++11 多线程编程中的数据保护。
数据丢失
让我们从一个简单的例子开始，请看如下代码：
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#include <iostream> |
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#include <string> |
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#include <thread> |
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#include <vector> |
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using std::thread;
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using std::vector;
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using std::cout;
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using std::endl;
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class Incrementer
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{ |
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private:
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int counter;
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public:
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Incrementer() : counter{0} { };
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void operator()()
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{
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for(int i = 0; i < 100000; i++)
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{
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this->counter++;
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}
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}
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int getCounter() const
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{
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return this->counter;
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}
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}; |
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int main()
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{ |
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// Create the threads which will each do some counting
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vector<thread> threads;
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Incrementer counter;
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threads.push_back(thread(std::ref(counter)));
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threads.push_back(thread(std::ref(counter)));
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threads.push_back(thread(std::ref(counter)));
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for(auto &t : threads)
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{
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t.join();
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}
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cout << counter.getCounter() << endl;
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return 0;
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} |