50 lines
1.3 KiB
C++
50 lines
1.3 KiB
C++
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#include <iostream>
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#include <thread>
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#include <future>
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using namespace std;
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void test1() {
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promise<int> p;
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future<int> f = p.get_future();
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thread t1([&]() {
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this_thread::sleep_for(chrono::milliseconds(1000));
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p.set_value(12);
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this_thread::sleep_for(chrono::milliseconds(1000));
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});
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t1.detach();
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std::cout << "test1:: res:: " << f.get() << endl;
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}
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void test2() {
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promise<int> p;
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future<int> f = p.get_future();
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shared_future<int> sf = f.share();
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thread t1([&]() {
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this_thread::sleep_for(chrono::milliseconds(1000));
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p.set_value(12);
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this_thread::sleep_for(chrono::milliseconds(1000));
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});
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t1.detach();
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std::cout << "test2:: res:: " << sf.get() << sf .get() << endl;
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}
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void test3() {
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auto fn = []()->int {
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this_thread::sleep_for(chrono::milliseconds(1000));
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return 12;
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};
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auto f = async(launch::async, fn);
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packaged_task<int()> t(fn);
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t();
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std::cout << "test3:: res:: " << f.get() << t.get_future().get() << endl;
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}
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int main() {
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test1();
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test2();
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test3();
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//这里通过条件变量 | 信号量 + 共享变量就能实现
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//用promise-future 感觉很浪费
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std::cout << "promise size:: " << sizeof(promise<int>) <<
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" future size:: " << sizeof(future<int>) <<
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" shared_future size:: " << sizeof(shared_future<int>) << endl;
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return 1;
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}
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