我有一个有自己线程的类播放器。
player. cpp
int soh::player::instance_count{ 0 };
int soh::player::current_player{ -1 };
std::mutex soh::player::mutex;
std::condition_variable soh::player::cv;
soh::player::player(std::string name)
: name{ std::move(name) }
, id{ soh::player::instance_count }
, thread{ &soh::player::routine, this }
{
++soh::player::instance_count;
std::cout << this->name << " created\n"; // prints player_0 created
}
soh::player::~player()
{
--soh::player::instance_count;
thread.join();
}
void soh::player::routine()
{
std::cout << soh::player::instance_count << '\n'; // prints 0
std::unique_lock<std::mutex> lk(mutex);
cv.wait(lk, [id = this->id]{return id == current_player;});
std::cout << "Worker thread " << id << " is processing data\n";
std::this_thread::sleep_for(std::chrono::seconds(1));
std::cout << "Worker thread " << id << " data processing completed\n";
lk.unlock();
cv.notify_all();
}
而当我尝试生成一些这种类型的对象时,主线程在创建第一个对象时就停止了。
int main(int argc, char* argv[])
{
soh::player{ "player_0" }; // <- main thread stops here
soh::player{ "player_1" };
{
std::lock_guard<std::mutex> lk(soh::player::mutex);
std::cout << "???\n";
soh::player::current_player = 0;
}
soh::player::cv.notify_all();
std::this_thread::sleep_for(std::chrono::seconds(2));
return 0;
}
我不明白为什么这段代码不会停止。如果有任何帮助,我将不胜感激
soh::player{ "player_0" };
创建一个未命名的临时对象,这个对象会在挂起时立即被销毁。.join()
因为线程程序在 cv.wait
. 你应该给它起个名字,这样它就能生存下去了,直到它离开范围。