我想要做的是将整数推送到我的线程安全队列实现多线程,并与另一系列的线程同时弹出插入的数字。所有这些操作都必须是线程安全的,但我想要的另一个选项是队列的大小必须是固定的,就像缓冲区一样。如果缓冲区已满,所有推送线程必须等待弹出线程释放一些插槽。固定大小的线程安全队列
这是我的队列/缓冲区的实现,它似乎工作,但经过几次迭代后,它停止并保持阻塞,没有任何错误。
#include <queue>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <iostream>
template <typename T>
class Queue
{
private:
std::queue<T> queue_;
std::mutex mutex_;
std::condition_variable cond_;
public:
T pop()
{
std::unique_lock<std::mutex> mlock(mutex_);
cond_.wait(mlock, [this]{return !queue_.empty();});
auto val = queue_.front();
queue_.pop();
return val;
}
void pop(T& item)
{
std::unique_lock<std::mutex> mlock(mutex_);
cond_.wait(mlock, [this]{return !queue_.empty();});
item = queue_.front();
queue_.pop();
}
void push(const T& item, int buffer)
{
std::unique_lock<std::mutex> mlock(mutex_);
while (queue_.size() >= buffer)
{
cond_.wait(mlock);
}
queue_.push(item);
mlock.unlock();
cond_.notify_one();
}
Queue()=default;
Queue(const Queue&) = delete; // disable copying
Queue& operator=(const Queue&) = delete; // disable assignment
};
缓冲区的大小是在带有可变缓冲区的推送函数中定义的。这是使用的例子:
void prepare(Queue<int>& loaded, int buffer, int num_frames)
{
for (int i = 0; i < num_frames; i++)
{
cout<< "push "<<i<<endl;
loaded.push(i, buffer);
}
}
void load (vector<Frame>& movie, Queue<int>& loaded, int num_frames,
int num_points, int buffer, int height, int width)
{
for (int i = 0; i < num_frames; i++)
{
int num = loaded.pop();
cout<< "pop "<<num<<endl;
}
}
int main()
{
srand(time(NULL));
int num_threadsXstage = 4;
int width = 500;
int height = 500;
int num_points = width * height;
int num_frames = 100;
int frames_thread = num_frames/num_threadsXstage;
int preset = 3;
int buffer = 10;
//Vectors of threads
vector<thread> loader;
//Final vector
vector<Frame> movie;
movie.resize(num_frames);
//Working queues
Queue<int> loaded;
//Prepare loading queue task
thread preparator(prepare, ref(loaded), buffer, num_frames);
for (int i = 0; i < num_threadsXstage; i++)
{
//stage 1
loader.push_back(thread(&load, ref(movie), ref(loaded), frames_thread,
num_points, buffer, height, width));
}
// JOIN
preparator.join();
join_all(loader);
return 0;
}
您在'pop()'中缺少一个'notify()'来发信号通知'push()'它现在很容易推送。另外,正如已经指出的那样,您需要在通知时保持锁定状态。 – TFM