add original source

source/listing_6.2.cpp

@@ -0,0 +1,72 @@
+#include <queue>
+#include <mutex>
+#include <condition_variable>
+#include <memory>
+
+template<typename T>
+class threadsafe_queue
+{
+private:
+    mutable std::mutex mut;
+    std::queue<T> data_queue;
+    std::condition_variable data_cond;
+public:
+    threadsafe_queue()
+    {}
+
+    void push(T new_value)
+    {
+        std::lock_guard<std::mutex> lk(mut);
+        data_queue.push(std::move(new_value));
+        data_cond.notify_one();
+    }
+
+    void wait_and_pop(T& value)
+    {
+        std::unique_lock<std::mutex> lk(mut);
+        data_cond.wait(lk,[this]{return !data_queue.empty();});
+        value=std::move(data_queue.front());
+        data_queue.pop();
+    }
+
+    std::shared_ptr<T> wait_and_pop()
+    {
+        std::unique_lock<std::mutex> lk(mut);
+        data_cond.wait(lk,[this]{return !data_queue.empty();});
+        std::shared_ptr<T> res(
+            std::make_shared<T>(std::move(data_queue.front())));
+        data_queue.pop();
+        return res;
+    }
+
+    bool try_pop(T& value)
+    {
+        std::lock_guard<std::mutex> lk(mut);
+        if(data_queue.empty())
+            return false;
+        value=std::move(data_queue.front());
+        data_queue.pop();
+    }
+
+    std::shared_ptr<T> try_pop()
+    {
+        std::lock_guard<std::mutex> lk(mut);
+        if(data_queue.empty())
+            return std::shared_ptr<T>();
+        std::shared_ptr<T> res(
+            std::make_shared<T>(std::move(data_queue.front())));
+        data_queue.pop();
+        return res;
+    }
+
+    bool empty() const
+    {
+        std::lock_guard<std::mutex> lk(mut);
+        return data_queue.empty();
+    }
+};
+
+int main()
+{
+    threadsafe_queue<int> rq;
+}