add original source

source/listing_6.9.cpp

@@ -0,0 +1,49 @@
+template<typename T>
+class threadsafe_queue
+{
+private:
+    node* get_tail()
+    {
+        std::lock_guard<std::mutex> tail_lock(tail_mutex);
+        return tail;
+    }
+
+    std::unique_ptr<node> pop_head()
+    {
+        std::unique_ptr<node> const old_head=std::move(head);
+        head=std::move(old_head->next);
+        return old_head;
+    }
+
+    std::unique_lock<std::mutex> wait_for_data()
+    {
+        std::unique_lock<std::mutex> head_lock(head_mutex);
+        data_cond.wait(head_lock,[&]{return head!=get_tail();});
+        return std::move(head_lock);
+    }
+
+    std::unique_ptr<node> wait_pop_head()
+    {
+        std::unique_lock<std::mutex> head_lock(wait_for_data());
+        return pop_head();
+    }
+
+    std::unique_ptr<node> wait_pop_head(T& value)
+    {
+        std::unique_lock<std::mutex> head_lock(wait_for_data());
+        value=std::move(*head->data);
+        return pop_head();
+    }
+        
+public:
+    std::shared_ptr<T> wait_and_pop()
+    {
+        std::unique_ptr<node> const old_head=wait_pop_head();
+        return old_head->data;
+    }
+
+    void wait_and_pop(T& value)
+    {
+        std::unique_ptr<node> const old_head=wait_pop_head(value);
+    }
+};