add original source

source/listing_9.6.cpp

@@ -0,0 +1,58 @@
+class thread_pool
+{
+    thread_safe_queue<function_wrapper> pool_work_queue;
+
+    typedef std::queue<function_wrapper> local_queue_type;
+    static thread_local std::unique_ptr<local_queue_type>
+        local_work_queue;
+   
+    void worker_thread()
+    {
+        local_work_queue.reset(new local_queue_type);
+        
+        while(!done)
+        {
+            run_pending_task();
+        }
+    }
+
+public:
+    template<typename FunctionType>
+    std::future<std::result_of<FunctionType()>::type>
+        submit(FunctionType f)
+    {
+        typedef std::result_of<FunctionType()>::type result_type;
+        
+        std::packaged_task<result_type()> task(f);
+        std::future<result_type> res(task.get_future());
+        if(local_work_queue)
+        {
+            local_work_queue->push(std::move(task));
+        }
+        else
+        {
+            pool_work_queue.push(std::move(task));
+        }
+        return res;
+    }
+
+    void run_pending_task()
+    {
+        function_wrapper task;
+        if(local_work_queue && !local_work_queue->empty())
+        {
+            task=std::move(local_work_queue->front());
+            local_work_queue->pop();
+            task();
+        }
+        else if(pool_work_queue.try_pop(task))
+        {
+            task();
+        }
+        else
+        {
+            std::this_thread::yield();
+        }
+    }
+    // rest as before
+};