добавил пример обработки данных, считанных из сокета, в пуле потоков и запись результата обратно в сокет (и все это в псевдолинейном стиле)

test/server/session.cpp

@@ -7,28 +7,24 @@ session::session(boost::asio::io_service &io_service): boost::asio::coroutine(),
 {
 }
 
-session::~session()
-{
-	std::cout << "session destructor" << std::endl;
-}
-
 void session::start(boost::system::error_code ec, std::size_t bytes_transferred)
 {
 	if(!ec)
 	{
-		reenter(this) for(;;)
+		reenter(this) for(;;) // псевдолинейный код
 		{
 			std::memset(_data, 0, 128);
 			yield _socket.async_read_some(boost::asio::buffer(_data, 128), std::bind(&session::start, this, std::placeholders::_1, std::placeholders::_2));
-			std::cout << "async_read " << bytes_transferred << " bytes" << std::endl;
-			std::cout << "number: " << std::atoi(_data) << std::endl;
 
-//			yield _pool<int>.add_task([this]{
-//				return 42;
-//			});
+			yield _fut = call_async<int>([this]{
+                int n = std::atoi(_data);
+                return n*n;
+            });
 
-			yield _socket.async_write_some(boost::asio::buffer(_data, 128), std::bind(&session::start, this, std::placeholders::_1, std::placeholders::_2));
-			std::cout << "async_write" << std::endl;
+			yield {
+                std::string res = std::to_string(_fut.get()) + "\n";
+                _socket.async_write_some(boost::asio::buffer(res), std::bind(&session::start, this, std::placeholders::_1, std::placeholders::_2));
+            }
 		}
 	}
 	else

test/server/session.h

@@ -15,12 +15,23 @@ private:
 	char _data[128];
 	threadpool _pool;
 
+    // "local" variables
+    std::future<int> _fut;
+
 public:
 	session() = delete;
 	session(session&) = delete;
 	session(boost::asio::io_service& io_service);
 	void start(boost::system::error_code ec = boost::system::error_code(), std::size_t bytes_transferred = 0);
-	~session();
+
+    template <typename R> std::future<R> call_async(std::function<R()> func)
+    {
+        return _pool.add_task<R>([this, &func]{
+            R result = func();
+            _socket.get_io_service().dispatch(std::bind(&session::start, this, boost::system::error_code(), 0));
+            return result;
+        });
+    }
 
 };