Remove WFFacilities::ReplyGuard.

docs/tutorial-05-http_proxy.md

@@ -220,17 +220,3 @@ int process(WFHttpTask *server_task)
     series_of(server_task)->push_back(task);
 }
 ~~~
-但鉴于很多用户不想了解series用法，我们加入一个便利类ReplyGuard，让用户可以在任何时候回复请求，用法如下：
-~~~cpp
-int process(WFHttpTask *server_task)
-{
-    auto *guard = new WFFacilities::ReplyGuard(server_task);
-    WFHttpTask *task = WFTaskFactory::create_http_task(..., [guard, server_task]{WFHttpTask *task) {
-        *server_task->get_resp() = std::move(*task->get_resp());
-        delete guard;  // 此时server才会回复。
-    });
-    task->start();
-}
-~~~
-WFFacilities::ReplyGuard用于阻止一个server task的回复，只有这个guard被析构，才会触发回复。  
-使用ReplyGuard一般不影响原server task series的使用，用户依然可以push_back任务。但**避免再调用series的cancel()**。

src/manager/WFFacilities.h

@@ -78,28 +78,6 @@ public:
 		WFFuture<void> future;
 	};
 
-public:
-	class ReplyGuard
-	{
-	public:
-		ReplyGuard(SubTask *server_task)
-		{
-			SeriesWork *series = series_of(server_task);
-			assert(series);
-			assert(server_task == series->get_last_task());
-			this->cond = WFTaskFactory::create_conditional(server_task);
-			series->set_last_task(this->cond);
-		}
-
-		~ReplyGuard()
-		{
-			this->cond->signal(NULL);
-		}
-
-	private:
-		WFConditional *cond;
-	};
-
 private:
 	static void __timer_future_callback(WFTimerTask *task);
 	static void __fio_future_callback(WFFileIOTask *task);