asio: Add example to use timer to achieve delayed response

examples/asio-sv.cc

@@ -64,22 +64,42 @@ int main(int argc, char *argv[]) {
 
     server.handle("/", [](const request &req, const response &res) {
       res.write_head(200, {{"foo", {"bar"}}});
-      res.end("hello, world");
+      res.end("hello, world\n");
     });
     server.handle("/secret/", [](const request &req, const response &res) {
       res.write_head(200);
-      res.end("under construction!");
+      res.end("under construction!\n");
     });
     server.handle("/push", [](const request &req, const response &res) {
       boost::system::error_code ec;
       auto push = res.push(ec, "GET", "/push/1");
       if (!ec) {
         push->write_head(200);
-        push->end("server push FTW!");
+        push->end("server push FTW!\n");
       }
 
       res.write_head(200);
-      res.end("you'll receive server push!");
+      res.end("you'll receive server push!\n");
+    });
+    server.handle("/delay", [](const request &req, const response &res) {
+      res.write_head(200);
+
+      auto timer = std::make_shared<boost::asio::deadline_timer>(
+          res.io_service(), boost::posix_time::seconds(3));
+      auto closed = std::make_shared<bool>();
+
+      res.on_close([timer, closed](uint32_t error_code) {
+        timer->cancel();
+        *closed = true;
+      });
+
+      timer->async_wait([&res, closed](const boost::system::error_code &ec) {
+        if (ec || *closed) {
+          return;
+        }
+
+        res.end("finally!\n");
+      });
     });
     server.listen("*", port);