third-party/mcrouter/src/mcrouter/lib/routes/NullRoute.h

   1 /*
   2  * Copyright (c) Meta Platforms, Inc. and affiliates.
   3  *
   4  * This source code is licensed under the MIT license found in the
   5  * LICENSE file in the root directory of this source tree.
   6  */
   7
   8 #pragma once
   9
  10 #include <memory>
  11 #include <string>
  12 #include <vector>
  13
  14 #include "mcrouter/lib/Reply.h"
  15 #include "mcrouter/lib/RouteHandleTraverser.h"
  16 #include "mcrouter/lib/config/RouteHandleBuilder.h"
  17
  18 namespace folly {
  19 struct dynamic;
  20 }
  21
  22 namespace facebook {
  23 namespace memcache {
  24
  25 template <class RouteHandleIf>
  26 class RouteHandleFactory;
  27
  28 /**
  29  * Returns the default reply for each request right away
  30  */
  31 template <class RouteHandleIf>
  32 struct NullRoute {
  33   static std::string routeName() {
  34     return "null";
  35   }
  36
  37   template <class Request>
  38   bool traverse(const Request&, const RouteHandleTraverser<RouteHandleIf>&)
  39       const {
  40     return false;
  41   }
  42
  43   template <class Request>
  44   static ReplyT<Request> route(const Request& req) {
  45     return createReply(DefaultReply, req);
  46   }
  47 };
  48
  49 namespace mcrouter {
  50
  51 template <class RouteHandleIf>
  52 std::shared_ptr<RouteHandleIf> createNullRoute() {
  53   return makeRouteHandle<RouteHandleIf, NullRoute>();
  54 }
  55
  56 template <class RouteHandleIf>
  57 std::shared_ptr<RouteHandleIf> makeNullRoute(
  58     RouteHandleFactory<RouteHandleIf>&,
  59     const folly::dynamic&) {
  60   return createNullRoute<RouteHandleIf>();
  61 }
  62
  63 template <class RouteHandleIf>
  64 std::shared_ptr<RouteHandleIf> makeNullOrSingletonRoute(
  65     std::vector<std::shared_ptr<RouteHandleIf>> rh) {
  66   assert(rh.size() <= 1);
  67   if (rh.empty()) {
  68     return createNullRoute<RouteHandleIf>();
  69   }
  70   return std::move(rh[0]);
  71 }
  72
  73 } // namespace mcrouter
  74 } // namespace memcache
  75 } // namespace facebook