1 /* 2 * Copyright 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <array> 20 21 #include "common/bind.h" 22 #include "common/callback.h" 23 #include "os/log.h" 24 25 namespace bluetooth { 26 namespace common { 27 28 // Tracks an observer registration on client (observer) code. Register() returns a wrapped callback object which can 29 // be passed to server's register API. Unregister() invalidates the wrapped callback so all callbacks that are posted 30 // to the client handler after the client called Unregister() call and before the server processed the Unregister() 31 // call on its handler, are dropped. 32 // Note: Register() invalidates the previous registration. 33 class SingleObserverRegistry { 34 public: 35 template <typename R, typename... T> decltype(auto)36 decltype(auto) Register(Callback<R(T...)> callback) { 37 session_++; 38 return Bind(&SingleObserverRegistry::callback_wrapper<R, T...>, Unretained(this), session_, callback); 39 } 40 Unregister()41 void Unregister() { 42 session_++; 43 } 44 45 private: 46 template <typename R, typename... T> callback_wrapper(int session,Callback<R (T...)> callback,T...t)47 void callback_wrapper(int session, Callback<R(T...)> callback, T... t) { 48 if (session == session_) { 49 callback.Run(std::forward<T>(t)...); 50 } 51 } 52 53 uint8_t session_ = 0; 54 }; 55 56 // Tracks observer registration for multiple event type. Each event type is represented as an integer in [0, Capacity). 57 template <int Capacity = 10> 58 class MultipleObserverRegistry { 59 public: 60 template <typename R, typename... T> decltype(auto)61 decltype(auto) Register(int event_type, Callback<R(T...)> callback) { 62 ASSERT(event_type < Capacity); 63 return registry_[event_type].Register(callback); 64 } 65 Unregister(int event_type)66 void Unregister(int event_type) { 67 ASSERT(event_type < Capacity); 68 registry_[event_type].Unregister(); 69 } 70 71 std::array<SingleObserverRegistry, Capacity> registry_; 72 }; 73 74 } // namespace common 75 } // namespace bluetooth 76