1 /* 2 * Copyright 2018 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 <base/functional/bind.h> 20 #include <base/location.h> 21 #include <base/run_loop.h> 22 #include <base/threading/platform_thread.h> 23 #include <bluetooth/log.h> 24 #include <unistd.h> 25 26 #include <future> 27 #include <string> 28 #include <thread> 29 30 #include "abstract_message_loop.h" 31 #include "common/postable_context.h" 32 33 namespace bluetooth { 34 35 namespace common { 36 37 /** 38 * An interface to various thread related functionality 39 */ 40 class MessageLoopThread final : public PostableContext { 41 public: 42 /** 43 * Create a message loop thread with name. Thread won't be running until 44 * StartUp is called. 45 * 46 * @param thread_name name of this worker thread 47 */ 48 explicit MessageLoopThread(const std::string& thread_name); 49 50 MessageLoopThread(const MessageLoopThread&) = delete; 51 MessageLoopThread& operator=(const MessageLoopThread&) = delete; 52 53 /** 54 * Destroys the message loop thread automatically when it goes out of scope 55 */ 56 ~MessageLoopThread(); 57 58 /** 59 * Start the underlying thread. Blocks until all thread infrastructure is 60 * setup. IsRunning() and DoInThread() should return true after this call. 61 * Blocks until the thread is successfully started. 62 * 63 * Repeated call to this method will only start this thread once 64 */ 65 void StartUp(); 66 67 /** 68 * Post a task to run on this thread 69 * 70 * @param task task created through base::Bind() 71 * @return true if task is successfully scheduled, false if task cannot be 72 * scheduled 73 */ 74 bool DoInThread(base::OnceClosure task); 75 76 /** 77 * Shutdown the current thread as if it is never started. IsRunning() and 78 * DoInThread() will return false after this call. Blocks until the thread is 79 * joined and freed. This thread can be re-started again using StartUp() 80 * 81 * Repeated call to this method will only stop this thread once 82 * 83 * NOTE: Should never be called on the thread itself to avoid deadlock 84 */ 85 void ShutDown(); 86 87 /** 88 * Get the current thread ID returned by PlatformThread::CurrentId() 89 * 90 * On Android platform, this value should be the same as the tid logged by 91 * logcat, which is returned by gettid(). On other platform, this thread id 92 * may have different meanings. Therefore, this ID is only good for logging 93 * and thread comparison purpose 94 * 95 * @return this thread's ID 96 */ 97 base::PlatformThreadId GetThreadId() const; 98 99 /** 100 * Get this thread's name set in constructor 101 * 102 * @return this thread's name set in constructor 103 */ 104 std::string GetName() const; 105 106 /** 107 * Get a string representation of this thread 108 * 109 * @return a string representation of this thread 110 */ 111 std::string ToString() const; 112 113 /** 114 * Check if this thread is running 115 * 116 * @return true iff this thread is running and is able to do task 117 */ 118 bool IsRunning() const; 119 120 /** 121 * Attempt to make scheduling for this thread real time 122 * 123 * @return true on success, false otherwise 124 */ 125 bool EnableRealTimeScheduling(); 126 127 /** 128 * Return the weak pointer to this object. This can be useful when posting 129 * delayed tasks to this MessageLoopThread using Timer. 130 */ 131 base::WeakPtr<MessageLoopThread> GetWeakPtr(); 132 133 /** 134 * Return the message loop for this thread. Accessing raw message loop is not 135 * recommended as message loop can be freed internally. 136 * 137 * @return message loop associated with this thread, nullptr if thread is not 138 * running 139 */ 140 btbase::AbstractMessageLoop* message_loop() const; 141 142 /** 143 * Post a task to run on this thread after a specified delay. If the task 144 * needs to be cancelable before it's run, use base::CancelableClosure type 145 * for task closure. For example: 146 * <code> 147 * base::CancelableClosure cancelable_task; 148 * cancelable_task.Reset(base::Bind(...)); // bind the task 149 * same_thread->DoInThreadDelayed(cancelable_task.callback(), delay); 150 * ... 151 * // Cancel the task closure 152 * same_thread->DoInThread(base::Bind(&base::CancelableClosure::Cancel, 153 * base::Unretained(&cancelable_task))); 154 * </code> 155 * 156 * Warning: base::CancelableClosure objects must be created on, posted to, 157 * cancelled on, and destroyed on the same thread. 158 * 159 * @param task task created through base::Bind() 160 * @param delay delay for the task to be executed 161 * @return true if task is successfully scheduled, false if task cannot be 162 * scheduled 163 */ 164 bool DoInThreadDelayed(base::OnceClosure task, std::chrono::microseconds delay); 165 /** 166 * Wrapper around DoInThread without a location. 167 */ 168 void Post(base::OnceClosure closure) override; 169 170 /** 171 * Returns a postable object 172 */ 173 PostableContext* Postable(); 174 175 private: 176 /** 177 * Static method to run the thread 178 * 179 * This is used instead of a C++ lambda because of the use of std::shared_ptr 180 * 181 * @param context needs to be a pointer to an instance of MessageLoopThread 182 * @param start_up_promise a std::promise that is used to notify calling 183 * thread the completion of message loop start-up 184 */ 185 static void RunThread(MessageLoopThread* context, std::promise<void> start_up_promise); 186 187 /** 188 * Actual method to run the thread, blocking until ShutDown() is called 189 * 190 * @param start_up_promise a std::promise that is used to notify calling 191 * thread the completion of message loop start-up 192 */ 193 void Run(std::promise<void> start_up_promise); 194 195 mutable std::recursive_mutex api_mutex_; 196 const std::string thread_name_; 197 btbase::AbstractMessageLoop* message_loop_; 198 base::RunLoop* run_loop_; 199 std::thread* thread_; 200 base::PlatformThreadId thread_id_; 201 // Linux specific abstractions 202 pid_t linux_tid_; 203 base::WeakPtrFactory<MessageLoopThread> weak_ptr_factory_; 204 bool shutting_down_; 205 }; 206 207 inline std::ostream& operator<<(std::ostream& os, const bluetooth::common::MessageLoopThread& a) { 208 os << a.ToString(); 209 return os; 210 } 211 212 } // namespace common 213 } // namespace bluetooth 214 215 namespace std { 216 template <> 217 struct formatter<bluetooth::common::MessageLoopThread> : ostream_formatter {}; 218 } // namespace std 219