/*
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* Copyright 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <unistd.h>
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#include <future>
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#include <memory>
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#include <string>
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#include <thread>
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#include <base/bind.h>
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#include <base/location.h>
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#include <base/message_loop/message_loop.h>
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#include <base/run_loop.h>
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#include <base/threading/platform_thread.h>
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namespace bluetooth {
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namespace common {
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/**
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* An interface to various thread related functionality
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*/
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class MessageLoopThread final {
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public:
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/**
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* Create a message loop thread with name. Thread won't be running until
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* StartUp is called.
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*
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* @param thread_name name of this worker thread
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*/
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explicit MessageLoopThread(const std::string& thread_name);
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/**
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* Destroys the message loop thread automatically when it goes out of scope
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*/
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~MessageLoopThread();
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/**
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* Start the underlying thread. Blocks until all thread infrastructure is
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* setup. IsRunning() and DoInThread() should return true after this call.
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* Blocks until the thread is successfully started.
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*
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* Repeated call to this method will only start this thread once
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*/
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void StartUp();
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/**
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* Post a task to run on this thread
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*
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* @param from_here location where this task is originated
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* @param task task created through base::Bind()
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* @return true if task is successfully scheduled, false if task cannot be
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* scheduled
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*/
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bool DoInThread(const base::Location& from_here, base::OnceClosure task);
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/**
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* Shutdown the current thread as if it is never started. IsRunning() and
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* DoInThread() will return false after this call. Blocks until the thread is
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* joined and freed. This thread can be re-started again using StartUp()
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*
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* Repeated call to this method will only stop this thread once
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*
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* NOTE: Should never be called on the thread itself to avoid deadlock
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*/
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void ShutDown();
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/**
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* Get the current thread ID returned by PlatformThread::CurrentId()
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*
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* On Android platform, this value should be the same as the tid logged by
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* logcat, which is returned by gettid(). On other platform, this thread id
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* may have different meanings. Therefore, this ID is only good for logging
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* and thread comparison purpose
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*
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* @return this thread's ID
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*/
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base::PlatformThreadId GetThreadId() const;
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/**
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* Get this thread's name set in constructor
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*
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* @return this thread's name set in constructor
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*/
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std::string GetName() const;
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/**
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* Get a string representation of this thread
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*
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* @return a string representation of this thread
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*/
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std::string ToString() const;
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/**
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* Check if this thread is running
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*
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* @return true iff this thread is running and is able to do task
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*/
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bool IsRunning() const;
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/**
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* Attempt to make scheduling for this thread real time
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*
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* @return true on success, false otherwise
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*/
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bool EnableRealTimeScheduling();
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/**
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* Return the weak pointer to this object. This can be useful when posting
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* delayed tasks to this MessageLoopThread using Timer.
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*/
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base::WeakPtr<MessageLoopThread> GetWeakPtr();
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/**
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* Return the message loop for this thread. Accessing raw message loop is not
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* recommended as message loop can be freed internally.
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*
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* @return message loop associated with this thread, nullptr if thread is not
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* running
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*/
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base::MessageLoop* message_loop() const;
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private:
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/**
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* Static method to run the thread
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*
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* This is used instead of a C++ lambda because of the use of std::shared_ptr
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*
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* @param context needs to be a pointer to an instance of MessageLoopThread
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* @param start_up_promise a std::promise that is used to notify calling
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* thread the completion of message loop start-up
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*/
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static void RunThread(MessageLoopThread* context,
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std::promise<void> start_up_promise);
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/**
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* Post a task to run on this thread after a specified delay. If the task
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* needs to be cancelable before it's run, use base::CancelableClosure type
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* for task closure. For example:
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* <code>
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* base::CancelableClosure cancelable_task;
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* cancelable_task.Reset(base::Bind(...)); // bind the task
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* same_thread->DoInThreadDelayed(FROM_HERE,
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* cancelable_task.callback(), delay);
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* ...
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* // Cancel the task closure
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* same_thread->DoInThread(FROM_HERE,
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* base::Bind(&base::CancelableClosure::Cancel,
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* base::Unretained(&cancelable_task)));
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* </code>
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*
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* Warning: base::CancelableClosure objects must be created on, posted to,
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* cancelled on, and destroyed on the same thread.
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*
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* @param from_here location where this task is originated
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* @param task task created through base::Bind()
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* @param delay delay for the task to be executed
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* @return true if task is successfully scheduled, false if task cannot be
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* scheduled
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*/
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bool DoInThreadDelayed(const base::Location& from_here,
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base::OnceClosure task, const base::TimeDelta& delay);
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friend class RepeatingTimer; // allow Timer to use DoInThreadDelayed()
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friend class OnceTimer; // allow OnceTimer to use DoInThreadDelayed()
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/**
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* Actual method to run the thread, blocking until ShutDown() is called
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*
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* @param start_up_promise a std::promise that is used to notify calling
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* thread the completion of message loop start-up
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*/
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void Run(std::promise<void> start_up_promise);
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mutable std::recursive_mutex api_mutex_;
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const std::string thread_name_;
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base::MessageLoop* message_loop_;
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base::RunLoop* run_loop_;
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std::thread* thread_;
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base::PlatformThreadId thread_id_;
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// Linux specific abstractions
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pid_t linux_tid_;
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base::WeakPtrFactory<MessageLoopThread> weak_ptr_factory_;
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bool shutting_down_;
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DISALLOW_COPY_AND_ASSIGN(MessageLoopThread);
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};
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inline std::ostream& operator<<(std::ostream& os,
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const bluetooth::common::MessageLoopThread& a) {
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os << a.ToString();
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return os;
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}
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} // namespace common
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} // namespace bluetooth
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