remoting/base/auto_thread.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef REMOTING_BASE_AUTO_THREAD_H_
   6 #define REMOTING_BASE_AUTO_THREAD_H_
   7
   8 #include <string>
   9
  10 #include "base/message_loop/message_loop.h"
  11 #include "base/threading/platform_thread.h"
  12 #include "remoting/base/auto_thread_task_runner.h"
  13
  14 namespace remoting {
  15
  16 // Thread implementation that runs a MessageLoop on a new thread, and manages
  17 // the lifetime of the MessageLoop and thread by tracking references to the
  18 // thread's TaskRunner.  The caller passes the thread's TaskRunner to each
  19 // object that needs to run code on the thread, and when no references to the
  20 // TaskRunner remain, the thread will exit.  When the caller destroys this
  21 // object they will be blocked until the thread exits.
  22 // All pending tasks queued on the thread's message loop will run to completion
  23 // before the thread is terminated.
  24 //
  25 // After the thread is stopped, the destruction sequence is:
  26 //
  27 //  (1) Thread::CleanUp()
  28 //  (2) MessageLoop::~MessageLoop
  29 //  (3.b)    MessageLoop::DestructionObserver::WillDestroyCurrentMessageLoop
  30 class AutoThread : base::PlatformThread::Delegate {
  31  public:
  32   // Create an AutoThread with the specified message-loop |type| and |name|.
  33   // The supplied AutoThreadTaskRunner will be used to join and delete the
  34   // new thread when no references to it remain.
  35   static scoped_refptr<AutoThreadTaskRunner> CreateWithType(
  36       const char* name,
  37       scoped_refptr<AutoThreadTaskRunner> joiner,
  38       base::MessageLoop::Type type);
  39   static scoped_refptr<AutoThreadTaskRunner> Create(
  40       const char* name,
  41       scoped_refptr<AutoThreadTaskRunner> joiner);
  42
  43 #if defined(OS_WIN)
  44   // Create an AutoThread initialized for COM.  |com_init_type| specifies the
  45   // type of COM apartment to initialize.
  46   enum ComInitType { COM_INIT_NONE, COM_INIT_STA, COM_INIT_MTA };
  47   static scoped_refptr<AutoThreadTaskRunner> CreateWithLoopAndComInitTypes(
  48       const char* name,
  49       scoped_refptr<AutoThreadTaskRunner> joiner,
  50       base::MessageLoop::Type loop_type,
  51       ComInitType com_init_type);
  52 #endif
  53
  54   // Construct the AutoThread.  |name| identifies the thread for debugging.
  55   explicit AutoThread(const char* name);
  56
  57   // Waits for the thread to exit, and then destroys it.
  58   ~AutoThread() override;
  59
  60   // Starts the thread, running the specified type of MessageLoop.  Returns
  61   // an AutoThreadTaskRunner through which tasks may be posted to the thread
  62   // if successful, or NULL on failure.
  63   //
  64   // Note: This function can't be called on Windows with the loader lock held;
  65   // i.e. during a DllMain, global object construction or destruction, atexit()
  66   // callback.
  67   //
  68   // NOTE: You must not call this MessageLoop's Quit method directly.  The
  69   // thread will exit when no references to the TaskRunner remain.
  70   scoped_refptr<AutoThreadTaskRunner> StartWithType(
  71       base::MessageLoop::Type type);
  72
  73 #if defined(OS_WIN)
  74   // Configures the thread to initialize the specified COM apartment type.
  75   // SetComInitType() must be called before Start().
  76   void SetComInitType(ComInitType com_init_type);
  77 #endif
  78
  79  private:
  80   AutoThread(const char* name, AutoThreadTaskRunner* joiner);
  81
  82   void QuitThread(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
  83   void JoinAndDeleteThread();
  84
  85   // base::PlatformThread::Delegate methods:
  86   void ThreadMain() override;
  87
  88   // Used to pass data to ThreadMain.
  89   struct StartupData;
  90   StartupData* startup_data_;
  91
  92 #if defined(OS_WIN)
  93   // Specifies which kind of COM apartment to initialize, if any.
  94   ComInitType com_init_type_;
  95 #endif
  96
  97   // The thread's handle.
  98   base::PlatformThreadHandle thread_;
  99
 100   // The name of the thread.  Used for debugging purposes.
 101   std::string name_;
 102
 103   // Flag used to indicate whether MessageLoop was quit properly.
 104   // This allows us to detect premature exit via MessageLoop::Quit().
 105   bool was_quit_properly_;
 106
 107   // AutoThreadTaskRunner to post a task to to join & delete this thread.
 108   scoped_refptr<AutoThreadTaskRunner> joiner_;
 109
 110   DISALLOW_COPY_AND_ASSIGN(AutoThread);
 111 };
 112
 113 }  // namespace remoting
 114
 115 #endif  // REMOTING_AUTO_THREAD_H_