[Chromoting] Introducing refcount-based life time management of the message loops in the service (d…

remoting/host/win/host_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This file implements the Windows service controlling Me2Me host processes
 // running within user sessions.
 
 #include "remoting/host/win/host_service.h"
 
 #include <windows.h>
 #include <shellapi.h>
 #include <wtsapi32.h>
 
 #include "base/at_exit.h"
 #include "base/base_paths.h"
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stringprintf.h"
 #include "base/threading/thread.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/wrapped_window_proc.h"
+#include "remoting/base/auto_message_loop.h"
+#include "remoting/base/auto_thread.h"
 #include "remoting/base/breakpad.h"
 #include "remoting/base/scoped_sc_handle_win.h"
 #include "remoting/base/stoppable.h"
 #include "remoting/host/branding.h"
 
 #if defined(REMOTING_MULTI_PROCESS)
 #include "remoting/host/daemon_process.h"
 #endif  // defined(REMOTING_MULTI_PROCESS)
 
 #include "remoting/host/usage_stats_consent.h"
@@ skipping 76 matching lines @@
 }
 
 void HostService::RemoveWtsConsoleObserver(WtsConsoleObserver* observer) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   console_observers_.RemoveObserver(observer);
 }
 
 void HostService::OnChildStopped() {
   child_.reset(NULL);
-  main_task_runner_->PostTask(FROM_HERE, MessageLoop::QuitClosure());
+  main_task_runner_ = NULL;
 }
 
 void HostService::OnSessionChange() {
   // WTSGetActiveConsoleSessionId is a very cheap API. It basically reads
   // a single value from shared memory. Therefore it is better to check if
   // the console session is still the same every time a session change
   // notification event is posted. This also takes care of coalescing multiple
   // events into one since we look at the latest state.
   uint32 console_session_id = WTSGetActiveConsoleSessionId();
   if (console_session_id_ != console_session_id) {
@@ skipping 55 matching lines @@
     run_routine_ = &HostService::RunInConsole;
   }
 
   return true;
 }
 
 int HostService::Run() {
   return (this->*run_routine_)();
 }
 
-void HostService::RunMessageLoop(MessageLoop* message_loop) {
+bool HostService::BeforeMessageLoop() {
   // Launch the I/O thread.
-  base::Thread io_thread(kIoThreadName);
+  scoped_refptr<AutoThread> io_thread(
+    new AutoThread(kIoThreadName, main_task_runner_));

[Wez, 2012/08/24 21:30:49]

Can you instead create a normal Thread in RunMessageLoop(), start it, wrap it in
an AutoMessageLoop and pass that to DaemonProcess::Create and
WtsSessionProcessLauncher?

The IO thread will then continue to run until it's no longer needed, and
RunMessageLoop() will block until it exits, and then delete it?

[alexeypa (please no reviews), 2012/08/27 21:19:40]

Done.

   base::Thread::Options io_thread_options(MessageLoop::TYPE_IO, 0);
-  if (!io_thread.StartWithOptions(io_thread_options)) {
-    LOG(ERROR) << "Failed to start the I/O thread";
-    stopped_event_.Signal();
-    return;
+  if (!io_thread->StartWithOptions(io_thread_options)) {
+    LOG(FATAL) << "Failed to start the I/O thread";
+    return false;
   }
 
 #if defined(REMOTING_MULTI_PROCESS)
 
   child_ = DaemonProcess::Create(
       main_task_runner_,
-      io_thread.message_loop_proxy(),
+      io_thread,
       base::Bind(&HostService::OnChildStopped,
                  base::Unretained(this))).PassAs<Stoppable>();
 
 #else  // !defined(REMOTING_MULTI_PROCESS)
 
   // Create the session process launcher.
   child_.reset(new WtsSessionProcessLauncher(
       base::Bind(&HostService::OnChildStopped, base::Unretained(this)),
       this,
       main_task_runner_,
-      io_thread.message_loop_proxy()));
+      io_thread));
 
 #endif  // !defined(REMOTING_MULTI_PROCESS)
 
+  return true;
+}
+
+void HostService::RunMessageLoop(MessageLoop* message_loop) {
   // Run the service.
-  message_loop->Run();
+  if (BeforeMessageLoop()) {
+    message_loop->Run();
+  }
 
   // Release the control handler.
   stopped_event_.Signal();
 }
 
 int HostService::Elevate() {
   // Get the name of the binary to launch.
   FilePath binary =
       CommandLine::ForCurrentProcess()->GetSwitchValuePath(kElevateSwitchName);
 
@@ skipping 32 matching lines @@
         << "Failed to connect to the service control manager";
     return kErrorExitCode;
   }
 
   return kSuccessExitCode;
 }
 
 int HostService::RunInConsole() {
   MessageLoop message_loop(MessageLoop::TYPE_UI);
 
-  // Allow other threads to post to our message loop.
-  main_task_runner_ = message_loop.message_loop_proxy();
+  // Keep a reference to the main message loop while it is used. Once the last
+  // reference is dropped QuitClosure() will be posted to the loop.
+  main_task_runner_ = new AutoMessageLoop(&message_loop);
 
   int result = kErrorExitCode;
 
   // Subscribe to Ctrl-C and other console events.
   if (!SetConsoleCtrlHandler(&HostService::ConsoleControlHandler, TRUE)) {
     LOG_GETLASTERROR(ERROR)
         << "Failed to set console control handler";
     return result;
   }
 
@@ skipping 74 matching lines @@
       self->main_task_runner_->PostTask(FROM_HERE, base::Bind(
           &HostService::OnSessionChange, base::Unretained(self)));
       return NO_ERROR;
 
     default:
       return ERROR_CALL_NOT_IMPLEMENTED;
   }
 }
 
 VOID WINAPI HostService::ServiceMain(DWORD argc, WCHAR* argv[]) {
-  MessageLoop message_loop;
+  MessageLoop message_loop(MessageLoop::TYPE_DEFAULT);
 
-  // Allow other threads to post to our message loop.
+  // Keep a reference to the main message loop while it is used. Once the last
+  // reference is dropped QuitClosure() will be posted to the loop.
   HostService* self = HostService::GetInstance();
-  self->main_task_runner_ = message_loop.message_loop_proxy();
+  self->main_task_runner_ = new AutoMessageLoop(&message_loop);
 
   // Register the service control handler.
   self->service_status_handle_ =
       RegisterServiceCtrlHandlerExW(kWindowsServiceName,
                                     &HostService::ServiceControlHandler,
                                     self);
   if (self->service_status_handle_ == 0) {
     LOG_GETLASTERROR(ERROR)
         << "Failed to register the service control handler";
     return;
@@ skipping 87 matching lines @@
   }
 
   remoting::HostService* service = remoting::HostService::GetInstance();
   if (!service->InitWithCommandLine(command_line)) {
     usage(command_line->GetProgram());
     return kUsageExitCode;
   }
 
   return service->Run();
 }