blob: c2de1e1b3e4270e641bab156336185bdcb4c6bed [file] [log] [blame]
// Copyright 2015 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.
#include "ui/views/win/windows_session_change_observer.h"
#include <wtsapi32.h>
#include <memory>
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/location.h"
#include "base/macros.h"
#include "base/memory/singleton.h"
#include "base/observer_list.h"
#include "base/task/post_task.h"
#include "ui/gfx/win/singleton_hwnd.h"
#include "ui/gfx/win/singleton_hwnd_observer.h"
#include "ui/views/views_delegate.h"
namespace views {
class WindowsSessionChangeObserver::WtsRegistrationNotificationManager {
public:
static WtsRegistrationNotificationManager* GetInstance() {
return base::Singleton<WtsRegistrationNotificationManager>::get();
}
WtsRegistrationNotificationManager() {
AddSingletonHwndObserver();
}
~WtsRegistrationNotificationManager() {
RemoveSingletonHwndObserver();
}
void AddObserver(WindowsSessionChangeObserver* observer) {
DCHECK(singleton_hwnd_observer_);
observer_list_.AddObserver(observer);
}
void RemoveObserver(WindowsSessionChangeObserver* observer) {
observer_list_.RemoveObserver(observer);
}
private:
friend struct base::DefaultSingletonTraits<
WtsRegistrationNotificationManager>;
void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
switch (message) {
case WM_WTSSESSION_CHANGE:
for (WindowsSessionChangeObserver& observer : observer_list_)
observer.OnSessionChange(wparam);
break;
case WM_DESTROY:
RemoveSingletonHwndObserver();
break;
}
}
void AddSingletonHwndObserver() {
DCHECK(!singleton_hwnd_observer_);
singleton_hwnd_observer_.reset(new gfx::SingletonHwndObserver(
base::Bind(&WtsRegistrationNotificationManager::OnWndProc,
base::Unretained(this))));
base::OnceClosure wts_register = base::BindOnce(
base::IgnoreResult(&WTSRegisterSessionNotification),
gfx::SingletonHwnd::GetInstance()->hwnd(), NOTIFY_FOR_THIS_SESSION);
// This should probably always be async but it wasn't async in the absence
// of a ViewsDelegate prior to the migration to TaskScheduler and making it
// async breaks many unrelated views unittests.
if (ViewsDelegate::GetInstance()) {
base::CreateCOMSTATaskRunnerWithTraits({})->PostTask(
FROM_HERE, std::move(wts_register));
} else {
std::move(wts_register).Run();
}
}
void RemoveSingletonHwndObserver() {
if (!singleton_hwnd_observer_)
return;
singleton_hwnd_observer_.reset(nullptr);
// There is no race condition between this code and the worker thread.
// RemoveSingletonHwndObserver is only called from two places:
// 1) Destruction due to Singleton Destruction.
// 2) WM_DESTROY fired by SingletonHwnd.
// Under both cases we are in shutdown, which means no other worker threads
// can be running.
WTSUnRegisterSessionNotification(gfx::SingletonHwnd::GetInstance()->hwnd());
for (WindowsSessionChangeObserver& observer : observer_list_)
observer.ClearCallback();
}
base::ObserverList<WindowsSessionChangeObserver, true>::Unchecked
observer_list_;
std::unique_ptr<gfx::SingletonHwndObserver> singleton_hwnd_observer_;
DISALLOW_COPY_AND_ASSIGN(WtsRegistrationNotificationManager);
};
WindowsSessionChangeObserver::WindowsSessionChangeObserver(
const WtsCallback& callback)
: callback_(callback) {
DCHECK(!callback_.is_null());
WtsRegistrationNotificationManager::GetInstance()->AddObserver(this);
}
WindowsSessionChangeObserver::~WindowsSessionChangeObserver() {
ClearCallback();
}
void WindowsSessionChangeObserver::OnSessionChange(WPARAM wparam) {
callback_.Run(wparam);
}
void WindowsSessionChangeObserver::ClearCallback() {
if (!callback_.is_null()) {
callback_.Reset();
WtsRegistrationNotificationManager::GetInstance()->RemoveObserver(this);
}
}
} // namespace views