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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gl/vsync_thread_win.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "base/memory/stack_allocated.h"
#include "base/notreached.h"
#include "base/power_monitor/power_monitor.h"
#include "base/synchronization/lock_subtle.h"
#include "base/time/time.h"
#include "base/trace_event/typed_macros.h"
#include "base/win/windows_version.h"
#include "ui/gl/direct_composition_support.h"
#include "ui/gl/gl_features.h"
#include "ui/gl/vsync_thread_win_dcomp.h"
#include "ui/gl/vsync_thread_win_dxgi.h"
namespace gl {
namespace {
// Whether the current thread holds the `VSyncThreadWin` lock.
thread_local bool g_current_thread_holds_lock = false;
} // namespace
// static
VSyncThreadWin* VSyncThreadWin::GetInstance() {
static VSyncThreadWin* vsync_thread = []() -> VSyncThreadWin* {
if (features::UseCompositorClockVSyncInterval()) {
return new VSyncThreadWinDComp();
} else {
Microsoft::WRL::ComPtr<ID3D11Device> d3d11_device(
GetDirectCompositionD3D11Device());
if (!d3d11_device) {
return nullptr;
}
Microsoft::WRL::ComPtr<IDXGIDevice> dxgi_device;
CHECK_EQ(d3d11_device.As(&dxgi_device), S_OK);
return new VSyncThreadWinDXGI(std::move(dxgi_device));
}
}();
return vsync_thread;
}
class VSyncThreadWin::AutoVSyncThreadLock {
STACK_ALLOCATED();
public:
AutoVSyncThreadLock(VSyncThreadWin* vsync_thread)
EXCLUSIVE_LOCK_FUNCTION(vsync_thread->lock_) {
if (g_current_thread_holds_lock) {
vsync_thread->lock_.AssertAcquired();
} else {
auto_lock_.emplace(
vsync_thread->lock_,
// This lock is used to satisfy a mutual exclusion guarantee verified
// by a SEQUENCE_CHECKER in `observers_`.
base::subtle::LockTracking::kEnabled);
g_current_thread_holds_lock = true;
}
}
~AutoVSyncThreadLock() UNLOCK_FUNCTION() {
DCHECK(g_current_thread_holds_lock);
if (auto_lock_.has_value()) {
g_current_thread_holds_lock = false;
}
}
private:
std::optional<base::AutoLock> auto_lock_;
};
VSyncThreadWin::VSyncThreadWin() : vsync_thread_("GpuVSyncThread") {
is_suspended_ = base::PowerMonitor::GetInstance()
->AddPowerSuspendObserverAndReturnSuspendedState(this);
vsync_thread_.StartWithOptions(
base::Thread::Options(base::ThreadType::kDisplayCritical));
}
VSyncThreadWin::~VSyncThreadWin() {
NOTREACHED();
}
void VSyncThreadWin::PostTaskIfNeeded() {
lock_.AssertAcquired();
// PostTaskIfNeeded is called from AddObserver and OnResume.
// Before queuing up a task, make sure that there are observers waiting for
// VSync and that we're not already firing events to consumers. Avoid firing
// events if we're suspended to conserve battery life.
if (!is_vsync_task_posted_ && !observers_.empty() && !is_suspended_) {
vsync_thread_.task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&VSyncThreadWin::WaitForVSync, base::Unretained(this)));
is_vsync_task_posted_ = true;
}
}
void VSyncThreadWin::AddObserver(VSyncObserver* obs) {
AutoVSyncThreadLock auto_lock(this);
observers_.AddObserver(obs);
PostTaskIfNeeded();
}
void VSyncThreadWin::RemoveObserver(VSyncObserver* obs) {
AutoVSyncThreadLock auto_lock(this);
observers_.RemoveObserver(obs);
}
void VSyncThreadWin::OnSuspend() {
AutoVSyncThreadLock auto_lock(this);
is_suspended_ = true;
}
void VSyncThreadWin::OnResume() {
AutoVSyncThreadLock auto_lock(this);
is_suspended_ = false;
PostTaskIfNeeded();
}
void VSyncThreadWin::WaitForVSync() {
base::TimeDelta vsync_interval;
const base::TimeTicks wait_for_vsync_start_time = base::TimeTicks::Now();
bool wait_succeeded = WaitForVSyncImpl(&vsync_interval);
const base::TimeDelta wait_for_vsync_elapsed_time =
base::TimeTicks::Now() - wait_for_vsync_start_time;
// WaitForVBlank and DCompositionWaitForCompositorClock returns very early
// instead of waiting until vblank when the monitor goes to sleep or is
// unplugged (nothing to present due to desktop occlusion). We use 1ms as
// a threshhold for the duration of the wait functions and fallback to
// Sleep() if it returns before that. This could happen during normal
// operation for the first call after the vsync thread becomes non-idle,
// but it shouldn't happen often.
constexpr auto kVBlankIntervalThreshold = base::Milliseconds(1);
if (!wait_succeeded ||
wait_for_vsync_elapsed_time < kVBlankIntervalThreshold) {
TRACE_EVENT0("gpu", "WaitForVSync Sleep");
base::Time::ActivateHighResolutionTimer(true);
Sleep(static_cast<DWORD>(vsync_interval.InMillisecondsRoundedUp()));
base::Time::ActivateHighResolutionTimer(false);
}
AutoVSyncThreadLock auto_lock(this);
DCHECK(is_vsync_task_posted_);
is_vsync_task_posted_ = false;
PostTaskIfNeeded();
const base::TimeTicks vsync_time = base::TimeTicks::Now();
observers_.Notify(&VSyncObserver::OnVSync, vsync_time, vsync_interval);
}
} // namespace gl
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