gecko-dev/dom/performance/PerformancePaintTiming.h
Sean Feng 49e2db87d2 Bug 1675543 - Cache PerformancePaintTiming's StartTime r=smaug
Currently we store the raw `StartTime` as a `TimeStamp` object, and
convert it to `DOMHighResTimeStamp` when calling `StartTime()`. However,
there's no need to do the conversion every time.

Differential Revision: https://phabricator.services.mozilla.com/D96296
2020-11-09 23:11:21 +00:00

53 lines
1.7 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_PerformancePaintTiming_h___
#define mozilla_dom_PerformancePaintTiming_h___
#include "mozilla/dom/PerformanceEntry.h"
#include "mozilla/dom/PerformancePaintTimingBinding.h"
namespace mozilla {
namespace dom {
class Performance;
// https://w3c.github.io/paint-timing/#sec-PerformancePaintTiming
// Unlike timeToContentfulPaint, this timing is generated during
// displaylist building, when a frame is contentful, we collect
// the timestamp. Whereas, timeToContentfulPaint uses a compositor-side
// timestamp.
class PerformancePaintTiming final : public PerformanceEntry {
public:
PerformancePaintTiming(Performance* aPerformance, const nsAString& aName,
const TimeStamp& aStartTime);
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(PerformancePaintTiming,
PerformanceEntry)
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override;
DOMHighResTimeStamp StartTime() const override;
size_t SizeOfIncludingThis(
mozilla::MallocSizeOf aMallocSizeOf) const override;
private:
~PerformancePaintTiming();
RefPtr<Performance> mPerformance;
const TimeStamp mRawStarTime;
mutable Maybe<DOMHighResTimeStamp> mCachedStartTime;
};
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_PerformanacePaintTiming_h___ */