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/* -*- 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/. */
#include "MainThreadIdlePeriod.h"
#include "mozilla/Maybe.h"
#include "mozilla/Preferences.h"
#include "mozilla/StaticPrefs_idle_period.h"
#include "mozilla/dom/Document.h"
#include "VRManagerChild.h"
#include "nsRefreshDriver.h"
#include "nsThreadUtils.h"
// The amount of idle time (milliseconds) reserved for a long idle period.
static const double kLongIdlePeriodMS = 50.0;
// The minimum amount of time (milliseconds) required for an idle period to be
// scheduled on the main thread. N.B. layout.idle_period.time_limit adds
// padding at the end of the idle period, which makes the point in time that we
// expect to become busy again be:
// now + idle_period.min + layout.idle_period.time_limit
// or during page load
// now + idle_period.during_page_load.min + layout.idle_period.time_limit
static const uint32_t kMaxTimerThreadBound = 5; // milliseconds
namespace mozilla {
NS_IMETHODIMP
MainThreadIdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline) {
MOZ_ASSERT(NS_IsMainThread());
MOZ_ASSERT(aIdleDeadline);
TimeStamp now = TimeStamp::Now();
TimeStamp currentGuess =
now + TimeDuration::FromMilliseconds(kLongIdlePeriodMS);
currentGuess = nsRefreshDriver::GetIdleDeadlineHint(
currentGuess, nsRefreshDriver::IdleCheck::AllVsyncListeners);
if (XRE_IsContentProcess()) {
currentGuess = gfx::VRManagerChild::GetIdleDeadlineHint(currentGuess);
}
currentGuess = NS_GetTimerDeadlineHintOnCurrentThread(currentGuess,
kMaxTimerThreadBound);
// If the idle period is too small, then just return a null time
// to indicate we are busy. Otherwise return the actual deadline.
//
// If we're in high frequency rate mode, idle.period.min isn't used but limit
// is 1.
TimeDuration minIdlePeriod = TimeDuration::FromMilliseconds(
nsRefreshDriver::IsInHighRateMode() ? 1 : StaticPrefs::idle_period_min());
bool busySoon = currentGuess.IsNull() ||
(now >= (currentGuess - minIdlePeriod)) ||
currentGuess < mLastIdleDeadline;
// During page load use higher minimum idle period.
if (!busySoon && XRE_IsContentProcess() &&
mozilla::dom::Document::HasRecentlyStartedForegroundLoads()) {
TimeDuration minIdlePeriod = TimeDuration::FromMilliseconds(
StaticPrefs::idle_period_during_page_load_min());
busySoon = (now >= (currentGuess - minIdlePeriod));
}
if (!busySoon) {
*aIdleDeadline = mLastIdleDeadline = currentGuess;
}
return NS_OK;
}
/* static */
float MainThreadIdlePeriod::GetLongIdlePeriod() { return kLongIdlePeriodMS; }
} // namespace mozilla
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