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-rw-r--r--xpcom/threads/MainThreadIdlePeriod.cpp78
1 files changed, 78 insertions, 0 deletions
diff --git a/xpcom/threads/MainThreadIdlePeriod.cpp b/xpcom/threads/MainThreadIdlePeriod.cpp
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+++ b/xpcom/threads/MainThreadIdlePeriod.cpp
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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