Bug 1541229, higher minimum idle period during page load, r=farre

Differential Revision: https://phabricator.services.mozilla.com/D37908

--HG--
extra : moz-landing-system : lando

dom/base/Document.cpp

@@ -346,6 +346,9 @@ namespace dom {
 
 typedef nsTArray<Link*> LinkArray;
 
+AutoTArray<Document*, 8>* Document::sLoadingForegroundTopLevelContentDocument =
+    nullptr;
+
 static LazyLogModule gDocumentLeakPRLog("DocumentLeak");
 static LazyLogModule gCspPRLog("CSP");
 LazyLogModule gUserInteractionPRLog("UserInteraction");
@@ -1667,6 +1670,8 @@ Document::~Document() {
   NS_ASSERTION(!mIsShowing, "Destroying a currently-showing document");
 
   if (IsTopLevelContentDocument()) {
+    RemoveToplevelLoadingDocument(this);
+
     // don't report for about: pages
     if (!IsAboutPage()) {
       // Record the page load
@@ -11152,6 +11157,14 @@ void Document::SetReadyStateInternal(ReadyState rs,
     return;
   }
 
+  if (IsTopLevelContentDocument()) {
+    if (rs == READYSTATE_LOADING) {
+      AddToplevelLoadingDocument(this);
+    } else if (rs == READYSTATE_COMPLETE) {
+      RemoveToplevelLoadingDocument(this);
+    }
+  }
+
   if (updateTimingInformation && READYSTATE_LOADING == rs) {
     mLoadingTimeStamp = mozilla::TimeStamp::Now();
   }
@@ -15783,5 +15796,57 @@ void Document::SetIsInitialDocument(bool aIsInitialDocument) {
   }
 }
 
+void Document::AddToplevelLoadingDocument(Document* aDoc) {
+  MOZ_ASSERT(aDoc && aDoc->IsTopLevelContentDocument());
+  // Currently we're interested in foreground documents only, so bail out early.
+  if (aDoc->IsInBackgroundWindow() || !XRE_IsContentProcess()) {
+    return;
+  }
+
+  if (!sLoadingForegroundTopLevelContentDocument) {
+    sLoadingForegroundTopLevelContentDocument = new AutoTArray<Document*, 8>();
+  }
+  if (!sLoadingForegroundTopLevelContentDocument->Contains(aDoc)) {
+    sLoadingForegroundTopLevelContentDocument->AppendElement(aDoc);
+  }
+}
+
+void Document::RemoveToplevelLoadingDocument(Document* aDoc) {
+  MOZ_ASSERT(aDoc && aDoc->IsTopLevelContentDocument());
+  if (sLoadingForegroundTopLevelContentDocument) {
+    sLoadingForegroundTopLevelContentDocument->RemoveElement(aDoc);
+    if (sLoadingForegroundTopLevelContentDocument->IsEmpty()) {
+      delete sLoadingForegroundTopLevelContentDocument;
+      sLoadingForegroundTopLevelContentDocument = nullptr;
+    }
+  }
+}
+
+bool Document::HasRecentlyStartedForegroundLoads() {
+  if (!sLoadingForegroundTopLevelContentDocument) {
+    return false;
+  }
+
+  for (size_t i = 0; i < sLoadingForegroundTopLevelContentDocument->Length();
+       ++i) {
+    Document* doc = sLoadingForegroundTopLevelContentDocument->ElementAt(i);
+    // A page loaded in foreground could be in background now.
+    if (!doc->IsInBackgroundWindow()) {
+      nsPIDOMWindowInner* win = doc->GetInnerWindow();
+      if (win) {
+        Performance* perf = win->GetPerformance();
+        if (perf && perf->Now() < 5000) {
+          return true;
+        }
+      }
+    }
+  }
+
+  // Didn't find any loading foreground documents, just clear the array.
+  delete sLoadingForegroundTopLevelContentDocument;
+  sLoadingForegroundTopLevelContentDocument = nullptr;
+  return false;
+}
+
 }  // namespace dom
 }  // namespace mozilla

dom/base/Document.h

@@ -4119,6 +4119,8 @@ class Document : public nsINode,
   bool InRDMPane() const { return mInRDMPane; }
   void SetInRDMPane(bool aInRDMPane) { mInRDMPane = aInRDMPane; }
 
+  static bool HasRecentlyStartedForegroundLoads();
+
  protected:
   void DoUpdateSVGUseElementShadowTrees();
 
@@ -4391,6 +4393,10 @@ class Document : public nsINode,
   already_AddRefed<nsIChannel> CreateDummyChannelForCookies(
       nsIURI* aContentURI);
 
+  void AddToplevelLoadingDocument(Document* aDoc);
+  void RemoveToplevelLoadingDocument(Document* aDoc);
+  static AutoTArray<Document*, 8>* sLoadingForegroundTopLevelContentDocument;
+
   nsCOMPtr<nsIReferrerInfo> mPreloadReferrerInfo;
   nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
 

xpcom/threads/MainThreadIdlePeriod.cpp

@@ -8,6 +8,7 @@
 
 #include "mozilla/Maybe.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/dom/Document.h"
 #include "nsRefreshDriver.h"
 #include "nsThreadUtils.h"
 
@@ -20,6 +21,7 @@ static const double kLongIdlePeriodMS = 50.0;
 // expect to become busy again be:
 //   now + kMinIdlePeriodMS + layout.idle_period.time_limit
 static const double kMinIdlePeriodMS = 3.0;
+static const double kMinIdlePeriodDuringLoadMS = 12.0;
 
 static const uint32_t kMaxTimerThreadBound = 5;        // milliseconds
 static const uint32_t kMaxTimerThreadBoundClamp = 15;  // milliseconds
@@ -46,6 +48,14 @@ MainThreadIdlePeriod::GetIdlePeriodHint(TimeStamp* aIdleDeadline) {
                   (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(kMinIdlePeriodDuringLoadMS);
+    busySoon = (now >= (currentGuess - minIdlePeriod));
+  }
+
   if (!busySoon) {
     *aIdleDeadline = mLastIdleDeadline = currentGuess;
   }