Backed out 4 changesets (bug 1730534) for conflicts with backout of bug 1536061. a=backout

Backed out changeset fc881c57d119 (bug 1730534)
Backed out changeset 0f72a8c5f8c5 (bug 1730534)
Backed out changeset 007cbeea4325 (bug 1730534)
Backed out changeset 83d53ed76e0f (bug 1730534)

mfbt/SegmentedVector.h

@@ -289,11 +289,7 @@ class SegmentedVector : private AllocPolicy {
     }
 
    public:
-    bool Done() const {
-      MOZ_ASSERT_IF(mSegment, mSegment->isInList());
-      MOZ_ASSERT_IF(mSegment, mIndex < mSegment->Length());
-      return !mSegment;
-    }
+    bool Done() const { return !mSegment; }
 
     T& Get() {
       MOZ_ASSERT(!Done());

xpcom/base/CycleCollectedJSRuntime.cpp

@@ -483,57 +483,43 @@ JSHolderMap::Entry::Entry(void* aHolder, nsScriptObjectTracer* aTracer,
 {
 }
 
-void JSHolderMap::EntryVectorIter::Settle() {
-  if (Done()) {
-    return;
+JSHolderMap::JSHolderMap() : mJSHolderMap(256) {}
+
+template <typename F>
+inline void JSHolderMap::ForEach(F&& f, WhichHolders aWhich) {
+  // Multi-zone JS holders must always be considered.
+  ForEach(mAnyZoneJSHolders, f, nullptr);
+
+  for (auto i = mPerZoneJSHolders.modIter(); !i.done(); i.next()) {
+    if (aWhich == HoldersInGrayMarkingZones &&
+        !JS::ZoneIsGrayMarking(i.get().key())) {
+      continue;
     }
 
-  Entry* entry = &mIter.Get();
+    EntryVector* holders = i.get().value().get();
+    ForEach(*holders, f, i.get().key());
+    if (holders->IsEmpty()) {
+      i.remove();
+    }
+  }
+}
+
+template <typename F>
+inline void JSHolderMap::ForEach(EntryVector& aJSHolders, const F& f,
+                                 JS::Zone* aZone) {
+  for (auto iter = aJSHolders.Iter(); !iter.Done(); iter.Next()) {
+    Entry* entry = &iter.Get();
 
     // If the entry has been cleared, remove it and shrink the vector.
-  if (!entry->mHolder && !mHolderMap.RemoveEntry(mVector, entry)) {
-    // We removed the last entry, so reset the iterator to an empty one.
-    mIter = EntryVector().Iter();
-    MOZ_ASSERT(Done());
-  }
+    if (!entry->mHolder && !RemoveEntry(aJSHolders, entry)) {
+      break;  // Removed the last entry.
     }
 
-inline JSHolderMap::Iter::Iter(JSHolderMap& aMap, WhichHolders aWhich)
-    : mHolderMap(aMap), mIter(aMap, aMap.mAnyZoneJSHolders) {
-#ifdef DEBUG
-  MOZ_RELEASE_ASSERT(!mHolderMap.mHasIterator);
-  mHolderMap.mHasIterator = true;
-#endif
-
-  // Populate vector of zones to iterate after the any-zone holders.
-  for (auto i = aMap.mPerZoneJSHolders.iter(); !i.done(); i.next()) {
-    JS::Zone* zone = i.get().key();
-    if (aWhich == AllHolders || JS::ZoneIsGrayMarking(zone)) {
-      MOZ_ALWAYS_TRUE(mZones.append(zone));
+    MOZ_ASSERT_IF(aZone, entry->mZone == aZone);
+    f(entry->mHolder, entry->mTracer, aZone);
   }
 }
 
-  Settle();
-}
-
-void JSHolderMap::Iter::Settle() {
-  while (mIter.Done()) {
-    if (mZone && mIter.Vector().IsEmpty()) {
-      mHolderMap.mPerZoneJSHolders.remove(mZone);
-    }
-
-    if (mZones.empty()) {
-      break;
-    }
-
-    mZone = mZones.popCopy();
-    EntryVector& vector = *mHolderMap.mPerZoneJSHolders.lookup(mZone)->value();
-    new (&mIter) EntryVectorIter(mHolderMap, vector);
-  }
-}
-
-JSHolderMap::JSHolderMap() : mJSHolderMap(256) {}
-
 bool JSHolderMap::RemoveEntry(EntryVector& aJSHolders, Entry* aEntry) {
   MOZ_ASSERT(aEntry);
   MOZ_ASSERT(!aEntry->mHolder);
@@ -772,9 +758,8 @@ size_t CycleCollectedJSRuntime::SizeOfExcludingThis(
 }
 
 void CycleCollectedJSRuntime::UnmarkSkippableJSHolders() {
-  for (JSHolderMap::Iter entry(mJSHolders); !entry.Done(); entry.Next()) {
-    entry->mTracer->CanSkip(entry->mHolder, true);
-  }
+  mJSHolders.ForEach([](void* holder, nsScriptObjectTracer* tracer,
+                        JS::Zone* zone) { tracer->CanSkip(holder, true); });
 }
 
 void CycleCollectedJSRuntime::DescribeGCThing(
@@ -957,10 +942,8 @@ void CycleCollectedJSRuntime::TraverseNativeRoots(
   // would hurt to do this after the JS holders.
   TraverseAdditionalNativeRoots(aCb);
 
-  for (JSHolderMap::Iter entry(mJSHolders); !entry.Done(); entry.Next()) {
-    void* holder = entry->mHolder;
-    nsScriptObjectTracer* tracer = entry->mTracer;
-
+  mJSHolders.ForEach(
+      [&aCb](void* holder, nsScriptObjectTracer* tracer, JS::Zone* zone) {
         bool noteRoot = false;
         if (MOZ_UNLIKELY(aCb.WantAllTraces())) {
           noteRoot = true;
@@ -973,7 +956,7 @@ void CycleCollectedJSRuntime::TraverseNativeRoots(
         if (noteRoot) {
           aCb.NoteNativeRoot(holder, tracer);
         }
-  }
+      });
 }
 
 /* static */
@@ -1408,21 +1391,19 @@ void CycleCollectedJSRuntime::TraceNativeGrayRoots(
   TraceAdditionalNativeGrayRoots(aTracer);
 
   bool checkSingleZoneHolders = ShouldCheckSingleZoneHolders();
-  for (JSHolderMap::Iter entry(mJSHolders, aWhich); !entry.Done();
-       entry.Next()) {
-    void* holder = entry->mHolder;
-    nsScriptObjectTracer* tracer = entry->mTracer;
-
+  mJSHolders.ForEach(
+      [aTracer, checkSingleZoneHolders](
+          void* holder, nsScriptObjectTracer* tracer, JS::Zone* zone) {
 #ifdef CHECK_SINGLE_ZONE_JS_HOLDERS
         if (checkSingleZoneHolders && !tracer->IsMultiZoneJSHolder()) {
-      CheckHolderIsSingleZone(holder, tracer, entry.Zone());
+          CheckHolderIsSingleZone(holder, tracer, zone);
         }
 #else
         Unused << checkSingleZoneHolders;
 #endif
-
         tracer->Trace(holder, JsGcTracer(), aTracer);
-  }
+      },
+      aWhich);
 }
 
 void CycleCollectedJSRuntime::AddJSHolder(void* aHolder,

xpcom/base/CycleCollectedJSRuntime.h

@@ -90,13 +90,11 @@ class JSHolderMap {
  public:
   enum WhichHolders { AllHolders, HoldersInGrayMarkingZones };
 
-  class Iter;
-
   JSHolderMap();
 
-#ifdef DEBUG
-  ~JSHolderMap() { MOZ_RELEASE_ASSERT(!mHasIterator); }
-#endif
+  // Call functor |f| for each holder.
+  template <typename F>
+  void ForEach(F&& f, WhichHolders aWhich = AllHolders);
 
   bool Has(void* aHolder) const;
   nsScriptObjectTracer* Get(void* aHolder) const;
@@ -126,7 +124,8 @@ class JSHolderMap {
       mozilla::HashMap<JS::Zone*, UniquePtr<EntryVector>,
                        DefaultHasher<JS::Zone*>, InfallibleAllocPolicy>;
 
-  class EntryVectorIter;
+  template <typename F>
+  void ForEach(EntryVector& aJSHolders, const F& f, JS::Zone* aZone);
 
   bool RemoveEntry(EntryVector& aJSHolders, Entry* aEntry);
 
@@ -143,73 +142,6 @@ class JSHolderMap {
   // Currently this will only contain wrapper cache wrappers since these are the
   // only holders to pass a zone parameter through to AddJSHolder.
   EntryVectorMap mPerZoneJSHolders;
-
-#ifdef DEBUG
-  // Iterators can mutate the element vectors by removing stale elements. Allow
-  // at most one to exist at a time.
-  bool mHasIterator = false;
-#endif
-};
-
-// An iterator over an EntryVector that skips over removed entries and removes
-// them from the map.
-class JSHolderMap::EntryVectorIter {
- public:
-  EntryVectorIter(JSHolderMap& aMap, EntryVector& aVector)
-      : mHolderMap(aMap), mVector(aVector), mIter(aVector.Iter()) {
-    Settle();
-  }
-
-  const EntryVector& Vector() const { return mVector; }
-
-  bool Done() const { return mIter.Done(); }
-  const Entry& Get() const { return mIter.Get(); }
-  void Next() {
-    mIter.Next();
-    Settle();
-  }
-
-  operator const Entry*() const { return &Get(); }
-  const Entry* operator->() const { return &Get(); }
-
- private:
-  void Settle();
-
-  JSHolderMap& mHolderMap;
-  EntryVector& mVector;
-  EntryVector::IterImpl mIter;
-};
-
-class JSHolderMap::Iter {
- public:
-  explicit Iter(JSHolderMap& aMap, WhichHolders aWhich = AllHolders);
-
-#ifdef DEBUG
-  ~Iter() {
-    MOZ_RELEASE_ASSERT(mHolderMap.mHasIterator);
-    mHolderMap.mHasIterator = false;
-  }
-#endif
-
-  bool Done() const { return mIter.Done(); }
-  const Entry& Get() const { return mIter.Get(); }
-  void Next() {
-    mIter.Next();
-    Settle();
-  }
-
-  operator const Entry*() const { return &Get(); }
-  const Entry* operator->() const { return &Get(); }
-
-  JS::Zone* Zone() const { return mZone; }
-
- private:
-  void Settle();
-
-  JSHolderMap& mHolderMap;
-  Vector<JS::Zone*, 1, InfallibleAllocPolicy> mZones;
-  JS::Zone* mZone = nullptr;
-  EntryVectorIter mIter;
 };
 
 class CycleCollectedJSRuntime {