Bug 1843477, add a nursery purple buffer for each cycle collector, r=mccr8

Depends on D187146

Differential Revision: https://phabricator.services.mozilla.com/D187147

xpcom/base/nsCycleCollector.cpp

@@ -198,33 +198,6 @@
 
 using namespace mozilla;
 
-struct NurseryPurpleBufferEntry {
-  void* mPtr;
-  nsCycleCollectionParticipant* mParticipant;
-  nsCycleCollectingAutoRefCnt* mRefCnt;
-};
-
-#define NURSERY_PURPLE_BUFFER_SIZE 2048
-bool gNurseryPurpleBufferEnabled = true;
-NurseryPurpleBufferEntry gNurseryPurpleBufferEntry[NURSERY_PURPLE_BUFFER_SIZE];
-uint32_t gNurseryPurpleBufferEntryCount = 0;
-
-void ClearNurseryPurpleBuffer();
-
-static void SuspectUsingNurseryPurpleBuffer(
-    void* aPtr, nsCycleCollectionParticipant* aCp,
-    nsCycleCollectingAutoRefCnt* aRefCnt) {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-  MOZ_ASSERT(gNurseryPurpleBufferEnabled);
-  if (gNurseryPurpleBufferEntryCount == NURSERY_PURPLE_BUFFER_SIZE) {
-    ClearNurseryPurpleBuffer();
-  }
-
-  gNurseryPurpleBufferEntry[gNurseryPurpleBufferEntryCount] = {aPtr, aCp,
-                                                               aRefCnt};
-  ++gNurseryPurpleBufferEntryCount;
-}
-
 // #define COLLECT_TIME_DEBUG
 
 // Enable assertions that are useful for diagnosing errors in graph
@@ -878,13 +851,26 @@ static nsISupports* CanonicalizeXPCOMParticipant(nsISupports* aIn) {
   return out;
 }
 
-struct nsPurpleBufferEntry {
-  nsPurpleBufferEntry(void* aObject, nsCycleCollectingAutoRefCnt* aRefCnt,
+#define NURSERY_PURPLE_BUFFER_SIZE 2048
+
+struct NurseryPurpleBufferEntry {
+  NurseryPurpleBufferEntry() = default;
+  NurseryPurpleBufferEntry(void* aObject, nsCycleCollectingAutoRefCnt* aRefCnt,
                            nsCycleCollectionParticipant* aParticipant)
       : mObject(aObject), mRefCnt(aRefCnt), mParticipant(aParticipant) {}
 
+  void* mObject;
+  nsCycleCollectingAutoRefCnt* mRefCnt;
+  nsCycleCollectionParticipant* mParticipant;  // nullptr for nsISupports
+};
+
+struct nsPurpleBufferEntry : public NurseryPurpleBufferEntry {
+  nsPurpleBufferEntry(void* aObject, nsCycleCollectingAutoRefCnt* aRefCnt,
+                      nsCycleCollectionParticipant* aParticipant)
+      : NurseryPurpleBufferEntry(aObject, aRefCnt, aParticipant) {}
+
   nsPurpleBufferEntry(nsPurpleBufferEntry&& aOther)
-      : mObject(nullptr), mRefCnt(nullptr), mParticipant(nullptr) {
+      : NurseryPurpleBufferEntry(nullptr, nullptr, nullptr) {
     Swap(aOther);
   }
 
@@ -906,17 +892,13 @@ struct nsPurpleBufferEntry {
       mRefCnt->RemoveFromPurpleBuffer();
     }
   }
-
-  void* mObject;
-  nsCycleCollectingAutoRefCnt* mRefCnt;
-  nsCycleCollectionParticipant* mParticipant;  // nullptr for nsISupports
 };
 
 class nsCycleCollector;
 
 struct nsPurpleBuffer {
  private:
-  uint32_t mCount;
+  uint32_t mCount = 0;
 
   // Try to match the size of a jemalloc bucket, to minimize slop bytes.
   // - On 32-bit platforms sizeof(nsPurpleBufferEntry) is 12, so mEntries'
@@ -931,8 +913,14 @@ struct nsPurpleBuffer {
       PurpleBufferVector;
   PurpleBufferVector mEntries;
 
+  NurseryPurpleBufferEntry
+      mNurseryPurpleBufferEntry[NURSERY_PURPLE_BUFFER_SIZE];
+  uint32_t mNurseryPurpleBufferEntryCount = 0;
+
+  bool mNurseryPurpleBufferEnabled = true;
+
  public:
-  nsPurpleBuffer() : mCount(0) {
+  explicit nsPurpleBuffer() {
     static_assert(
         sizeof(PurpleBufferVector::Segment) == 16372 ||      // 32-bit
             sizeof(PurpleBufferVector::Segment) == 32760 ||  // 64-bit
@@ -942,15 +930,14 @@ struct nsPurpleBuffer {
 
   ~nsPurpleBuffer() = default;
 
+  void DisableNurseryPurpleBuffer() { mNurseryPurpleBufferEnabled = false; }
+
   // This method compacts mEntries.
   template <class PurpleVisitor>
   void VisitEntries(PurpleVisitor& aVisitor) {
-    Maybe<AutoRestore<bool>> ar;
-    if (NS_IsMainThread()) {
-      ar.emplace(gNurseryPurpleBufferEnabled);
-      gNurseryPurpleBufferEnabled = false;
-      ClearNurseryPurpleBuffer();
-    }
+    AutoRestore<bool> ar(mNurseryPurpleBufferEnabled);
+    mNurseryPurpleBufferEnabled = false;
+    SuspectNurseryEntries();
 
     if (mEntries.IsEmpty()) {
       return;
@@ -1047,19 +1034,46 @@ struct nsPurpleBuffer {
 
   MOZ_ALWAYS_INLINE void Put(void* aObject, nsCycleCollectionParticipant* aCp,
                              nsCycleCollectingAutoRefCnt* aRefCnt) {
+    if (mNurseryPurpleBufferEnabled) {
+      if (mNurseryPurpleBufferEntryCount == NURSERY_PURPLE_BUFFER_SIZE) {
+        SuspectNurseryEntries();
+      }
+
+      mNurseryPurpleBufferEntry[mNurseryPurpleBufferEntryCount] = {
+          aObject, aRefCnt, aCp};
+      ++mNurseryPurpleBufferEntryCount;
+      return;
+    }
+
+    PutToMainBuffer(aObject, aCp, aRefCnt);
+  }
+
+ private:
+  MOZ_ALWAYS_INLINE void PutToMainBuffer(void* aObject,
+                                         nsCycleCollectionParticipant* aCp,
+                                         nsCycleCollectingAutoRefCnt* aRefCnt) {
     nsPurpleBufferEntry entry(aObject, aRefCnt, aCp);
     Unused << mEntries.Append(std::move(entry));
     MOZ_ASSERT(!entry.mRefCnt, "Move didn't work!");
     ++mCount;
   }
 
+  void SuspectNurseryEntries() {
+    while (mNurseryPurpleBufferEntryCount) {
+      NurseryPurpleBufferEntry& entry =
+          mNurseryPurpleBufferEntry[--mNurseryPurpleBufferEntryCount];
+      PutToMainBuffer(entry.mObject, entry.mParticipant, entry.mRefCnt);
+    }
+  }
+
+ public:
   void Remove(nsPurpleBufferEntry* aEntry) {
     MOZ_ASSERT(mCount != 0, "must have entries");
     --mCount;
     aEntry->Clear();
   }
 
-  uint32_t Count() const { return mCount; }
+  uint32_t Count() const { return mCount + mNurseryPurpleBufferEntryCount; }
 
   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
     return mEntries.SizeOfExcludingThis(aMallocSizeOf);
@@ -1176,7 +1190,6 @@ class nsCycleCollector : public nsIMemoryReporter {
 
   void Suspect(void* aPtr, nsCycleCollectionParticipant* aCp,
                nsCycleCollectingAutoRefCnt* aRefCnt);
-  void SuspectNurseryEntries();
   uint32_t SuspectedCount();
   void ForgetSkippable(js::SliceBudget& aBudget, bool aRemoveChildlessNodes,
                        bool aAsyncSnowWhiteFreeing);
@@ -3286,15 +3299,6 @@ MOZ_ALWAYS_INLINE void nsCycleCollector::Suspect(
   mPurpleBuf.Put(aPtr, aParti, aRefCnt);
 }
 
-void nsCycleCollector::SuspectNurseryEntries() {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-  while (gNurseryPurpleBufferEntryCount) {
-    NurseryPurpleBufferEntry& entry =
-        gNurseryPurpleBufferEntry[--gNurseryPurpleBufferEntryCount];
-    mPurpleBuf.Put(entry.mPtr, entry.mParticipant, entry.mRefCnt);
-  }
-}
-
 void nsCycleCollector::CheckThreadSafety() {
 #ifdef DEBUG
   MOZ_ASSERT(mEventTarget->IsOnCurrentThread());
@@ -3701,19 +3705,13 @@ void nsCycleCollector::BeginCollection(
 
 uint32_t nsCycleCollector::SuspectedCount() {
   CheckThreadSafety();
-  if (NS_IsMainThread()) {
-    return gNurseryPurpleBufferEntryCount + mPurpleBuf.Count();
-  }
-
   return mPurpleBuf.Count();
 }
 
 void nsCycleCollector::Shutdown(bool aDoCollect) {
   CheckThreadSafety();
 
-  if (NS_IsMainThread()) {
-    gNurseryPurpleBufferEnabled = false;
-  }
+  mPurpleBuf.DisableNurseryPurpleBuffer();
 
   // Always delete snow white objects.
   FreeSnowWhite(true);
@@ -3852,27 +3850,6 @@ void NS_CycleCollectorSuspect3(void* aPtr, nsCycleCollectionParticipant* aCp,
   SuspectAfterShutdown(aPtr, aCp, aRefCnt, aShouldDelete);
 }
 
-void ClearNurseryPurpleBuffer() {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-  CollectorData* data = sCollectorData.get();
-  MOZ_ASSERT(data);
-  MOZ_ASSERT(data->mCollector);
-  data->mCollector->SuspectNurseryEntries();
-}
-
-void NS_CycleCollectorSuspectUsingNursery(void* aPtr,
-                                          nsCycleCollectionParticipant* aCp,
-                                          nsCycleCollectingAutoRefCnt* aRefCnt,
-                                          bool* aShouldDelete) {
-  MOZ_ASSERT(NS_IsMainThread(), "Wrong thread!");
-  if (!gNurseryPurpleBufferEnabled) {
-    NS_CycleCollectorSuspect3(aPtr, aCp, aRefCnt, aShouldDelete);
-    return;
-  }
-
-  SuspectUsingNurseryPurpleBuffer(aPtr, aCp, aRefCnt);
-}
-
 uint32_t nsCycleCollector_suspectedCount() {
   CollectorData* data = sCollectorData.get();
 

xpcom/build/nsXPCOM.h

@@ -297,12 +297,6 @@ NS_CycleCollectorSuspect3(void* aPtr, nsCycleCollectionParticipant* aCp,
                           nsCycleCollectingAutoRefCnt* aRefCnt,
                           bool* aShouldDelete);
 
-XPCOM_API(void)
-NS_CycleCollectorSuspectUsingNursery(void* aPtr,
-                                     nsCycleCollectionParticipant* aCp,
-                                     nsCycleCollectingAutoRefCnt* aRefCnt,
-                                     bool* aShouldDelete);
-
 #endif
 
 /**