Allow Oilpan heap objects account for their external allocations.

Source/core/dom/Text.cpp

Index: Source/core/dom/Text.cpp
diff --git a/Source/core/dom/Text.cpp b/Source/core/dom/Text.cpp
index c983fbd9874729c34dc3b92ddc3c86b7b47abf15..9db26bb8de3df3b6c77c654958f9fa5f0c32f1d2 100644
--- a/Source/core/dom/Text.cpp
+++ b/Source/core/dom/Text.cpp
@@ -42,13 +42,48 @@
 
 namespace blink {
 
+#if ENABLE(OILPAN)
+namespace {
+// If the external string kept by a Text node exceed this threshold length,
+// Oilpan is informed. External allocation amounts owned by heap objects are
+// taken into account when scheduling urgent Oilpan GCs.
+//
+// FIXME: having only Text nodes with strings above an ad-hoc local threshold
+// influence Oilpan's GC behavior isn't a satisfactory long-term solution.
+// But code that allocates a lot of Text nodes in tight loops, and not much more,
+// we do have to trigger Oilpan GCs to avoid PartitionAlloc OOMs. The accounting
+// does add overhead on the allocation of every Text node however, so for now, only
+// register those above the given threshold. TBC.
+const size_t stringLengthThreshold = 256;
+
+enum RegistrationMode { AsNew, AsAlive };
+
+void registerExternalAllocation(size_t length, RegistrationMode mode)
+{
+    if (length > stringLengthThreshold) {
+        if (mode == AsNew)
+            Heap::increaseExternallyAllocatedBytes(length);
+        else
+            Heap::increaseExternallyAllocatedBytesAlive(length);
+    }
+}
+
+} // namespace
+#endif
+
 PassRefPtrWillBeRawPtr<Text> Text::create(Document& document, const String& data)
 {
+#if ENABLE(OILPAN)
+    registerExternalAllocation(data.length(), AsNew);
+#endif
     return adoptRefWillBeNoop(new Text(document, data, CreateText));
 }
 
 PassRefPtrWillBeRawPtr<Text> Text::createEditingText(Document& document, const String& data)
 {
+#if ENABLE(OILPAN)
+    registerExternalAllocation(data.length(), AsNew);
+#endif
     return adoptRefWillBeNoop(new Text(document, data, CreateEditingText));
 }
 
@@ -408,6 +443,14 @@ PassRefPtrWillBeRawPtr<Text> Text::cloneWithData(const String& data)
     return create(document(), data);
 }
 
+#if ENABLE(OILPAN)
+void Text::trace(Visitor* visitor)
+{
+    registerExternalAllocation(m_data.length(), AsAlive);
+    CharacterData::trace(visitor);
+}
+#endif
+
 #ifndef NDEBUG
 void Text::formatForDebugger(char *buffer, unsigned length) const
 {