[tracing] Adding class-wise memory statistics to blink gc memory dumps

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index 6128cc158873b46a2adad6c85f38efdd4d6e7305..7cb24a5767344b19ca2a976aa1793ab9a06d8430 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -33,12 +33,14 @@
 
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/TraceEvent.h"
+#include "platform/heap/BlinkGCMemoryDumpProvider.h"
 #include "platform/heap/CallbackStack.h"
 #include "platform/heap/Handle.h"
 #include "platform/heap/Heap.h"
 #include "platform/heap/MarkingVisitor.h"
 #include "platform/heap/SafePoint.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebMemoryAllocatorDump.h"
 #include "public/platform/WebScheduler.h"
 #include "public/platform/WebThread.h"
 #include "public/platform/WebTraceLocation.h"
@@ -380,6 +382,18 @@ void ThreadState::visitPersistents(Visitor* visitor)
     }
 }
 
+size_t ThreadState::GCSnapshotInfo::getClassTag(const GCInfo* gcInfo)
+{
+    ClassTagMap::AddResult result = classTags.add(gcInfo, classTags.size());
+    if (result.isNewEntry) {
+        liveCount.append(0);
+        deadCount.append(0);
+        liveSize.append(0);
+        deadSize.append(0);
+    }
+    return result.storedValue->value;
+}
+
 #if ENABLE(GC_PROFILING)
 const GCInfo* ThreadState::findGCInfo(Address address)
 {
@@ -1378,6 +1392,7 @@ void ThreadState::promptlyFreed(size_t gcInfoIndex)
 
 void ThreadState::takeSnapshot(SnapshotType type)
 {
+    GCSnapshotInfo info;
     ASSERT(isInGC());
 
     int numberOfHeapsReported = 0;
@@ -1388,7 +1403,7 @@ void ThreadState::takeSnapshot(SnapshotType type)
         allocatorBaseName = String::format("blink_gc/thread_%lu/heaps/" #HeapType, (unsigned long)(m_thread)); \
         switch (type) {                                                                                        \
         case SnapshotType::HeapSnapshot:                                                                       \
-            m_heaps[HeapType##HeapIndex]->takeSnapshot(allocatorBaseName);                                     \
+            m_heaps[HeapType##HeapIndex]->takeSnapshot(allocatorBaseName, info);                               \
             break;                                                                                             \
         case SnapshotType::FreelistSnapshot:                                                                   \
             m_heaps[HeapType##HeapIndex]->takeFreelistSnapshot(allocatorBaseName);                             \
@@ -1415,6 +1430,19 @@ void ThreadState::takeSnapshot(SnapshotType type)
     ASSERT(numberOfHeapsReported == NumberOfHeaps);
 
 #undef SNAPSHOT_HEAP
+
+    Vector<String> classNameVector(info.classTags.size());
+    for (GCSnapshotInfo::ClassTagMap::iterator it = info.classTags.begin(); it != info.classTags.end(); ++it)
+        classNameVector[it->value] = it->key->m_className;
+
+    for (size_t i = 0; i < classNameVector.size(); ++i) {
+        String dumpName = String::format("blink_gc/thread_%lu/classes/", (unsigned long)(m_thread)) + classNameVector[i];
+        WebMemoryAllocatorDump* classDump = BlinkGCMemoryDumpProvider::instance()->createMemoryAllocatorDumpForCurrentGC(dumpName);
+        classDump->AddScalar("live_count", "objects", info.liveCount[i]);
+        classDump->AddScalar("dead_count", "objects", info.deadCount[i]);
+        classDump->AddScalar("live_size", "bytes", info.liveSize[i]);
+        classDump->AddScalar("dead_size", "bytes", info.deadSize[i]);
+    }
 }
 
 #if ENABLE(GC_PROFILING)