Fix HeapSnapshotsDiff test, diff implementation, and a bug introduced

test/cctest/test-heap-profiler.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 //
 // Tests for heap profiler
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
 
 #include "v8.h"
 #include "heap-profiler.h"
 #include "snapshot.h"
 #include "string-stream.h"
@@ skipping 769 matching lines @@
 }
 
 
 TEST(HeapSnapshotsDiff) {
   v8::HandleScope scope;
   LocalContext env;
 
   CompileAndRunScript(
       "function A() {}\n"
       "function B(x) { this.x = x; }\n"
+      "function A2(a) { for (var i = 0; i < a; ++i) this[i] = i; }\n"
       "var a = new A();\n"
       "var b = new B(a);");
   const v8::HeapSnapshot* snapshot1 =
       v8::HeapProfiler::TakeSnapshot(v8::String::New("s1"));
 
   CompileAndRunScript(
       "delete a;\n"
       "b.x = null;\n"
-      "var a = new A();\n"
+      "var a = new A2(20);\n"
       "var b2 = new B(a);");
   const v8::HeapSnapshot* snapshot2 =
       v8::HeapProfiler::TakeSnapshot(v8::String::New("s2"));
 
   const v8::HeapSnapshotsDiff* diff = snapshot1->CompareWith(snapshot2);
 
   // Verify additions: ensure that addition of A and B was detected.
   const v8::HeapGraphNode* additions_root = diff->GetAdditionsRoot();
   bool found_A = false, found_B = false;
   uint64_t s1_A_id = 0;
   for (int i = 0, count = additions_root->GetChildrenCount(); i < count; ++i) {
     const v8::HeapGraphEdge* prop = additions_root->GetChild(i);
     const v8::HeapGraphNode* node = prop->GetToNode();
     if (node->GetType() == v8::HeapGraphNode::kObject) {
       v8::String::AsciiValue node_name(node->GetName());
-      if (strcmp(*node_name, "A") == 0) {
+      if (strcmp(*node_name, "A2") == 0) {
         CHECK(IsNodeRetainedAs(node, v8::HeapGraphEdge::kProperty, "a"));
         CHECK(!found_A);
         found_A = true;
         s1_A_id = node->GetId();
       } else if (strcmp(*node_name, "B") == 0) {
         CHECK(IsNodeRetainedAs(node, v8::HeapGraphEdge::kProperty, "b2"));
         CHECK(!found_B);
         found_B = true;
       }
     }
@@ skipping 17 matching lines @@
         s2_A_id = node->GetId();
       }
     }
   }
   CHECK(found_A_del);
   CHECK_NE_UINT64_T(0, s1_A_id);
   CHECK(s1_A_id != s2_A_id);
 }
 
 
+TEST(HeapSnapshotRootPreservedAfterSorting) {
+  v8::HandleScope scope;
+  LocalContext env;
+  const v8::HeapSnapshot* snapshot =
+      v8::HeapProfiler::TakeSnapshot(v8::String::New("s"));
+  const v8::HeapGraphNode* root1 = snapshot->GetRoot();
+  const_cast<i::HeapSnapshot*>(reinterpret_cast<const i::HeapSnapshot*>(
+      snapshot))->GetSortedEntriesList();
+  const v8::HeapGraphNode* root2 = snapshot->GetRoot();
+  CHECK_EQ(root1, root2);
+}
+
+
 namespace v8 {
 namespace internal {
 
 class HeapSnapshotTester {
  public:
   static int CalculateNetworkSize(JSObject* obj) {
     return HeapSnapshot::CalculateNetworkSize(obj);
   }
 };
 
@@ skipping 273 matching lines @@
   LocalContext env;
   const v8::HeapSnapshot* snapshot =
       v8::HeapProfiler::TakeSnapshot(v8::String::New("abort"));
   TestJSONStream stream(5);
   snapshot->Serialize(&stream, v8::HeapSnapshot::kJSON);
   CHECK_GT(stream.size(), 0);
   CHECK_EQ(0, stream.eos_signaled());
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING