A temporary workaround for huge heap snapshots problem.

Do not try to serialize them into JSON to avoid crashing / hanging DevTools.

R=sgjesse@chromium.org
BUG=v8:1658,89268
TEST=none

Review URL: http://codereview.chromium.org/7832003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9123 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/profile-generator.cc

@@ -1195,12 +1195,9 @@ void HeapSnapshot::AllocateEntries(int entries_count,
                                    int children_count,
                                    int retainers_count) {
   ASSERT(raw_entries_ == NULL);
-  raw_entries_ = NewArray<char>(
-      HeapEntry::EntriesSize(entries_count, children_count, retainers_count));
-#ifdef DEBUG
   raw_entries_size_ =
       HeapEntry::EntriesSize(entries_count, children_count, retainers_count);
-#endif
+  raw_entries_ = NewArray<char>(raw_entries_size_);
 }
 
 
@@ -2984,10 +2981,19 @@ class OutputStreamWriter {
   bool aborted_;
 };
 
+const int HeapSnapshotJSONSerializer::kMaxSerializableSnapshotRawSize =
+    256 * MB;
+
 void HeapSnapshotJSONSerializer::Serialize(v8::OutputStream* stream) {
   ASSERT(writer_ == NULL);
   writer_ = new OutputStreamWriter(stream);
 
+  HeapSnapshot* original_snapshot = NULL;
+  if (snapshot_->raw_entries_size() >= kMaxSerializableSnapshotRawSize) {
+    // The snapshot is too big. Serialize a fake snapshot.
+    original_snapshot = snapshot_;
+    snapshot_ = CreateFakeSnapshot();
+  }
   // Since nodes graph is cyclic, we need the first pass to enumerate
   // them. Strings can be serialized in one pass.
   EnumerateNodes();
@@ -2995,6 +3001,26 @@ void HeapSnapshotJSONSerializer::Serialize(v8::OutputStream* stream) {
 
   delete writer_;
   writer_ = NULL;
+
+  if (original_snapshot != NULL) {
+    delete snapshot_;
+    snapshot_ = original_snapshot;
+  }
+}
+
+
+HeapSnapshot* HeapSnapshotJSONSerializer::CreateFakeSnapshot() {
+  HeapSnapshot* result = new HeapSnapshot(snapshot_->collection(),
+                                          HeapSnapshot::kFull,
+                                          snapshot_->title(),
+                                          snapshot_->uid());
+  result->AllocateEntries(2, 1, 0);
+  HeapEntry* root = result->AddRootEntry(1);
+  HeapEntry* message = result->AddEntry(
+      HeapEntry::kString, "The snapshot is too big", 0, 4, 0, 0);
+  root->SetUnidirElementReference(0, 1, message);
+  result->SetDominatorsToSelf();
+  return result;
 }
 
 

src/profile-generator.h

@@ -654,6 +654,7 @@ class HeapSnapshot {
   HeapEntry* gc_roots() { return gc_roots_entry_; }
   HeapEntry* natives_root() { return natives_root_entry_; }
   List<HeapEntry*>* entries() { return &entries_; }
+  int raw_entries_size() { return raw_entries_size_; }
 
   void AllocateEntries(
       int entries_count, int children_count, int retainers_count);
@@ -689,9 +690,7 @@ class HeapSnapshot {
   char* raw_entries_;
   List<HeapEntry*> entries_;
   bool entries_sorted_;
-#ifdef DEBUG
   int raw_entries_size_;
-#endif
 
   friend class HeapSnapshotTester;
 
@@ -1097,6 +1096,7 @@ class HeapSnapshotJSONSerializer {
   }
 
   void EnumerateNodes();
+  HeapSnapshot* CreateFakeSnapshot();
   int GetNodeId(HeapEntry* entry);
   int GetStringId(const char* s);
   void SerializeEdge(HeapGraphEdge* edge);
@@ -1108,6 +1108,8 @@ class HeapSnapshotJSONSerializer {
   void SerializeStrings();
   void SortHashMap(HashMap* map, List<HashMap::Entry*>* sorted_entries);
 
+  static const int kMaxSerializableSnapshotRawSize;
+
   HeapSnapshot* snapshot_;
   HashMap nodes_;
   HashMap strings_;