Expose last seen heap object id via v8 public api.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/10444137

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11702 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8-profiler.h

@@ -448,11 +448,12 @@ class V8EXPORT HeapProfiler {
    * reports updates for all previous time intervals via the OutputStream
    * object. Updates on each time interval are provided as a stream of the
    * HeapStatsUpdate structure instances.
+   * The return value of the function is the last seen heap object Id.
    *
    * StartHeapObjectsTracking must be called before the first call to this
    * method.
    */
-  static void PushHeapObjectsStats(OutputStream* stream);
+  static SnapshotObjectId PushHeapObjectsStats(OutputStream* stream);
 
   /**
    * Stops tracking of heap objects population statistics, cleans up all

src/api.cc

@@ -6229,7 +6229,7 @@ void HeapProfiler::StopHeapObjectsTracking() {
 }
 
 
-void HeapProfiler::PushHeapObjectsStats(OutputStream* stream) {
+SnapshotObjectId HeapProfiler::PushHeapObjectsStats(OutputStream* stream) {
   i::Isolate* isolate = i::Isolate::Current();
   IsDeadCheck(isolate, "v8::HeapProfiler::PushHeapObjectsStats");
   return i::HeapProfiler::PushHeapObjectsStats(stream);

src/heap-profiler.cc

@@ -97,7 +97,7 @@ void HeapProfiler::StopHeapObjectsTracking() {
 }
 
 
-void HeapProfiler::PushHeapObjectsStats(v8::OutputStream* stream) {
+SnapshotObjectId HeapProfiler::PushHeapObjectsStats(v8::OutputStream* stream) {
   ASSERT(Isolate::Current()->heap_profiler() != NULL);
   return Isolate::Current()->heap_profiler()->PushHeapObjectsStatsImpl(stream);
 }
@@ -158,8 +158,8 @@ void HeapProfiler::StartHeapObjectsTrackingImpl() {
 }
 
 
-void HeapProfiler::PushHeapObjectsStatsImpl(OutputStream* stream) {
-  snapshots_->PushHeapObjectsStats(stream);
+SnapshotObjectId HeapProfiler::PushHeapObjectsStatsImpl(OutputStream* stream) {
+  return snapshots_->PushHeapObjectsStats(stream);
 }
 
 

src/heap-profiler.h

@@ -58,7 +58,7 @@ class HeapProfiler {
 
   static void StartHeapObjectsTracking();
   static void StopHeapObjectsTracking();
-  static void PushHeapObjectsStats(OutputStream* stream);
+  static SnapshotObjectId PushHeapObjectsStats(OutputStream* stream);
   static int GetSnapshotsCount();
   static HeapSnapshot* GetSnapshot(int index);
   static HeapSnapshot* FindSnapshot(unsigned uid);
@@ -89,7 +89,7 @@ class HeapProfiler {
 
   void StartHeapObjectsTrackingImpl();
   void StopHeapObjectsTrackingImpl();
-  void PushHeapObjectsStatsImpl(OutputStream* stream);
+  SnapshotObjectId PushHeapObjectsStatsImpl(OutputStream* stream);
 
   HeapSnapshotsCollection* snapshots_;
   unsigned next_snapshot_uid_;

src/profile-generator.cc

@@ -1357,7 +1357,7 @@ void HeapObjectsMap::UpdateHeapObjectsMap() {
 }
 
 
-void HeapObjectsMap::PushHeapObjectsStats(OutputStream* stream) {
+SnapshotObjectId HeapObjectsMap::PushHeapObjectsStats(OutputStream* stream) {
   UpdateHeapObjectsMap();
   time_intervals_.Add(TimeInterval(next_id_));
   int prefered_chunk_size = stream->GetChunkSize();
@@ -1387,7 +1387,7 @@ void HeapObjectsMap::PushHeapObjectsStats(OutputStream* stream) {
       if (stats_buffer.length() >= prefered_chunk_size) {
         OutputStream::WriteResult result = stream->WriteHeapStatsChunk(
             &stats_buffer.first(), stats_buffer.length());
-        if (result == OutputStream::kAbort) return;
+        if (result == OutputStream::kAbort) return last_assigned_id();
         stats_buffer.Clear();
       }
     }
@@ -1396,9 +1396,10 @@ void HeapObjectsMap::PushHeapObjectsStats(OutputStream* stream) {
   if (!stats_buffer.is_empty()) {
     OutputStream::WriteResult result = stream->WriteHeapStatsChunk(
         &stats_buffer.first(), stats_buffer.length());
-    if (result == OutputStream::kAbort) return;
+    if (result == OutputStream::kAbort) return last_assigned_id();
   }
   stream->EndOfStream();
+  return last_assigned_id();
 }
 
 

src/profile-generator.h

@@ -649,7 +649,7 @@ class HeapObjectsMap {
   }
 
   void StopHeapObjectsTracking();
-  void PushHeapObjectsStats(OutputStream* stream);
+  SnapshotObjectId PushHeapObjectsStats(OutputStream* stream);
 
   static SnapshotObjectId GenerateId(v8::RetainedObjectInfo* info);
   static inline SnapshotObjectId GetNthGcSubrootId(int delta);
@@ -707,7 +707,7 @@ class HeapSnapshotsCollection {
   ~HeapSnapshotsCollection();
 
   bool is_tracking_objects() { return is_tracking_objects_; }
-  void PushHeapObjectsStats(OutputStream* stream) {
+  SnapshotObjectId PushHeapObjectsStats(OutputStream* stream) {
     return ids_.PushHeapObjectsStats(stream);
   }
   void StartHeapObjectsTracking() { is_tracking_objects_ = true; }

test/cctest/test-heap-profiler.cc

@@ -691,9 +691,13 @@ class TestStatsStream : public v8::OutputStream {
 
 }  // namespace
 
-static TestStatsStream GetHeapStatsUpdate() {
+static TestStatsStream GetHeapStatsUpdate(
+    v8::SnapshotObjectId* object_id = NULL) {
   TestStatsStream stream;
-  v8::HeapProfiler::PushHeapObjectsStats(&stream);
+  v8::SnapshotObjectId last_seen_id =
+      v8::HeapProfiler::PushHeapObjectsStats(&stream);
+  if (object_id)
+    *object_id = last_seen_id;
   CHECK_EQ(1, stream.eos_signaled());
   return stream;
 }
@@ -710,9 +714,10 @@ TEST(HeapSnapshotObjectsStats) {
     HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
   }
 
+  v8::SnapshotObjectId initial_id;
   {
     // Single chunk of data expected in update. Initial data.
-    TestStatsStream stats_update = GetHeapStatsUpdate();
+    TestStatsStream stats_update = GetHeapStatsUpdate(&initial_id);
     CHECK_EQ(1, stats_update.intervals_count());
     CHECK_EQ(1, stats_update.updates_written());
     CHECK_LT(0, stats_update.entries_size());
@@ -720,13 +725,18 @@ TEST(HeapSnapshotObjectsStats) {
   }
 
   // No data expected in update because nothing has happened.
-  CHECK_EQ(0, GetHeapStatsUpdate().updates_written());
+  v8::SnapshotObjectId same_id;
+  CHECK_EQ(0, GetHeapStatsUpdate(&same_id).updates_written());
+  CHECK_EQ_SNAPSHOT_OBJECT_ID(initial_id, same_id);
+
   {
+    v8::SnapshotObjectId additional_string_id;
     v8::HandleScope inner_scope_1;
     v8_str("string1");
     {
       // Single chunk of data with one new entry expected in update.
-      TestStatsStream stats_update = GetHeapStatsUpdate();
+      TestStatsStream stats_update = GetHeapStatsUpdate(&additional_string_id);
+      CHECK_LT(same_id, additional_string_id);
       CHECK_EQ(1, stats_update.intervals_count());
       CHECK_EQ(1, stats_update.updates_written());
       CHECK_LT(0, stats_update.entries_size());
@@ -735,7 +745,9 @@ TEST(HeapSnapshotObjectsStats) {
     }
 
     // No data expected in update because nothing happened.
-    CHECK_EQ(0, GetHeapStatsUpdate().updates_written());
+    v8::SnapshotObjectId last_id;
+    CHECK_EQ(0, GetHeapStatsUpdate(&last_id).updates_written());
+    CHECK_EQ_SNAPSHOT_OBJECT_ID(additional_string_id, last_id);
 
     {
       v8::HandleScope inner_scope_2;