Save heap object tracking data in heap snapshot

src/heap-snapshot-generator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/heap-snapshot-generator-inl.h"
 
 #include "src/allocation-tracker.h"
 #include "src/code-stubs.h"
@@ skipping 2725 matching lines @@
 
   writer_->AddString("\"trace_function_infos\":[");
   SerializeTraceNodeInfos();
   if (writer_->aborted()) return;
   writer_->AddString("],\n");
   writer_->AddString("\"trace_tree\":[");
   SerializeTraceTree();
   if (writer_->aborted()) return;
   writer_->AddString("],\n");
 
+  writer_->AddString("\"samples\":[");
+  SerializeSamples();
+  if (writer_->aborted()) return;
+  writer_->AddString("],\n");
+
   writer_->AddString("\"strings\":[");
   SerializeStrings();
   if (writer_->aborted()) return;
   writer_->AddCharacter(']');
   writer_->AddCharacter('}');
   writer_->Finalize();
 }
 
 
 int HeapSnapshotJSONSerializer::GetStringId(const char* s) {
@@ skipping 176 matching lines @@
         JSON_S("name") ","
         JSON_S("script_name") ","
         JSON_S("script_id") ","
         JSON_S("line") ","
         JSON_S("column")) ","
     JSON_S("trace_node_fields") ":" JSON_A(
         JSON_S("id") ","
         JSON_S("function_info_index") ","
         JSON_S("count") ","
         JSON_S("size") ","
-        JSON_S("children"))));
+        JSON_S("children")) ","
+    JSON_S("sample_fields") ":" JSON_A(
+        JSON_S("timstamp_ms") ","
+        JSON_S("next_object_id"))));
 #undef JSON_S
 #undef JSON_O
 #undef JSON_A
   writer_->AddString(",\"node_count\":");
   writer_->AddNumber(snapshot_->entries().length());
   writer_->AddString(",\"edge_count\":");
   writer_->AddNumber(snapshot_->edges().length());
   writer_->AddString(",\"trace_function_count\":");
   uint32_t count = 0;
   AllocationTracker* tracker = snapshot_->profiler()->allocation_tracker();
   if (tracker) {
     count = tracker->function_info_list().length();
   }
   writer_->AddNumber(count);
+  writer_->AddString(",\"sample_count\":");
+  const List<HeapObjectsMap::TimeInterval>& samples =
+      snapshot_->profiler()->heap_object_map()->samples();
+  writer_->AddNumber(samples.length());
 }
 
 
 static void WriteUChar(OutputStreamWriter* w, unibrow::uchar u) {
   static const char hex_chars[] = "0123456789ABCDEF";
   w->AddString("\\u");
   w->AddCharacter(hex_chars[(u >> 12) & 0xf]);
   w->AddCharacter(hex_chars[(u >> 8) & 0xf]);
   w->AddCharacter(hex_chars[(u >> 4) & 0xf]);
   w->AddCharacter(hex_chars[u & 0xf]);
@@ skipping 83 matching lines @@
     buffer_pos = SerializePosition(info->line, buffer, buffer_pos);
     buffer[buffer_pos++] = ',';
     buffer_pos = SerializePosition(info->column, buffer, buffer_pos);
     buffer[buffer_pos++] = '\n';
     buffer[buffer_pos++] = '\0';
     writer_->AddString(buffer.start());
   }
 }
 
 
+void HeapSnapshotJSONSerializer::SerializeSamples() {
+  const List<HeapObjectsMap::TimeInterval>& samples =
+      snapshot_->profiler()->heap_object_map()->samples();
+  if (samples.is_empty()) return;
+  base::TimeTicks start_time = samples[0].timestamp;
+  // The buffer needs space for 2 unsigned ints, 2 commas, \n and \0
+  const int kBufferSize =
+      2 * MaxDecimalDigitsIn<sizeof(
+              base::TimeDelta().InMilliseconds())>::kUnsigned  // NOLINT

[alph, 2015/03/19 14:05:27]

one is timedelta, another is id. these are two different types.

[yurys, 2015/03/19 14:13:26]

Done.

+      +
+      2 + 1 + 1;
+  EmbeddedVector<char, kBufferSize> buffer;
+  bool first_entry = true;
+  for (int i = 0; i < samples.length(); i++) {
+    HeapObjectsMap::TimeInterval& sample = samples[i];
+    int buffer_pos = 0;
+    if (first_entry) {

[alph, 2015/03/19 14:05:27]

i != 0

[yurys, 2015/03/19 14:13:26]

Done.

+      first_entry = false;
+    } else {
+      buffer[buffer_pos++] = ',';
+    }
+    base::TimeDelta time_delta = sample.timestamp - start_time;
+    buffer_pos = utoa(time_delta.InMilliseconds(), buffer, buffer_pos);

[alph, 2015/03/19 14:05:27]

Let's use microseconds as we do in cpu profiler to be consistent. wdyt?

[yurys, 2015/03/19 14:13:26]

Done.

+    buffer[buffer_pos++] = ',';
+    buffer_pos = utoa(sample.id, buffer, buffer_pos);
+    buffer[buffer_pos++] = '\n';
+    buffer[buffer_pos++] = '\0';
+    writer_->AddString(buffer.start());
+  }
+}
+
+
 void HeapSnapshotJSONSerializer::SerializeString(const unsigned char* s) {
   writer_->AddCharacter('\n');
   writer_->AddCharacter('\"');
   for ( ; *s != '\0'; ++s) {
     switch (*s) {
       case '\b':
         writer_->AddString("\\b");
         continue;
       case '\f':
         writer_->AddString("\\f");
@@ skipping 49 matching lines @@
   writer_->AddString("\"<dummy>\"");
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 } }  // namespace v8::internal