Rewrite SamplingCircularQueue

src/cpu-profiler-inl.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 49 matching lines @@
   CodeEntry* entry = code_map->FindEntry(start);
   if (!entry) {
     // Code objects for builtins should already have been added to the map but
     // some of them have been filtered out by CpuProfiler.
     return;
   }
   entry->SetBuiltinId(builtin_id);
 }
 
 
-TickSample* ProfilerEventsProcessor::TickSampleEvent() {
+TickSample* CpuProfiler::StartTickSample() {
+  if (is_profiling_) return processor_->StartTickSample();
+  return NULL;
+}
+
+
+void CpuProfiler::FinishTickSample() {
+  processor_->FinishTickSample();
+}
+
+
+TickSample* ProfilerEventsProcessor::StartTickSample() {
+  void* address = ticks_buffer_.StartEnqueue();
+  if (address == NULL) return NULL;
   TickSampleEventRecord* evt =
-      new(ticks_buffer_.Enqueue()) TickSampleEventRecord(last_code_event_id_);
+      new(address) TickSampleEventRecord(last_code_event_id_);
   return &evt->sample;
 }
 
 
+void ProfilerEventsProcessor::FinishTickSample() {
+  ticks_buffer_.FinishEnqueue();
+}
+
 } }  // namespace v8::internal
 
 #endif  // V8_CPU_PROFILER_INL_H_