[WIP] A sampler thread in d8 for consuming the new API.

src/sampler.h

Index: src/sampler.h
diff --git a/src/sampler.h b/src/sampler.h
index c3dce4ed7c2fec7e353cb06d1641f63e82092a84..8afaafaaab58bae28691170de1f3ddfe29bb58b3 100644
--- a/src/sampler.h
+++ b/src/sampler.h
@@ -5,6 +5,8 @@
 #ifndef V8_SAMPLER_H_
 #define V8_SAMPLER_H_
 
+#include "include/v8-sampler.h"
+
 #include "src/base/atomicops.h"
 #include "src/frames.h"
 #include "src/globals.h"
@@ -14,6 +16,15 @@ namespace internal {
 
 class Isolate;
 
+class ScopedSemaphore {
+ public:
+  explicit ScopedSemaphore(base::Semaphore* sem) {semaphore_ = sem;}
+  ~ScopedSemaphore() {semaphore_->Signal();}
+ private:
+  base::Semaphore* semaphore_;
+};
+
+
 // ----------------------------------------------------------------------------
 // Sampler
 //
@@ -29,26 +40,22 @@ struct RegisterState {
 };
 
 // TickSample captures the information collected for each sample.
-struct TickSample {
+struct TickSample : v8::Sample {
   TickSample()
       : state(OTHER),
         pc(NULL),
         external_callback(NULL),
-        frames_count(0),
         has_external_callback(false),
         top_frame_type(StackFrame::NONE) {}
-  void Init(Isolate* isolate, const RegisterState& state);
+  void Init(Isolate* isolate,
+            const RegisterState& state);
   StateTag state;  // The state of the VM.
   Address pc;      // Instruction pointer.
   union {
     Address tos;   // Top stack value (*sp).
     Address external_callback;
   };
-  static const unsigned kMaxFramesCountLog2 = 8;
-  static const unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1;
-  Address stack[kMaxFramesCount];  // Call stack.
   base::TimeTicks timestamp;
-  unsigned frames_count : kMaxFramesCountLog2;  // Number of captured frames.
   bool has_external_callback : 1;
   StackFrame::Type top_frame_type : 4;
 };
@@ -85,6 +92,7 @@ class Sampler {
   bool IsActive() const { return base::NoBarrier_Load(&active_); }
 
   void DoSample();
+  v8::Sample* GetSample(v8::Sample* sample);
   // If true next sample must be initiated on the profiler event processor
   // thread right after latest sample is processed.
   void SetHasProcessingThread(bool value) {
@@ -120,6 +128,9 @@ class Sampler {
   bool is_counting_samples_;
   // Counts stack samples taken in JS VM state.
   unsigned js_and_external_sample_count_;
+  void* GetSampleHelper();
+  static void CopyTickSampleToSample(TickSample* tick_sample,
+                                     v8::Sample* sample);
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };