Initial GetSample implementation.

src/sampler.h

Index: src/sampler.h
diff --git a/src/sampler.h b/src/sampler.h
index c3dce4ed7c2fec7e353cb06d1641f63e82092a84..197bdba67972220f73e4016a22fcf51579c30560 100644
--- a/src/sampler.h
+++ b/src/sampler.h
@@ -5,14 +5,30 @@
 #ifndef V8_SAMPLER_H_
 #define V8_SAMPLER_H_
 
+#include "include/v8.h"
+
 #include "src/base/atomicops.h"
 #include "src/frames.h"
 #include "src/globals.h"
 
+#if V8_OS_WIN || V8_OS_CYGWIN
+#include "src/base/win32-headers.h"
+#endif
+
 namespace v8 {
 namespace internal {
 
 class Isolate;
+class SignalHandler;

[alph, 2014/09/17 11:55:43]

seems to be unused in the header.

+
+class ScopedSemaphore {
+ public:
+  explicit ScopedSemaphore(base::Semaphore* sem) {semaphore_ = sem;}

[alph, 2014/09/17 11:55:43]

nit: should be an initializer.

+  ~ScopedSemaphore() {semaphore_->Signal();}
+ private:
+  base::Semaphore* semaphore_;
+};
+
 
 // ----------------------------------------------------------------------------
 // Sampler
@@ -34,21 +50,20 @@ struct 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);
-  StateTag state;  // The state of the VM.
-  Address pc;      // Instruction pointer.
+  enum { kMaxFramesCount = 255u };
+
+  void* stack[kMaxFramesCount];  // Call stack.
+  size_t frames_count;           // Number of captured frames.
+  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;
 };
@@ -59,6 +74,9 @@ class Sampler {
   static void SetUp();
   static void TearDown();
 
+  // For new sampling API, initialize and install just the SignalHandler
+  static void SetUpForNewSamplingAPI();

[alph, 2014/09/17 11:55:43]

Avoid using words like 'old' and 'new' in the function names. Something that was
new becomes old at some point.

+
   // Initialize sampler.
   Sampler(Isolate* isolate, int interval);
   virtual ~Sampler();
@@ -85,6 +103,13 @@ class Sampler {
   bool IsActive() const { return base::NoBarrier_Load(&active_); }
 
   void DoSample();
+#if V8_OS_POSIX && !V8_OS_CYGWIN
+  static void GetSample(v8::Sample* sample);
+#elif V8_OS_WIN || V8_OS_CYGWIN
+  static void GetSample(Isolate* isolate,
+                        const CONTEXT& context,
+                        v8::Sample* sample);
+#endif
   // If true next sample must be initiated on the profiler event processor
   // thread right after latest sample is processed.
   void SetHasProcessingThread(bool value) {