Initial GetSample implementation.

src/sampler.h

 // 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.
 
 #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
 //
 // A sampler periodically samples the state of the VM and optionally
 // (if used for profiling) the program counter and stack pointer for
 // the thread that created it.
 
 struct RegisterState {
   RegisterState() : pc(NULL), sp(NULL), fp(NULL) {}
   Address pc;      // Instruction pointer.
   Address sp;      // Stack pointer.
   Address fp;      // Frame pointer.
 };
 
 // TickSample captures the information collected for each sample.
 struct TickSample {
   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;
 };
 
 class Sampler {
  public:
   // Initializes the Sampler support. Called once at VM startup.
   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();
 
   Isolate* isolate() const { return isolate_; }
   int interval() const { return interval_; }
 
   // Performs stack sampling.
   void SampleStack(const RegisterState& regs);
 
   // Start and stop sampler.
   void Start();
   void Stop();
 
   // Whether the sampling thread should use this Sampler for CPU profiling?
   bool IsProfiling() const {
     return base::NoBarrier_Load(&profiling_) > 0 &&
         !base::NoBarrier_Load(&has_processing_thread_);
   }
   void IncreaseProfilingDepth();
   void DecreaseProfilingDepth();
 
   // Whether the sampler is running (that is, consumes resources).
   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) {
     base::NoBarrier_Store(&has_processing_thread_, value);
   }
 
   // Used in tests to make sure that stack sampling is performed.
   unsigned js_and_external_sample_count() const {
     return js_and_external_sample_count_;
   }
@@ skipping 22 matching lines @@
   bool is_counting_samples_;
   // Counts stack samples taken in JS VM state.
   unsigned js_and_external_sample_count_;
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SAMPLER_H_