Create libsampler as V8 sampler library.

src/profiler/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_PROFILER_SAMPLER_H_
-#define V8_PROFILER_SAMPLER_H_
-
-#include "include/v8.h"
-
-#include "src/base/atomicops.h"
-#include "src/base/macros.h"
-
-namespace v8 {
-namespace internal {
-
-class Isolate;
-struct TickSample;
-
-// ----------------------------------------------------------------------------
-// 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.
-
-class Sampler {
- public:
-  // Initializes the Sampler support. Called once at VM startup.
-  static void SetUp();
-  static void TearDown();
-
-  // 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 v8::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_); }
-
-  // CpuProfiler collects samples by calling DoSample directly
-  // without calling Start. To keep it working, we register the sampler
-  // with the CpuProfiler.
-  bool IsRegistered() const { return base::NoBarrier_Load(&registered_); }
-
-  void DoSample();
-  // 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_sample_count() const { return js_sample_count_; }
-  unsigned external_sample_count() const { return external_sample_count_; }
-  void StartCountingSamples() {
-    js_sample_count_ = 0;
-    external_sample_count_ = 0;
-    is_counting_samples_ = true;
-  }
-
-  class PlatformData;
-  PlatformData* platform_data() const { return data_; }
-
- protected:
-  // This method is called for each sampling period with the current
-  // program counter.
-  virtual void Tick(TickSample* sample) = 0;
-
- private:
-  void SetActive(bool value) { base::NoBarrier_Store(&active_, value); }
-
-  void SetRegistered(bool value) { base::NoBarrier_Store(&registered_, value); }
-
-  Isolate* isolate_;
-  const int interval_;
-  base::Atomic32 profiling_;
-  base::Atomic32 has_processing_thread_;
-  base::Atomic32 active_;
-  base::Atomic32 registered_;
-  PlatformData* data_;  // Platform specific data.
-  // Counts stack samples taken in various VM states.
-  bool is_counting_samples_;
-  unsigned js_sample_count_;
-  unsigned external_sample_count_;
-  DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
-};
-
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_PROFILER_SAMPLER_H_