blob: 7ae3c8c4766d8b2f6f630e7df592d4fd363204c8 [file] [log] [blame]
// Copyright 2016 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.
#include "include/v8.h"
#include "src/base/atomicops.h"
#include "src/base/macros.h"
namespace v8 {
namespace sampler {
// ----------------------------------------------------------------------------
// 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 {
static const int kMaxFramesCountLog2 = 8;
static const unsigned kMaxFramesCount = (1u << kMaxFramesCountLog2) - 1;
// Initializes the Sampler support. Called once at VM startup.
static void SetUp();
static void TearDown();
// Initialize sampler.
explicit Sampler(Isolate* isolate);
virtual ~Sampler();
Isolate* isolate() const { return isolate_; }
// Performs stack sampling.
// Clients should override this method in order to do something on samples,
// for example buffer samples in a queue.
virtual void SampleStack(const v8::RegisterState& regs) = 0;
// 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 &&
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();
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_; }
// Counts stack samples taken in various VM states.
bool is_counting_samples_;
unsigned js_sample_count_;
unsigned external_sample_count_;
void SetActive(bool value) { base::NoBarrier_Store(&active_, value); }
void SetRegistered(bool value) { base::NoBarrier_Store(&registered_, value); }
Isolate* isolate_;
base::Atomic32 profiling_;
base::Atomic32 has_processing_thread_;
base::Atomic32 active_;
base::Atomic32 registered_;
PlatformData* data_; // Platform specific data.
} // namespace sampler
} // namespace v8