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| 1 // Copyright 2013 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef V8_PROFILER_SAMPLER_H_ |
| 6 #define V8_PROFILER_SAMPLER_H_ |
| 7 |
| 8 #include "include/v8.h" |
| 9 |
| 10 #include "src/base/atomicops.h" |
| 11 #include "src/base/macros.h" |
| 12 |
| 13 namespace v8 { |
| 14 namespace internal { |
| 15 |
| 16 class Isolate; |
| 17 struct TickSample; |
| 18 |
| 19 // ---------------------------------------------------------------------------- |
| 20 // Sampler |
| 21 // |
| 22 // A sampler periodically samples the state of the VM and optionally |
| 23 // (if used for profiling) the program counter and stack pointer for |
| 24 // the thread that created it. |
| 25 |
| 26 class Sampler { |
| 27 public: |
| 28 // Initializes the Sampler support. Called once at VM startup. |
| 29 static void SetUp(); |
| 30 static void TearDown(); |
| 31 |
| 32 // Initialize sampler. |
| 33 Sampler(Isolate* isolate, int interval); |
| 34 virtual ~Sampler(); |
| 35 |
| 36 Isolate* isolate() const { return isolate_; } |
| 37 int interval() const { return interval_; } |
| 38 |
| 39 // Performs stack sampling. |
| 40 void SampleStack(const v8::RegisterState& regs); |
| 41 |
| 42 // Start and stop sampler. |
| 43 void Start(); |
| 44 void Stop(); |
| 45 |
| 46 // Whether the sampling thread should use this Sampler for CPU profiling? |
| 47 bool IsProfiling() const { |
| 48 return base::NoBarrier_Load(&profiling_) > 0 && |
| 49 !base::NoBarrier_Load(&has_processing_thread_); |
| 50 } |
| 51 void IncreaseProfilingDepth(); |
| 52 void DecreaseProfilingDepth(); |
| 53 |
| 54 // Whether the sampler is running (that is, consumes resources). |
| 55 bool IsActive() const { return base::NoBarrier_Load(&active_); } |
| 56 |
| 57 // CpuProfiler collects samples by calling DoSample directly |
| 58 // without calling Start. To keep it working, we register the sampler |
| 59 // with the CpuProfiler. |
| 60 bool IsRegistered() const { return base::NoBarrier_Load(®istered_); } |
| 61 |
| 62 void DoSample(); |
| 63 // If true next sample must be initiated on the profiler event processor |
| 64 // thread right after latest sample is processed. |
| 65 void SetHasProcessingThread(bool value) { |
| 66 base::NoBarrier_Store(&has_processing_thread_, value); |
| 67 } |
| 68 |
| 69 // Used in tests to make sure that stack sampling is performed. |
| 70 unsigned js_sample_count() const { return js_sample_count_; } |
| 71 unsigned external_sample_count() const { return external_sample_count_; } |
| 72 void StartCountingSamples() { |
| 73 js_sample_count_ = 0; |
| 74 external_sample_count_ = 0; |
| 75 is_counting_samples_ = true; |
| 76 } |
| 77 |
| 78 class PlatformData; |
| 79 PlatformData* platform_data() const { return data_; } |
| 80 |
| 81 protected: |
| 82 // This method is called for each sampling period with the current |
| 83 // program counter. |
| 84 virtual void Tick(TickSample* sample) = 0; |
| 85 |
| 86 private: |
| 87 void SetActive(bool value) { base::NoBarrier_Store(&active_, value); } |
| 88 |
| 89 void SetRegistered(bool value) { base::NoBarrier_Store(®istered_, value); } |
| 90 |
| 91 Isolate* isolate_; |
| 92 const int interval_; |
| 93 base::Atomic32 profiling_; |
| 94 base::Atomic32 has_processing_thread_; |
| 95 base::Atomic32 active_; |
| 96 base::Atomic32 registered_; |
| 97 PlatformData* data_; // Platform specific data. |
| 98 // Counts stack samples taken in various VM states. |
| 99 bool is_counting_samples_; |
| 100 unsigned js_sample_count_; |
| 101 unsigned external_sample_count_; |
| 102 DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler); |
| 103 }; |
| 104 |
| 105 } // namespace internal |
| 106 } // namespace v8 |
| 107 |
| 108 #endif // V8_PROFILER_SAMPLER_H_ |
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