Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 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/platform/time.h" |
| 12 | #include "src/frames.h" |
| 13 | #include "src/globals.h" |
| 14 | |
| 15 | namespace v8 { |
| 16 | namespace internal { |
| 17 | |
| 18 | class Isolate; |
| 19 | |
| 20 | // ---------------------------------------------------------------------------- |
| 21 | // Sampler |
| 22 | // |
| 23 | // A sampler periodically samples the state of the VM and optionally |
| 24 | // (if used for profiling) the program counter and stack pointer for |
| 25 | // the thread that created it. |
| 26 | |
| 27 | // TickSample captures the information collected for each sample. |
| 28 | struct TickSample { |
| 29 | // Internal profiling (with --prof + tools/$OS-tick-processor) wants to |
| 30 | // include the runtime function we're calling. Externally exposed tick |
| 31 | // samples don't care. |
| 32 | enum RecordCEntryFrame { kIncludeCEntryFrame, kSkipCEntryFrame }; |
| 33 | |
| 34 | TickSample() |
| 35 | : state(OTHER), |
| 36 | pc(NULL), |
| 37 | external_callback(NULL), |
| 38 | frames_count(0), |
| 39 | has_external_callback(false), |
| 40 | top_frame_type(StackFrame::NONE) {} |
| 41 | void Init(Isolate* isolate, const v8::RegisterState& state, |
| 42 | RecordCEntryFrame record_c_entry_frame); |
| 43 | static void GetStackSample(Isolate* isolate, const v8::RegisterState& state, |
| 44 | RecordCEntryFrame record_c_entry_frame, |
| 45 | void** frames, size_t frames_limit, |
| 46 | v8::SampleInfo* sample_info); |
| 47 | StateTag state; // The state of the VM. |
| 48 | Address pc; // Instruction pointer. |
| 49 | union { |
| 50 | Address tos; // Top stack value (*sp). |
| 51 | Address external_callback; |
| 52 | }; |
| 53 | static const unsigned kMaxFramesCountLog2 = 8; |
| 54 | static const unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1; |
| 55 | Address stack[kMaxFramesCount]; // Call stack. |
| 56 | base::TimeTicks timestamp; |
| 57 | unsigned frames_count : kMaxFramesCountLog2; // Number of captured frames. |
| 58 | bool has_external_callback : 1; |
| 59 | StackFrame::Type top_frame_type : 4; |
| 60 | }; |
| 61 | |
| 62 | class Sampler { |
| 63 | public: |
| 64 | // Initializes the Sampler support. Called once at VM startup. |
| 65 | static void SetUp(); |
| 66 | static void TearDown(); |
| 67 | |
| 68 | // Initialize sampler. |
| 69 | Sampler(Isolate* isolate, int interval); |
| 70 | virtual ~Sampler(); |
| 71 | |
| 72 | Isolate* isolate() const { return isolate_; } |
| 73 | int interval() const { return interval_; } |
| 74 | |
| 75 | // Performs stack sampling. |
| 76 | void SampleStack(const v8::RegisterState& regs); |
| 77 | |
| 78 | // Start and stop sampler. |
| 79 | void Start(); |
| 80 | void Stop(); |
| 81 | |
| 82 | // Whether the sampling thread should use this Sampler for CPU profiling? |
| 83 | bool IsProfiling() const { |
| 84 | return base::NoBarrier_Load(&profiling_) > 0 && |
| 85 | !base::NoBarrier_Load(&has_processing_thread_); |
| 86 | } |
| 87 | void IncreaseProfilingDepth(); |
| 88 | void DecreaseProfilingDepth(); |
| 89 | |
| 90 | // Whether the sampler is running (that is, consumes resources). |
| 91 | bool IsActive() const { return base::NoBarrier_Load(&active_); } |
| 92 | |
| 93 | void DoSample(); |
| 94 | // If true next sample must be initiated on the profiler event processor |
| 95 | // thread right after latest sample is processed. |
| 96 | void SetHasProcessingThread(bool value) { |
| 97 | base::NoBarrier_Store(&has_processing_thread_, value); |
| 98 | } |
| 99 | |
| 100 | // Used in tests to make sure that stack sampling is performed. |
| 101 | unsigned js_and_external_sample_count() const { |
| 102 | return js_and_external_sample_count_; |
| 103 | } |
| 104 | void StartCountingSamples() { |
| 105 | is_counting_samples_ = true; |
| 106 | js_and_external_sample_count_ = 0; |
| 107 | } |
| 108 | |
| 109 | class PlatformData; |
| 110 | PlatformData* platform_data() const { return data_; } |
| 111 | |
| 112 | protected: |
| 113 | // This method is called for each sampling period with the current |
| 114 | // program counter. |
| 115 | virtual void Tick(TickSample* sample) = 0; |
| 116 | |
| 117 | private: |
| 118 | void SetActive(bool value) { base::NoBarrier_Store(&active_, value); } |
| 119 | |
| 120 | Isolate* isolate_; |
| 121 | const int interval_; |
| 122 | base::Atomic32 profiling_; |
| 123 | base::Atomic32 has_processing_thread_; |
| 124 | base::Atomic32 active_; |
| 125 | PlatformData* data_; // Platform specific data. |
| 126 | bool is_counting_samples_; |
| 127 | // Counts stack samples taken in JS VM state. |
| 128 | unsigned js_and_external_sample_count_; |
| 129 | DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler); |
| 130 | }; |
| 131 | |
| 132 | |
| 133 | } // namespace internal |
| 134 | } // namespace v8 |
| 135 | |
| 136 | #endif // V8_PROFILER_SAMPLER_H_ |