Create libsampler as V8 sampler library.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index 8ec267a61003cf4e158b2ba9b5976bd68d0ccbee..859c51121ac6266a54c945b10e744b996d358334 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -15,11 +15,12 @@
 #include "src/global-handles.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/interpreter/interpreter.h"
+#include "src/libsampler/v8-sampler.h"
 #include "src/log-inl.h"
 #include "src/log-utils.h"
 #include "src/macro-assembler.h"
 #include "src/perf-jit.h"
-#include "src/profiler/cpu-profiler.h"
+#include "src/profiler/cpu-profiler-inl.h"
 #include "src/runtime-profiler.h"
 #include "src/string-stream.h"
 #include "src/vm-state-inl.h"
@@ -539,6 +540,31 @@ void JitLogger::EndCodePosInfoEvent(AbstractCode* code,
 }
 
 
+// TODO(lpy): Keeping sampling thread inside V8 is a workaround currently,
+// the reason is to reduce code duplication during migration to sampler library,
+// sampling thread, as well as the sampler, will be moved to D8 eventually.
+class SamplingThread : public base::Thread {
+ public:
+  static const int kSamplingThreadStackSize = 64 * KB;
+
+  SamplingThread(sampler::Sampler* sampler, int interval)
+      : base::Thread(base::Thread::Options("SamplingThread",
+                                           kSamplingThreadStackSize)),
+        sampler_(sampler),
+        interval_(interval) {}
+  void Run() override {
+    while (sampler_->IsProfiling()) {
+      sampler_->DoSample();
+      base::OS::Sleep(base::TimeDelta::FromMilliseconds(interval_));
+    }
+  }
+
+ private:
+  sampler::Sampler* sampler_;
+  const int interval_;
+};
+
+
 // The Profiler samples pc and sp values for the main thread.
 // Each sample is appended to a circular buffer.
 // An independent thread removes data and writes it to the log.
@@ -611,16 +637,16 @@ class Profiler: public base::Thread {
 // Ticker used to provide ticks to the profiler and the sliding state
 // window.
 //
-class Ticker: public Sampler {
+class Ticker: public sampler::Sampler {
  public:
   Ticker(Isolate* isolate, int interval):
-      Sampler(isolate, interval),
-      profiler_(NULL) {}
-
-  ~Ticker() { if (IsActive()) Stop(); }
+      sampler::Sampler(reinterpret_cast<v8::Isolate*>(isolate)),
+      profiler_(NULL),
+      sampling_thread_(new SamplingThread(this, interval)) {}
 
-  virtual void Tick(TickSample* sample) {
-    if (profiler_) profiler_->Insert(sample);
+  ~Ticker() {
+    if (IsActive()) Stop();
+    delete sampling_thread_;
   }
 
   void SetProfiler(Profiler* profiler) {
@@ -628,16 +654,40 @@ class Ticker: public Sampler {
     profiler_ = profiler;
     IncreaseProfilingDepth();
     if (!IsActive()) Start();
+    sampling_thread_->StartSynchronously();
   }
 
   void ClearProfiler() {
     profiler_ = NULL;
     if (IsActive()) Stop();
     DecreaseProfilingDepth();
+    sampling_thread_->Join();
+  }
+
+  void SampleStack(const v8::RegisterState& state) override {
+    v8::Isolate* v8_isolate = isolate();
+    Isolate* isolate = reinterpret_cast<Isolate*>(v8_isolate);
+#if defined(USE_SIMULATOR)
+    SimulatorHelper::FillRegisters(isolate,
+                                   const_cast<v8::RegisterState*>(&state));
+#endif
+    TickSample* sample = isolate->cpu_profiler()->StartTickSample();
+    TickSample sample_obj;
+    if (sample == NULL) sample = &sample_obj;
+    sample->Init(isolate, state, TickSample::kIncludeCEntryFrame, true);
+    if (is_counting_samples_ && !sample->timestamp.IsNull()) {
+      if (sample->state == JS) ++js_sample_count_;
+      if (sample->state == EXTERNAL) ++external_sample_count_;
+    }
+    if (profiler_) profiler_->Insert(sample);
+    if (sample != &sample_obj) {
+      isolate->cpu_profiler()->FinishTickSample();
+    }
   }
 
  private:
   Profiler* profiler_;
+  SamplingThread* sampling_thread_;
 };
 
 
@@ -1810,7 +1860,7 @@ void Logger::SetCodeEventHandler(uint32_t options,
 }
 
 
-Sampler* Logger::sampler() {
+sampler::Sampler* Logger::sampler() {
   return ticker_;
 }