Do not start sampler thread when CpuProfiler is active

src/cpu-profiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 121 matching lines @@
       // All ticks of the current dequeue_order are processed,
       // proceed to the next code event.
       ProcessCodeEvent();
     }
   }
   // Schedule next sample. sampler_ is NULL in tests.
   if (sampler_) sampler_->DoSample();
 }
 
 
-void ProfilerEventsProcessor::ProcessEventsAndYield() {
-  // Process ticks until we have any.
-  if (ProcessTicks()) {
-    // All ticks of the current dequeue_order are processed,
-    // proceed to the next code event.
-    ProcessCodeEvent();
-  }
-  YieldCPU();
-}
-
-
 void ProfilerEventsProcessor::Run() {
   while (running_) {
-    if (Sampler::CanSampleOnProfilerEventsProcessorThread()) {
-      ProcessEventsAndDoSample();
-    } else {
-      ProcessEventsAndYield();
-    }
+    ProcessEventsAndDoSample();
   }
 
   // Process remaining tick events.
   do {
     ProcessTicks();
   } while (ProcessCodeEvent());
 }
 
 
 int CpuProfiler::GetProfilesCount() {
@@ skipping 205 matching lines @@
   processor_->Enqueue(evt_rec);
 }
 
 
 CpuProfiler::CpuProfiler(Isolate* isolate)
     : isolate_(isolate),
       profiles_(new CpuProfilesCollection()),
       next_profile_uid_(1),
       generator_(NULL),
       processor_(NULL),
-      need_to_stop_sampler_(false),
       is_profiling_(false) {
 }
 
 
 CpuProfiler::CpuProfiler(Isolate* isolate,
                          CpuProfilesCollection* test_profiles,
                          ProfileGenerator* test_generator,
                          ProfilerEventsProcessor* test_processor)
     : isolate_(isolate),
       profiles_(test_profiles),
       next_profile_uid_(1),
       generator_(test_generator),
       processor_(test_processor),
-      need_to_stop_sampler_(false),
       is_profiling_(false) {
 }
 
 
 CpuProfiler::~CpuProfiler() {
   ASSERT(!is_profiling_);
   delete profiles_;
 }
 
 
@@ skipping 30 matching lines @@
     is_profiling_ = true;
     // Enumerate stuff we already have in the heap.
     ASSERT(isolate_->heap()->HasBeenSetUp());
     if (!FLAG_prof_browser_mode) {
       logger->LogCodeObjects();
     }
     logger->LogCompiledFunctions();
     logger->LogAccessorCallbacks();
     LogBuiltins();
     // Enable stack sampling.
-    if (Sampler::CanSampleOnProfilerEventsProcessorThread()) {
-      sampler->SetHasProcessingThread(true);
-    }
+    sampler->SetHasProcessingThread(true);
     sampler->IncreaseProfilingDepth();
-    if (!sampler->IsActive()) {
-      sampler->Start();
-      need_to_stop_sampler_ = true;
-    }
     processor_->StartSynchronously();
   }
 }
 
 
 CpuProfile* CpuProfiler::StopProfiling(const char* title) {
   if (!is_profiling_) return NULL;
   StopProcessorIfLastProfile(title);
   CpuProfile* result = profiles_->StopProfiling(title);
   if (result != NULL) {
@@ skipping 12 matching lines @@
 
 
 void CpuProfiler::StopProcessorIfLastProfile(const char* title) {
   if (profiles_->IsLastProfile(title)) StopProcessor();
 }
 
 
 void CpuProfiler::StopProcessor() {
   Logger* logger = isolate_->logger();
   Sampler* sampler = reinterpret_cast<Sampler*>(logger->ticker_);
-  sampler->DecreaseProfilingDepth();
   is_profiling_ = false;
   processor_->StopSynchronously();
   delete processor_;
   delete generator_;
   processor_ = NULL;
   generator_ = NULL;
-  if (Sampler::CanSampleOnProfilerEventsProcessorThread()) {
-    sampler->SetHasProcessingThread(false);
-  }
-  if (need_to_stop_sampler_) {
-    sampler->Stop();
-    need_to_stop_sampler_ = false;
-  }
+  sampler->SetHasProcessingThread(false);
+  sampler->DecreaseProfilingDepth();
   logger->is_logging_ = saved_is_logging_;
 }
 
 
 void CpuProfiler::LogBuiltins() {
   Builtins* builtins = isolate_->builtins();
   ASSERT(builtins->is_initialized());
   for (int i = 0; i < Builtins::builtin_count; i++) {
     CodeEventsContainer evt_rec(CodeEventRecord::REPORT_BUILTIN);
     ReportBuiltinEventRecord* rec = &evt_rec.ReportBuiltinEventRecord_;
     Builtins::Name id = static_cast<Builtins::Name>(i);
     rec->start = builtins->builtin(id)->address();
     rec->builtin_id = id;
     processor_->Enqueue(evt_rec);
   }
 }
 
 
 } }  // namespace v8::internal