Replacing circular queue by single buffer in CPU Profiler.

src/platform-linux.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 994 matching lines @@
     return;
   }
   if (v8::Locker::IsActive() &&
       !isolate->thread_manager()->IsLockedByCurrentThread()) {
     return;
   }
 
   Sampler* sampler = isolate->logger()->sampler();
   if (sampler == NULL || !sampler->IsActive()) return;
 
-  TickSample sample_obj;
-  TickSample* sample = CpuProfiler::TickSampleEvent(isolate);
-  if (sample == NULL) sample = &sample_obj;
+  TickSample* sample = CpuProfiler::StartTickSampleEvent(isolate);
+  if (sample == NULL) return;
 
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
   mcontext_t& mcontext = ucontext->uc_mcontext;
   sample->state = isolate->current_vm_state();
 #if V8_HOST_ARCH_IA32
   sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_EIP]);
   sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_ESP]);
   sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_EBP]);
 #elif V8_HOST_ARCH_X64
@@ skipping 14 matching lines @@
   sample->fp = reinterpret_cast<Address>(mcontext.arm_fp);
 #endif  // defined(__GLIBC__) && !defined(__UCLIBC__) &&
         // (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3))
 #elif V8_HOST_ARCH_MIPS
   sample->pc = reinterpret_cast<Address>(mcontext.pc);
   sample->sp = reinterpret_cast<Address>(mcontext.gregs[29]);
   sample->fp = reinterpret_cast<Address>(mcontext.gregs[30]);
 #endif  // V8_HOST_ARCH_*
   sampler->SampleStack(sample);
   sampler->Tick(sample);
+  CpuProfiler::FinishTickSampleEvent(isolate);
 }
 
 
 class CpuProfilerSignalHandler {
  public:
   static void SetUp() { if (!mutex_) mutex_ = OS::CreateMutex(); }
   static void TearDown() { delete mutex_; }
 
   static void InstallSignalHandler() {
     struct sigaction sa;
@@ skipping 222 matching lines @@
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   CpuProfilerSignalHandler::RestoreSignalHandler();
   SignalSender::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal