Replacing circular queue by single buffer in CPU Profiler.

src/platform-freebsd.cc

Index: src/platform-freebsd.cc
diff --git a/src/platform-freebsd.cc b/src/platform-freebsd.cc
index 87c252c2d1d8c0401bbc17ed6ba3fb30ced8cabb..6d1bccda99fc999ccddfaafdf974e93ddde4264e 100644
--- a/src/platform-freebsd.cc
+++ b/src/platform-freebsd.cc
@@ -678,9 +678,8 @@ static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
   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);
@@ -701,6 +700,7 @@ static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
 #endif
   sampler->SampleStack(sample);
   sampler->Tick(sample);
+  CpuProfiler::FinishTickSampleEvent(isolate);
 }