Replacing circular queue by single buffer in CPU Profiler.

src/cpu-profiler.h

 // 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 12 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_CPU_PROFILER_H_
 #define V8_CPU_PROFILER_H_
 
 #include "allocation.h"
 #include "atomicops.h"
-#include "circular-queue.h"
 #include "unbound-queue.h"
 
 namespace v8 {
 namespace internal {
 
 // Forward declarations.
 class CodeEntry;
 class CodeMap;
 class CpuProfile;
 class CpuProfilesCollection;
@@ skipping 105 matching lines @@
                        Address start, unsigned size);
   void CodeMoveEvent(Address from, Address to);
   void CodeDeleteEvent(Address from);
   void SharedFunctionInfoMoveEvent(Address from, Address to);
   void RegExpCodeCreateEvent(Logger::LogEventsAndTags tag,
                              const char* prefix, String* name,
                              Address start, unsigned size);
   // Puts current stack into tick sample events buffer.
   void AddCurrentStack();
 
-  // Tick sample events are filled directly in the buffer of the circular
-  // queue (because the structure is of fixed width, but usually not all
-  // stack frame entries are filled.) This method returns a pointer to the
-  // next record of the buffer.
-  INLINE(TickSample* TickSampleEvent());
+  // StartTickSampleEvent returns a pointer only if the ticks_buffer_ is empty,
+  // FinishTickSampleEvent marks the ticks_buffer_ as filled.
+  // Finish should be called only after successful Start (returning non-NULL pointer).

[Jakob Kummerow, 2012/09/04 11:25:18]

long line.
Also, can you put in an ASSERT that makes sure this rule is not violated?

+  INLINE(TickSample* StartTickSampleEvent());
+  INLINE(void FinishTickSampleEvent()) { ticks_buffer_is_empty_ = false; }
 
  private:
   union CodeEventsContainer {
     CodeEventRecord generic;
 #define DECLARE_CLASS(ignore, type) type type##_;
     CODE_EVENTS_TYPE_LIST(DECLARE_CLASS)
 #undef DECLARE_TYPE
   };
 
   // Called from events processing thread (Run() method.)
   bool ProcessCodeEvent(unsigned* dequeue_order);
-  bool ProcessTicks(int64_t stop_time, unsigned dequeue_order);
+  bool ProcessTicks(unsigned dequeue_order);
   void ProcessEventsQueue(int64_t stop_time, unsigned* dequeue_order);
 
   INLINE(static bool FilterOutCodeCreateEvent(Logger::LogEventsAndTags tag));
 
   ProfileGenerator* generator_;
   Sampler* sampler_;
   bool running_;
   // Sampling interval in microseconds.
   const int interval_in_useconds_;
   UnboundQueue<CodeEventsContainer> events_buffer_;
-  SamplingCircularQueue ticks_buffer_;
+  TickSampleEventRecord ticks_buffer_;
+  bool ticks_buffer_is_empty_;
   UnboundQueue<TickSampleEventRecord> ticks_from_vm_buffer_;
   unsigned enqueue_order_;
 };
 
 } }  // namespace v8::internal
 
 
 #define PROFILE(isolate, Call)                                \
   LOG(isolate, Call);                                         \
   do {                                                        \
@@ skipping 18 matching lines @@
   static CpuProfile* StopProfiling(const char* title);
   static CpuProfile* StopProfiling(Object* security_token, String* title);
   static int GetProfilesCount();
   static CpuProfile* GetProfile(Object* security_token, int index);
   static CpuProfile* FindProfile(Object* security_token, unsigned uid);
   static void DeleteAllProfiles();
   static void DeleteProfile(CpuProfile* profile);
   static bool HasDetachedProfiles();
 
   // Invoked from stack sampler (thread or signal handler.)
-  static TickSample* TickSampleEvent(Isolate* isolate);
+  // Finish should be called only after successful Start (returning non-NULL pointer).

[Jakob Kummerow, 2012/09/04 11:25:18]

long line

+  static TickSample* StartTickSampleEvent(Isolate* isolate);
+  static void FinishTickSampleEvent(Isolate* isolate);
 
   // Must be called via PROFILE macro, otherwise will crash when
   // profiling is not enabled.
   static void CallbackEvent(String* name, Address entry_point);
   static void CodeCreateEvent(Logger::LogEventsAndTags tag,
                               Code* code, const char* comment);
   static void CodeCreateEvent(Logger::LogEventsAndTags tag,
                               Code* code, String* name);
   static void CodeCreateEvent(Logger::LogEventsAndTags tag,
                               Code* code,
@@ skipping 42 matching lines @@
   Atomic32 is_profiling_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CpuProfiler);
 };
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_CPU_PROFILER_H_