Involve more log compression techniques.

src/log.h

 // Copyright 2006-2008 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 53 matching lines @@
 // --prof
 // Collect statistical profiling information (ticks), default is off.  The
 // tick profiler requires code events, so --prof implies --log-code.
 
 // Forward declarations.
 class Ticker;
 class Profiler;
 class Semaphore;
 class SlidingStateWindow;
 class LogMessageBuilder;
+class CompressionHelper;
 
 #undef LOG
 #ifdef ENABLE_LOGGING_AND_PROFILING
 #define LOG(Call)                           \
   do {                                      \
     if (v8::internal::Logger::IsEnabled()) \
       v8::internal::Logger::Call;           \
   } while (false)
 #else
 #define LOG(Call) ((void) 0)
@@ skipping 165 matching lines @@
   static int GetLogLines(int from_pos, char* dest_buf, int max_size);
 
   // Logs all compiled functions found in the heap.
   static void LogCompiledFunctions();
 
  private:
 
   // Profiler's sampling interval (in milliseconds).
   static const int kSamplingIntervalMs = 1;
 
+  // Size of window used for log records compression.
+  static const int kCompressionWindowSize = 4;
+
   // Emits the profiler's first message.
   static void ProfilerBeginEvent();
 
   // Emits aliases for compressed messages.
   static void LogAliases();
 
   // Emits the source code of a regexp. Used by regexp events.
   static void LogRegExpSource(Handle<JSRegExp> regexp);
 
   // Emits a profiler tick event. Used by the profiler thread.
@@ skipping 24 matching lines @@
   // Singleton bottom or default vm state.
   static VMState bottom_state_;
 
   // SlidingStateWindow instance keeping a sliding window of the most
   // recent VM states.
   static SlidingStateWindow* sliding_state_window_;
 
   // An array of log events names.
   static const char** log_events_;
 
-  // Counter for repeated tick events.
-  static int tick_repeat_count_;
+  // An instance of helper created if log compression is enabled.
+  static CompressionHelper* compression_helper_;
 
   // Internal implementation classes with access to
   // private members.
+  friend class CompressionHelper;
   friend class EventLog;
   friend class TimeLog;
   friend class Profiler;
   friend class SlidingStateWindow;
   friend class VMState;
 
   friend class LoggerTestHelper;
 #else
   static bool is_enabled() { return false; }
 #endif
 };
 
 
 // Class that extracts stack trace, used for profiling.
 class StackTracer : public AllStatic {
  public:
   static void Trace(TickSample* sample);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOG_H_