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 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 //------------------------------------------------------------------------------

 // Tracked is the base class for all tracked objects.  During construction, it

 // registers the fact that an instance was created, and at destruction time, it

 // records that event.  The instance may be tagged with a name, which is refered

 // to as its Location.  The Location is a file and line number, most

 // typically indicated where the object was constructed.  In some cases, as the

 // object's significance is refined (for example, a Task object is augmented to

 // do additonal things), its Location may be redefined to that later location.

 // Tracking includes (for each instance) recording the birth thread, death

 // thread, and duration of life (from construction to destruction).  All this

 // data is accumulated and filtered for review at about:objects.

 #ifndef BASE_TRACKED_H_

 #define BASE_TRACKED_H_

 #include <string>

 #include "base/time.h"

 #ifndef NDEBUG

 #ifndef TRACK_ALL_TASK_OBJECTS

 #define TRACK_ALL_TASK_OBJECTS

 #endif   // TRACK_ALL_TASK_OBJECTS

 #endif  // NDEBUG

 namespace tracked_objects {

 //------------------------------------------------------------------------------

 // Location provides basic info where of an object was constructed, or was

 // significantly brought to life.

 class Location {

  public:

   // Constructor should be called with a long-lived char*, such as __FILE__.

   // It assumes the provided value will persist as a global constant, and it

   // will not make a copy of it.

   Location(const char* function_name, const char* file_name, int line_number)

       : function_name_(function_name),

         file_name_(file_name),

         line_number_(line_number) { }

   // Provide a default constructor for easy of debugging.

   Location()

       : function_name_("Unknown"),

         file_name_("Unknown"),

         line_number_(-1) { }

   // Comparison operator for insertion into a std::map<> hash tables.

   // All we need is *some* (any) hashing distinction.  Strings should already

   // be unique, so we don't bother with strcmp or such.

   // Use line number as the primary key (because it is fast, and usually gets us

   // a difference), and then pointers as secondary keys (just to get some

   // distinctions).

   bool operator < (const Location& other) const {

     if (line_number_ != other.line_number_)

       return line_number_ < other.line_number_;

     if (file_name_ != other.file_name_)

       return file_name_ < other.file_name_;

     return function_name_ < other.function_name_;

   }

   const char* function_name() const { return function_name_; }

   const char* file_name()     const { return file_name_; }

   int line_number()           const { return line_number_; }

   void Write(bool display_filename, bool display_function_name,

              std::string* output) const;

   // Write function_name_ in HTML with '<' and '>' properly encoded.

   void WriteFunctionName(std::string* output) const;

  private:

   const char* const function_name_;

   const char* const file_name_;

   const int line_number_;

 };

 //------------------------------------------------------------------------------

 // Define a macro to record the current source location.

 #define FROM_HERE tracked_objects::Location(__FUNCTION__, __FILE__, __LINE__)

 //------------------------------------------------------------------------------

 class Births;

 class Tracked {

  public:

   Tracked();

   virtual ~Tracked();

   // Used to record the FROM_HERE location of a caller.

   void SetBirthPlace(const Location& from_here);

   // When a task sits around a long time, such as in a timer, or object watcher,

   // this method should be called when the task becomes active, and its

   // significant lifetime begins (and its waiting to be woken up has passed).

   void ResetBirthTime();

   bool MissingBirthplace() const;

  private:

 #ifdef TRACK_ALL_TASK_OBJECTS

   // Pointer to instance were counts of objects with the same birth location

   // (on the same thread) are stored.

   Births* tracked_births_;

   // The time this object was constructed.  If its life consisted of a long

   // waiting period, and then it became active, then this value is generally

   // reset before the object begins it active life.

   base::Time tracked_birth_time_;

 #endif  // TRACK_ALL_TASK_OBJECTS

   DISALLOW_COPY_AND_ASSIGN(Tracked);

 };

 }  // namespace tracked_objects

 #endif  // BASE_TRACKED_H_