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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_
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