tracked.h revision 513209b27ff55e2841eac0e4120199c23acce758 
1// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//------------------------------------------------------------------------------
6// Tracked is the base class for all tracked objects.  During construction, it
7// registers the fact that an instance was created, and at destruction time, it
8// records that event.  The instance may be tagged with a name, which is refered
9// to as its Location.  The Location is a file and line number, most
10// typically indicated where the object was constructed.  In some cases, as the
11// object's significance is refined (for example, a Task object is augmented to
12// do additonal things), its Location may be redefined to that later location.
13
14// Tracking includes (for each instance) recording the birth thread, death
15// thread, and duration of life (from construction to destruction).  All this
16// data is accumulated and filtered for review at about:objects.
17
18#ifndef BASE_TRACKED_H_
19#define BASE_TRACKED_H_
20#pragma once
21
22#include <string>
23
24#include "base/time.h"
25
26#ifndef NDEBUG
27#ifndef TRACK_ALL_TASK_OBJECTS
28#define TRACK_ALL_TASK_OBJECTS
29#endif   // TRACK_ALL_TASK_OBJECTS
30#endif  // NDEBUG
31
32namespace tracked_objects {
33
34//------------------------------------------------------------------------------
35// Location provides basic info where of an object was constructed, or was
36// significantly brought to life.
37
38class Location {
39 public:
40  // Constructor should be called with a long-lived char*, such as __FILE__.
41  // It assumes the provided value will persist as a global constant, and it
42  // will not make a copy of it.
43  Location(const char* function_name, const char* file_name, int line_number);
44
45  // Provide a default constructor for easy of debugging.
46  Location();
47
48  // Comparison operator for insertion into a std::map<> hash tables.
49  // All we need is *some* (any) hashing distinction.  Strings should already
50  // be unique, so we don't bother with strcmp or such.
51  // Use line number as the primary key (because it is fast, and usually gets us
52  // a difference), and then pointers as secondary keys (just to get some
53  // distinctions).
54  bool operator < (const Location& other) const {
55    if (line_number_ != other.line_number_)
56      return line_number_ < other.line_number_;
57    if (file_name_ != other.file_name_)
58      return file_name_ < other.file_name_;
59    return function_name_ < other.function_name_;
60  }
61
62  const char* function_name() const { return function_name_; }
63  const char* file_name()     const { return file_name_; }
64  int line_number()           const { return line_number_; }
65
66  void Write(bool display_filename, bool display_function_name,
67             std::string* output) const;
68
69  // Write function_name_ in HTML with '<' and '>' properly encoded.
70  void WriteFunctionName(std::string* output) const;
71
72 private:
73  const char* const function_name_;
74  const char* const file_name_;
75  const int line_number_;
76};
77
78
79//------------------------------------------------------------------------------
80// Define a macro to record the current source location.
81
82#define FROM_HERE tracked_objects::Location(__FUNCTION__, __FILE__, __LINE__)
83
84
85//------------------------------------------------------------------------------
86
87
88class Births;
89
90class Tracked {
91 public:
92  Tracked();
93  virtual ~Tracked();
94
95  // Used to record the FROM_HERE location of a caller.
96  void SetBirthPlace(const Location& from_here);
97  const Location GetBirthPlace() const;
98
99  // When a task sits around a long time, such as in a timer, or object watcher,
100  // this method should be called when the task becomes active, and its
101  // significant lifetime begins (and its waiting to be woken up has passed).
102  void ResetBirthTime();
103
104  bool MissingBirthplace() const;
105
106#if defined(TRACK_ALL_TASK_OBJECTS)
107  base::TimeTicks tracked_birth_time() const { return tracked_birth_time_; }
108#else
109  base::TimeTicks tracked_birth_time() const { return base::TimeTicks::Now(); }
110#endif  // defined(TRACK_ALL_TASK_OBJECTS)
111
112 private:
113#if defined(TRACK_ALL_TASK_OBJECTS)
114
115  // Pointer to instance were counts of objects with the same birth location
116  // (on the same thread) are stored.
117  Births* tracked_births_;
118  // The time this object was constructed.  If its life consisted of a long
119  // waiting period, and then it became active, then this value is generally
120  // reset before the object begins it active life.
121  base::TimeTicks tracked_birth_time_;
122
123#endif  // defined(TRACK_ALL_TASK_OBJECTS)
124
125  DISALLOW_COPY_AND_ASSIGN(Tracked);
126};
127
128}  // namespace tracked_objects
129
130#endif  // BASE_TRACKED_H_
131