1 // Copyright (c) 2011 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/base_api.h" 25 #include "base/time.h" 26 27 #ifndef NDEBUG 28 #ifndef TRACK_ALL_TASK_OBJECTS 29 #define TRACK_ALL_TASK_OBJECTS 30 #endif // TRACK_ALL_TASK_OBJECTS 31 #endif // NDEBUG 32 33 namespace tracked_objects { 34 35 //------------------------------------------------------------------------------ 36 // Location provides basic info where of an object was constructed, or was 37 // significantly brought to life. 38 39 class BASE_API Location { 40 public: 41 // Constructor should be called with a long-lived char*, such as __FILE__. 42 // It assumes the provided value will persist as a global constant, and it 43 // will not make a copy of it. 44 Location(const char* function_name, const char* file_name, int line_number); 45 46 // Provide a default constructor for easy of debugging. 47 Location(); 48 49 // Comparison operator for insertion into a std::map<> hash tables. 50 // All we need is *some* (any) hashing distinction. Strings should already 51 // be unique, so we don't bother with strcmp or such. 52 // Use line number as the primary key (because it is fast, and usually gets us 53 // a difference), and then pointers as secondary keys (just to get some 54 // distinctions). 55 bool operator < (const Location& other) const { 56 if (line_number_ != other.line_number_) 57 return line_number_ < other.line_number_; 58 if (file_name_ != other.file_name_) 59 return file_name_ < other.file_name_; 60 return function_name_ < other.function_name_; 61 } 62 63 const char* function_name() const { return function_name_; } 64 const char* file_name() const { return file_name_; } 65 int line_number() const { return line_number_; } 66 67 void Write(bool display_filename, bool display_function_name, 68 std::string* output) const; 69 70 // Write function_name_ in HTML with '<' and '>' properly encoded. 71 void WriteFunctionName(std::string* output) const; 72 73 private: 74 const char* const function_name_; 75 const char* const file_name_; 76 const int line_number_; 77 }; 78 79 80 //------------------------------------------------------------------------------ 81 // Define a macro to record the current source location. 82 83 #define FROM_HERE tracked_objects::Location(__FUNCTION__, __FILE__, __LINE__) 84 85 86 //------------------------------------------------------------------------------ 87 88 89 class Births; 90 91 class BASE_API Tracked { 92 public: 93 Tracked(); 94 virtual ~Tracked(); 95 96 // Used to record the FROM_HERE location of a caller. 97 void SetBirthPlace(const Location& from_here); 98 const Location GetBirthPlace() const; 99 100 // When a task sits around a long time, such as in a timer, or object watcher, 101 // this method should be called when the task becomes active, and its 102 // significant lifetime begins (and its waiting to be woken up has passed). 103 void ResetBirthTime(); 104 105 bool MissingBirthplace() const; 106 107 #if defined(TRACK_ALL_TASK_OBJECTS) 108 base::TimeTicks tracked_birth_time() const { return tracked_birth_time_; } 109 #else 110 base::TimeTicks tracked_birth_time() const { return base::TimeTicks::Now(); } 111 #endif // defined(TRACK_ALL_TASK_OBJECTS) 112 113 private: 114 #if defined(TRACK_ALL_TASK_OBJECTS) 115 116 // Pointer to instance were counts of objects with the same birth location 117 // (on the same thread) are stored. 118 Births* tracked_births_; 119 // The time this object was constructed. If its life consisted of a long 120 // waiting period, and then it became active, then this value is generally 121 // reset before the object begins it active life. 122 base::TimeTicks tracked_birth_time_; 123 124 #endif // defined(TRACK_ALL_TASK_OBJECTS) 125 126 DISALLOW_COPY_AND_ASSIGN(Tracked); 127 }; 128 129 } // namespace tracked_objects 130 131 #endif // BASE_TRACKED_H_ 132
