Add trace code to track all posted tasks in message_loop.

base/tracked.h

 // Copyright (c) 2011 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_
 #pragma once
 
 #include <string>
 
 #include "base/base_export.h"
+#include "base/string_piece.h"
+#include "base/stringize_macros.h"
 #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 BASE_EXPORT 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,
+  // Constructor should be called with a long-lived char*. It assumes the
+  // provided value will persist as a global constant, and it will not make a
+  // copy of it.
+  // |file_line| is formatted as "FILE:LINE".
+  Location(const char* file_line,
+           const char* function_name,
            const void* program_counter);
 
-  // Provide a default constructor for easy of debugging.
+  // Default constructor initializes to "Unknown:-1", "Unknown", NULL.
   Location();
 
   // 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_;
+    if (file_line_ != other.file_line_)
+      return file_line_ < other.file_line_;
     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_; }
+  // Get long-lived file_line string "FILE:LINE".
+  const char* file_line() const { return file_line_; }
+  const base::StringPiece file_name() const;
+  int line_number() const;
+  const base::StringPiece function_name() const;
   const void* program_counter() const { return program_counter_; }
 
   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_;
-  const void* const program_counter_;
+  const char* file_line_;
+  const char* function_name_;
+  const void* program_counter_;
 };
 
 BASE_EXPORT const void* GetProgramCounter();
 
 //------------------------------------------------------------------------------
 // Define a macro to record the current source location.
 
-#define FROM_HERE tracked_objects::Location(                                   \
-    __FUNCTION__,                                                              \
-    __FILE__,                                                                  \
-    __LINE__,                                                                  \
-    tracked_objects::GetProgramCounter())                                      \
+#define FROM_HERE tracked_objects::Location( \
+    __FILE__ ":" STRINGIZE(__LINE__), __FUNCTION__, \

[joth, 2011/09/15 10:38:09]

random musing:
if we passed in (sizeof(__FILE__) + sizeof( STRINGIZE(__LINE__) - 1) as an
additional param here, we'll get it as a compile time constant, and then we
could store file_line_ as a string piece with a compile-time generated length,
meaning we never need to run it searching for the null-term in the file_name()
and line_number() methods. 
which in turn brings them nearer to the hacker_style() requirement of being mere
getters; at the moment they feel rather like they should be FileName() style
methods.

[jar (doing other things), 2011/09/15 16:26:39]

I think that sizeof(__FILE__) == sizeof(char*)

I don't think you get what you're hoping for.  You may perchance be thinking
about:

static array[] = __FILE__;
then sizeof(array) == strlen(array) I think.

On 2011/09/15 10:38:09, joth wrote:

[jbates, 2011/09/15 16:48:33]

I think it's best to just change to FileName style - there are no performance
critical usecases for file_name.

+    tracked_objects::GetProgramCounter())
 
 
 //------------------------------------------------------------------------------
 
 
 class Births;
 
 class BASE_EXPORT Tracked {
  public:
   Tracked();
@@ skipping 35 matching lines @@
 #endif  // defined(TRACK_ALL_TASK_OBJECTS)
 
   const void* birth_program_counter_;
 
   DISALLOW_COPY_AND_ASSIGN(Tracked);
 };
 
 }  // namespace tracked_objects
 
 #endif  // BASE_TRACKED_H_