Record Chrome trace events in tcmalloc heap profiles

base/debug/trace_event.h

 // Copyright (c) 2012 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.
 
 // This header file defines the set of trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // events to some other universe, you can copy-and-paste this file as well as
 // trace_event.h, modifying the macros contained there as necessary for the
 // target platform. The end result is that multiple libraries can funnel events
 // through to a shared trace event collector.
@@ skipping 175 matching lines @@
 // trace points would carry a significant performance cost of aquiring a lock
 // and resolving the category.
 
 #ifndef BASE_DEBUG_TRACE_EVENT_H_
 #define BASE_DEBUG_TRACE_EVENT_H_
 
 #include <string>
 
 #include "base/atomicops.h"
 #include "base/debug/trace_event_impl.h"
+#include "base/debug/trace_event_memory.h"
 #include "build/build_config.h"
 
 // By default, const char* argument values are assumed to have long-lived scope
 // and will not be copied. Use this macro to force a const char* to be copied.
 #define TRACE_STR_COPY(str) \
     trace_event_internal::TraceStringWithCopy(str)
 
 // This will mark the trace event as disabled by default. The user will need
 // to explicitly enable the event.
 #define TRACE_DISABLED_BY_DEFAULT(name) "disabled-by-default-" name
 
 // By default, uint64 ID argument values are not mangled with the Process ID in
 // TRACE_EVENT_ASYNC macros. Use this macro to force Process ID mangling.
 #define TRACE_ID_MANGLE(id) \
     trace_event_internal::TraceID::ForceMangle(id)
 
 // By default, pointers are mangled with the Process ID in TRACE_EVENT_ASYNC
 // macros. Use this macro to prevent Process ID mangling.
 #define TRACE_ID_DONT_MANGLE(id) \
     trace_event_internal::TraceID::DontMangle(id)
 
 // Records a pair of begin and end events called "name" for the current
 // scope, with 0, 1 or 2 associated arguments. If the category is not
 // enabled, then this does nothing.
 // - category and name strings must have application lifetime (statics or
 //   literals). They may not include " chars.
 #define TRACE_EVENT0(category_group, name) \
+    INTERNAL_TRACE_MEMORY(category_group, name) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name)
 #define TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
+    INTERNAL_TRACE_MEMORY(category_group, name) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val)
-#define TRACE_EVENT2(category_group, name, arg1_name, arg1_val, arg2_name, \
-                     arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
+#define TRACE_EVENT2( \
+    category_group, name, arg1_name, arg1_val, arg2_name, arg2_val) \
+  INTERNAL_TRACE_MEMORY(category_group, name) \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED( \
+      category_group, name, arg1_name, arg1_val, arg2_name, arg2_val)
 
 // UNSHIPPED_TRACE_EVENT* are like TRACE_EVENT* except that they are not
 // included in official builds.
 
 #if OFFICIAL_BUILD
 #undef TRACING_IS_OFFICIAL_BUILD
 #define TRACING_IS_OFFICIAL_BUILD 1
 #elif !defined(TRACING_IS_OFFICIAL_BUILD)
 #define TRACING_IS_OFFICIAL_BUILD 0

[jar (doing other things), 2013/07/13 00:51:08]

I wish I could find a standard style.... but I couldn't :-(

IMO, this should read:
#undef TRACING_IS_OFFICIAL_BUILD

The big question is, should we test via:
#if defined(TRACING_IS_OFFICIAL)
or via
#if TRACING_IS_OFFICIAL

If you use the undef, then both tests will work "as expected."  If you use the
define of 0, then one will work, and will will be consistently wrong :-(.

There should be a style standard, and I can <sadly> see this is confusing others
(I went searching for conflicting code).  

Take for instance:
https://code.google.com/p/chromium/codesearch#chromium/src/base/logging.h&q=O...
which usesd "defined(OFFICIAL_BUILD)".

Then look at:
https://code.google.com/p/chromium/codesearch#chromium/src/remoting/remoting....

which sadly defines (in a gyp) OFFICIAL_BUILD to be 0 :-(.

IMO, it is better to use a definition which is safe with either test.  I think
the gyp is wrong in the above example... but I probably need a standard... and I
couldn't find one in the style guide.

[James Cook, 2013/07/15 16:58:27]

Could we resolve the issue about official build macros outside my review?  That
piece of code pre-dates my changes and I'm not an owner of this module -- maybe
nduca or dsinclair could help you sort it out?

[jar (doing other things), 2013/07/16 22:54:48]

Please switch to one of these alternatives in all cases: 

#define TRACING_IS_OFFICIAL_BUILD 1
vs
#undef TRACING_IS_OFFICIAL_BUILD 

The latter is what you should use on line 242.

 #endif
 
 #if TRACING_IS_OFFICIAL_BUILD
 #define UNSHIPPED_TRACE_EVENT0(category_group, name) (void)0
 #define UNSHIPPED_TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
     (void)0
 #define UNSHIPPED_TRACE_EVENT2(category_group, name, arg1_name, arg1_val, \
                                arg2_name, arg2_val) (void)0
 #define UNSHIPPED_TRACE_EVENT_INSTANT0(category_group, name, scope) (void)0
 #define UNSHIPPED_TRACE_EVENT_INSTANT1(category_group, name, scope, \
@@ skipping 1291 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 } // namespace debug
 } // namespace base
 
 #endif /* BASE_DEBUG_TRACE_EVENT_H_ */