Have all trace points emit to ETW.

base/debug/trace_event_win.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 file contains the Windows-specific declarations for trace_event.h.
 #ifndef BASE_DEBUG_TRACE_EVENT_WIN_H_
 #define BASE_DEBUG_TRACE_EVENT_WIN_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/debug/trace_event.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/win/event_trace_provider.h"
 
 // Fwd.
 template <typename Type>
 struct StaticMemorySingletonTraits;
 
 namespace base {
 namespace debug {
 
 // This EtwTraceProvider subclass implements ETW logging
 // for the macros above on Windows.
 class BASE_EXPORT TraceEventETWProvider : public base::win::EtwTraceProvider {
  public:
   // Start logging trace events.
   // This is a noop in this implementation.
   static bool StartTracing();
 
-  // Trace begin/end/instant events, this is the bottleneck implementation
-  // all the others defer to.
+  // Trace begin/end/instant events.
   // Allowing the use of std::string for name or extra is a convenience,
   // whereas passing name or extra as a const char* avoids the construction
   // of temporary std::string instances.
-  // If -1 is passed for name_len or extra_len, the strlen of the string will
-  // be used for length.
   static void Trace(const char* name,
-                    size_t name_len,
                     char type,
                     const void* id,
-                    const char* extra,
-                    size_t extra_len);
+                    const char* extra);
 
   // Allows passing extra as a std::string for convenience.
   static void Trace(const char* name,
                     char type,
                     const void* id,
                     const std::string& extra) {
-    return Trace(name, -1, type, id, extra.c_str(), extra.length());
+    return Trace(name, type, id, extra.c_str());
   }
 
-  // Allows passing extra as a const char* to avoid constructing temporary
-  // std::string instances where not needed.
-  static void Trace(const char* name,
-                    char type,
-                    const void* id,
-                    const char* extra) {
-    return Trace(name, -1, type, id, extra, -1);
-  }
+  // Emit a trace event.
+  // The event is defined by |category_group|, |name| and |type|.
+  // |id| helps to identify related events.
+  // |thread_name| is the name of the thread that produced the event.
+  // |num_args| indicates the number of custom arguments to add to the trace.
+  // It must be <= |kTraceMaxNumArgs|. The names of the arguments are specified
+  // in |arg_names|. |arg_types| indicates how to interpret the value of
+  // each argument. Finally, the value of an argument is obtained from
+  // |convertable_values| if its type is TRACE_VALUE_TYPE_CONVERTABLE,
+  // from |arg_values| otherwise.
+  static void TraceWithArgs(
+      const char* category_group,
+      const char* name,
+      char type,
+      unsigned long long id,
+      const std::string& thread_name,
+      int num_args,
+      const char** arg_names,
+      const unsigned char* arg_types,
+      const unsigned long long* arg_values,
+      scoped_ptr<ConvertableToTraceFormat> convertable_values[]);
 
   // Retrieves the singleton.
   // Note that this may return NULL post-AtExit processing.
   static TraceEventETWProvider* GetInstance();
 
   // Returns true iff tracing is turned on.
   bool IsTracing() {
     return enable_level() >= TRACE_LEVEL_INFORMATION;
   }
 
-  // Emit a trace of type |type| containing |name|, |id|, and |extra|.
-  // Note: |name| and |extra| must be NULL, or a zero-terminated string of
-  //    length |name_len| or |extra_len| respectively.
-  // Note: if name_len or extra_len are -1, the length of the corresponding
-  //    string will be used.
-  void TraceEvent(const char* name,
-                  size_t name_len,
-                  char type,
-                  const void* id,
-                  const char* extra,
-                  size_t extra_len);
-
   // Exposed for unittesting only, allows resurrecting our
   // singleton instance post-AtExit processing.
   static void Resurrect();
 
  private:
   // Ensure only the provider can construct us.
   friend struct StaticMemorySingletonTraits<TraceEventETWProvider>;
   TraceEventETWProvider();
 
+  // Emit a trace event.

[Sigurður Ásgeirsson, 2013/09/10 21:15:54]

If you're defining a message format that's incompatible with what's previously
been logged under a facility/ID pair, then you should allocate either a new
facility GUID or a new ID (or both) for your message.

[fdoray, 2013/09/16 00:51:03]

Done.

+  // It's possible to add up to |kTraceMaxNumArgs| custom arguments to
+  // the trace. |arg_values| and |arg_names| are arrays of |num_args| strings
+  // that indicate the names and values of the custom arguments.
+  // The payload of the produced trace follows this format:
+  // - Name (string)
+  // - Id (unsigned long long)
+  // - Category (string)
+  // - Thread name (string)
+  // - Name of parameter 1, or '\0' (string)
+  // - Value of parameter 1, or '\0' (string)
+  // - Name of parameter 2, or '\0' (string)
+  // - Value of parameter 2, or '\0' (string)
+  // If stack capture is enabled for the trace session:

[Sigurður Ásgeirsson, 2013/09/10 21:15:54]

It's not clear to me that this message format can be uniquely parsed, as the
format is stated here.
How do you disambiguate between an additional trailing string or a stack trace
at the end of a message?

[fdoray, 2013/09/16 00:51:03]

The new format can be parsed using this schema:
https://docs.google.com/file/d/0B3wWyRavE9yeVEcyV1B2SUpJT1k/edit?usp=sharing

mofcomp -N:root\wmi chrome_event_declaration.mof
tracerpt [trace file].etl

Tested for all combination of number of arguments / capture stack trace enabled
or disabled. Gives an output like that:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
	<System>
		<Provider Guid="{3dada31d-19ef-4dc1-b345-037927193422}" />
		<EventID>0</EventID>
		<Version>0</Version>
		<Level>4</Level>
		<Task>0</Task>
		<Opcode>16</Opcode>
		<Keywords>0x0</Keywords>
		<TimeCreated SystemTime="2013-09-15T11:27:39.016608600Z" />
		<Correlation ActivityID="{00000000-0000-0000-0000-000000000000}" />
		<Execution ProcessID="8180" ThreadID="4516" ProcessorID="5" KernelTime="0"
UserTime="30" />
		<Channel />
		<Computer />
	</System>
	<EventData>
		<Data Name="name">MessageLoop::RunTask</Data>
		<Data Name="id">0x0</Data>
		<Data Name="category">task</Data>
		<Data Name="arg1_label">src_file</Data>
		<Data Name="arg1_value">d:\\chrome\\src\\ipc\\ipc_channel_proxy.cc</Data>
		<Data Name="arg2_label">src_func</Data>
		<Data Name="arg2_value">IPC::ChannelProxy::Send</Data>
		<Data Name="stack_size">      21</Data>
		<Data Name="stack_pointers">0x100CF4DA</Data>
		<Data Name="stack_pointers">0x100CF9C9</Data>
                ...
	</EventData>
	<RenderingInfo Culture="en-US">
		<Opcode>ChromeBegin</Opcode>
		<Provider>ChromeProvider</Provider>
	</RenderingInfo>
	<ExtendedTracingInfo
xmlns="http://schemas.microsoft.com/win/2004/08/events/trace">
		<EventGuid>{4b82d4e7-f6d5-4e64-8855-f55ed5f8f457}</EventGuid>
	</ExtendedTracingInfo>
</Event>


On 2013/09/10 21:15:54, Sigurður Ásgeirsson wrote:

+  // - Stack size (DWORD)
+  // - Stack pointers (stack size * void*)
+  // Strings are null-terminated and have a variable size.
+  //
+  // Note: |name| and |category_group| must be NULL, or a zero-terminated
+  //       string. The length of |name| must be specified by |name_len|.
+  void TraceEvent(const char* category_group,
+                  const char* name,
+                  char type,
+                  unsigned long long id,
+                  const std::string& thread_name,
+                  int num_args,
+                  const char** arg_names,
+                  std::string* arg_values);
+
   DISALLOW_COPY_AND_ASSIGN(TraceEventETWProvider);
 };
 
 // The ETW trace provider GUID.
 BASE_EXPORT extern const GUID kChromeTraceProviderName;
 
 // The ETW event class GUID for 32 bit events.
 BASE_EXPORT extern const GUID kTraceEventClass32;
 
 // The ETW event class GUID for 64 bit events.
@@ skipping 13 matching lines @@
 // The "name" string as a zero-terminated ASCII string.
 // The id pointer in the machine bitness.
 // The "extra" string as a zero-terminated ASCII string.
 // Optionally the stack trace, consisting of a DWORD "depth", followed
 //    by an array of void* (machine bitness) of length "depth".
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_WIN_H_