base/trace_event/trace_event_win.h

   1 // Copyright (c) 2012 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 // This file contains the Windows-specific declarations for trace_event.h.
   6 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_WIN_H_
   7 #define BASE_TRACE_EVENT_TRACE_EVENT_WIN_H_
   8
   9 #include <string>
  10
  11 #include "base/base_export.h"
  12 #include "base/trace_event/trace_event.h"
  13 #include "base/win/event_trace_provider.h"
  14
  15 // Fwd.
  16 template <typename Type>
  17 struct StaticMemorySingletonTraits;
  18
  19 namespace base {
  20 namespace trace_event {
  21
  22 // This EtwTraceProvider subclass implements ETW logging
  23 // for the macros above on Windows.
  24 class BASE_EXPORT TraceEventETWProvider : public base::win::EtwTraceProvider {
  25  public:
  26    static const size_t kUseStrlen = static_cast<size_t>(-1);
  27
  28   // Start logging trace events.
  29   // This is a noop in this implementation.
  30   static bool StartTracing();
  31
  32   // Trace begin/end/instant events, this is the bottleneck implementation
  33   // all the others defer to.
  34   // Allowing the use of std::string for name or extra is a convenience,
  35   // whereas passing name or extra as a const char* avoids the construction
  36   // of temporary std::string instances.
  37   // If kUseStrlen is passed for name_len or extra_len, the strlen of the string
  38   // will be used for length.
  39   static void Trace(const char* name,
  40                     size_t name_len,
  41                     char type,
  42                     const void* id,
  43                     const char* extra,
  44                     size_t extra_len);
  45
  46   // Allows passing extra as a std::string for convenience.
  47   static void Trace(const char* name,
  48                     char type,
  49                     const void* id,
  50                     const std::string& extra) {
  51     return Trace(name, kUseStrlen, type, id, extra.c_str(), extra.length());
  52   }
  53
  54   // Allows passing extra as a const char* to avoid constructing temporary
  55   // std::string instances where not needed.
  56   static void Trace(const char* name,
  57                     char type,
  58                     const void* id,
  59                     const char* extra) {
  60     return Trace(name, kUseStrlen, type, id, extra, kUseStrlen);
  61   }
  62
  63   // Retrieves the singleton.
  64   // Note that this may return NULL post-AtExit processing.
  65   static TraceEventETWProvider* GetInstance();
  66
  67   // Returns true iff tracing is turned on.
  68   bool IsTracing() {
  69     return enable_level() >= TRACE_LEVEL_INFORMATION;
  70   }
  71
  72   // Emit a trace of type |type| containing |name|, |id|, and |extra|.
  73   // Note: |name| and |extra| must be NULL, or a zero-terminated string of
  74   //    length |name_len| or |extra_len| respectively.
  75   // Note: if name_len or extra_len are kUseStrlen, the length of the
  76   //    corresponding string will be used.
  77   void TraceEvent(const char* name,
  78                   size_t name_len,
  79                   char type,
  80                   const void* id,
  81                   const char* extra,
  82                   size_t extra_len);
  83
  84   // Exposed for unittesting only, allows resurrecting our
  85   // singleton instance post-AtExit processing.
  86   static void Resurrect();
  87
  88  private:
  89   // Ensure only the provider can construct us.
  90   friend struct StaticMemorySingletonTraits<TraceEventETWProvider>;
  91   TraceEventETWProvider();
  92
  93   DISALLOW_COPY_AND_ASSIGN(TraceEventETWProvider);
  94 };
  95
  96 // The ETW trace provider GUID.
  97 BASE_EXPORT extern const GUID kChromeTraceProviderName;
  98
  99 // The ETW event class GUID for 32 bit events.
 100 BASE_EXPORT extern const GUID kTraceEventClass32;
 101
 102 // The ETW event class GUID for 64 bit events.
 103 BASE_EXPORT extern const GUID kTraceEventClass64;
 104
 105 // The ETW event types, IDs 0x00-0x09 are reserved, so start at 0x10.
 106 const base::win::EtwEventType kTraceEventTypeBegin = 0x10;
 107 const base::win::EtwEventType kTraceEventTypeEnd = 0x11;
 108 const base::win::EtwEventType kTraceEventTypeInstant = 0x12;
 109
 110 // If this flag is set in enable flags
 111 enum TraceEventETWFlags {
 112   CAPTURE_STACK_TRACE = 0x0001,
 113 };
 114
 115 // The event format consists of:
 116 // The "name" string as a zero-terminated ASCII string.
 117 // The id pointer in the machine bitness.
 118 // The "extra" string as a zero-terminated ASCII string.
 119 // Optionally the stack trace, consisting of a DWORD "depth", followed
 120 //    by an array of void* (machine bitness) of length "depth".
 121
 122 }  // namespace trace_event
 123 }  // namespace base
 124
 125 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_WIN_H_