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      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 // This file contains the Windows-specific declarations for trace_event.h.
      6 #ifndef BASE_DEBUG_TRACE_EVENT_WIN_H_
      7 #define BASE_DEBUG_TRACE_EVENT_WIN_H_
      8 #pragma once
      9 
     10 #include <string>
     11 
     12 #include "base/base_api.h"
     13 #include "base/win/event_trace_provider.h"
     14 
     15 #define TRACE_EVENT_BEGIN(name, id, extra) \
     16   base::debug::TraceLog::Trace( \
     17       name, \
     18       base::debug::TraceLog::EVENT_BEGIN, \
     19       reinterpret_cast<const void*>(id), \
     20       extra);
     21 
     22 #define TRACE_EVENT_END(name, id, extra) \
     23   base::debug::TraceLog::Trace( \
     24       name, \
     25       base::debug::TraceLog::EVENT_END, \
     26       reinterpret_cast<const void*>(id), \
     27       extra);
     28 
     29 #define TRACE_EVENT_INSTANT(name, id, extra) \
     30   base::debug::TraceLog::Trace( \
     31       name, \
     32       base::debug::TraceLog::EVENT_INSTANT, \
     33       reinterpret_cast<const void*>(id), \
     34       extra);
     35 
     36 // Fwd.
     37 template <typename Type>
     38 struct StaticMemorySingletonTraits;
     39 
     40 namespace base {
     41 namespace debug {
     42 
     43 // This EtwTraceProvider subclass implements ETW logging
     44 // for the macros above on Windows.
     45 class BASE_API TraceLog : public base::win::EtwTraceProvider {
     46  public:
     47   enum EventType {
     48     EVENT_BEGIN,
     49     EVENT_END,
     50     EVENT_INSTANT
     51   };
     52 
     53   // Start logging trace events.
     54   // This is a noop in this implementation.
     55   static bool StartTracing();
     56 
     57   // Trace begin/end/instant events, this is the bottleneck implementation
     58   // all the others defer to.
     59   // Allowing the use of std::string for name or extra is a convenience,
     60   // whereas passing name or extra as a const char* avoids the construction
     61   // of temporary std::string instances.
     62   // If -1 is passed for name_len or extra_len, the strlen of the string will
     63   // be used for length.
     64   static void Trace(const char* name,
     65                     size_t name_len,
     66                     EventType type,
     67                     const void* id,
     68                     const char* extra,
     69                     size_t extra_len);
     70 
     71   // Allows passing extra as a std::string for convenience.
     72   static void Trace(const char* name,
     73                     EventType type,
     74                     const void* id,
     75                     const std::string& extra) {
     76     return Trace(name, -1, type, id, extra.c_str(), extra.length());
     77   }
     78 
     79   // Allows passing extra as a const char* to avoid constructing temporary
     80   // std::string instances where not needed.
     81   static void Trace(const char* name,
     82                     EventType type,
     83                     const void* id,
     84                     const char* extra) {
     85     return Trace(name, -1, type, id, extra, -1);
     86   }
     87 
     88   // Retrieves the singleton.
     89   // Note that this may return NULL post-AtExit processing.
     90   static TraceLog* GetInstance();
     91 
     92   // Returns true iff tracing is turned on.
     93   bool IsTracing() {
     94     return enable_level() >= TRACE_LEVEL_INFORMATION;
     95   }
     96 
     97   // Emit a trace of type |type| containing |name|, |id|, and |extra|.
     98   // Note: |name| and |extra| must be NULL, or a zero-terminated string of
     99   //    length |name_len| or |extra_len| respectively.
    100   // Note: if name_len or extra_len are -1, the length of the corresponding
    101   //    string will be used.
    102   void TraceEvent(const char* name,
    103                   size_t name_len,
    104                   EventType type,
    105                   const void* id,
    106                   const char* extra,
    107                   size_t extra_len);
    108 
    109   // Exposed for unittesting only, allows resurrecting our
    110   // singleton instance post-AtExit processing.
    111   static void Resurrect();
    112 
    113  private:
    114   // Ensure only the provider can construct us.
    115   friend struct StaticMemorySingletonTraits<TraceLog>;
    116   TraceLog();
    117 
    118   DISALLOW_COPY_AND_ASSIGN(TraceLog);
    119 };
    120 
    121 // The ETW trace provider GUID.
    122 BASE_API extern const GUID kChromeTraceProviderName;
    123 
    124 // The ETW event class GUID for 32 bit events.
    125 BASE_API extern const GUID kTraceEventClass32;
    126 
    127 // The ETW event class GUID for 64 bit events.
    128 BASE_API extern const GUID kTraceEventClass64;
    129 
    130 // The ETW event types, IDs 0x00-0x09 are reserved, so start at 0x10.
    131 const base::win::EtwEventType kTraceEventTypeBegin = 0x10;
    132 const base::win::EtwEventType kTraceEventTypeEnd = 0x11;
    133 const base::win::EtwEventType kTraceEventTypeInstant = 0x12;
    134 
    135 // If this flag is set in enable flags
    136 enum TraceEventFlags {
    137   CAPTURE_STACK_TRACE = 0x0001,
    138 };
    139 
    140 // The event format consists of:
    141 // The "name" string as a zero-terminated ASCII string.
    142 // The id pointer in the machine bitness.
    143 // The "extra" string as a zero-terminated ASCII string.
    144 // Optionally the stack trace, consisting of a DWORD "depth", followed
    145 //    by an array of void* (machine bitness) of length "depth".
    146 
    147 // Forward decl.
    148 struct TraceLogSingletonTraits;
    149 
    150 }  // nemspace debug
    151 }  // namespace base
    152 
    153 #endif  // BASE_DEBUG_TRACE_EVENT_WIN_H_
    154