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