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// Declaration of a Windows event trace consumer base class. 6#ifndef BASE_WIN_EVENT_TRACE_CONSUMER_H_ 7#define BASE_WIN_EVENT_TRACE_CONSUMER_H_ 8 9#include <windows.h> 10#include <wmistr.h> 11#include <evntrace.h> 12#include <stddef.h> 13#include <vector> 14 15#include "base/macros.h" 16 17namespace base { 18namespace win { 19 20// This class is a base class that makes it easier to consume events 21// from realtime or file sessions. Concrete consumers need to subclass 22// a specialization of this class and override the ProcessEvent and/or 23// the ProcessBuffer methods to implement the event consumption logic. 24// Usage might look like: 25// class MyConsumer: public EtwTraceConsumerBase<MyConsumer, 1> { 26// protected: 27// static VOID WINAPI ProcessEvent(PEVENT_TRACE event); 28// }; 29// 30// MyConsumer consumer; 31// consumer.OpenFileSession(file_path); 32// consumer.Consume(); 33template <class ImplClass> 34class EtwTraceConsumerBase { 35 public: 36 // Constructs a closed consumer. 37 EtwTraceConsumerBase() { 38 } 39 40 ~EtwTraceConsumerBase() { 41 Close(); 42 } 43 44 // Opens the named realtime session, which must be existent. 45 // Note: You can use OpenRealtimeSession or OpenFileSession 46 // to open as many as MAXIMUM_WAIT_OBJECTS (63) sessions at 47 // any one time, though only one of them may be a realtime 48 // session. 49 HRESULT OpenRealtimeSession(const wchar_t* session_name); 50 51 // Opens the event trace log in "file_name", which must be a full or 52 // relative path to an existing event trace log file. 53 // Note: You can use OpenRealtimeSession or OpenFileSession 54 // to open as many as kNumSessions at any one time. 55 HRESULT OpenFileSession(const wchar_t* file_name); 56 57 // Consume all open sessions from beginning to end. 58 HRESULT Consume(); 59 60 // Close all open sessions. 61 HRESULT Close(); 62 63 protected: 64 // Override in subclasses to handle events. 65 static void ProcessEvent(EVENT_TRACE* event) { 66 } 67 // Override in subclasses to handle buffers. 68 static bool ProcessBuffer(EVENT_TRACE_LOGFILE* buffer) { 69 return true; // keep going 70 } 71 72 protected: 73 // Currently open sessions. 74 std::vector<TRACEHANDLE> trace_handles_; 75 76 private: 77 // These delegate to ImplClass callbacks with saner signatures. 78 static void WINAPI ProcessEventCallback(EVENT_TRACE* event) { 79 ImplClass::ProcessEvent(event); 80 } 81 static ULONG WINAPI ProcessBufferCallback(PEVENT_TRACE_LOGFILE buffer) { 82 return ImplClass::ProcessBuffer(buffer); 83 } 84 85 DISALLOW_COPY_AND_ASSIGN(EtwTraceConsumerBase); 86}; 87 88template <class ImplClass> inline 89HRESULT EtwTraceConsumerBase<ImplClass>::OpenRealtimeSession( 90 const wchar_t* session_name) { 91 EVENT_TRACE_LOGFILE logfile = {}; 92 logfile.LoggerName = const_cast<wchar_t*>(session_name); 93 logfile.LogFileMode = EVENT_TRACE_REAL_TIME_MODE; 94 logfile.BufferCallback = &ProcessBufferCallback; 95 logfile.EventCallback = &ProcessEventCallback; 96 logfile.Context = this; 97 TRACEHANDLE trace_handle = ::OpenTrace(&logfile); 98 if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle) 99 return HRESULT_FROM_WIN32(::GetLastError()); 100 101 trace_handles_.push_back(trace_handle); 102 return S_OK; 103} 104 105template <class ImplClass> inline 106HRESULT EtwTraceConsumerBase<ImplClass>::OpenFileSession( 107 const wchar_t* file_name) { 108 EVENT_TRACE_LOGFILE logfile = {}; 109 logfile.LogFileName = const_cast<wchar_t*>(file_name); 110 logfile.BufferCallback = &ProcessBufferCallback; 111 logfile.EventCallback = &ProcessEventCallback; 112 logfile.Context = this; 113 TRACEHANDLE trace_handle = ::OpenTrace(&logfile); 114 if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle) 115 return HRESULT_FROM_WIN32(::GetLastError()); 116 117 trace_handles_.push_back(trace_handle); 118 return S_OK; 119} 120 121template <class ImplClass> inline 122HRESULT EtwTraceConsumerBase<ImplClass>::Consume() { 123 ULONG err = ::ProcessTrace(&trace_handles_[0], 124 static_cast<ULONG>(trace_handles_.size()), 125 NULL, 126 NULL); 127 return HRESULT_FROM_WIN32(err); 128} 129 130template <class ImplClass> inline 131HRESULT EtwTraceConsumerBase<ImplClass>::Close() { 132 HRESULT hr = S_OK; 133 for (size_t i = 0; i < trace_handles_.size(); ++i) { 134 if (NULL != trace_handles_[i]) { 135 ULONG ret = ::CloseTrace(trace_handles_[i]); 136 trace_handles_[i] = NULL; 137 138 if (FAILED(HRESULT_FROM_WIN32(ret))) 139 hr = HRESULT_FROM_WIN32(ret); 140 } 141 } 142 trace_handles_.clear(); 143 144 return hr; 145} 146 147} // namespace win 148} // namespace base 149 150#endif // BASE_WIN_EVENT_TRACE_CONSUMER_H_ 151