1 // Copyright (c) 2009 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 #pragma once 9 10 #include <windows.h> 11 #include <wmistr.h> 12 #include <evntrace.h> 13 #include <vector> 14 #include "base/basictypes.h" 15 16 namespace base { 17 namespace win { 18 19 // This class is a base class that makes it easier to consume events 20 // from realtime or file sessions. Concrete consumers need to sublass 21 // a specialization of this class and override the ProcessEvent and/or 22 // the ProcessBuffer methods to implement the event consumption logic. 23 // Usage might look like: 24 // class MyConsumer: public EtwTraceConsumerBase<MyConsumer, 1> { 25 // protected: 26 // static VOID WINAPI ProcessEvent(PEVENT_TRACE event); 27 // }; 28 // 29 // MyConsumer consumer; 30 // consumer.OpenFileSession(file_path); 31 // consumer.Consume(); 32 template <class ImplClass> 33 class EtwTraceConsumerBase { 34 public: 35 // Constructs a closed consumer. EtwTraceConsumerBase()36 EtwTraceConsumerBase() { 37 } 38 ~EtwTraceConsumerBase()39 ~EtwTraceConsumerBase() { 40 Close(); 41 } 42 43 // Opens the named realtime session, which must be existent. 44 // Note: You can use OpenRealtimeSession or OpenFileSession 45 // to open as many as MAXIMUM_WAIT_OBJECTS (63) sessions at 46 // any one time, though only one of them may be a realtime 47 // session. 48 HRESULT OpenRealtimeSession(const wchar_t* session_name); 49 50 // Opens the event trace log in "file_name", which must be a full or 51 // relative path to an existing event trace log file. 52 // Note: You can use OpenRealtimeSession or OpenFileSession 53 // to open as many as kNumSessions at any one time. 54 HRESULT OpenFileSession(const wchar_t* file_name); 55 56 // Consume all open sessions from beginning to end. 57 HRESULT Consume(); 58 59 // Close all open sessions. 60 HRESULT Close(); 61 62 protected: 63 // Override in subclasses to handle events. ProcessEvent(EVENT_TRACE * event)64 static void ProcessEvent(EVENT_TRACE* event) { 65 } 66 // Override in subclasses to handle buffers. ProcessBuffer(EVENT_TRACE_LOGFILE * buffer)67 static bool ProcessBuffer(EVENT_TRACE_LOGFILE* buffer) { 68 return true; // keep going 69 } 70 71 protected: 72 // Currently open sessions. 73 std::vector<TRACEHANDLE> trace_handles_; 74 75 private: 76 // These delegate to ImplClass callbacks with saner signatures. ProcessEventCallback(EVENT_TRACE * event)77 static void WINAPI ProcessEventCallback(EVENT_TRACE* event) { 78 ImplClass::ProcessEvent(event); 79 } ProcessBufferCallback(PEVENT_TRACE_LOGFILE buffer)80 static ULONG WINAPI ProcessBufferCallback(PEVENT_TRACE_LOGFILE buffer) { 81 return ImplClass::ProcessBuffer(buffer); 82 } 83 84 DISALLOW_COPY_AND_ASSIGN(EtwTraceConsumerBase); 85 }; 86 87 template <class ImplClass> inline OpenRealtimeSession(const wchar_t * session_name)88HRESULT EtwTraceConsumerBase<ImplClass>::OpenRealtimeSession( 89 const wchar_t* session_name) { 90 EVENT_TRACE_LOGFILE logfile = {}; 91 logfile.LoggerName = const_cast<wchar_t*>(session_name); 92 logfile.LogFileMode = EVENT_TRACE_REAL_TIME_MODE; 93 logfile.BufferCallback = &ProcessBufferCallback; 94 logfile.EventCallback = &ProcessEventCallback; 95 logfile.Context = this; 96 TRACEHANDLE trace_handle = ::OpenTrace(&logfile); 97 if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle) 98 return HRESULT_FROM_WIN32(::GetLastError()); 99 100 trace_handles_.push_back(trace_handle); 101 return S_OK; 102 } 103 104 template <class ImplClass> inline OpenFileSession(const wchar_t * file_name)105HRESULT EtwTraceConsumerBase<ImplClass>::OpenFileSession( 106 const wchar_t* file_name) { 107 EVENT_TRACE_LOGFILE logfile = {}; 108 logfile.LogFileName = const_cast<wchar_t*>(file_name); 109 logfile.BufferCallback = &ProcessBufferCallback; 110 logfile.EventCallback = &ProcessEventCallback; 111 logfile.Context = this; 112 TRACEHANDLE trace_handle = ::OpenTrace(&logfile); 113 if (reinterpret_cast<TRACEHANDLE>(INVALID_HANDLE_VALUE) == trace_handle) 114 return HRESULT_FROM_WIN32(::GetLastError()); 115 116 trace_handles_.push_back(trace_handle); 117 return S_OK; 118 } 119 120 template <class ImplClass> inline Consume()121HRESULT EtwTraceConsumerBase<ImplClass>::Consume() { 122 ULONG err = ::ProcessTrace(&trace_handles_[0], 123 trace_handles_.size(), 124 NULL, 125 NULL); 126 return HRESULT_FROM_WIN32(err); 127 } 128 129 template <class ImplClass> inline Close()130HRESULT EtwTraceConsumerBase<ImplClass>::Close() { 131 HRESULT hr = S_OK; 132 for (size_t i = 0; i < trace_handles_.size(); ++i) { 133 if (NULL != trace_handles_[i]) { 134 ULONG ret = ::CloseTrace(trace_handles_[i]); 135 trace_handles_[i] = NULL; 136 137 if (FAILED(HRESULT_FROM_WIN32(ret))) 138 hr = HRESULT_FROM_WIN32(ret); 139 } 140 141 trace_handles_.clear(); 142 } 143 144 return hr; 145 } 146 147 } // namespace win 148 } // namespace base 149 150 #endif // BASE_WIN_EVENT_TRACE_CONSUMER_H_ 151