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