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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 // Declaration of a Windows event trace controller class. | |
| 6 // The controller takes care of creating and manipulating event trace | |
| 7 // sessions. | |
| 8 // | |
| 9 // Event tracing for Windows is a system-provided service that provides | |
| 10 // logging control and high-performance transport for generic, binary trace | |
| 11 // events. Event trace providers register with the system by their name, | |
| 12 // which is a GUID, and can from that point forward receive callbacks that | |
| 13 // start or end tracing and that change their trace level and enable mask. | |
| 14 // | |
| 15 // A trace controller can create an event tracing session, which either | |
| 16 // sends events to a binary file, or to a realtime consumer, or both. | |
| 17 // | |
| 18 // A trace consumer consumes events from zero or one realtime session, | |
| 19 // as well as potentially from multiple binary trace files. | |
| 20 #ifndef BASE_WIN_EVENT_TRACE_CONTROLLER_H_ | |
| 21 #define BASE_WIN_EVENT_TRACE_CONTROLLER_H_ | |
| 22 | |
| 23 #include <windows.h> | |
| 24 #include <wmistr.h> | |
| 25 #include <evntrace.h> | |
| 26 #include <string> | |
| 27 | |
| 28 #include "base/base_export.h" | |
| 29 #include "base/basictypes.h" | |
| 30 | |
| 31 namespace base { | |
| 32 namespace win { | |
| 33 | |
| 34 // Utility class to make it easier to work with EVENT_TRACE_PROPERTIES. | |
| 35 // The EVENT_TRACE_PROPERTIES structure contains information about an | |
| 36 // event tracing session. | |
| 37 class BASE_EXPORT EtwTraceProperties { | |
| 38 public: | |
| 39 EtwTraceProperties(); | |
| 40 | |
| 41 EVENT_TRACE_PROPERTIES* get() { | |
| 42 return &properties_; | |
| 43 } | |
| 44 | |
| 45 const EVENT_TRACE_PROPERTIES* get() const { | |
| 46 return reinterpret_cast<const EVENT_TRACE_PROPERTIES*>(&properties_); | |
| 47 } | |
| 48 | |
| 49 const wchar_t* GetLoggerName() const { | |
| 50 return reinterpret_cast<const wchar_t *>(buffer_ + get()->LoggerNameOffset); | |
| 51 } | |
| 52 | |
| 53 // Copies logger_name to the properties structure. | |
| 54 HRESULT SetLoggerName(const wchar_t* logger_name); | |
| 55 const wchar_t* GetLoggerFileName() const { | |
| 56 return reinterpret_cast<const wchar_t*>(buffer_ + get()->LogFileNameOffset); | |
| 57 } | |
| 58 | |
| 59 // Copies logger_file_name to the properties structure. | |
| 60 HRESULT SetLoggerFileName(const wchar_t* logger_file_name); | |
| 61 | |
| 62 // Max string len for name and session name is 1024 per documentation. | |
| 63 static const size_t kMaxStringLen = 1024; | |
| 64 // Properties buffer allocates space for header and for | |
| 65 // max length for name and session name. | |
| 66 static const size_t kBufSize = sizeof(EVENT_TRACE_PROPERTIES) | |
| 67 + 2 * sizeof(wchar_t) * (kMaxStringLen); | |
| 68 | |
| 69 private: | |
| 70 // The EVENT_TRACE_PROPERTIES structure needs to be overlaid on a | |
| 71 // larger buffer to allow storing the logger name and logger file | |
| 72 // name contiguously with the structure. | |
| 73 union { | |
| 74 public: | |
| 75 // Our properties header. | |
| 76 EVENT_TRACE_PROPERTIES properties_; | |
| 77 // The actual size of the buffer is forced by this member. | |
| 78 char buffer_[kBufSize]; | |
| 79 }; | |
| 80 | |
| 81 DISALLOW_COPY_AND_ASSIGN(EtwTraceProperties); | |
| 82 }; | |
| 83 | |
| 84 // This class implements an ETW controller, which knows how to start and | |
| 85 // stop event tracing sessions, as well as controlling ETW provider | |
| 86 // log levels and enable bit masks under the session. | |
| 87 class BASE_EXPORT EtwTraceController { | |
| 88 public: | |
| 89 EtwTraceController(); | |
| 90 ~EtwTraceController(); | |
| 91 | |
| 92 // Start a session with given name and properties. | |
| 93 HRESULT Start(const wchar_t* session_name, EtwTraceProperties* prop); | |
| 94 | |
| 95 // Starts a session tracing to a file with some default properties. | |
| 96 HRESULT StartFileSession(const wchar_t* session_name, | |
| 97 const wchar_t* logfile_path, | |
| 98 bool realtime = false); | |
| 99 | |
| 100 // Starts a realtime session with some default properties. | |
| 101 HRESULT StartRealtimeSession(const wchar_t* session_name, | |
| 102 size_t buffer_size); | |
| 103 | |
| 104 // Enables "provider" at "level" for this session. | |
| 105 // This will cause all providers registered with the GUID | |
| 106 // "provider" to start tracing at the new level, systemwide. | |
| 107 HRESULT EnableProvider(const GUID& provider, UCHAR level, | |
| 108 ULONG flags = 0xFFFFFFFF); | |
| 109 // Disables "provider". | |
| 110 HRESULT DisableProvider(const GUID& provider); | |
| 111 | |
| 112 // Stops our session and retrieve the new properties of the session, | |
| 113 // properties may be NULL. | |
| 114 HRESULT Stop(EtwTraceProperties* properties); | |
| 115 | |
| 116 // Flushes our session and retrieve the current properties, | |
| 117 // properties may be NULL. | |
| 118 HRESULT Flush(EtwTraceProperties* properties); | |
| 119 | |
| 120 // Static utility functions for controlling | |
| 121 // sessions we don't necessarily own. | |
| 122 static HRESULT Start(const wchar_t* session_name, | |
| 123 EtwTraceProperties* properties, | |
| 124 TRACEHANDLE* session_handle); | |
| 125 | |
| 126 static HRESULT Query(const wchar_t* session_name, | |
| 127 EtwTraceProperties* properties); | |
| 128 | |
| 129 static HRESULT Update(const wchar_t* session_name, | |
| 130 EtwTraceProperties* properties); | |
| 131 | |
| 132 static HRESULT Stop(const wchar_t* session_name, | |
| 133 EtwTraceProperties* properties); | |
| 134 static HRESULT Flush(const wchar_t* session_name, | |
| 135 EtwTraceProperties* properties); | |
| 136 | |
| 137 // Accessors. | |
| 138 TRACEHANDLE session() const { return session_; } | |
| 139 const wchar_t* session_name() const { return session_name_.c_str(); } | |
| 140 | |
| 141 private: | |
| 142 std::wstring session_name_; | |
| 143 TRACEHANDLE session_; | |
| 144 | |
| 145 DISALLOW_COPY_AND_ASSIGN(EtwTraceController); | |
| 146 }; | |
| 147 | |
| 148 } // namespace win | |
| 149 } // namespace base | |
| 150 | |
| 151 #endif // BASE_WIN_EVENT_TRACE_CONTROLLER_H_ | |
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