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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 provider class, to allow using | |
6 // Windows Event Tracing for logging transport and control. | |
7 #ifndef BASE_WIN_EVENT_TRACE_PROVIDER_H_ | |
8 #define BASE_WIN_EVENT_TRACE_PROVIDER_H_ | |
9 | |
10 #include <windows.h> | |
11 #include <wmistr.h> | |
12 #include <evntrace.h> | |
13 | |
14 #include "base/base_export.h" | |
15 #include "base/basictypes.h" | |
16 | |
17 namespace base { | |
18 namespace win { | |
19 | |
20 typedef GUID EtwEventClass; | |
21 typedef UCHAR EtwEventType; | |
22 typedef UCHAR EtwEventLevel; | |
23 typedef USHORT EtwEventVersion; | |
24 typedef ULONG EtwEventFlags; | |
25 | |
26 // Base class is a POD for correctness. | |
27 template <size_t N> struct EtwMofEventBase { | |
28 EVENT_TRACE_HEADER header; | |
29 MOF_FIELD fields[N]; | |
30 }; | |
31 | |
32 // Utility class to auto-initialize event trace header structures. | |
33 template <size_t N> class EtwMofEvent: public EtwMofEventBase<N> { | |
34 public: | |
35 typedef EtwMofEventBase<N> Super; | |
36 | |
37 // Clang and the C++ standard don't allow unqualified lookup into dependent | |
38 // bases, hence these using decls to explicitly pull the names out. | |
39 using EtwMofEventBase<N>::header; | |
40 using EtwMofEventBase<N>::fields; | |
41 | |
42 EtwMofEvent() { | |
43 memset(static_cast<Super*>(this), 0, sizeof(Super)); | |
44 } | |
45 | |
46 EtwMofEvent(const EtwEventClass& event_class, EtwEventType type, | |
47 EtwEventLevel level) { | |
48 memset(static_cast<Super*>(this), 0, sizeof(Super)); | |
49 header.Size = sizeof(Super); | |
50 header.Guid = event_class; | |
51 header.Class.Type = type; | |
52 header.Class.Level = level; | |
53 header.Flags = WNODE_FLAG_TRACED_GUID | WNODE_FLAG_USE_MOF_PTR; | |
54 } | |
55 | |
56 EtwMofEvent(const EtwEventClass& event_class, EtwEventType type, | |
57 EtwEventVersion version, EtwEventLevel level) { | |
58 memset(static_cast<Super*>(this), 0, sizeof(Super)); | |
59 header.Size = sizeof(Super); | |
60 header.Guid = event_class; | |
61 header.Class.Type = type; | |
62 header.Class.Version = version; | |
63 header.Class.Level = level; | |
64 header.Flags = WNODE_FLAG_TRACED_GUID | WNODE_FLAG_USE_MOF_PTR; | |
65 } | |
66 | |
67 void SetField(int field, size_t size, const void *data) { | |
68 // DCHECK(field < N); | |
69 if ((field < N) && (size <= kuint32max)) { | |
70 fields[field].DataPtr = reinterpret_cast<ULONG64>(data); | |
71 fields[field].Length = static_cast<ULONG>(size); | |
72 } | |
73 } | |
74 | |
75 EVENT_TRACE_HEADER* get() { return& header; } | |
76 | |
77 private: | |
78 DISALLOW_COPY_AND_ASSIGN(EtwMofEvent); | |
79 }; | |
80 | |
81 // Trace provider with Event Tracing for Windows. The trace provider | |
82 // registers with ETW by its name which is a GUID. ETW calls back to | |
83 // the object whenever the trace level or enable flags for this provider | |
84 // name changes. | |
85 // Users of this class can test whether logging is currently enabled at | |
86 // a particular trace level, and whether particular enable flags are set, | |
87 // before other resources are consumed to generate and issue the log | |
88 // messages themselves. | |
89 class BASE_EXPORT EtwTraceProvider { | |
90 public: | |
91 // Creates an event trace provider identified by provider_name, which | |
92 // will be the name registered with Event Tracing for Windows (ETW). | |
93 explicit EtwTraceProvider(const GUID& provider_name); | |
94 | |
95 // Creates an unnamed event trace provider, the provider must be given | |
96 // a name before registration. | |
97 EtwTraceProvider(); | |
98 virtual ~EtwTraceProvider(); | |
99 | |
100 // Registers the trace provider with Event Tracing for Windows. | |
101 // Note: from this point forward ETW may call the provider's control | |
102 // callback. If the provider's name is enabled in some trace session | |
103 // already, the callback may occur recursively from this call, so | |
104 // call this only when you're ready to handle callbacks. | |
105 ULONG Register(); | |
106 // Unregisters the trace provider with ETW. | |
107 ULONG Unregister(); | |
108 | |
109 // Accessors. | |
110 void set_provider_name(const GUID& provider_name) { | |
111 provider_name_ = provider_name; | |
112 } | |
113 const GUID& provider_name() const { return provider_name_; } | |
114 TRACEHANDLE registration_handle() const { return registration_handle_; } | |
115 TRACEHANDLE session_handle() const { return session_handle_; } | |
116 EtwEventFlags enable_flags() const { return enable_flags_; } | |
117 EtwEventLevel enable_level() const { return enable_level_; } | |
118 | |
119 // Returns true iff logging should be performed for "level" and "flags". | |
120 // Note: flags is treated as a bitmask, and should normally have a single | |
121 // bit set, to test whether to log for a particular sub "facility". | |
122 bool ShouldLog(EtwEventLevel level, EtwEventFlags flags) { | |
123 return NULL != session_handle_ && level >= enable_level_ && | |
124 (0 != (flags & enable_flags_)); | |
125 } | |
126 | |
127 // Simple wrappers to log Unicode and ANSI strings. | |
128 // Do nothing if !ShouldLog(level, 0xFFFFFFFF). | |
129 ULONG Log(const EtwEventClass& event_class, EtwEventType type, | |
130 EtwEventLevel level, const char *message); | |
131 ULONG Log(const EtwEventClass& event_class, EtwEventType type, | |
132 EtwEventLevel level, const wchar_t *message); | |
133 | |
134 // Log the provided event. | |
135 ULONG Log(EVENT_TRACE_HEADER* event); | |
136 | |
137 protected: | |
138 // Called after events have been enabled, override in subclasses | |
139 // to set up state or log at the start of a session. | |
140 // Note: This function may be called ETW's thread and may be racy, | |
141 // bring your own locking if needed. | |
142 virtual void OnEventsEnabled() {} | |
143 | |
144 // Called just before events are disabled, override in subclasses | |
145 // to tear down state or log at the end of a session. | |
146 // Note: This function may be called ETW's thread and may be racy, | |
147 // bring your own locking if needed. | |
148 virtual void OnEventsDisabled() {} | |
149 | |
150 // Called just after events have been disabled, override in subclasses | |
151 // to tear down state at the end of a session. At this point it's | |
152 // to late to log anything to the session. | |
153 // Note: This function may be called ETW's thread and may be racy, | |
154 // bring your own locking if needed. | |
155 virtual void PostEventsDisabled() {} | |
156 | |
157 private: | |
158 ULONG EnableEvents(PVOID buffer); | |
159 ULONG DisableEvents(); | |
160 ULONG Callback(WMIDPREQUESTCODE request, PVOID buffer); | |
161 static ULONG WINAPI ControlCallback(WMIDPREQUESTCODE request, PVOID context, | |
162 ULONG *reserved, PVOID buffer); | |
163 | |
164 GUID provider_name_; | |
165 TRACEHANDLE registration_handle_; | |
166 TRACEHANDLE session_handle_; | |
167 EtwEventFlags enable_flags_; | |
168 EtwEventLevel enable_level_; | |
169 | |
170 // We don't use this, but on XP we're obliged to pass one in to | |
171 // RegisterTraceGuids. Non-const, because that's how the API needs it. | |
172 static TRACE_GUID_REGISTRATION obligatory_guid_registration_; | |
173 | |
174 DISALLOW_COPY_AND_ASSIGN(EtwTraceProvider); | |
175 }; | |
176 | |
177 } // namespace win | |
178 } // namespace base | |
179 | |
180 #endif // BASE_WIN_EVENT_TRACE_PROVIDER_H_ | |
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