TraceLoggingOpcode macro (traceloggingprovider.h)
TraceLogging wrapper macro that sets the opcode for the event.
Syntax
void TraceLoggingOpcode(
[in] eventOpcode
);
Parameters
[in] eventOpcode
An 8-bit number used to mark events with special semantics. This value must be a compile-time constant in the range 0 to 255.
The opcode will be used by trace decoders to organize and correlate events.
Globally-recognized opcode values are defined in winmeta.h. Most events use 0
(WINEVENT_OPCODE_INFO) to indicate that the event has no special semantics.
Opcode values 10 through 239 can be given user-defined semantics.
See EVENT_DESCRIPTOR for details about the event opcode.
Return value
None
Remarks
TraceLoggingOpcode(eventOpcode) can be used as a parameter to an invocation of
a TraceLoggingWrite macro to
set the event's opcode.
If no TraceLoggingOpcode macros are provided to a TraceLoggingWrite call, the event's default opcode is 0 (WINEVENT_OPCODE_INFO). If multiple TraceLoggingOpcode macros are provided, the last value is used.
Opcodes WINEVENT_OPCODE_START (1) and WINEVENT_OPCODE_STOP (2) are used to indicate the beginning and end of ETW activities as follows:
- Generate an activity ID that is unique within the trace, typically using EventActivityIdControl or UuidCreate.
- Write a start event with opcode = START, activity ID = the generated activity ID, and related activity ID = the parent activity ID (or NULL if no parent activity ID).
- Write any number of activity information events with opcode = INFO, activity ID = the generated activity ID.
- Write a stop event with opcode = STOP, activity ID = the generated activity ID.
Trace decoding tools will then be able to organize these events into groups based on their activity IDs.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows Vista [desktop apps | UWP apps] |
| Minimum supported server | Windows Server 2008 [desktop apps | UWP apps] |
| Target Platform | Windows |
| Header | traceloggingprovider.h |