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EVENT_HEADER structure (evntcons.h)

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Defines information about the event.

Syntax

typedef struct _EVENT_HEADER {
  USHORT           Size;
  USHORT           HeaderType;
  USHORT           Flags;
  USHORT           EventProperty;
  ULONG            ThreadId;
  ULONG            ProcessId;
  LARGE_INTEGER    TimeStamp;
  GUID             ProviderId;
  EVENT_DESCRIPTOR EventDescriptor;
  union {
    struct {
      ULONG KernelTime;
      ULONG UserTime;
    } DUMMYSTRUCTNAME;
    ULONG64 ProcessorTime;
  } DUMMYUNIONNAME;
  GUID             ActivityId;
} EVENT_HEADER, *PEVENT_HEADER;

Members

Size

Size of the event record, in bytes.

HeaderType

Reserved.

Flags

Flags that provide information about the event such as the type of session it was logged to and if the event contains extended data. This member can contain one or more of the following flags.

Value Meaning
EVENT_HEADER_FLAG_EXTENDED_INFO
 The ExtendedData member of EVENT_RECORD contains data.
EVENT_HEADER_FLAG_PRIVATE_SESSION
 The event was logged to a private session. Use ProcessorTime for elapsed execution time.
EVENT_HEADER_FLAG_STRING_ONLY
 The event data is a null-terminated Unicode string. You do not need a manifest to parse the UserData member of EVENT_RECORD.
EVENT_HEADER_FLAG_TRACE_MESSAGE
 The provider used TraceMessage or TraceMessageVa to log the event. Most providers do not use these functions to write events, so this flag typically indicates that the event was written by Windows Software Trace Preprocessor (WPP).
EVENT_HEADER_FLAG_NO_CPUTIME
 Use ProcessorTime for elapsed execution time.
EVENT_HEADER_FLAG_32_BIT_HEADER
 Indicates that the provider was running on a 32-bit computer or in a WOW64 session.
EVENT_HEADER_FLAG_64_BIT_HEADER
 Indicates that the provider was running on a 64-bit computer.
EVENT_HEADER_FLAG_CLASSIC_HEADER
 Indicates that provider used TraceEvent to log the event.

EventProperty

Indicates the source to use for parsing the event data.

Value Meaning
EVENT_HEADER_PROPERTY_XML
 Indicates that you need a manifest to parse the event data.
EVENT_HEADER_PROPERTY_FORWARDED_XML
 Indicates that the event data contains within itself a fully-rendered XML description of the data, so you do not need a manifest to parse the event data.
EVENT_HEADER_PROPERTY_LEGACY_EVENTLOG
 Indicates that you need a WMI MOF class to parse the event data.

ThreadId

Identifies the thread that generated the event.

ProcessId

Identifies the process that generated the event.

TimeStamp

Contains the time that the event occurred. The resolution is system time unless the ProcessTraceMode member of EVENT_TRACE_LOGFILE contains the PROCESS_TRACE_MODE_RAW_TIMESTAMP flag, in which case the resolution depends on the value of the Wnode.ClientContext member of EVENT_TRACE_PROPERTIES at the time the controller created the session.

ProviderId

GUID that uniquely identifies the provider that logged the event.

EventDescriptor

Defines the information about the event such as the event identifier and severity level. For details, see EVENT_DESCRIPTOR.

DUMMYUNIONNAME

DUMMYUNIONNAME.DUMMYSTRUCTNAME

DUMMYUNIONNAME.DUMMYSTRUCTNAME.KernelTime

Elapsed execution time for kernel-mode instructions, in CPU time units. If you are using a private session, use the value in the ProcessorTime member instead. For more information, see Remarks.

DUMMYUNIONNAME.DUMMYSTRUCTNAME.UserTime

Elapsed execution time for user-mode instructions, in CPU time units. If you are using a private session, use the value in the ProcessorTime member instead. For more information, see Remarks.

DUMMYUNIONNAME.ProcessorTime

For private sessions, the elapsed execution time for user-mode instructions, in CPU ticks.

ActivityId

Identifier that relates two events. For details, see EventWriteTransfer.

Remarks

You can use the KernelTime and UserTime members to determine the CPU cost in units for a set of instructions (the values indicate the CPU usage charged to that thread at the time of logging). For example, if Event A and Event B are consecutively logged by the same thread and they have CPU usage numbers 150 and 175, then the activity that was performed by that thread between events A and B cost 25 CPU time units (175 – 150).

The TimerResolution of the TRACE_LOGFILE_HEADER structure contains the resolution of the CPU usage timer in 100-nanosecond units. You can use the timer resolution with the kernel time and user time values to determine the amount of CPU time that the set of instructions used. For example, if the timer resolution is 156,250, then 25 CPU time units is 0.39 seconds (156,250 * 25 * 100 / 1,000,000,000). This is the amount of CPU time (not elapsed wall clock time) used by the set of instructions between events A and B.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Header evntcons.h (include Evntcons.h)

See also

EVENT_RECORD