TRACE_LOGFILE_HEADER structure (evntrace.h)
The TRACE_LOGFILE_HEADER structure contains information about an event tracing session and its events. It is the raw data format of the trace information data in the header of an ETW log file. It is also a part of the information returned by OpenTrace and provided to the BufferCallback during trace processing.
Syntax
typedef struct _TRACE_LOGFILE_HEADER {
ULONG BufferSize;
union {
ULONG Version;
struct {
UCHAR MajorVersion;
UCHAR MinorVersion;
UCHAR SubVersion;
UCHAR SubMinorVersion;
} VersionDetail;
} DUMMYUNIONNAME;
ULONG ProviderVersion;
ULONG NumberOfProcessors;
LARGE_INTEGER EndTime;
ULONG TimerResolution;
ULONG MaximumFileSize;
ULONG LogFileMode;
ULONG BuffersWritten;
union {
GUID LogInstanceGuid;
struct {
ULONG StartBuffers;
ULONG PointerSize;
ULONG EventsLost;
ULONG CpuSpeedInMHz;
} DUMMYSTRUCTNAME;
} DUMMYUNIONNAME2;
#if ...
PWCHAR LoggerName;
#if ...
PWCHAR LogFileName;
#if ...
RTL_TIME_ZONE_INFORMATION TimeZone;
#else
LPWSTR LoggerName;
#endif
#else
LPWSTR LogFileName;
#endif
#else
TIME_ZONE_INFORMATION TimeZone;
#endif
LARGE_INTEGER BootTime;
LARGE_INTEGER PerfFreq;
LARGE_INTEGER StartTime;
ULONG ReservedFlags;
ULONG BuffersLost;
} TRACE_LOGFILE_HEADER, *PTRACE_LOGFILE_HEADER;
Members
BufferSize
Size of the event tracing session's buffers, in bytes.
DUMMYUNIONNAME
DUMMYUNIONNAME.Version
Version number of the operating system where the trace was collected. This is a roll-up of the members of VersionDetail. Starting with the low-order bytes, the first two bytes contain MajorVersion, the next two bytes contain MinorVersion, the next two bytes contain SubVersion, and the last two bytes contain SubMinorVersion.
DUMMYUNIONNAME.VersionDetail
DUMMYUNIONNAME.VersionDetail.MajorVersion
Major version number of the operating system where the trace was collected.
DUMMYUNIONNAME.VersionDetail.MinorVersion
Minor version number of the operating system where the trace was collected.
DUMMYUNIONNAME.VersionDetail.SubVersion
Reserved.
DUMMYUNIONNAME.VersionDetail.SubMinorVersion
Reserved.
ProviderVersion
Build number of the operating system where the trace was collected.
NumberOfProcessors
Number of processors on the system where the trace was collected.
EndTime
Time at which the event tracing session stopped, in 100-nanosecond intervals since midnight, January 1, 1601. This value may be 0 if you are consuming events in real time or from a log file that was not finalized (i.e. was not properly closed).
TimerResolution
Resolution of the hardware timer, in units of 100 nanoseconds. For usage, see the Remarks for EVENT_TRACE_HEADER.
MaximumFileSize
Maximum size of the log file, in megabytes.
LogFileMode
Logging mode for the event tracing session. For a list of values, see Logging Mode Constants.
BuffersWritten
Total number of buffers written by the event tracing session.
DUMMYUNIONNAME2
DUMMYUNIONNAME2.LogInstanceGuid
Reserved.
DUMMYUNIONNAME2.DUMMYSTRUCTNAME
DUMMYUNIONNAME2.DUMMYSTRUCTNAME.StartBuffers
Reserved.
DUMMYUNIONNAME2.DUMMYSTRUCTNAME.PointerSize
Default size of a pointer data type, in bytes.
DUMMYUNIONNAME2.DUMMYSTRUCTNAME.EventsLost
Number of events lost during the event tracing session. Events are primarily lost due to insufficient memory allocated to a trace logging session or a very high rate of incoming events.
DUMMYUNIONNAME2.DUMMYSTRUCTNAME.CpuSpeedInMHz
CPU speed, in megahertz, of the system where the trace was collected.
Windows 2000: This member is not supported.
LoggerName
Do not use this field.
The name of the event tracing session is the first null-terminated string following this structure in memory.
LogFileName
Do not use this field.
The name of the event tracing log file is the second null-terminated string following this structure in memory. The first string is the name of the session.
TimeZone
A TIME_ZONE_INFORMATION structure that contains the time zone for the BootTime, EndTime and StartTime members.
BootTime
Time at which the system was started, in 100-nanosecond intervals since midnight, January 1, 1601. BootTime is supported only for traces written to the Global Logger session.
PerfFreq
Frequency of the high-resolution performance counter, if one exists.
StartTime
Time at which the event tracing session started, in 100-nanosecond intervals since midnight, January 1, 1601.
ReservedFlags
Specifies the clock type. For details, see the ClientContext member of WNODE_HEADER.
BuffersLost
Total number of buffers lost during the event tracing session.
Remarks
Be sure to initialize the memory for this structure to zero before setting any members.
The first event from any log file contains the data defined in this structure. You can use this structure to access the event data or you can use the EventTrace_Header MOF class to decode the event data. Using this structure to read the event data may return unexpected results if the consumer is on a different computer from the one that generated the log file or the log file was written in a WOW (32-bit) session on a 64-bit computer. This is because the LoggerName and LogFileName members are pointers and can vary in size depending on the PointerSize member.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Header | evntrace.h |