PdhReadRawLogRecord function (pdh.h)

Article
02/22/2024

Reads the information in the specified binary trace log file.

Syntax

PDH_FUNCTION PdhReadRawLogRecord(
  [in]  PDH_HLOG            hLog,
  [in]  FILETIME            ftRecord,
  [out] PPDH_RAW_LOG_RECORD pRawLogRecord,
  [in]  LPDWORD             pdwBufferLength
);

Parameters

[in] hLog

Handle to the log file. The PdhOpenLog or PdhBindInputDataSource function returns this handle.

[in] ftRecord

Time stamp of the record to be read. If the time stamp does not match a record in the log file, the function returns the record that has a time stamp closest to (but not greater than) the given time stamp.

[out] pRawLogRecord

Caller-allocated buffer that receives a PDH_RAW_LOG_RECORD structure; the structure contains the log file record information. Set to NULL if pdwBufferLength is zero.

[in] pdwBufferLength

Size of the pRawLogRecord buffer, in TCHARs. If zero on input, the function returns PDH_MORE_DATA and sets this parameter to the required buffer size. If the buffer is larger than the required size, the function sets this parameter to the actual size of the buffer that was used. If the specified size on input is greater than zero but less than the required size, you should not rely on the returned size to reallocate the buffer.

Return value

If the function succeeds, it returns ERROR_SUCCESS.

If the function fails, the return value is a system error code or a PDH error code. The following are possible values.

Return code	Description
PDH_INVALID_ARGUMENT	A parameter is not valid. For example, on some releases you could receive this error if the specified size on input is greater than zero but less than the required size.
PDH_MORE_DATA	The pRawLogRecord buffer is too small to contain the path elements. This return value is expected if pdwBufferLength is zero on input. If the specified size on input is greater than zero but less than the required size, you should not rely on the returned size to reallocate the buffer.
PDH_MEMORY_ALLOCATION_FAILURE	Unable to allocate memory in order to complete the function.

Remarks

You should call this function twice, the first time to get the required buffer size (set pRawLogRecord to NULL and pdwBufferLength to 0), and the second time to get the data.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	pdh.h
Library	Pdh.lib
DLL	Pdh.dll