PdhGetDefaultPerfObjectHW function (pdh.h)
Retrieves the name of the default object. This name can be used to set the initial object selection in the Browse Counter dialog box.
This function is identical to the PdhGetDefaultPerfObject function, except that it supports the use of handles to data sources.
Syntax
PDH_FUNCTION PdhGetDefaultPerfObjectHW(
[in] PDH_HLOG hDataSource,
[in] LPCWSTR szMachineName,
[out] LPWSTR szDefaultObjectName,
[in, out] LPDWORD pcchBufferSize
);
Parameters
[in] hDataSource
Should be NULL.
If you specify a log file handle, szDefaultObjectName will be a null string.
[in] szMachineName
Null-terminated string that specifies the name of the computer used to verify the object name. If NULL, the local computer is used to verify the name.
[out] szDefaultObjectName
Caller-allocated buffer that receives the null-terminated default object name. Set to NULL if pcchBufferSize is zero.
Note that PDH always returns Processor for the default object name.
[in, out] pcchBufferSize
Size of the szDefaultObjectName 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 |
|---|---|
|
The szDefaultObjectName buffer is too small to contain the object name. This return value is expected if pcchBufferSize 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. |
|
A required 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. |
|
Unable to allocate memory in order to complete the function. |
|
The specified computer is offline or unavailable. |
|
The default object name cannot be read or found. |
Remarks
You should call this function twice, the first time to get the required buffer size (set szDefaultObjectName to NULL and pcchBufferSize to 0), and the second time to get the data.
Note
The pdh.h header defines PdhGetDefaultPerfObjectH as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
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 |