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PdhGetDefaultPerfCounterHW function (pdh.h)

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Retrieves the name of the default counter for the specified object. This name can be used to set the initial counter selection in the Browse Counter dialog box.

This function is identical to PdhGetDefaultPerfCounter, except that it supports the use of handles to data sources.

Syntax

PDH_FUNCTION PdhGetDefaultPerfCounterHW(
  [in]      PDH_HLOG hDataSource,
  [in]      LPCWSTR  szMachineName,
  [in]      LPCWSTR  szObjectName,
  [out]     LPWSTR   szDefaultCounterName,
  [in, out] LPDWORD  pcchBufferSize
);

Parameters

[in] hDataSource

Should be NULL.

If you specify a log file handle, szDefaultCounterName 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.

[in] szObjectName

Null-terminated string that specifies the name of the object whose default counter name you want to retrieve.

[out] szDefaultCounterName

Caller-allocated buffer that receives the null-terminated default counter name. Set to NULL if pcchBufferSize is zero.

[in, out] pcchBufferSize

Size of the szDefaultCounterName 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_MORE_DATA
 The szDefaultCounterName buffer is too small to contain the counter 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.
PDH_INVALID_ARGUMENT
 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.
PDH_MEMORY_ALLOCATION_FAILURE
 Unable to allocate memory in order to complete the function.
PDH_CSTATUS_NO_MACHINE
 The specified computer is offline or unavailable.
PDH_CSTATUS_NO_COUNTERNAME
 The default counter name cannot be read or found.
PDH_CSTATUS_NO_OBJECT
 The specified object could not be found.
PDH_CSTATUS_NO_COUNTER
 The object did not specify a default counter.

Remarks

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

Note

The pdh.h header defines PdhGetDefaultPerfCounterH 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

See also

PdhBindInputDataSource

PdhBrowseCountersH

PdhGetDefaultPerfObjectH