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PMATOMSTR(3) Library Functions Manual PMATOMSTR(3)


pmAtomStr, pmAtomStr_r - convert a performance metric value into a string


#include <pcp/pmapi.h>

const char *pmAtomStr(const pmAtomValue *avp, int type);
char *pmAtomStr_r(const pmAtomValue *avp, int type, char *buf, int buflen);

cc ... -lpcp


All performance metric values may be encoded in a pmAtomValue union, defined as follows;

typedef union {
__int32_t l; /* 32-bit signed */
__uint32_t ul; /* 32-bit unsigned */
__int64_t ll; /* 64-bit signed */
__uint64_t ull; /* 64-bit unsigned */
float f; /* 32-bit floating point */
double d; /* 64-bit floating point */
char *cp; /* char ptr */
pmValueBlock *vbp; /* pmValueBlock ptr */ } pmAtomValue;

Given the performance metric value pointed to by avp, and a performance metric type defined by type, pmAtomStr will generate the corresponding metric value as a string, suitable for diagnostic or report output. The pmAtomStr_r function does the same, but stores the result in a user-supplied buffer buf of length buflen, which should have room for at least 80 bytes.

The value for type is typically extracted from a pmDesc structure, following a call to pmLookupDesc(3) for a particular performance metric.

If the type is PM_TYPE_STRING values longer than 38 characters will be truncated after 34 characters, and truncation shown with ellipsis ``...'' at the end of the value.

If the type is PM_TYPE_AGGREGATE then up to the first three 32-bit words are displayed as hexadecimal values.

If the type is PM_TYPE_EVENT then a summary of the number of event records found in the value is generated.

The return value from pmAtomStr is held in a single static buffer, so the returned value is only valid until the next call to pmAtomStr.


pmAtomStr returns a pointer to a static buffer and hence is not thread-safe. Multi-threaded applications should use pmAtomStr_r instead.


PMAPI(3), pmConvScale(3), pmExtractValue(3), pmLookupDesc(3), pmPrintValue(3), pmTypeStr(3) and pmUnitsStr(3).

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