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 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 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.