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pmAtomStr(3)

Performance Co-Pilot
Aliases: pmatomstr(3), pmatomstr(3), pmAtomStr_r(3), pmAtomStr_r(3)

libpcp3-dev

Performance Co-Pilot library and headers

pcp-doc

Documentation and tutorial for the Performance Co-Pilot

NAME

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

C SYNOPSIS

#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

DESCRIPTION

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.

NOTES

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