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NAME | C SYNOPSIS | PYTHON SYNOPSIS | DESCRIPTION | PYTHON EXAMPLE | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMMERGELABELS(3) Library Functions Manual PMMERGELABELS(3)
pmMergeLabels, pmMergeLabelSets - merge sets of performance
metric labels
#include <pcp/pmapi.h>
int pmMergeLabels(char **sets, int nsets, char *buffer, int
length);
int pmMergeLabelSets(pmLabelSet **sets, int nsets, char *buffer,
int length, int (*filter)(const pmLabel *, const char *,
void *), void *arg);
cc ... -lpcp
from pcp import pmapi
buffer = pmapi.pmContext().pmMergeLabels(sets)
buffer = pmapi.pmContext().pmMergeLabelSets(sets, filter)
pmMergeLabels takes multiple (nsets) performance metric label
sets and merges them into a single result buffer of length bytes.
Both the input sets and the result buffer are name:value pairs in
the "JSONB" format described on pmLookupLabels(3).
The pmMergeLabelSets interface serves the same purpose, but
allows for indexed sets of labels to be merged. The format of
the pmLabelSet data structure is described in detail in
pmLookupLabels(3).
Although names may repeat across the provided label sets,
duplicate names are not allowed in the final buffer. Any label
names occuring in more than one of the input label sets are
reduced to one using the rules described in the "PRECEDENCE"
section of pmLookupLabels. The position of each element in the
sets array is significant in terms of the precedence rules -
earlier positions are taken to be of lower precedence to later
positions.
Values must be primitive JSON entities (e.g. numbers, strings),
one-dimensional arrays or maps (i.e. simple associative arrays).
In addition to using indexed label sets the pmMergeLabelSets
interface provides an optional filter callback function. If non-
NULL, this function will be called for each label that would be
added to the output buffer, allowing finer-grained control over
the final merged set. This mechanism can be used to filter
individual labels based on their name, value, and/or flags. If
the filter function returns zero (false), then the given label is
filtered from the resulting set. Any non-zero return value
indicates that the label should be included in the buffer.
import sys
import json
from pcp import pmapi
import cpmapi as c_api
def merge_callback(label, jsondata, data=None):
d = json.loads(jsondata)
labelsD.update(d)
return 0
ctx = pmapi.pmContext()
for metric in sys.argv[1:]:
pmid = ctx.pmLookupName(metric)[0]
lset = ctx.pmLookupLabels(pmid)
labelsD = {}
ctx.pmMergeLabelSets(lset, merge_callback)
print("== %s ===" % metric)
for n,v in labelsD.items():
print(" %s = %s" % (n,v))
ctx.pmFreeLabelSets(lset)
On success, both pmMergeLabels and pmMergeLabelSets returns the
number of bytes written into the supplied buffer.
Failure to parse the input strings, failure to allocate memory,
or any internal inconsistencies found will result in a negative
return code.
pminfo(1), PMAPI(3) and pmLookupLabels(3).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at
⟨http://www.pcp.io/⟩. If you have a bug report for this manual
page, send it to pcp@groups.io. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2020-12-18.
(At that time, the date of the most recent commit that was found
in the repository was 2020-12-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMMERGELABELS(3)
Pages that refer to this page: pmlookuplabels(3)
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