As part of the Performance Metrics Domain Agent (PMDA) API (see
PMDA(3)), pmdaChildren is the generic callback for returning dynamic
metric names (and their status) that are descendants of name.
Because implementing dynamic performance metrics requires specific
PMDA support, and the facility is an optional component of a PMDA
(most PMDAs do not support dynamic performance metrics), pmdaChildren
is a skeleton implementation that returns PM_ERR_NAME.
A PMDA that supports dynamic performance metrics will provide a
private callback that replaces pmdaChildren (by assignment to
version.four.children of the pmdaInterface structure) and takes the
initial metric name and returns names via offspring and the leaf or
non-leaf status of each via status.
If traverse is 0, then the behaviour is akin to pmGetChildren(3) and
offspring contains the relative name component for the immediate
descendants of name.
If traverse is 1, then the behaviour is akin to pmTraversePMNS(3) and
offspring contains the absolute names of all dynamic metrics that
are decedents of name.
The resulting list of pointers offspringand the values (the names)
that the pointers reference will have been allocated by pmdaChildren
with a single call to malloc(3), and the caller of pmdaChildren will
call free(offspring) to release the space when it is no longer
required. The same holds true for the status array.
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