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NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMTRAVERSEPMNS(3) Library Functions Manual PMTRAVERSEPMNS(3)
pmTraversePMNS, pmTraversePMNS_r - traverse the performance
metrics name space
#include <pcp/pmapi.h>
int pmTraversePMNS(const char *name, void (*dometric)(const char *));
int pmTraversePMNS_r(const char *name, void (*dometric_r)(const char *, void *), void *closure);
cc ... -lpcp
The routine pmTraversePMNS may be used to perform a depth-first
traversal of the Performance Metrics Name Space (PMNS).
The traversal starts at the node identified by name - if name is
an empty string (i.e. ""), the traversal starts at the root of
the PMNS. Usually name would be the pathname of a non-leaf node
in the PMNS.
For each leaf node (i.e. performance metric) found in the
traversal, the user-supplied routine dometric is called with the
full pathname of that metric in the PMNS as the single argument.
This argument is null-byte terminated, and is constructed from a
buffer that is managed internally to pmTraversePMNS.
Consequently the value is only valid during the call to dometric
- if the pathname needs to be retained, it should be copied using
strdup(3) before returning from dometric.
The pmTraversePMNS_r routine performs the same function, except
the callback method func_r has an additional parameter that will
be closure from the initial call to pmTraversePMNS_r. The
additional parameter to pmTraversePMNS_r and the callback method
allows the caller to pass context through pmTraversePMNS_r and
into the callback method func_r, making the service more useful
for multi-threaded applications where thread-private data can be
accessed in the callback method via the closure argument.
On success pmTraversePMNS and pmTraversePMNS_r return the number
of leaf nodes found in the traversal, which will be one (1) if
name is either a leaf node, or a derived metric or a non-leaf
node with one child. If name is a non-leaf node, the returned
value will be zero or greater (zero is returned in the special
case where name is a dynamic root node that currently has no
children). In all cases, derived metrics present in the PMNS
subtree below name are counted as leaf-nodes. If an an error
occurs, pmTraversePMNS and pmTraversePMNS_r will return a
negative error code, as described in the DIAGNOSTICS section
below.
PM_ERR_NOPMNS
Failed to access a PMNS for operation. Note that if the
application hasn't a priori called pmLoadNameSpace(3) and
wants to use the distributed PMNS, then a call to
pmTraversePMNS must be made inside a current context.
PM_ERR_NAME
The initial pathname name is not valid in the current
PMNS.
PM_ERR_*
Other diagnostics are for protocol failures when accessing
the distributed PMNS.
PMAPI(3) and pmGetChildren(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 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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 PMTRAVERSEPMNS(3)
Pages that refer to this page: pcp-mpstat(1), pmdachildren(3), pmdainit(3), pmgetderivedcontrol(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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