|
HTML rendering created 2025-09-06 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. |
|
|
NAME | C SYNOPSIS | DESCRIPTION | SEE ALSO | COLOPHON |
|
|
|
PMDAEVENTCLIENT(3) Library Functions Manual PMDAEVENTCLIENT(3)
pmdaEventNewClient, pmdaEventEndClient, pmdaEventClients - client
context tracking interfaces for event queues
#include <pcp/pmapi.h>
#include <pcp/pmda.h>
int pmdaEventNewClient(int context);
int pmdaEventEndClient(int context);
int pmdaEventClients(pmAtomValue *avp);
cc ... -lpcp_pmda -lpcp
A Performance Metrics Domain Agent (PMDA) that exports event
records needs to track which clients are connected to it, in order
that it can track which events have been sent to which clients so
far. Only once an event has been sent to all monitoring tools
that registered an interest can the event be discarded and any
memory reclaimed.
The PMDA(3) library provides callback routines for PMDA developers
to provide custom handling of client connections and disconnec‐
tions. If the PMDA is making use of the event queuing mechanism
provided by pmdaEventNewQueue(3) and friends, client connections
and disconnections must be tracked via calls to pmdaEventNewClient
and pmdaEventEndClient respectively. This allows the library to
keep track of when events can be discarded from a queue, for exam‐
ple, for the context specified. This parameter is passed into the
e_endCallBack function directly, and for other callback functions
is available via the e_context field of the pmdaExt structure.
Additionally, it can be queried at any time using
pmdaGetContext(3).
Sometimes it is useful for the PMDA to export a metric indicating
the current count of attached clients - this is available using
the pmdaEventClients routine, which will fill in the avp pmAtom‐
Value structure on behalf of a PMDA fetch callback routine.
pmdaEventNewArray(3), pmdaEventNewQueue(3), PMAPI(3), PMDA(3) and
pmEventFlagsStr(3).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) 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 PMDAEVENTCLIENT(3)
Pages that refer to this page: pmdaeventarray(3), pmdaeventqueue(3)
|
HTML rendering created 2025-09-06 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. |
|