|
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
disconnections. If the PMDA is making use of the event queueing
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 example, 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
pmAtomValue 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.
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 2022-12-17.
(At that time, the date of the most recent commit that was found
in the repository was 2022-12-16.) 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 2022-12-18 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|