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NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | FILES | SEE ALSO | COLOPHON |
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PMDISCOVERSETUP(3) Library Functions Manual PMDISCOVERSETUP(3)
pmDiscoverSetup, pmDiscoverSetSlots, pmDiscoverSetEventLoop,
pmDiscoverSetConfiguration, pmDiscoverSetMetricRegistry,
pmDiscoverClose - asynchronous archive location and contents
discovery services
#include <pcp/pmwebapi.h>
int pmDiscoverSetup(pmDiscoverModule *module, pmDiscoverCallBacks
*callbacks, void *arg);
int pmDiscoverSetSlots(pmDiscoverModule *module, void *slots);
int pmDiscoverSetEventLoop(pmDiscoverModule *module, void
*uvloop);
int pmDiscoverSetConfiguration(pmDiscoverModule *module, struct
dict *config);
int pmDiscoverSetMetricRegistry(pmDiscoverModule *module, struct
mmv_registry *registry);
int pmDiscoverClose(pmDiscoverModule *module);
cc ... -lpcp_web
The pmDiscoverSetup and related functions are an integral part of
the libpcp_web API library, as used by and described in
pmwebapi(3), pmproxy(1), pmseries(1) and elsewhere. These func‐
tions provide an asynchronous event driven mechanism to automati‐
cally discover PCP archives created by pmlogger(1) and any other
application capable of writing PCP archives. This includes
pmrep(1) and other applications using the LOGIMPORT(3) API for
importing performance data into the PCP infrastructure and writ‐
ing PCP archives.
The pmDiscover API services dynamically discover, monitor and
manage directories of PCP archives as they are created, written
to, compressed and eventually deleted. The underlying archive
life-cycle is normally managed by the PCP archive management in‐
frastructure (see pmlogger_daily(1)). Discovered archives that
are active (currently being written) are "log-tailed" to extract
near live/real-time performance data which is then passed off via
registered callbacks for further processing, e.g. to add the data
to a redis-server(1) instance. Archives that are compressed or
inactive are tracked/monitored but not log-tailed - this is be‐
cause compressed archives never grow and so log-tailing would
never discover any new data. See the --load option in
pmseries(1) for a supported mechanism for ingesting previously
collected (inctive) PCP archives, whether compressed or not, into
a redis-server(1) instance.
The pmDiscover routines can be configured to automatically dis‐
cover and monitor PCP archives in one or more directories as
specified in the pmDiscoverModule, which is initially set up by
calling pmDiscoverSetConfiguration to create a module of type
pmDiscoverModule, as described above. The resulting module is
then passed to pmDiscoverSetup along with an initialized struc‐
ture of callbacks of type pmDiscoverCallBacks.
Setting up a discovery module and callbacks would normally de‐
clare an instance of pmDiscoverSettings, e.g.
#include <pcp/pmwebapi.h>
static pmDiscoverSettings someapp_discover = {
.callbacks.on_source = pmSomeappDiscoverSource,
.callbacks.on_closed = pmSomeappDiscoverClosed,
.callbacks.on_labels = pmSomeappDiscoverLabels,
.callbacks.on_metric = pmSomeappDiscoverMetric,
.callbacks.on_values = pmSomeappDiscoverValues,
.callbacks.on_indom = pmSomeappDiscoverInDom,
.callbacks.on_text = pmSomeappDiscoverText,
.module.on_info = someapp_logging_function,
};
And then initialize this with API calls similar to the following:
pmDiscoverSetEventLoop(&someapp_discover.module, myevents);
pmDiscoverSetConfiguration(&someapp_discover.module, myconfig);
pmDiscoverSetMetricRegistry(&someapp_discover.module, metric_registry);
pmDiscoverSetup(&someapp_discover.module, &someapp_discover.callbacks, &privatedata);
The above code must then implement each of the declared callbacks
etc. to do whatever is required with the data passed in to the
callback. Prototypes for these callbacks can be found in the
pmwebapi.h header. The callbacks will be made asynchronously, as
archives are discovered or deleted and as new data is written to
active archive volume and metadata files.
In the case of pmproxy(1), callbacks are registered to capture
performance data, which is then sent to redis-server(1) as the
database back-end for fast scalable time-series queries by
clients of the PMWEBAPI(3) REST API services. Such clients in‐
clude the pmseries(1) application and pmproxy(1), which is the
back-end REST API server for grafana-pcp, a native
grafana-server(1) data-source for PCP.
Generally zero on success, or on error a negative return code,
see pmerr(1).
The default archive directory is $PCP_ARCHIVE_DIR, which is nor‐
mally /var/log/pcp/pmlogger. The API recursively descends all
sub-directories and also dynamically discovers any new directo‐
ries or archives found therein.
grafana-server(1), pmerr(1), pmlogger(1), pmproxy(1),
pmseries(1), PMWEBAPI(3), mmv_stats_registry(3), PMAPI(3),
pmErrStr(3), pcp.conf(5) and pcp.env(5).
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
[email protected]. 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
[email protected]
Performance Co-Pilot PCP PMDISCOVERSETUP(3)
Pages that refer to this page: pmseriesquery(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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