NAME

pmdaDSO - initialize the PMDA to run as a DSO

C SYNOPSIS

#include <pcp/pmapi.h>
#include <pcp/pmda.h>

int pmdaDSO(pmdaInterface *dispatch, int interface, char *name, char *helptext);

cc ... -lpcp_pmda -lpcp

DESCRIPTION

pmdaDSO initializes the pmdaInterface structure to use the interface extensions, assuming the PMDA(3) is to be run as a DSO. The pmdaInterface structure is initialized with:

name

The name of the agent.

helptext

The default path to the help text (see pmdaText(3)). If no help text is installed, or you are not using pmdaText(3), then this should be set to NULL, otherwise helptext will be copied, so the storage associated with helptext may be released after the call to pmdaDSO.

The callbacks are initialized to pmdaProfile(3), pmdaFetch(3), pmdaDesc(3), pmdaText(3), pmdaInstance(3) and pmdaStore(3).

The interface structure also contains the domain of the PMDA(3), which is defined in the pmcd(1) configuration file. The domain is used to initialize the metric and instance descriptors (see pmdaInit(3)).

DIAGNOSTICS

Incompatible version of pmcd detected

When pmcd(1) creates the pmdaInterface structure, the dispatch.comm.version field is set to the highest protocol that pmcd(1) understands. This message indicates that the pmcd(1) process does not understand the protocol used by pmdaDSO.

Unable to allocate memory for pmdaExt structure

In addition, dispatch->status is set to a value less than zero.

CAVEAT

The PMDA must be using PMDA_INTERFACE_2 or later.

Once pmdaDSO has been called, it is expected that the pmdaInterface structure pointed to by dispatch will remain accessible to the routines in libpcp_pmda (not reclaimed off the stack, not freed or oherwise released, etc.). If the caller needs to move or relocate the pmdaInterface structure for any reason, then after the move pmdaInterfaceMoved(3) must be called to resestablish the internal integrity of the pmdaInterface structure at the new location before any other routine in libpcp_pmda is called.

SEE ALSO

pmcd(1), PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaInit(3), pmdaInterfaceMoved(3) and pmdaText(3).