pmTraversePMNS man page

pmTraversePMNS, pmTraversePMNS_r — traverse the performance metrics name space

C Synopsis

#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

Description

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 returns the number of children of name, which may be zero.

See Also

PMAPI(3) and pmGetChildren(3).

Diagnostics

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.

Referenced By

pcp-mpstat(1), pmdaChildren(3).

pmtraversepmns(3) is an alias of pmTraversePMNS(3).

PCP Performance Co-Pilot