pmReceiveTraversePMNS(3) traverse the performance metrics name space

Other Alias

pmTraversePMNS, pmRequestTraversePMNS


#include <pcp/pmapi.h>

int pmTraversePMNS(const char *name, void (*dometric)(const char *))
int pmRequestTraversePMNS(int ctx, const char *name)
int pmReceiveTraversePMNS(int ctx, void (*dometric)(const char *))

cc ... -lpcp


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(3C) before returning from dometric.

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

pmRequestTraversePMNS and pmReceiveTraversePMNS are used by applications which must communicate with the PMCD asynchronously. These functions take explict context handle ctx which must refer to a host context (i.e. created by passing PM_CONTEXT_HOST to pmNewContext). pmRequestTraversePMNS sends request to PMCD to return sub-tree of PMNS and returns without waiting for the response, pmReceiveTraversePMNS reads reply from PMCD and executes depth-first traversal over returned sub-tree. It is the responsibility of the application to make sure the data are ready before calling pmReceiveTraversePMNS.

Unlike its synchronous counterpart pmTraversePMNS, pmReceiveTraversePMNS does not perform any additional queries to provide compatibility with older versions of PCP, it is the responsibility of an application to implement additional traversals.


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.
The initial pathname name is not valid in the current PMNS.
Other diagnostics are for protocol failures when accessing the distributed PMNS.
Context is currently in use by another asynchronous call.