PMTRAVERSEPMNS(3) Library Functions Manual PMTRAVERSEPMNS(3)
pmTraversePMNS, pmTraversePMNS_r - traverse the performance metrics name space
#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
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 and pmTraversePMNS_r return the number of leaf nodes found in the traversal, which will be one (1) if name is either a leaf node, or a derived metric or a non-leaf node with one child. If name is a non-leaf node, the returned value will be zero or greater (zero is returned in the special case where name is a dynamic root node that currently has no children). In all cases, derived metrics present in the PMNS subtree below name are counted as leaf-nodes. If an an error occurs, pmTraversePMNS and pmTraversePMNS_r will return a negative error code, as described in the DIAGNOSTICS section below.
PMAPI(3) and pmGetChildren(3).
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.
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Pages that refer to this page: pcp-mpstat(1), pmdachildren(3), pmdainit(3), pmgetderivedcontrol(3)