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pmdaattribute(3) [centos man page]

PMDAATTRIBUTE(3)					     Library Functions Manual						  PMDAATTRIBUTE(3)

pmdaAttribute - informs a PMDA about client connection attributes C SYNOPSIS
#include <pcp/pmapi.h> #include <pcp/impl.h> #include <pcp/pmda.h> int pmdaAttribute(int context, int key, char *value, int length, pmdaExt *pmda); cc ... -lpcp_pmda -lpcp DESCRIPTION
As part of the Performance Metrics Domain Agent (PMDA) API (see PMDA(3)), pmdaAttribute is the generic callback for responding to client connection attributes. These attributes include client credential information, such as user ID and group ID. A PMDA that supports connection attributes will provide a private pmdaAttribute callback by assignment to version.six.attribute of the pmdaInterface structure, and implement custom logic for any of the attribute key-value pairs of interest to it. All attributes are associated with a specific client context, and these can be uniquely identified using the ctx first argument. The PMDA should track client connections, and disconnections using the pmdaSetEndContextCallBack(3) interface, as a result. The pmdaGetContext(3) interface may be particularly helpful also. All attributes are passed as key-value pairs and the value is always passed as a null-terminated string of given length. This includes numeric attributes like the user ID. The most commonly used attributes would be PCP_ATTR_USERID and PCP_ATTR_GROUPID but others may also be optionally passed (such as PCP_ATTR_USERNAME) if they are available. Some attributes will be consumed by pmcd and never through passed to PMDAs, such as PCP_ATTR_PASSWORD. A complete list of all possible attributes can be found in the headers listed above, all are prefixed by PCP_ATTR. DIAGNOSTICS
pmdaAttribute should return either zero on success, or a negative return code to indicate an error in handling the attribute. This return code cannot be used to indicate a client should be disallowed access - such functionality must be performed by the agent in response to callbacks for the client in question (using PM_ERR_PERMISSION for those specific callbacks, for that specific client. In other words, errors will be be passed to PMCD but there is no guarantee made that the error will be return to the client and result in termination of the client, for example. CAVEAT
The PMDA must be using PMDA_PROTOCOL_6 or later, as specified in the call to pmdaDSO(3) or pmdaDaemon(3). SEE ALSO
PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3) and pmdaGetContext(3). Performance Co-Pilot PCP PMDAATTRIBUTE(3)

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PMDACHILDREN(3) 					     Library Functions Manual						   PMDACHILDREN(3)

pmdaChildren - translate a PMID to a set of dynamic performance metric names C SYNOPSIS
#include <pcp/pmapi.h> #include <pcp/impl.h> #include <pcp/pmda.h> int pmdaChildren(char *name, int traverse, char ***offspring, int **status, pmdaExt *pmda); cc ... -lpcp_pmda -lpcp DESCRIPTION
As part of the Performance Metrics Domain Agent (PMDA) API (see PMDA(3)), pmdaChildren is the generic callback for returning dynamic metric names (and their status) that are descendants of name. Because implementing dynamic performance metrics requires specific PMDA support, and the facility is an optional component of a PMDA (most PMDAs do not support dynamic performance metrics), pmdaChildren is a skeleton implementation that returns PM_ERR_NAME. A PMDA that supports dynamic performance metrics will provide a private callback that replaces pmdaChildren (by assignment to ver- sion.four.children of the pmdaInterface structure) and takes the initial metric name and returns names via offspring[] and the leaf or non- leaf status of each via status[]. If traverse is 0, then the behaviour is akin to pmGetChildren(3) and offspring[] contains the relative name component for the immediate de- scendants of name. If traverse is 1, then the behaviour is akin to pmTraversePMNS(3) and offspring[] contains the absolute names of all dynamic metrics that are decedents of name. The resulting list of pointers offspring and the values (the names) that the pointers reference will have been allocated by pmdaChildren with a single call to malloc(3C), and the caller of pmdaChildren will call free(offspring) to release the space when it is no longer re- quired. The same holds true for the status array. DIAGNOSTICS
pmdaChildren returns PM_ERR_NAME if the name is not recognized or cannot be translated, otherwise the number of descendent metric names found. CAVEAT
The PMDA must be using PMDA_PROTOCOL_4 or later, as specified in the call to pmdaDSO(3) or pmdaDaemon(3). SEE ALSO
PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3), pmGetChildren(3) and pmTraversePMNS(3). Performance Co-Pilot PCP PMDACHILDREN(3)
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