Manpage of LIBCLUSTER

LIBCLUSTER

Section: OpenSSI Prog Manual (3ssi)
Updated: 30 October 2003

NAME

cluster_membership - returns list of nodes in the UP state

SYNOPSIS

#include <sys/cluster.h>

int cluster_membership(transid_t *transid, int arraylength,
    clusternode_t *membershiparray)

cc [flag ...] file -lcluster [library ...]

DESCRIPTION

The cluster_membership function stores in the location pointed to by membershiparray a list of nodes that are in the CLUSTERNODE_UP state at the time of the call. The cluster_membership function fills the array with the node numbers of the nodes that are in the UP state. For example, if the array has six elements but only two nodes are up (nodes 1 and 2), membershiparray[0] equals 1, membershiparray[1] equals 2, and membershiparray[2-5] equals 0. The application can check the filled-in membershiparray to see which nodes are up. A value of zero (0) terminates the list of UP nodes.

It returns in transid the membership transition ID that identifies the last membership transition that occurred in the cluster prior to the call to cluster_membership. The transition ID serves as a label for the membership list and can be used in other Cluster API functions. For example, the transid can be used in a call to cluster_transition(3ssi) to determine what has changed since that point. If the membership transition ID is NULL, no membership transition ID is returned.

For details about node states and transitions, see the cluster(8ssi) manual page. The value for the arraylength parameter should be obtained by a call to cluster_maxnodes(3ssi)

PARAMETERS

transid: A pointer to the returned transition ID that identifies the last membership transition that occurred in the cluster prior to a call to cluster_membership. This value can be NULL.
arraylength: The number of elements in membershiparray. Obtain this number with a call to cluster_maxnodes(3ssi).
membershiparray: A pointer to the array of nodes in the cluster that are in the UP state.

RETURN VALUE

The cluster_membership function returns the number of UP nodes on success, or -1 if an error occurred (in which case, errno is set appropriately).

ERRORS

EINVAL: if arraylength is less than the number of nodes currently in the UP state. If this function fails, transid and membershiparray are not modified.