.\"############################################################################ .\" $Id: genders_query.3,v 1.14 2010-02-02 00:04:34 chu11 Exp $ .\"############################################################################ .\" Copyright (C) 2007-2011 Lawrence Livermore National Security, LLC. .\" Copyright (C) 2001-2007 The Regents of the University of California. .\" Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). .\" Written by Jim Garlick and Albert Chu . .\" UCRL-CODE-2003-004. .\" .\" This file is part of Genders, a cluster configuration database. .\" For details, see . .\" .\" Genders is free software; you can redistribute it and/or modify it under .\" the terms of the GNU General Public License as published by the Free .\" Software Foundation; either version 2 of the License, or (at your option) .\" any later version. .\" .\" Genders is distributed in the hope that it will be useful, but WITHOUT ANY .\" WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS .\" FOR A PARTICULAR PURPOSE. See the GNU General Public License for more .\" details. .\" .\" You should have received a copy of the GNU General Public License along .\" with Genders. If not, see . .\"############################################################################ .TH GENDERS_QUERY 3 "June 2004" "LLNL" "LIBGENDERS" .SH NAME genders_query \- query genders database for a set of nodes .SH SYNOPSIS .B #include .sp .BI "int genders_query(genders_t handle, char *nodes[], int len, const char *query);" .br .SH DESCRIPTION \fBgenders_query()\fR queries the genders database for a set of nodes based on the union, intersection, difference, or complement of genders attributes and values. The query for a set of nodes is passed as a string through the \fIquery\fR parameter. The set operation union is represented by two pipe symbols ('||'), intersection by two ampersand symbols ('&&'), difference by two minus symbols ('--'), and complement by a tilde ('~'). Set operations are performed left to right. Parentheses may be used to change the order of operations. A list of query examples are listed below. A NULL query retrieves all nodes from the genders database. The nodes from the query are stored in the list pointed to by \fInodes\fR. \fIlen\fR indicates the number of nodes that can be stored in the list. To avoid passing in a list that is not large enough to store all the nodes, .BR genders_getnumnodes (3) should be used to determine the minimum number of elements \fInodes\fR should be able to store. .BR genders_nodelist_create (3) could be used to create a list that is guaranteed to be large enough to store all of the nodes. .br .SH EXAMPLES The following are example queries that can be passed to \fBgenders_query()\fR. .LP Determine the set of nodes with the mgmt or login attribute: "mgmt||login" .LP Determine the set of nodes that are not login nodes: "all--login" .LP Determine the set of nodes that both login nodes and ntp servers: "login&&ntpserv" .LP Determine the set of nodes that are not mgmt or login nodes: "~(mgmt||login)" .SH RETURN VALUES On success, the number of nodes stored in \fInodes\fR is returned. On error, -1 is returned, and an error code is returned in \fIhandle\fR. The error code can be retrieved via .BR genders_errnum (3) , and a description of the error code can be retrieved via .BR genders_strerror (3). Error codes are defined in genders.h. .br .SH ERRORS .TP .B GENDERS_ERR_NULLHANDLE The \fIhandle\fR parameter is NULL. The genders handle must be created with .BR genders_handle_create (3). .TP .B GENDERS_ERR_NOTLOADED .BR genders_load_data (3) has not been called to load genders data. .TP .B GENDERS_ERR_OVERFLOW The list pointed to by \fInodes\fR is not large enough to store all the nodes. .TP .B GENDERS_ERR_PARAMETERS An incorrect parameter has been passed in. .TP .B GENDERS_ERR_SYNTAX There is a syntax error in the query. .TP .B GENDERS_ERR_OUTMEM .BR malloc (3) has failed internally, system is out of memory. .TP .B GENDERS_ERR_NULLPTR A null pointer has been found in the list passed in. .TP .B GENDERS_ERR_MAGIC \fIhandle\fR has an incorrect magic number. \fIhandle\fR does not point to a genders handle or \fIhandle\fR has been destroyed by .BR genders_handle_destroy (3). .TP .B GENDERS_ERR_INTERNAL An internal system error has occurred. .br .SH FILES /usr/include/genders.h .SH SEE ALSO libgenders(3), genders_handle_create(3), genders_load_data(3), genders_getnumnodes(3), genders_nodelist_create(3), genders_errnum(3), genders_strerror(3)