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/* majority.c: quorum module
* policy --- if it has more than half of total number of nodes, you have the quorum
* if you have exactly half othe total number of nodes, you don't have the quorum
* otherwise you have a tie
*
* Copyright (C) 2005 Guochun Shi <gshi@ncsa.uiuc.edu>
*
* SECURITY NOTE: It would be very easy for someone to masquerade as the
* device that you're pinging. If they don't know the password, all they can
* do is echo back the packets that you're sending out, or send out old ones.
* This does mean that if you're using such an approach, that someone could
* make you think you have quorum when you don't during a cluster partition.
* The danger in that seems small, but you never know ;-)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <portability.h>
#include <pils/plugin.h>
#include <clplumbing/cl_log.h>
#include <string.h>
#include <clplumbing/cl_quorum.h>
#define PIL_PLUGINTYPE HB_QUORUM_TYPE
#define PIL_PLUGINTYPE_S HB_QUORUM_TYPE_S
#define PIL_PLUGIN majority
#define PIL_PLUGIN_S "majority"
#define PIL_PLUGINLICENSE LICENSE_LGPL
#define PIL_PLUGINLICENSEURL URL_LGPL
static struct hb_quorum_fns majorityOps;
PIL_PLUGIN_BOILERPLATE2("1.0", Debug)
static const PILPluginImports* PluginImports;
static PILPlugin* OurPlugin;
static PILInterface* OurInterface;
static struct hb_media_imports* OurImports;
static void* interfprivate = NULL;
#define LOG PluginImports->log
#define MALLOC PluginImports->alloc
#define STRDUP PluginImports->mstrdup
#define FREE PluginImports->mfree
PIL_rc
PIL_PLUGIN_INIT(PILPlugin*us, const PILPluginImports* imports);
PIL_rc
PIL_PLUGIN_INIT(PILPlugin*us, const PILPluginImports* imports)
{
/* Force the compiler to do a little type checking */
(void)(PILPluginInitFun)PIL_PLUGIN_INIT;
PluginImports = imports;
OurPlugin = us;
/* Register ourself as a plugin */
imports->register_plugin(us, &OurPIExports);
/* Register our interface implementation */
return imports->register_interface(us, PIL_PLUGINTYPE_S,
PIL_PLUGIN_S,
&majorityOps,
NULL,
&OurInterface,
(void*)&OurImports,
interfprivate);
}
static int
majority_getquorum(const char* cluster
, int member_count, int member_quorum_votes
, int total_node_count, int total_quorum_votes)
{
cl_log(LOG_DEBUG, "quorum plugin: majority");
cl_log(LOG_DEBUG, "cluster:%s, member_count=%d, member_quorum_votes=%d",
cluster, member_count, member_quorum_votes);
cl_log(LOG_DEBUG, "total_node_count=%d, total_quorum_votes=%d",
total_node_count, total_quorum_votes);
if(member_count >= total_node_count/2 + 1){
return QUORUM_YES;
} else if ( total_node_count % 2 == 0 && member_count == total_node_count/2){
return QUORUM_TIE;
}
return QUORUM_NO;
}
static struct hb_quorum_fns majorityOps ={
majority_getquorum
};
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