int leader_init(){
char msg_buffer[strlen(PREAMBLE) + strlen(MSG) + strlen(LE) + UID_LEN + ROUND_LEN];
gossip_node_t* node;
node = gossip_get_neighbour(RANDOM);
while ( node && node->id == leader) {
DEBUG("D: random neighbour is: %d\n", node->id);
node = gossip_get_neighbour(RANDOM);
}
if(!node){
WARN("W: no non-leader neighbours, election init failed.\n");
return 1;
}
leader_set_leader( gossip_id );
DEBUG("D: initial leader: %d\n",leader);
DEBUG("D: round: %i\n", election_round);
sprintf(msg_buffer, "%s%s%s%0" ROUND_LEN_STR "i%0" UID_LEN_STR "i",
PREAMBLE, MSG, LE, election_round, leader);
int r=gossip_send(node, msg_buffer, strlen(msg_buffer));
if(r)
DEBUG("D: send failed\n");
return r;
}
void leader_elect(){
char msg_buffer[strlen(PREAMBLE) + strlen(MSG) + strlen(LE) + UID_LEN + ROUND_LEN];
gossip_node_t* node;
for(int i=0;i<ROUNDS;i++){
sprintf(msg_buffer, "%s%s%s%0" ROUND_LEN_STR "i%0" UID_LEN_STR "i",
PREAMBLE, MSG, LE, election_round, leader);
node = gossip_get_neighbour(RANDOM);
if(!node){
WARN("W: no neighbours, election failed.\n");
return;
}
gossip_send(node, msg_buffer, strlen(msg_buffer));
vtimer_usleep(1000*1000*10);
}
if( leader_get_leader() == gossip_id ){
timesync_set_trusted(1);
timesync_set_synced(1);
}
leader_set_active(0);
}
void do_gossip( CHAR_DATA * ch, char * argument ) {
gossip_send(ch->name, argument);
talk_channel( ch, argument, CHANNEL_GOSSIP, "gossip" );
return;
}
void leader_handle_msg(void* msg_text, size_t size, uint16_t src){
uint16_t received_leader;
uint16_t round;
gossip_node_t* node;
char round_buffer[3];
int len = strlen(PREAMBLE) + strlen(MSG) + strlen(LE) + size;
char* msg_buffer;
msg_buffer = malloc(len);
memset(msg_buffer, 0, len);
DEBUG("D: received msg of size %d\n",size);
/* we received something, that means LE started */
leader_set_initialized(1);
strncpy( round_buffer, (char*)msg_text+strlen(LE) , sizeof(round_buffer) );
round = atol(round_buffer);
DEBUG("D: got round %i (current round %i)\n",round,election_round);
// a new election round, invalidate leader and elect the next one
if(round > election_round) { // TODO: fix possible overflow
DEBUG("D: got new election round %i (was %i)\n",round,election_round);
election_round = round;
leader_init();
free(msg_buffer);
return;
}
// got leader from an old round, inform sending node
if(round < election_round) { // TODO: fix possible overflow
DEBUG("D: got round %i (current is %i) informing sender\n",round,election_round);
sprintf(msg_buffer, "%s%s%s%0" ROUND_LEN_STR "i%0" UID_LEN_STR "i",
PREAMBLE, MSG, LE, election_round, leader);
node = gossip_find_node_by_id(src);
gossip_send(node, msg_buffer, strlen(msg_buffer));
free(msg_buffer);
return;
}
received_leader = atol((char*)msg_text+strlen(LE)+UID_LEN);
DEBUG("D: received candidate: %i\n",received_leader);
/* XXX: misuse MAX_UID as ACK identifier */
if(received_leader == MAX_UID){
free(msg_buffer);
return;
}
// TODO: add custom metrics functions here instead of a<b
if(received_leader < leader ){
DEBUG("D: discarding candidate and informing sender\n");
sprintf(msg_buffer, "%s%s%s%0" ROUND_LEN_STR "i%0" UID_LEN_STR "i",
PREAMBLE, MSG, LE, round, leader);
}
// update leader if we receive a better candidate
if(received_leader >= leader ){
DEBUG("D: adding a new, better leader\n");
leader_set_leader(received_leader);
sprintf(msg_buffer, "%s%s%s%0" ROUND_LEN_STR "i%0" UID_LEN_STR "i",
PREAMBLE, MSG, LE, round, MAX_UID);
}
node = gossip_find_node_by_id(src);
DEBUG("D: sending msg of size %d\n",strlen(msg_buffer));
gossip_send(node, msg_buffer, strlen(msg_buffer));
free(msg_buffer);
}