int leader_handle_remove_neighbour(gossip_node_t* neighbour) {
if (neighbour->id == leader) {
// Leader was removed from neighbour table; start a new election
// round
election_round++;
// This obviously won't work as intended as of now;
// leader_elect() needs to be a thread. But this is the general
// idea.
leader_init();
}
return 1;
}
//This function is invoked when a new message is ready to be read
// from the leader election oracle UDP socket
static void
pro_handle_oracle_msg(int sock, short event, void *arg) {
//Make the compiler happy!
UNUSED_ARG(sock);
UNUSED_ARG(event);
UNUSED_ARG(arg);
assert(sock == from_oracle->sock);
//Read the next message
int valid = udp_read_next_message(from_oracle);
if (valid < 0) {
printf("Dropping invalid oracle message\n");
return;
}
//The message is valid, take the appropriate action
// based on the type
paxos_msg * msg = (paxos_msg*) &from_oracle->recv_buffer;
switch(msg->type) {
case leader_announce: {
leader_announce_msg * la = (leader_announce_msg *)msg->data;
if(LEADER_IS_ME && la->current_leader != this_proposer_id) {
//Some other proposer was nominated leader instead of this one,
// step down from leadership
leader_shutdown();
} else if (!LEADER_IS_ME
&& la->current_leader == this_proposer_id) {
//This proposer has just been promoted to leader
leader_init();
}
current_leader_id = la->current_leader;
}
break;
default: {
printf("Unknow msg type %d received from oracle\n", msg->type);
}
}
}
//Proposer initialization, this function is invoked by
// the underlying learner after it's normal initialization
static int init_proposer() {
//Add network events and prepare send buffer
if(init_pro_network() != 0) {
printf("Proposer network init failed\n");
return -1;
}
//Add additional timers to libevent loop
if(init_pro_fd_events() != 0){
printf("Proposer timers init failed\n");
return -1;
}
//Normal proposer initialization, private structures
if(init_pro_structs() != 0) {
printf("Proposer structs init failed\n");
return -1;
}
//By default, proposer 0 starts as leader,
// later on the failure detector may change that
if(LEADER_IS_ME) {
if(leader_init() != 0) {
printf("Proposer Leader init failed\n");
return -1;
}
}
//Call custom init (i.e. to register additional events)
if(client_custom_init != NULL && client_custom_init() != 0) {
printf("Error in client_custom_init\n");
return -1;
} else {
LOG(DBG, ("Custom init completed\n"));
}
return 0;
}
/*
* Place a swarm at start with a number of leaders that all have
* the same initial velocity.
*/
Swarm *swarm_create(Point *start, Vector *initVel, Module *shape,
int numLeaders, int numActorsPerLeader, float spread){
int i, j, id = 0, verbose = 1;
float genX, genY, genZ;
if(verbose) printf("creating swarm\n");
Swarm *s = malloc(sizeof(Swarm));
s->leaders = malloc(sizeof(Leader)*numLeaders);
s->actors = malloc(sizeof(Actor)*numActorsPerLeader*numLeaders);
s->numActors = numActorsPerLeader*numLeaders;
s->numLeaders = numLeaders;
for(i=0; i<numLeaders; i++){
genX = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
genY = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
genZ = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
leader_init(&(s->leaders[i]), shape);
leader_setLocation(&(s->leaders[i]),
start->val[0] + genX,
start->val[1] + genY,
start->val[2] + genZ);
leader_setVelocity(&(s->leaders[i]), initVel);
for(j=0; j<numActorsPerLeader; j++){
genX = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
genY = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
genZ = spread - ((double)rand() / RAND_MAX) * 2.0 * spread;
actor_init(&(s->actors[j+(i*numActorsPerLeader)]), &(s->leaders[i]), shape);
actor_setLocation(&(s->actors[j+(i*numActorsPerLeader)]),
start->val[0] + genX,
start->val[1] + genY,
start->val[2] + genZ);
actor_setID(&(s->actors[j+(i*numActorsPerLeader)]), id++);
}
}
return s;
}
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);
}
