/*检查超时的提案，进行重新提议*/
static void proposer_check_timeouts(evutil_socket_t fd, short event, void* arg)
{
struct evproposer* p = arg;
struct timeout_iterator* iter = proposer_timeout_iterator(p->state);
/*第一个阶段超时提案*/
prepare_req* pr;
while((pr == timeout_iterator_prepare(iter)) != NULL){ /*获取超时的提案(第一阶段)*/
paxos_log_info("Instance %d timed out.", pr->iid);
/*对超时提案重新发起提议过程*/
send_prepares(p, pr);
free(pr);
}
accept_req* ar;
while((ar = timeout_iterator_accept(iter)) != NULL){ /*获得超时提案(第二阶段)*/
paxos_log_info("Instance %d timed out.", ar->iid);
send_accepts(p, ar);
free(ar);
}
/*释放超时管理的迭代器*/
timeout_iterator_free(iter);
/*插入一个定时器*/
event_add(p->timeout_ev, &p->tv);
}
static void
proposer_handle_prepare_ack(struct evproposer* p, prepare_ack* ack)
{
prepare_req pr;
int preempted = proposer_receive_prepare_ack(p->state, ack, &pr);
if (preempted)
send_prepares(p, &pr);
}
static void
proposer_preexecute(struct evproposer* p)
{
int i;
prepare_req pr;
int count = p->preexec_window - proposer_prepared_count(p->state); //先进先出队列保存准备实例，队列长128，用一个释放一个，有空间了就把新的加到队列末尾。
if (count <= 0) return;
for (i = 0; i < count; i++) {
proposer_prepare(p->state, &pr); //发送prepare请求
send_prepares(p, &pr);
}
paxos_log_debug("Opened %d new instances", count);
}
static void proposer_preexecute(struct evproposer* p)
{
int i;
prepare_req pr;
/*获得可以发起提案的个数*/
int count = p->preexec_window - proposer_prepared_count(p->state);
for(i = 0; i < count; i ++){
/*构建一个prepare_req消息*/
proposer_prepare(p->state, &pr);
/*发起一个提案*/
send_prepares(p, &pr);
}
}
static void
proposer_check_timeouts(evutil_socket_t fd, short event, void *arg)
{
struct evproposer* p = arg;
struct timeout_iterator* iter = proposer_timeout_iterator(p->state);
prepare_req* pr;
while ((pr = timeout_iterator_prepare(iter)) != NULL) {
paxos_log_info("Instance %d timed out.", pr->iid);
send_prepares(p, pr);
free(pr);
}
accept_req* ar;
while ((ar = timeout_iterator_accept(iter)) != NULL) {
paxos_log_info("Instance %d timed out.", ar->iid);
send_accepts(p, ar);
free(ar);
}
timeout_iterator_free(iter);
event_add(p->timeout_ev, &p->tv); //Thus, if you want to make the event pending again, you can call event_add() on it again from inside the callback function.将超时事件重新加入
}
/*proposer对accept ack的处理和响应*/
static void proposer_handle_accept_ack(struct evproposer* p, accept_ack* ack)
{
prepare_req pr;
if (proposer_receive_accept_ack(p->state, ack, &pr))/*对accept ack的响应处理，判断返回值是否是需要重新发起第一阶段*/
send_prepares(p, &pr);
}