static int
lmdb_storage_get(void* handle, iid_t iid, paxos_accepted* out)
{
struct lmdb_storage* s = handle;
int result;
MDB_val key, data;
memset(&data, 0, sizeof(data));
key.mv_data = &iid;
key.mv_size = sizeof(iid_t);
if ((result = mdb_get(s->txn, s->dbi, &key, &data)) != 0) {
if (result == MDB_NOTFOUND) {
paxos_log_debug("There is no record for iid: %d", iid);
} else {
paxos_log_error("Could not find record for iid: %d : %s",
iid, mdb_strerror(result));
}
return 0;
}
paxos_accepted_from_buffer(data.mv_data, out);
assert(iid == out->iid);
return 1;
}
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);
}
acceptor_record*
storage_get_record(struct storage* s, iid_t iid)
{
int flags, result;
DBT dbkey, dbdata;
DB* dbp = s->db;
DB_TXN* txn = s->txn;
acceptor_record* record_buffer = NULL;
memset(&dbkey, 0, sizeof(DBT));
memset(&dbdata, 0, sizeof(DBT));
//Key is iid
dbkey.data = &iid;
dbkey.size = sizeof(iid_t);
//Force copy to the specified buffer
dbdata.flags = DB_DBT_MALLOC;
//Read the record
flags = 0;
result = dbp->get(dbp,
txn,
&dbkey,
&dbdata,
flags);
if (result == DB_NOTFOUND || result == DB_KEYEMPTY) {
paxos_log_debug("The record for iid: %d does not exist", iid);
return NULL;
} else if (result != 0) {
paxos_log_error("Error while reading record with iid%u : %s",
iid, db_strerror(result));
return NULL;
}
record_buffer = (acceptor_record*) dbdata.data;
assert(record_buffer != NULL);
//Record found
assert(iid == record_buffer->iid);
return record_buffer;
}
