// open opens the the in-memory or file-based database.
func (s *Store) open() (*sql.DB, error) {
var db *sql.DB
var err error
if !s.dbConf.Memory {
// as it will be rebuilt from (possibly) a snapshot and committed log entries.
if err := os.Remove(s.dbPath); err != nil && !os.IsNotExist(err) {
return nil, err
}
db, err = sql.OpenWithDSN(s.dbPath, s.dbConf.DSN)
if err != nil {
return nil, err
}
s.logger.Println("SQLite database opened at", s.dbPath)
} else {
db, err = sql.OpenInMemoryWithDSN(s.dbConf.DSN)
if err != nil {
return nil, err
}
s.logger.Println("SQLite in-memory database opened")
}
return db, nil
}
// Restore restores the node to a previous state.
func (s *Store) Restore(rc io.ReadCloser) error {
if err := s.db.Close(); err != nil {
return err
}
// Get size of database.
var sz uint64
if err := binary.Read(rc, binary.LittleEndian, &sz); err != nil {
return err
}
// Now read in the database file data and restore.
database := make([]byte, sz)
if _, err := io.ReadFull(rc, database); err != nil {
return err
}
var db *sql.DB
var err error
if !s.dbConf.Memory {
// Write snapshot over any existing database file.
if err := ioutil.WriteFile(s.dbPath, database, 0660); err != nil {
return err
}
// Re-open it.
db, err = sql.OpenWithDSN(s.dbPath, s.dbConf.DSN)
if err != nil {
return err
}
} else {
// In memory. Copy to temporary file, and then load memory from file.
f, err := ioutil.TempFile("", "rqlilte-snap-")
if err != nil {
return err
}
f.Close()
defer os.Remove(f.Name())
if err := ioutil.WriteFile(f.Name(), database, 0660); err != nil {
return err
}
// Load an in-memory database from the snapshot now on disk.
db, err = sql.LoadInMemoryWithDSN(f.Name(), s.dbConf.DSN)
if err != nil {
return err
}
}
s.db = db
// Read remaining bytes, and set to cluster meta.
b, err := ioutil.ReadAll(rc)
if err != nil {
return err
}
return func() error {
s.metaMu.Lock()
defer s.metaMu.Unlock()
return json.Unmarshal(b, &s.meta)
}()
}
// Open opens the store. If enableSingle is set, and there are no existing peers,
// then this node becomes the first node, and therefore leader, of the cluster.
func (s *Store) Open(enableSingle bool) error {
if err := os.MkdirAll(s.raftDir, 0755); err != nil {
return err
}
// Create the database. Unless it's a memory-based database, it must be deleted
var db *sql.DB
var err error
if !s.dbConf.Memory {
// as it will be rebuilt from (possibly) a snapshot and committed log entries.
if err := os.Remove(s.dbPath); err != nil && !os.IsNotExist(err) {
return err
}
db, err = sql.OpenWithDSN(s.dbPath, s.dbConf.DSN)
if err != nil {
return err
}
s.logger.Println("SQLite database opened at", s.dbPath)
} else {
db, err = sql.OpenInMemoryWithDSN(s.dbConf.DSN)
if err != nil {
return err
}
s.logger.Println("SQLite in-memory database opened")
}
s.db = db
// Setup Raft configuration.
config := raft.DefaultConfig()
// Check for any existing peers.
peers, err := readPeersJSON(filepath.Join(s.raftDir, "peers.json"))
if err != nil {
return err
}
s.joinRequired = len(peers) <= 1
// Allow the node to entry single-mode, potentially electing itself, if
// explicitly enabled and there is only 1 node in the cluster already.
if enableSingle && len(peers) <= 1 {
s.logger.Println("enabling single-node mode")
config.EnableSingleNode = true
config.DisableBootstrapAfterElect = false
}
// Setup Raft communication.
transport := raft.NewNetworkTransport(s.raftTransport, 3, 10*time.Second, os.Stderr)
// Create peer storage.
peerStore := raft.NewJSONPeers(s.raftDir, transport)
// Create the snapshot store. This allows Raft to truncate the log.
snapshots, err := raft.NewFileSnapshotStore(s.raftDir, retainSnapshotCount, os.Stderr)
if err != nil {
return fmt.Errorf("file snapshot store: %s", err)
}
// Create the log store and stable store.
logStore, err := raftboltdb.NewBoltStore(filepath.Join(s.raftDir, "raft.db"))
if err != nil {
return fmt.Errorf("new bolt store: %s", err)
}
// Instantiate the Raft system.
ra, err := raft.NewRaft(config, s, logStore, logStore, snapshots, peerStore, transport)
if err != nil {
return fmt.Errorf("new raft: %s", err)
}
s.raft = ra
return nil
}