// BlpPosition returns the current position for a controller, as read from
// the database.
func (bpc *BinlogPlayerController) BlpPosition(vtClient *binlogplayer.DBClient) (*blproto.BlpPosition, string, error) {
return binlogplayer.ReadStartPosition(vtClient, bpc.sourceShard.Uid)
}
// Iteration is a single iteration for the player: get the current status,
// try to play, and plays until interrupted, or until an error occurs.
func (bpc *BinlogPlayerController) Iteration() (err error) {
defer func() {
if x := recover(); x != nil {
log.Errorf("%v: caught panic: %v", bpc, x)
err = fmt.Errorf("panic: %v", x)
}
}()
// Apply any special settings necessary for playback of binlogs.
// We do it on every iteration to be sure, in case MySQL was restarted.
if err := bpc.mysqld.EnableBinlogPlayback(); err != nil {
// We failed to apply the required settings, so we shouldn't keep going.
return err
}
// create the db connection, connect it
vtClient := binlogplayer.NewDbClient(bpc.dbConfig)
if err := vtClient.Connect(); err != nil {
return fmt.Errorf("can't connect to database: %v", err)
}
defer vtClient.Close()
// Read the start position
startPosition, flags, err := binlogplayer.ReadStartPosition(vtClient, bpc.sourceShard.Uid)
if err != nil {
return fmt.Errorf("can't read startPosition: %v", err)
}
// if we shouldn't start, we just error out and try again later
if strings.Index(flags, binlogplayer.BLP_FLAG_DONT_START) != -1 {
return fmt.Errorf("not starting because flag '%v' is set", binlogplayer.BLP_FLAG_DONT_START)
}
// Find the server list for the source shard in our cell
addrs, err := bpc.ts.GetEndPoints(bpc.cell, bpc.sourceShard.Keyspace, bpc.sourceShard.Shard, topo.TYPE_REPLICA)
if err != nil {
return fmt.Errorf("can't find any source tablet for %v %v %v: %v", bpc.cell, bpc.sourceShard.String(), topo.TYPE_REPLICA, err)
}
if len(addrs.Entries) == 0 {
return fmt.Errorf("empty source tablet list for %v %v %v", bpc.cell, bpc.sourceShard.String(), topo.TYPE_REPLICA)
}
newServerIndex := rand.Intn(len(addrs.Entries))
port, ok := addrs.Entries[newServerIndex].NamedPortMap["vt"]
if !ok {
port = addrs.Entries[newServerIndex].NamedPortMap["_vtocc"]
}
addr := fmt.Sprintf("%v:%v", addrs.Entries[newServerIndex].Host, port)
// save our current server
bpc.playerMutex.Lock()
bpc.sourceTablet = topo.TabletAlias{
Cell: bpc.cell,
Uid: addrs.Entries[newServerIndex].Uid,
}
bpc.lastError = nil
bpc.playerMutex.Unlock()
// check which kind of replication we're doing, tables or keyrange
if len(bpc.sourceShard.Tables) > 0 {
// tables, first resolve wildcards
tables, err := bpc.mysqld.ResolveTables(bpc.dbName, bpc.sourceShard.Tables)
if err != nil {
return fmt.Errorf("failed to resolve table names: %v", err)
}
// tables, just get them
player := binlogplayer.NewBinlogPlayerTables(vtClient, addr, tables, startPosition, bpc.stopPosition, bpc.binlogPlayerStats)
return player.ApplyBinlogEvents(bpc.interrupted)
} else {
// the data we have to replicate is the intersection of the
// source keyrange and our keyrange
overlap, err := key.KeyRangesOverlap(bpc.sourceShard.KeyRange, bpc.keyRange)
if err != nil {
return fmt.Errorf("Source shard %v doesn't overlap destination shard %v", bpc.sourceShard.KeyRange, bpc.keyRange)
}
player := binlogplayer.NewBinlogPlayerKeyRange(vtClient, addr, bpc.keyspaceIdType, overlap, startPosition, bpc.stopPosition, bpc.binlogPlayerStats)
return player.ApplyBinlogEvents(bpc.interrupted)
}
}