// BinlogInfo returns the filename and position for a Google MySQL group_id.
// This command only exists in Google MySQL.
func (mysqld *Mysqld) BinlogInfo(pos proto.ReplicationPosition) (fileName string, filePos uint, err error) {
if pos.IsZero() {
return fileName, filePos, fmt.Errorf("input position for BinlogInfo is uninitialized")
}
// Extract the group_id from the GoogleGTID. We can't just use String() on the
// ReplicationPosition, because that includes the server_id.
gtid, ok := pos.GTIDSet.(proto.GoogleGTID)
if !ok {
return "", 0, fmt.Errorf("Non-Google GTID in BinlogInfo(%#v), which is only supported on Google MySQL", pos)
}
info, err := mysqld.fetchSuperQueryMap(fmt.Sprintf("SHOW BINLOG INFO FOR %v", gtid.GroupID))
if err != nil {
return "", 0, err
}
fileName = info["Log_name"]
temp, err := strconv.ParseUint(info["Pos"], 10, 32)
if err != nil {
return fileName, filePos, err
}
filePos = uint(temp)
return fileName, filePos, err
}
// Check all the tablets to see if we can proceed with reparenting.
// masterPosition is supplied from the demoted master if we are doing
// this gracefully.
func (wr *Wrangler) checkSlaveConsistency(tabletMap map[uint32]*topo.TabletInfo, masterPosition myproto.ReplicationPosition) error {
wr.logger.Infof("checkSlaveConsistency %v %#v", topotools.MapKeys(tabletMap), masterPosition)
// FIXME(msolomon) Something still feels clumsy here and I can't put my finger on it.
calls := make(chan *rpcContext, len(tabletMap))
f := func(ti *topo.TabletInfo) {
ctx := &rpcContext{tablet: ti}
defer func() {
calls <- ctx
}()
if !masterPosition.IsZero() {
// If the master position is known, do our best to wait for replication to catch up.
status, err := wr.tmc.WaitSlavePosition(ti, masterPosition, wr.ActionTimeout())
if err != nil {
ctx.err = err
return
}
ctx.status = status
} else {
// If the master is down, just get the slave status.
status, err := wr.tmc.SlaveStatus(ti, wr.ActionTimeout())
if err != nil {
ctx.err = err
return
}
ctx.status = status
}
}
for _, tablet := range tabletMap {
// Pass loop variable explicitly so we don't have a concurrency issue.
go f(tablet)
}
// map positions to tablets
positionMap := make(map[string][]uint32)
for i := 0; i < len(tabletMap); i++ {
ctx := <-calls
mapKey := "unavailable-tablet-error"
if ctx.err == nil {
mapKey = ctx.status.Position.String()
}
if _, ok := positionMap[mapKey]; !ok {
positionMap[mapKey] = make([]uint32, 0, 32)
}
positionMap[mapKey] = append(positionMap[mapKey], ctx.tablet.Alias.Uid)
}
if len(positionMap) == 1 {
// great, everyone agrees
// demotedMasterReplicationState is nil if demotion failed
if !masterPosition.IsZero() {
demotedMapKey := masterPosition.String()
if _, ok := positionMap[demotedMapKey]; !ok {
for slaveMapKey := range positionMap {
return fmt.Errorf("slave position doesn't match demoted master: %v != %v", demotedMapKey,
slaveMapKey)
}
}
}
} else {
// FIXME(msolomon) in the event of a crash, do you pick replica that is
// furthest along or do you promote the majority? data loss vs availability
// sounds like you pick the latest group and reclone.
items := make([]string, 0, 32)
for slaveMapKey, uids := range positionMap {
tabletPaths := make([]string, len(uids))
for i, uid := range uids {
tabletPaths[i] = tabletMap[uid].Alias.String()
}
items = append(items, fmt.Sprintf(" %v\n %v", slaveMapKey, strings.Join(tabletPaths, "\n ")))
}
sort.Strings(items)
return fmt.Errorf("inconsistent slaves, mark some offline with vtctl ScrapTablet\n%v", strings.Join(items, "\n"))
}
return nil
}