69 lines
1.8 KiB
Go
69 lines
1.8 KiB
Go
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package failover
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import (
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"github.com/juju/errors"
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"github.com/siddontang/go-mysql/mysql"
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)
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// Failover will do below things after the master down
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// 1. Elect a slave which has the most up-to-date data with old master
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// 2. Promote the slave to new master
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// 3. Change other slaves to the new master
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//
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// Limitation:
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// 1, All slaves must have the same master before, Failover will check using master server id or uuid
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// 2, If the failover error, the whole topology may be wrong, we must handle this error manually
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// 3, Slaves must have same replication mode, all use GTID or not
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//
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func Failover(flavor string, slaves []*Server) ([]*Server, error) {
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var h Handler
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var err error
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switch flavor {
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case mysql.MySQLFlavor:
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h = new(MysqlGTIDHandler)
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case mysql.MariaDBFlavor:
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return nil, errors.Errorf("MariaDB failover is not supported now")
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default:
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return nil, errors.Errorf("invalid flavor %s", flavor)
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}
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// First check slaves use gtid or not
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if err := h.CheckGTIDMode(slaves); err != nil {
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return nil, errors.Trace(err)
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}
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// Stop all slave IO_THREAD and wait the relay log done
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for _, slave := range slaves {
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if err = h.WaitRelayLogDone(slave); err != nil {
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return nil, errors.Trace(err)
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}
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}
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var bestSlave *Server
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// Find best slave which has the most up-to-data data
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if bestSlaves, err := h.FindBestSlaves(slaves); err != nil {
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return nil, errors.Trace(err)
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} else {
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bestSlave = bestSlaves[0]
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}
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// Promote the best slave to master
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if err = h.Promote(bestSlave); err != nil {
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return nil, errors.Trace(err)
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}
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// Change master
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for i := 0; i < len(slaves); i++ {
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if bestSlave == slaves[i] {
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continue
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}
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if err = h.ChangeMasterTo(slaves[i], bestSlave); err != nil {
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return nil, errors.Trace(err)
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}
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}
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return slaves, nil
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}
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