gh-ost/go/mysql/utils.go

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/*
Copyright 2016 GitHub Inc.
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See https://github.com/github/gh-ost/blob/master/LICENSE
*/
package mysql
import (
gosql "database/sql"
"fmt"
"time"
"github.com/github/gh-ost/go/sql"
"github.com/outbrain/golib/log"
"github.com/outbrain/golib/sqlutils"
)
type ReplicationLagResult struct {
Key InstanceKey
Lag time.Duration
Err error
}
func NewNoReplicationLagResult() *ReplicationLagResult {
return &ReplicationLagResult{Lag: 0, Err: nil}
}
func (this *ReplicationLagResult) HasLag() bool {
return this.Lag > 0
}
// GetReplicationLag returns replication lag for a given connection config; either by explicit query
// or via SHOW SLAVE STATUS
func GetReplicationLag(connectionConfig *ConnectionConfig) (replicationLag time.Duration, err error) {
dbUri := connectionConfig.GetDBUri("information_schema")
var db *gosql.DB
if db, _, err = sqlutils.GetDB(dbUri); err != nil {
return replicationLag, err
}
err = sqlutils.QueryRowsMap(db, `show slave status`, func(m sqlutils.RowMap) error {
slaveIORunning := m.GetString("Slave_IO_Running")
slaveSQLRunning := m.GetString("Slave_SQL_Running")
secondsBehindMaster := m.GetNullInt64("Seconds_Behind_Master")
if !secondsBehindMaster.Valid {
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return fmt.Errorf("replication not running; Slave_IO_Running=%+v, Slave_SQL_Running=%+v", slaveIORunning, slaveSQLRunning)
}
replicationLag = time.Duration(secondsBehindMaster.Int64) * time.Second
return nil
})
return replicationLag, err
}
func GetMasterKeyFromSlaveStatus(connectionConfig *ConnectionConfig) (masterKey *InstanceKey, err error) {
currentUri := connectionConfig.GetDBUri("information_schema")
db, _, err := sqlutils.GetDB(currentUri)
if err != nil {
return nil, err
}
err = sqlutils.QueryRowsMap(db, `show slave status`, func(rowMap sqlutils.RowMap) error {
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// We wish to recognize the case where the topology's master actually has replication configuration.
// This can happen when a DBA issues a `RESET SLAVE` instead of `RESET SLAVE ALL`.
// An empty log file indicates this is a master:
if rowMap.GetString("Master_Log_File") == "" {
return nil
}
slaveIORunning := rowMap.GetString("Slave_IO_Running")
slaveSQLRunning := rowMap.GetString("Slave_SQL_Running")
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//
if slaveIORunning != "Yes" || slaveSQLRunning != "Yes" {
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return fmt.Errorf("Replication on %+v is broken: Slave_IO_Running: %s, Slave_SQL_Running: %s. Please make sure replication runs before using gh-ost.",
connectionConfig.Key,
slaveIORunning,
slaveSQLRunning,
)
}
masterKey = &InstanceKey{
Hostname: rowMap.GetString("Master_Host"),
Port: rowMap.GetInt("Master_Port"),
}
return nil
})
return masterKey, err
}
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func GetMasterConnectionConfigSafe(connectionConfig *ConnectionConfig, visitedKeys *InstanceKeyMap, allowMasterMaster bool) (masterConfig *ConnectionConfig, err error) {
log.Debugf("Looking for master on %+v", connectionConfig.Key)
masterKey, err := GetMasterKeyFromSlaveStatus(connectionConfig)
if err != nil {
return nil, err
}
if masterKey == nil {
return connectionConfig, nil
}
if !masterKey.IsValid() {
return connectionConfig, nil
}
masterConfig = connectionConfig.Duplicate()
masterConfig.Key = *masterKey
log.Debugf("Master of %+v is %+v", connectionConfig.Key, masterConfig.Key)
if visitedKeys.HasKey(masterConfig.Key) {
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if allowMasterMaster {
return connectionConfig, nil
}
return nil, fmt.Errorf("There seems to be a master-master setup at %+v. This is unsupported. Bailing out", masterConfig.Key)
}
visitedKeys.AddKey(masterConfig.Key)
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return GetMasterConnectionConfigSafe(masterConfig, visitedKeys, allowMasterMaster)
}
func GetReplicationBinlogCoordinates(db *gosql.DB) (readBinlogCoordinates *BinlogCoordinates, executeBinlogCoordinates *BinlogCoordinates, err error) {
err = sqlutils.QueryRowsMap(db, `show slave status`, func(m sqlutils.RowMap) error {
readBinlogCoordinates = &BinlogCoordinates{
LogFile: m.GetString("Master_Log_File"),
LogPos: m.GetInt64("Read_Master_Log_Pos"),
}
executeBinlogCoordinates = &BinlogCoordinates{
LogFile: m.GetString("Relay_Master_Log_File"),
LogPos: m.GetInt64("Exec_Master_Log_Pos"),
}
return nil
})
return readBinlogCoordinates, executeBinlogCoordinates, err
}
func GetSelfBinlogCoordinates(db *gosql.DB) (selfBinlogCoordinates *BinlogCoordinates, err error) {
err = sqlutils.QueryRowsMap(db, `show master status`, func(m sqlutils.RowMap) error {
selfBinlogCoordinates = &BinlogCoordinates{
LogFile: m.GetString("File"),
LogPos: m.GetInt64("Position"),
}
return nil
})
return selfBinlogCoordinates, err
}
// GetInstanceKey reads hostname and port on given DB
func GetInstanceKey(db *gosql.DB) (instanceKey *InstanceKey, err error) {
instanceKey = &InstanceKey{}
err = db.QueryRow(`select @@global.hostname, @@global.port`).Scan(&instanceKey.Hostname, &instanceKey.Port)
return instanceKey, err
}
// GetTableColumns reads column list from given table
func GetTableColumns(db *gosql.DB, databaseName, tableName string) (*sql.ColumnList, error) {
query := fmt.Sprintf(`
show columns from %s.%s
`,
sql.EscapeName(databaseName),
sql.EscapeName(tableName),
)
columnNames := []string{}
err := sqlutils.QueryRowsMap(db, query, func(rowMap sqlutils.RowMap) error {
columnNames = append(columnNames, rowMap.GetString("Field"))
return nil
})
if err != nil {
return nil, err
}
if len(columnNames) == 0 {
return nil, log.Errorf("Found 0 columns on %s.%s. Bailing out",
sql.EscapeName(databaseName),
sql.EscapeName(tableName),
)
}
return sql.NewColumnList(columnNames), nil
}