96 lines
2.8 KiB
Go
96 lines
2.8 KiB
Go
/*
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Copyright 2016 GitHub Inc.
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See https://github.com/github/gh-osc/blob/master/LICENSE
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*/
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package logic
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import (
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gosql "database/sql"
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"fmt"
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"github.com/github/gh-osc/go/base"
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"github.com/github/gh-osc/go/mysql"
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"github.com/github/gh-osc/go/sql"
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"github.com/outbrain/golib/log"
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"github.com/outbrain/golib/sqlutils"
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)
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// Applier reads data from the read-MySQL-server (typically a replica, but can be the master)
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// It is used for gaining initial status and structure, and later also follow up on progress and changelog
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type Applier struct {
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connectionConfig *mysql.ConnectionConfig
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db *gosql.DB
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migrationContext *base.MigrationContext
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}
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func NewApplier() *Applier {
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return &Applier{
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connectionConfig: base.GetMigrationContext().MasterConnectionConfig,
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migrationContext: base.GetMigrationContext(),
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}
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}
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func (this *Applier) InitDBConnections() (err error) {
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ApplierUri := this.connectionConfig.GetDBUri(this.migrationContext.DatabaseName)
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if this.db, _, err = sqlutils.GetDB(ApplierUri); err != nil {
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return err
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}
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if err := this.validateConnection(); err != nil {
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return err
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}
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return nil
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}
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// validateConnection issues a simple can-connect to MySQL
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func (this *Applier) validateConnection() error {
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query := `select @@global.port`
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var port int
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if err := this.db.QueryRow(query).Scan(&port); err != nil {
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return err
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}
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if port != this.connectionConfig.Key.Port {
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return fmt.Errorf("Unexpected database port reported: %+v", port)
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}
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log.Infof("connection validated on %+v", this.connectionConfig.Key)
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return nil
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}
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// CreateGhostTable creates the ghost table on the master
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func (this *Applier) CreateGhostTable() error {
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query := fmt.Sprintf(`create /* gh-osc */ table %s.%s like %s.%s`,
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sql.EscapeName(this.migrationContext.DatabaseName),
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sql.EscapeName(this.migrationContext.GetGhostTableName()),
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sql.EscapeName(this.migrationContext.DatabaseName),
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sql.EscapeName(this.migrationContext.OriginalTableName),
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)
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log.Infof("Creating ghost table %s.%s",
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sql.EscapeName(this.migrationContext.DatabaseName),
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sql.EscapeName(this.migrationContext.GetGhostTableName()),
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)
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if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
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return err
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}
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log.Infof("Table created")
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return nil
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}
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// CreateGhostTable creates the ghost table on the master
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func (this *Applier) AlterGhost() error {
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query := fmt.Sprintf(`alter /* gh-osc */ table %s.%s %s`,
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sql.EscapeName(this.migrationContext.DatabaseName),
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sql.EscapeName(this.migrationContext.GetGhostTableName()),
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this.migrationContext.AlterStatement,
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)
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log.Infof("Altering ghost table %s.%s",
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sql.EscapeName(this.migrationContext.DatabaseName),
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sql.EscapeName(this.migrationContext.GetGhostTableName()),
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)
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log.Debugf("ALTER statement: %s", query)
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if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
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return err
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}
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log.Infof("Table altered")
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return nil
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}
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