gh-ost/go/logic/applier.go
Shlomi Noach eeffa701d6 - Added ok-to-drop-table flag
- Added `switch-to-rbr` flag; applying binlog format change if needed
- Using dedicated db instance for locking & renaming on applier (must be used from within same connection)
- Heartbeat now uses `time.RFC3339Nano`
- Swap tables works! Caveat: short table outage
- `--test-on-replica` works!
- retries: using `panicAbort`: from any goroutine, regardless of context, it is possible to terminate the operation
- Reintroduced changelog events listener on streamer. This is the correct implementation.
2016-04-18 10:57:18 -07:00

536 lines
18 KiB
Go

/*
Copyright 2016 GitHub Inc.
See https://github.com/github/gh-osc/blob/master/LICENSE
*/
package logic
import (
gosql "database/sql"
"fmt"
"sync/atomic"
"time"
"github.com/github/gh-osc/go/base"
"github.com/github/gh-osc/go/binlog"
"github.com/github/gh-osc/go/mysql"
"github.com/github/gh-osc/go/sql"
"github.com/outbrain/golib/log"
"github.com/outbrain/golib/sqlutils"
)
// Applier reads data from the read-MySQL-server (typically a replica, but can be the master)
// It is used for gaining initial status and structure, and later also follow up on progress and changelog
type Applier struct {
connectionConfig *mysql.ConnectionConfig
db *gosql.DB
singletonDB *gosql.DB
migrationContext *base.MigrationContext
}
func NewApplier() *Applier {
return &Applier{
connectionConfig: base.GetMigrationContext().ApplierConnectionConfig,
migrationContext: base.GetMigrationContext(),
}
}
func (this *Applier) InitDBConnections() (err error) {
applierUri := this.connectionConfig.GetDBUri(this.migrationContext.DatabaseName)
if this.db, _, err = sqlutils.GetDB(applierUri); err != nil {
return err
}
singletonApplierUri := fmt.Sprintf("%s?timeout=0", applierUri)
if this.singletonDB, _, err = sqlutils.GetDB(singletonApplierUri); err != nil {
return err
}
this.singletonDB.SetMaxOpenConns(1)
if err := this.validateConnection(this.db); err != nil {
return err
}
if err := this.validateConnection(this.singletonDB); err != nil {
return err
}
return nil
}
// validateConnection issues a simple can-connect to MySQL
func (this *Applier) validateConnection(db *gosql.DB) error {
query := `select @@global.port`
var port int
if err := db.QueryRow(query).Scan(&port); err != nil {
return err
}
if port != this.connectionConfig.Key.Port {
return fmt.Errorf("Unexpected database port reported: %+v", port)
}
log.Infof("connection validated on %+v", this.connectionConfig.Key)
return nil
}
// CreateGhostTable creates the ghost table on the applier host
func (this *Applier) CreateGhostTable() error {
query := fmt.Sprintf(`create /* gh-osc */ table %s.%s like %s.%s`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetGhostTableName()),
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.OriginalTableName),
)
log.Infof("Creating ghost table %s.%s",
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetGhostTableName()),
)
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
log.Infof("Ghost table created")
return nil
}
// AlterGhost applies `alter` statement on ghost table
func (this *Applier) AlterGhost() error {
query := fmt.Sprintf(`alter /* gh-osc */ table %s.%s %s`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetGhostTableName()),
this.migrationContext.AlterStatement,
)
log.Infof("Altering ghost table %s.%s",
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetGhostTableName()),
)
log.Debugf("ALTER statement: %s", query)
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
log.Infof("Ghost table altered")
return nil
}
// CreateChangelogTable creates the changelog table on the applier host
func (this *Applier) CreateChangelogTable() error {
query := fmt.Sprintf(`create /* gh-osc */ table %s.%s (
id bigint auto_increment,
last_update timestamp not null DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
hint varchar(64) charset ascii not null,
value varchar(255) charset ascii not null,
primary key(id),
unique key hint_uidx(hint)
) auto_increment=256
`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetChangelogTableName()),
)
log.Infof("Creating changelog table %s.%s",
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetChangelogTableName()),
)
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
log.Infof("Changelog table created")
return nil
}
// dropTable drops a given table on the applied host
func (this *Applier) dropTable(tableName string) error {
if this.migrationContext.Noop {
log.Debugf("Noop operation; not really dropping table %s", sql.EscapeName(tableName))
return nil
}
query := fmt.Sprintf(`drop /* gh-osc */ table if exists %s.%s`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(tableName),
)
log.Infof("Droppping table %s.%s",
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(tableName),
)
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
log.Infof("Table dropped")
return nil
}
// DropChangelogTable drops the changelog table on the applier host
func (this *Applier) DropChangelogTable() error {
return this.dropTable(this.migrationContext.GetChangelogTableName())
}
// DropGhostTable drops the ghost table on the applier host
func (this *Applier) DropGhostTable() error {
return this.dropTable(this.migrationContext.GetGhostTableName())
}
// WriteChangelog writes a value to the changelog table.
// It returns the hint as given, for convenience
func (this *Applier) WriteChangelog(hint, value string) (string, error) {
explicitId := 0
switch hint {
case "heartbeat":
explicitId = 1
case "state":
explicitId = 2
case "throttle":
explicitId = 3
}
query := fmt.Sprintf(`
insert /* gh-osc */ into %s.%s
(id, hint, value)
values
(NULLIF(?, 0), ?, ?)
on duplicate key update
last_update=NOW(),
value=VALUES(value)
`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetChangelogTableName()),
)
_, err := sqlutils.Exec(this.db, query, explicitId, hint, value)
return hint, err
}
func (this *Applier) WriteAndLogChangelog(hint, value string) (string, error) {
this.WriteChangelog(hint, value)
return this.WriteChangelog(fmt.Sprintf("%s at %d", hint, time.Now().UnixNano()), value)
}
func (this *Applier) WriteChangelogState(value string) (string, error) {
return this.WriteAndLogChangelog("state", value)
}
// InitiateHeartbeat creates a heartbeat cycle, writing to the changelog table.
// This is done asynchronously
func (this *Applier) InitiateHeartbeat(heartbeatIntervalMilliseconds int64) {
numSuccessiveFailures := 0
injectHeartbeat := func() error {
if _, err := this.WriteChangelog("heartbeat", time.Now().Format(time.RFC3339Nano)); err != nil {
numSuccessiveFailures++
if numSuccessiveFailures > this.migrationContext.MaxRetries() {
return log.Errore(err)
}
} else {
numSuccessiveFailures = 0
}
return nil
}
injectHeartbeat()
heartbeatTick := time.Tick(time.Duration(heartbeatIntervalMilliseconds) * time.Millisecond)
for range heartbeatTick {
// Generally speaking, we would issue a goroutine, but I'd actually rather
// have this blocked rather than spam the master in the event something
// goes wrong
if err := injectHeartbeat(); err != nil {
return
}
}
}
// ReadMigrationMinValues
func (this *Applier) ReadMigrationMinValues(uniqueKey *sql.UniqueKey) error {
log.Debugf("Reading migration range according to key: %s", uniqueKey.Name)
query, err := sql.BuildUniqueKeyMinValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, uniqueKey.Columns.Names)
if err != nil {
return err
}
rows, err := this.db.Query(query)
if err != nil {
return err
}
for rows.Next() {
this.migrationContext.MigrationRangeMinValues = sql.NewColumnValues(uniqueKey.Len())
if err = rows.Scan(this.migrationContext.MigrationRangeMinValues.ValuesPointers...); err != nil {
return err
}
}
log.Infof("Migration min values: [%s]", this.migrationContext.MigrationRangeMinValues)
return err
}
// ReadMigrationMinValues
func (this *Applier) ReadMigrationMaxValues(uniqueKey *sql.UniqueKey) error {
log.Debugf("Reading migration range according to key: %s", uniqueKey.Name)
query, err := sql.BuildUniqueKeyMaxValuesPreparedQuery(this.migrationContext.DatabaseName, this.migrationContext.OriginalTableName, uniqueKey.Columns.Names)
if err != nil {
return err
}
rows, err := this.db.Query(query)
if err != nil {
return err
}
for rows.Next() {
this.migrationContext.MigrationRangeMaxValues = sql.NewColumnValues(uniqueKey.Len())
if err = rows.Scan(this.migrationContext.MigrationRangeMaxValues.ValuesPointers...); err != nil {
return err
}
}
log.Infof("Migration max values: [%s]", this.migrationContext.MigrationRangeMaxValues)
return err
}
func (this *Applier) ReadMigrationRangeValues() error {
if err := this.ReadMigrationMinValues(this.migrationContext.UniqueKey); err != nil {
return err
}
if err := this.ReadMigrationMaxValues(this.migrationContext.UniqueKey); err != nil {
return err
}
return nil
}
// __unused_IterationIsComplete lets us know when the copy-iteration phase is complete, i.e.
// we've exhausted all rows
func (this *Applier) __unused_IterationIsComplete() (bool, error) {
if !this.migrationContext.HasMigrationRange() {
return false, nil
}
if this.migrationContext.MigrationIterationRangeMinValues == nil {
return false, nil
}
args := sqlutils.Args()
compareWithIterationRangeStart, explodedArgs, err := sql.BuildRangePreparedComparison(this.migrationContext.UniqueKey.Columns.Names, this.migrationContext.MigrationIterationRangeMinValues.AbstractValues(), sql.GreaterThanOrEqualsComparisonSign)
if err != nil {
return false, err
}
args = append(args, explodedArgs...)
compareWithRangeEnd, explodedArgs, err := sql.BuildRangePreparedComparison(this.migrationContext.UniqueKey.Columns.Names, this.migrationContext.MigrationRangeMaxValues.AbstractValues(), sql.LessThanComparisonSign)
if err != nil {
return false, err
}
args = append(args, explodedArgs...)
query := fmt.Sprintf(`
select /* gh-osc IterationIsComplete */ 1
from %s.%s
where (%s) and (%s)
limit 1
`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.OriginalTableName),
compareWithIterationRangeStart,
compareWithRangeEnd,
)
moreRowsFound := false
err = sqlutils.QueryRowsMap(this.db, query, func(rowMap sqlutils.RowMap) error {
moreRowsFound = true
return nil
}, args...)
if err != nil {
return false, err
}
return !moreRowsFound, nil
}
// CalculateNextIterationRangeEndValues reads the next-iteration-range-end unique key values,
// which will be used for copying the next chunk of rows. Ir returns "false" if there is
// no further chunk to work through, i.e. we're past the last chunk and are done with
// itrating the range (and this done with copying row chunks)
func (this *Applier) CalculateNextIterationRangeEndValues() (hasFurtherRange bool, err error) {
this.migrationContext.MigrationIterationRangeMinValues = this.migrationContext.MigrationIterationRangeMaxValues
if this.migrationContext.MigrationIterationRangeMinValues == nil {
this.migrationContext.MigrationIterationRangeMinValues = this.migrationContext.MigrationRangeMinValues
}
query, explodedArgs, err := sql.BuildUniqueKeyRangeEndPreparedQuery(
this.migrationContext.DatabaseName,
this.migrationContext.OriginalTableName,
this.migrationContext.UniqueKey.Columns.Names,
this.migrationContext.MigrationIterationRangeMinValues.AbstractValues(),
this.migrationContext.MigrationRangeMaxValues.AbstractValues(),
this.migrationContext.ChunkSize,
fmt.Sprintf("iteration:%d", this.migrationContext.GetIteration()),
)
if err != nil {
return hasFurtherRange, err
}
rows, err := this.db.Query(query, explodedArgs...)
if err != nil {
return hasFurtherRange, err
}
iterationRangeMaxValues := sql.NewColumnValues(this.migrationContext.UniqueKey.Len())
for rows.Next() {
if err = rows.Scan(iterationRangeMaxValues.ValuesPointers...); err != nil {
return hasFurtherRange, err
}
hasFurtherRange = true
}
if !hasFurtherRange {
log.Debugf("Iteration complete: no further range to iterate")
return hasFurtherRange, nil
}
this.migrationContext.MigrationIterationRangeMaxValues = iterationRangeMaxValues
return hasFurtherRange, nil
}
func (this *Applier) ApplyIterationInsertQuery() (chunkSize int64, rowsAffected int64, duration time.Duration, err error) {
startTime := time.Now()
chunkSize = atomic.LoadInt64(&this.migrationContext.ChunkSize)
query, explodedArgs, err := sql.BuildRangeInsertPreparedQuery(
this.migrationContext.DatabaseName,
this.migrationContext.OriginalTableName,
this.migrationContext.GetGhostTableName(),
this.migrationContext.SharedColumns.Names,
this.migrationContext.UniqueKey.Name,
this.migrationContext.UniqueKey.Columns.Names,
this.migrationContext.MigrationIterationRangeMinValues.AbstractValues(),
this.migrationContext.MigrationIterationRangeMaxValues.AbstractValues(),
this.migrationContext.GetIteration() == 0,
this.migrationContext.IsTransactionalTable(),
)
if err != nil {
return chunkSize, rowsAffected, duration, err
}
sqlResult, err := sqlutils.Exec(this.db, query, explodedArgs...)
if err != nil {
return chunkSize, rowsAffected, duration, err
}
rowsAffected, _ = sqlResult.RowsAffected()
duration = time.Now().Sub(startTime)
log.Debugf(
"Issued INSERT on range: [%s]..[%s]; iteration: %d; chunk-size: %d",
this.migrationContext.MigrationIterationRangeMinValues,
this.migrationContext.MigrationIterationRangeMaxValues,
this.migrationContext.GetIteration(),
chunkSize)
return chunkSize, rowsAffected, duration, nil
}
// LockTables
func (this *Applier) LockTables() error {
if this.migrationContext.Noop {
log.Debugf("Noop operation; not really locking tables")
return nil
}
// query := fmt.Sprintf(`lock /* gh-osc */ tables %s.%s write, %s.%s write, %s.%s write`,
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.OriginalTableName),
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.GetGhostTableName()),
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.GetChangelogTableName()),
// )
query := fmt.Sprintf(`lock /* gh-osc */ tables %s.%s write`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.OriginalTableName),
)
log.Infof("Locking tables")
this.migrationContext.LockTablesStartTime = time.Now()
if _, err := sqlutils.ExecNoPrepare(this.singletonDB, query); err != nil {
return err
}
log.Infof("Tables locked")
return nil
}
// UnlockTables
func (this *Applier) UnlockTables() error {
query := `unlock /* gh-osc */ tables`
log.Infof("Unlocking tables")
if _, err := sqlutils.ExecNoPrepare(this.singletonDB, query); err != nil {
return err
}
log.Infof("Tables unlocked")
return nil
}
// LockTables
func (this *Applier) SwapTables() error {
if this.migrationContext.Noop {
log.Debugf("Noop operation; not really swapping tables")
return nil
}
// query := fmt.Sprintf(`rename /* gh-osc */ table %s.%s to %s.%s, %s.%s to %s.%s`,
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.OriginalTableName),
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.GetOldTableName()),
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.GetGhostTableName()),
// sql.EscapeName(this.migrationContext.DatabaseName),
// sql.EscapeName(this.migrationContext.OriginalTableName),
// )
// log.Infof("Renaming tables")
// if _, err := sqlutils.ExecNoPrepare(this.singletonDB, query); err != nil {
// return err
// }
query := fmt.Sprintf(`alter /* gh-osc */ table %s.%s rename %s`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.OriginalTableName),
sql.EscapeName(this.migrationContext.GetOldTableName()),
)
log.Infof("Renaming original table")
this.migrationContext.RenameTablesStartTime = time.Now()
if _, err := sqlutils.ExecNoPrepare(this.singletonDB, query); err != nil {
return err
}
query = fmt.Sprintf(`alter /* gh-osc */ table %s.%s rename %s`,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.GetGhostTableName()),
sql.EscapeName(this.migrationContext.OriginalTableName),
)
log.Infof("Renaming ghost table")
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
this.migrationContext.RenameTablesEndTime = time.Now()
log.Infof("Tables renamed")
return nil
}
// StopSlaveIOThread is applicable with --test-on-replica; it stops the IO thread
func (this *Applier) StopSlaveIOThread() error {
query := `stop /* gh-osc */ slave io_thread`
log.Infof("Stopping replication")
if _, err := sqlutils.ExecNoPrepare(this.db, query); err != nil {
return err
}
log.Infof("Replication stopped")
return nil
}
func (this *Applier) ShowStatusVariable(variableName string) (result int64, err error) {
query := fmt.Sprintf(`show global status like '%s'`, variableName)
if err := this.db.QueryRow(query).Scan(&variableName, &result); err != nil {
return 0, err
}
return result, nil
}
func (this *Applier) buildDMLEventQuery(dmlEvent *binlog.BinlogDMLEvent) (query string, args []interface{}, err error) {
switch dmlEvent.DML {
case binlog.DeleteDML:
{
query, uniqueKeyArgs, err := sql.BuildDMLDeleteQuery(dmlEvent.DatabaseName, this.migrationContext.GetGhostTableName(), this.migrationContext.OriginalTableColumns, &this.migrationContext.UniqueKey.Columns, dmlEvent.WhereColumnValues.AbstractValues())
return query, uniqueKeyArgs, err
}
case binlog.InsertDML:
{
query, sharedArgs, err := sql.BuildDMLInsertQuery(dmlEvent.DatabaseName, this.migrationContext.GetGhostTableName(), this.migrationContext.OriginalTableColumns, this.migrationContext.SharedColumns, dmlEvent.NewColumnValues.AbstractValues())
return query, sharedArgs, err
}
case binlog.UpdateDML:
{
query, sharedArgs, uniqueKeyArgs, err := sql.BuildDMLUpdateQuery(dmlEvent.DatabaseName, this.migrationContext.GetGhostTableName(), this.migrationContext.OriginalTableColumns, this.migrationContext.SharedColumns, &this.migrationContext.UniqueKey.Columns, dmlEvent.NewColumnValues.AbstractValues(), dmlEvent.WhereColumnValues.AbstractValues())
args = append(args, sharedArgs...)
args = append(args, uniqueKeyArgs...)
return query, args, err
}
}
return "", args, fmt.Errorf("Unknown dml event type: %+v", dmlEvent.DML)
}
func (this *Applier) ApplyDMLEventQuery(dmlEvent *binlog.BinlogDMLEvent) error {
query, args, err := this.buildDMLEventQuery(dmlEvent)
if err != nil {
return err
}
log.Errorf(query)
_, err = sqlutils.Exec(this.db, query, args...)
return err
}