gh-ost/go/base/context.go
Shlomi Noach 97adbf1ff8 - --cut-over no longer mandatory; default to safe
- Removed `CutOverVoluntaryLock` and associated code
- Removed `CutOverUdfWait`
- `RenameTablesRollback()` first attempts an atomic swap
2016-06-14 09:01:06 +02:00

351 lines
10 KiB
Go

/*
Copyright 2016 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
package base
import (
"fmt"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/github/gh-ost/go/mysql"
"github.com/github/gh-ost/go/sql"
"gopkg.in/gcfg.v1"
)
// RowsEstimateMethod is the type of row number estimation
type RowsEstimateMethod string
const (
TableStatusRowsEstimate RowsEstimateMethod = "TableStatusRowsEstimate"
ExplainRowsEstimate = "ExplainRowsEstimate"
CountRowsEstimate = "CountRowsEstimate"
)
type CutOver int
const (
CutOverSafe CutOver = iota
CutOverTwoStep = iota
)
const (
maxRetries = 10
)
// MigrationContext has the general, global state of migration. It is used by
// all components throughout the migration process.
type MigrationContext struct {
DatabaseName string
OriginalTableName string
AlterStatement string
CountTableRows bool
AllowedRunningOnMaster bool
SwitchToRowBinlogFormat bool
NullableUniqueKeyAllowed bool
config ContextConfig
configMutex *sync.Mutex
ConfigFile string
CliUser string
CliPassword string
ChunkSize int64
MaxLagMillisecondsThrottleThreshold int64
ReplictionLagQuery string
ThrottleControlReplicaKeys *mysql.InstanceKeyMap
ThrottleFlagFile string
ThrottleAdditionalFlagFile string
ThrottleCommandedByUser int64
maxLoad map[string]int64
maxLoadMutex *sync.Mutex
PostponeCutOverFlagFile string
SwapTablesTimeoutSeconds int64
ServeSocketFile string
ServeTCPPort int64
Noop bool
TestOnReplica bool
OkToDropTable bool
InitiallyDropOldTable bool
InitiallyDropGhostTable bool
CutOverType CutOver
TableEngine string
RowsEstimate int64
UsedRowsEstimateMethod RowsEstimateMethod
OriginalBinlogFormat string
OriginalBinlogRowImage string
InspectorConnectionConfig *mysql.ConnectionConfig
ApplierConnectionConfig *mysql.ConnectionConfig
StartTime time.Time
RowCopyStartTime time.Time
LockTablesStartTime time.Time
RenameTablesStartTime time.Time
RenameTablesEndTime time.Time
pointOfInterestTime time.Time
pointOfInterestTimeMutex *sync.Mutex
CurrentLag int64
TotalRowsCopied int64
TotalDMLEventsApplied int64
isThrottled bool
throttleReason string
throttleMutex *sync.Mutex
IsPostponingCutOver int64
OriginalTableColumns *sql.ColumnList
OriginalTableUniqueKeys [](*sql.UniqueKey)
GhostTableColumns *sql.ColumnList
GhostTableUniqueKeys [](*sql.UniqueKey)
UniqueKey *sql.UniqueKey
SharedColumns *sql.ColumnList
MigrationRangeMinValues *sql.ColumnValues
MigrationRangeMaxValues *sql.ColumnValues
Iteration int64
MigrationIterationRangeMinValues *sql.ColumnValues
MigrationIterationRangeMaxValues *sql.ColumnValues
CanStopStreaming func() bool
}
type ContextConfig struct {
Client struct {
User string
Password string
}
Osc struct {
Chunk_Size int64
Max_Lag_Millis int64
Replication_Lag_Query string
Max_Load string
}
}
var context *MigrationContext
func init() {
context = newMigrationContext()
}
func newMigrationContext() *MigrationContext {
return &MigrationContext{
ChunkSize: 1000,
InspectorConnectionConfig: mysql.NewConnectionConfig(),
ApplierConnectionConfig: mysql.NewConnectionConfig(),
MaxLagMillisecondsThrottleThreshold: 1000,
SwapTablesTimeoutSeconds: 3,
maxLoad: make(map[string]int64),
maxLoadMutex: &sync.Mutex{},
throttleMutex: &sync.Mutex{},
ThrottleControlReplicaKeys: mysql.NewInstanceKeyMap(),
configMutex: &sync.Mutex{},
pointOfInterestTimeMutex: &sync.Mutex{},
}
}
// GetMigrationContext
func GetMigrationContext() *MigrationContext {
return context
}
// GetGhostTableName generates the name of ghost table, based on original table name
func (this *MigrationContext) GetGhostTableName() string {
return fmt.Sprintf("_%s_gst", this.OriginalTableName)
}
// GetOldTableName generates the name of the "old" table, into which the original table is renamed.
func (this *MigrationContext) GetOldTableName() string {
return fmt.Sprintf("_%s_old", this.OriginalTableName)
}
// GetChangelogTableName generates the name of changelog table, based on original table name
func (this *MigrationContext) GetChangelogTableName() string {
return fmt.Sprintf("_%s_osc", this.OriginalTableName)
}
// GetVoluntaryLockName returns a name of a voluntary lock to be used throughout
// the swap-tables process.
func (this *MigrationContext) GetVoluntaryLockName() string {
return fmt.Sprintf("%s.%s.lock", this.DatabaseName, this.OriginalTableName)
}
// RequiresBinlogFormatChange is `true` when the original binlog format isn't `ROW`
func (this *MigrationContext) RequiresBinlogFormatChange() bool {
return this.OriginalBinlogFormat != "ROW"
}
// InspectorIsAlsoApplier is `true` when the both inspector and applier are the
// same database instance. This would be true when running directly on master or when
// testing on replica.
func (this *MigrationContext) InspectorIsAlsoApplier() bool {
return this.InspectorConnectionConfig.Equals(this.ApplierConnectionConfig)
}
// HasMigrationRange tells us whether there's a range to iterate for copying rows.
// It will be `false` if the table is initially empty
func (this *MigrationContext) HasMigrationRange() bool {
return this.MigrationRangeMinValues != nil && this.MigrationRangeMaxValues != nil
}
func (this *MigrationContext) MaxRetries() int {
return maxRetries
}
func (this *MigrationContext) IsTransactionalTable() bool {
switch strings.ToLower(this.TableEngine) {
case "innodb":
{
return true
}
case "tokudb":
{
return true
}
}
return false
}
// ElapsedTime returns time since very beginning of the process
func (this *MigrationContext) ElapsedTime() time.Duration {
return time.Now().Sub(this.StartTime)
}
// ElapsedRowCopyTime returns time since starting to copy chunks of rows
func (this *MigrationContext) ElapsedRowCopyTime() time.Duration {
return time.Now().Sub(this.RowCopyStartTime)
}
// GetTotalRowsCopied returns the accurate number of rows being copied (affected)
// This is not exactly the same as the rows being iterated via chunks, but potentially close enough
func (this *MigrationContext) GetTotalRowsCopied() int64 {
return atomic.LoadInt64(&this.TotalRowsCopied)
}
func (this *MigrationContext) GetIteration() int64 {
return atomic.LoadInt64(&this.Iteration)
}
func (this *MigrationContext) MarkPointOfInterest() int64 {
this.pointOfInterestTimeMutex.Lock()
defer this.pointOfInterestTimeMutex.Unlock()
this.pointOfInterestTime = time.Now()
return atomic.LoadInt64(&this.Iteration)
}
func (this *MigrationContext) TimeSincePointOfInterest() time.Duration {
this.pointOfInterestTimeMutex.Lock()
defer this.pointOfInterestTimeMutex.Unlock()
return time.Now().Sub(this.pointOfInterestTime)
}
func (this *MigrationContext) SetChunkSize(chunkSize int64) {
if chunkSize < 100 {
chunkSize = 100
}
if chunkSize > 100000 {
chunkSize = 100000
}
atomic.StoreInt64(&this.ChunkSize, chunkSize)
}
func (this *MigrationContext) SetThrottled(throttle bool, reason string) {
this.throttleMutex.Lock()
defer this.throttleMutex.Unlock()
this.isThrottled = throttle
this.throttleReason = reason
}
func (this *MigrationContext) IsThrottled() (bool, string) {
this.throttleMutex.Lock()
defer this.throttleMutex.Unlock()
return this.isThrottled, this.throttleReason
}
func (this *MigrationContext) GetMaxLoad() map[string]int64 {
this.maxLoadMutex.Lock()
defer this.maxLoadMutex.Unlock()
tmpMaxLoadMap := make(map[string]int64)
for k, v := range this.maxLoad {
tmpMaxLoadMap[k] = v
}
return tmpMaxLoadMap
}
// ReadMaxLoad parses the `--max-load` flag, which is in multiple key-value format,
// such as: 'Threads_running=100,Threads_connected=500'
// It only applies changes in case there's no parsing error.
func (this *MigrationContext) ReadMaxLoad(maxLoadList string) error {
if maxLoadList == "" {
return nil
}
this.maxLoadMutex.Lock()
defer this.maxLoadMutex.Unlock()
tmpMaxLoadMap := make(map[string]int64)
maxLoadConditions := strings.Split(maxLoadList, ",")
for _, maxLoadCondition := range maxLoadConditions {
maxLoadTokens := strings.Split(maxLoadCondition, "=")
if len(maxLoadTokens) != 2 {
return fmt.Errorf("Error parsing max-load condition: %s", maxLoadCondition)
}
if maxLoadTokens[0] == "" {
return fmt.Errorf("Error parsing status variable in max-load condition: %s", maxLoadCondition)
}
if n, err := strconv.ParseInt(maxLoadTokens[1], 10, 0); err != nil {
return fmt.Errorf("Error parsing numeric value in max-load condition: %s", maxLoadCondition)
} else {
tmpMaxLoadMap[maxLoadTokens[0]] = n
}
}
this.maxLoad = tmpMaxLoadMap
return nil
}
// ApplyCredentials sorts out the credentials between the config file and the CLI flags
func (this *MigrationContext) ApplyCredentials() {
this.configMutex.Lock()
defer this.configMutex.Unlock()
if this.config.Client.User != "" {
this.InspectorConnectionConfig.User = this.config.Client.User
}
if this.CliUser != "" {
// Override
this.InspectorConnectionConfig.User = this.CliUser
}
if this.config.Client.Password != "" {
this.InspectorConnectionConfig.Password = this.config.Client.Password
}
if this.CliPassword != "" {
// Override
this.InspectorConnectionConfig.Password = this.CliPassword
}
}
// ReadConfigFile attempts to read the config file, if it exists
func (this *MigrationContext) ReadConfigFile() error {
this.configMutex.Lock()
defer this.configMutex.Unlock()
if this.ConfigFile == "" {
return nil
}
if err := gcfg.ReadFileInto(&this.config, this.ConfigFile); err != nil {
return err
}
return nil
}