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Merge pull request #76 from github/cut-over-no-throttle

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not throttling during cut-over operation
This commit is contained in:
Shlomi Noach 2016-06-21 09:23:23 +02:00 committed by GitHub
commit dc8d27466c
1 changed files with 17 additions and 1 deletions
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18
go/logic/migrator.go
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@ -65,6 +65,7 @@ type Migrator struct {
rowCopyCompleteFlag int64
allEventsUpToLockProcessedInjectedFlag int64
inCutOverCriticalActionFlag int64
cleanupImminentFlag int64
// copyRowsQueue should not be buffered; if buffered some non-damaging but
// excessive work happens at the end of the iteration as new copy-jobs arrive befroe realizing the copy is complete
@ -414,6 +415,7 @@ func (this *Migrator) Migrate() (err error) {
this.consumeRowCopyComplete()
log.Infof("Row copy complete")
this.printStatus(ForcePrintStatusRule)
this.migrationContext.MarkPointOfInterest()
if err := this.cutOver(); err != nil {
return err
@ -507,6 +509,9 @@ func (this *Migrator) waitForEventsUpToLock() (err error) {
// There is a point in time where the "original" table does not exist and queries are non-blocked
// and failing.
func (this *Migrator) cutOverTwoStep() (err error) {
atomic.StoreInt64(&this.inCutOverCriticalActionFlag, 1)
defer atomic.StoreInt64(&this.inCutOverCriticalActionFlag, 0)
if err := this.retryOperation(this.applier.LockOriginalTable); err != nil {
return err
}
@ -531,6 +536,9 @@ func (this *Migrator) cutOverTwoStep() (err error) {
// is being locked until swapped, hence DML queries being locked and unaware of the cut-over.
// In the worst case, there will ba a minor outage, where the original table would not exist.
func (this *Migrator) safeCutOver() (err error) {
atomic.StoreInt64(&this.inCutOverCriticalActionFlag, 1)
defer atomic.StoreInt64(&this.inCutOverCriticalActionFlag, 0)
okToUnlockTable := make(chan bool, 2)
originalTableRenamed := make(chan error, 1)
defer func() {
@ -1102,7 +1110,15 @@ func (this *Migrator) executeWriteFuncs() error {
return nil
}
for {
this.throttle(nil)
if atomic.LoadInt64(&this.inCutOverCriticalActionFlag) == 0 {
// we don't throttle when cutting over. We _do_ throttle:
// - during copy phase
// - just before cut-over
// - in between cut-over retries
this.throttle(nil)
// When cutting over, we need to be aggressive. Cut-over holds table locks.
// We need to release those asap.
}
// We give higher priority to event processing, then secondary priority to
// rowcopy
select {