txn.go
func (o *oracle) setDiscardTs(ts uint64) {
	o.Lock()
	defer o.Unlock()
	o.discardTs = ts
}
func (o *oracle) setDiscardTs(ts uint64) {
	o.Lock()
	defer o.Unlock()
	o.discardTs = ts
}
func ( o * oracle ) setDiscardTs ( ts uint64 ) { o . Lock ( ) defer o . Unlock ( ) o . discardTs = ts }
// Any deleted or invalid versions at or below ts would be discarded during
// compaction to reclaim disk space in LSM tree and thence value log.
Any deleted or invalid versions at or below ts would be discarded during compaction to reclaim disk space in LSM tree and thence value log .