// StartAutoDAG() spawns a go routine that checks the DAG every autoDAGcheckInterval
// by default that is 10 times per epoch
// in epoch n, if we past autoDAGepochHeight within-epoch blocks,
// it calls ethash.MakeDAG to pregenerate the DAG for the next epoch n+1
// if it does not exist yet as well as remove the DAG for epoch n-1
// the loop quits if autodagquit channel is closed, it can safely restart and
// stop any number of times.
// For any more sophisticated pattern of DAG generation, use CLI subcommand
// makedag
func (self *Ethereum) StartAutoDAG() {
if self.autodagquit != nil {
return // already started
}
go func() {
glog.V(logger.Info).Infof("Automatic pregeneration of ethash DAG ON (ethash dir: %s)", ethash.DefaultDir)
var nextEpoch uint64
timer := time.After(0)
self.autodagquit = make(chan bool)
for {
select {
case <-timer:
glog.V(logger.Info).Infof("checking DAG (ethash dir: %s)", ethash.DefaultDir)
currentBlock := self.BlockChain().CurrentBlock().NumberU64()
thisEpoch := currentBlock / epochLength
if nextEpoch <= thisEpoch {
if currentBlock%epochLength > autoDAGepochHeight {
if thisEpoch > 0 {
previousDag, previousDagFull := dagFiles(thisEpoch - 1)
os.Remove(filepath.Join(ethash.DefaultDir, previousDag))
os.Remove(filepath.Join(ethash.DefaultDir, previousDagFull))
glog.V(logger.Info).Infof("removed DAG for epoch %d (%s)", thisEpoch-1, previousDag)
}
nextEpoch = thisEpoch + 1
dag, _ := dagFiles(nextEpoch)
if _, err := os.Stat(dag); os.IsNotExist(err) {
glog.V(logger.Info).Infof("Pregenerating DAG for epoch %d (%s)", nextEpoch, dag)
err := ethash.MakeDAG(nextEpoch*epochLength, "") // "" -> ethash.DefaultDir
if err != nil {
glog.V(logger.Error).Infof("Error generating DAG for epoch %d (%s)", nextEpoch, dag)
return
}
} else {
glog.V(logger.Error).Infof("DAG for epoch %d (%s)", nextEpoch, dag)
}
}
}
timer = time.After(autoDAGcheckInterval)
case <-self.autodagquit:
return
}
}
}()
}
// MakeDAG creates the new DAG for the given block number
func (s *PrivateMinerAPI) MakeDAG(blockNr rpc.BlockNumber) (bool, error) {
if err := ethash.MakeDAG(uint64(blockNr.Int64()), ""); err != nil {
return false, err
}
return true, nil
}