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consensus/ethash: use DAGs for remote mining, generate async

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This commit is contained in:
Péter Szilágyi
2018-08-15 13:50:16 +03:00
parent e598ae5c01
commit d8541a9f99
3 changed files with 83 additions and 24 deletions
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52
consensus/ethash/consensus.go
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@ -461,6 +461,13 @@ func calcDifficultyFrontier(time uint64, parent *types.Header) *big.Int {
// VerifySeal implements consensus.Engine, checking whether the given block satisfies
// the PoW difficulty requirements.
func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
return ethash.verifySeal(chain, header, false)
}
// verifySeal checks whether a block satisfies the PoW difficulty requirements,
// either using the usual ethash cache for it, or alternatively using a full DAG
// to make remote mining fast.
func (ethash *Ethash) verifySeal(chain consensus.ChainReader, header *types.Header, fulldag bool) error {
// If we're running a fake PoW, accept any seal as valid
if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
time.Sleep(ethash.fakeDelay)
@ -471,25 +478,48 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Head
}
// If we're running a shared PoW, delegate verification to it
if ethash.shared != nil {
return ethash.shared.VerifySeal(chain, header)
return ethash.shared.verifySeal(chain, header, fulldag)
}
// Ensure that we have a valid difficulty for the block
if header.Difficulty.Sign() <= 0 {
return errInvalidDifficulty
}
// Recompute the digest and PoW value and verify against the header
// Recompute the digest and PoW values
number := header.Number.Uint64()
cache := ethash.cache(number)
size := datasetSize(number)
if ethash.config.PowMode == ModeTest {
size = 32 * 1024
}
digest, result := hashimotoLight(size, cache.cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
// Caches are unmapped in a finalizer. Ensure that the cache stays live
// until after the call to hashimotoLight so it's not unmapped while being used.
runtime.KeepAlive(cache)
var (
digest []byte
result []byte
)
// If fast-but-heavy PoW verification was requested, use an ethash dataset
if fulldag {
dataset := ethash.dataset(number, true)
if dataset.generated() {
digest, result = hashimotoFull(dataset.dataset, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
// Datasets are unmapped in a finalizer. Ensure that the dataset stays alive
// until after the call to hashimotoFull so it's not unmapped while being used.
runtime.KeepAlive(dataset)
} else {
// Dataset not yet generated, don't hang, use a cache instead
fulldag = false
}
}
// If slow-but-light PoW verification was requested (or DAG not yet ready), use an ethash cache
if !fulldag {
cache := ethash.cache(number)
size := datasetSize(number)
if ethash.config.PowMode == ModeTest {
size = 32 * 1024
}
digest, result = hashimotoLight(size, cache.cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
// Caches are unmapped in a finalizer. Ensure that the cache stays alive
// until after the call to hashimotoLight so it's not unmapped while being used.
runtime.KeepAlive(cache)
}
// Verify the calculated values against the ones provided in the header
if !bytes.Equal(header.MixDigest[:], digest) {
return errInvalidMixDigest
}