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consensus/ethash: improve cache/dataset handling (#15864)

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* consensus/ethash: add maxEpoch constant

* consensus/ethash: improve cache/dataset handling

There are two fixes in this commit:

Unmap the memory through a finalizer like the libethash wrapper did. The
release logic was incorrect and freed the memory while it was being
used, leading to crashes like in #14495 or #14943.

Track caches and datasets using simplelru instead of reinventing LRU
logic. This should make it easier to see whether it's correct.

* consensus/ethash: restore 'future item' logic in lru

* consensus/ethash: use mmap even in test mode

This makes it possible to shorten the time taken for TestCacheFileEvict.

* consensus/ethash: shuffle func calc*Size comments around

* consensus/ethash: ensure future cache/dataset is in the lru cache

* consensus/ethash: add issue link to the new test

* consensus/ethash: fix vet

* consensus/ethash: fix test

* consensus: tiny issue + nitpick fixes
This commit is contained in:
Felix Lange
2018-01-23 11:05:30 +01:00
committed by Péter Szilágyi
parent 5d4267911a
commit 924065e19d
8 changed files with 208 additions and 213 deletions
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10
consensus/ethash/consensus.go
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@ -476,7 +476,7 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Head
}
// Sanity check that the block number is below the lookup table size (60M blocks)
number := header.Number.Uint64()
if number/epochLength >= uint64(len(cacheSizes)) {
if number/epochLength >= maxEpoch {
// Go < 1.7 cannot calculate new cache/dataset sizes (no fast prime check)
return errNonceOutOfRange
}
@ -484,14 +484,18 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Head
if header.Difficulty.Sign() <= 0 {
return errInvalidDifficulty
}
// Recompute the digest and PoW value and verify against the header
cache := ethash.cache(number)
size := datasetSize(number)
if ethash.config.PowMode == ModeTest {
size = 32 * 1024
}
digest, result := hashimotoLight(size, cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
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)
if !bytes.Equal(header.MixDigest[:], digest) {
return errInvalidMixDigest
}