924065e19d
* 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
64 lines
2.3 KiB
Go
64 lines
2.3 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// +build go1.8
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package ethash
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import "math/big"
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// cacheSize returns the size of the ethash verification cache that belongs to a certain
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// block number.
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func cacheSize(block uint64) uint64 {
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epoch := int(block / epochLength)
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if epoch < maxEpoch {
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return cacheSizes[epoch]
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}
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return calcCacheSize(epoch)
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}
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// calcCacheSize calculates the cache size for epoch. The cache size grows linearly,
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// however, we always take the highest prime below the linearly growing threshold in order
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// to reduce the risk of accidental regularities leading to cyclic behavior.
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func calcCacheSize(epoch int) uint64 {
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size := cacheInitBytes + cacheGrowthBytes*uint64(epoch) - hashBytes
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for !new(big.Int).SetUint64(size / hashBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * hashBytes
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}
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return size
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}
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// datasetSize returns the size of the ethash mining dataset that belongs to a certain
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// block number.
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func datasetSize(block uint64) uint64 {
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epoch := int(block / epochLength)
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if epoch < maxEpoch {
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return datasetSizes[epoch]
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}
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return calcDatasetSize(epoch)
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}
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// calcDatasetSize calculates the dataset size for epoch. The dataset size grows linearly,
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// however, we always take the highest prime below the linearly growing threshold in order
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// to reduce the risk of accidental regularities leading to cyclic behavior.
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func calcDatasetSize(epoch int) uint64 {
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size := datasetInitBytes + datasetGrowthBytes*uint64(epoch) - mixBytes
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for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * mixBytes
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}
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return size
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}
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