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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
Download Patch File Download Diff File Expand all files Collapse all files

17
consensus/ethash/sealer.go
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@ -97,10 +97,9 @@ func (ethash *Ethash) Seal(chain consensus.ChainReader, block *types.Block, stop
func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
// Extract some data from the header
var (
header = block.Header()
hash = header.HashNoNonce().Bytes()
target = new(big.Int).Div(maxUint256, header.Difficulty)
header = block.Header()
hash = header.HashNoNonce().Bytes()
target = new(big.Int).Div(maxUint256, header.Difficulty)
number = header.Number.Uint64()
dataset = ethash.dataset(number)
)
@ -111,13 +110,14 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
)
logger := log.New("miner", id)
logger.Trace("Started ethash search for new nonces", "seed", seed)
search:
for {
select {
case <-abort:
// Mining terminated, update stats and abort
logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
ethash.hashrate.Mark(attempts)
return
break search
default:
// We don't have to update hash rate on every nonce, so update after after 2^X nonces
@ -127,7 +127,7 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
attempts = 0
}
// Compute the PoW value of this nonce
digest, result := hashimotoFull(dataset, hash, nonce)
digest, result := hashimotoFull(dataset.dataset, hash, nonce)
if new(big.Int).SetBytes(result).Cmp(target) <= 0 {
// Correct nonce found, create a new header with it
header = types.CopyHeader(header)
@ -141,9 +141,12 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
case <-abort:
logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
}
return
break search
}
nonce++
}
}
// Datasets are unmapped in a finalizer. Ensure that the dataset stays live
// during sealing so it's not unmapped while being read.
runtime.KeepAlive(dataset)
}