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consensus/ethash: better block submission pow verification #19899

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consensus/ethash: better block submission pow verification #19899

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8c84443
consensus: don't use mmap if cache/dataset disk item is not allowed
Jul 21, 2019
6f19978
consensus: use light pow verification during block submission
Jul 21, 2019
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4 changes: 2 additions & 2 deletions consensus/ethash/ethash.go
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Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ func (c *cache) generate(dir string, limit int, test bool) {
size = 1024
}
// If we don't store anything on disk, generate and return.
if dir == "" {
if dir == "" || limit <= 0 {
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@CoreyLin CoreyLin Aug 9, 2019 •
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The logic of func (c *cache) generate(dir string, limit int, test bool) has already guaranteed that cache is generated before use. This method would firstly load the cache file and memory map it. If the cache file doesn't exist, it would create a new one and memory map it. So it seems that the mechanism here has no problem.

The parameter limit here indicates that how many cache files are allowed to exist on disk. Even if limit <= 0 , it doesn't directly indicate that no cache file exists. At least using limit <= 0 here is not rigorous logically.

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@de1acr0ix de1acr0ix Aug 26, 2019 •
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The intention here is to reuse the limit flag so that there is a way to disable mmap, which is impossible for existing logic. Of course we can introduce a new flag but I believe implicitly disabling mmap when limit is not a positive number is a reasonable choice.

c.cache = make([]uint32, size/4)
generateCache(c.cache, c.epoch, seed)
return
Expand Down Expand Up @@ -305,7 +305,7 @@ func (d *dataset) generate(dir string, limit int, test bool) {
dsize = 32 * 1024
}
// If we don't store anything on disk, generate and return
if dir == "" {
if dir == "" || limit <= 0 {
cache := make([]uint32, csize/4)
generateCache(cache, d.epoch, seed)

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2 changes: 1 addition & 1 deletion consensus/ethash/sealer.go
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Expand Up @@ -269,7 +269,7 @@ func (ethash *Ethash) remote(notify []string, noverify bool) {

start := time.Now()
if !noverify {
if err := ethash.verifySeal(nil, header, true); err != nil {
if err := ethash.verifySeal(nil, header, false); err != nil {
log.Warn("Invalid proof-of-work submitted", "sealhash", sealhash, "elapsed", common.PrettyDuration(time.Since(start)), "err", err)
return false
}
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