nimbus-eth1/nimbus/core/pow/pow_dataset.nim

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Nim

# Nimbus
# Copyright (c) 2018 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
# http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
# http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed except
# according to those terms.
## LRU Cache for Epoch Indexed Hashimoto Dataset
## =============================================
##
## This module uses the eth-block number (mapped to epoch) to hold and re-use
## the dataset needed for running the `hasimotoFull()` proof-of-work function.
import
std/[options],
./pow_cache,
eth/common,
ethash,
stew/keyed_queue
{.push raises: [Defect].}
type
PowDatasetItemRef* = ref object
size*: uint64
data*: seq[MDigest[512]]
PowDatasetStats* = tuple
maxItems: int
size: int
PowDataset* = object
datasetMax: int
dataset: KeyedQueue[uint64,PowDatasetItemRef]
cache: PowCacheRef
PowDatasetRef* = ref PowDataset
const
nItemsMax = 2
nItemsInit = 2
# ------------------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------------------
proc toKey(bn: BlockNumber): uint64 =
bn.truncate(uint64) div EPOCH_LENGTH
proc init(pd: var PowDataset;
maxItems: Option[int]; cache: Option[PowCacheRef]) =
## Constructor for LRU cache
pd.dataset.init(nItemsInit)
if maxItems.isSome:
pd.datasetMax = maxItems.get
else:
pd.datasetMax = nItemsMax
if cache.isSome:
pd.cache = cache.get
else:
pd.cache = PowCacheRef.new(nItemsInit)
# ------------------------------------------------------------------------------
# Public functions, constructor
# ------------------------------------------------------------------------------
proc init*(pd: var PowDataset; maxItems = nItemsMax; cache: PowCacheRef) =
## Constructor for PoW dataset
pd.init(some(maxItems), some(cache))
proc init*(pd: var PowDataset; maxItems = nItemsMax) =
## Constructor variant
pd.init(some(maxItems), none(PowCacheRef))
proc init*(T: type PowDataset; maxItems = nItemsMax; cache: PowCacheRef): T =
## Constructor variant
result.init(some(maxItems), some(cache))
proc init*(T: type PowDataset; maxItems = nItemsMax): T =
## Constructor variant
result.init(some(maxItems), none(PowCacheRef))
proc new*(T: type PowDatasetRef; maxItems = nItemsMax; cache: PowCacheRef): T =
## Constructor variant
new result
result[].init(some(maxItems), some(cache))
proc new*(T: type PowDatasetRef; maxItems = nItemsMax): T =
## Constructor for PoW dataset reference
new result
result[].init(some(maxItems), none(PowCacheRef))
# ------------------------------------------------------------------------------
# Public functions, constructor
# ------------------------------------------------------------------------------
proc get*(pd: var PowDataset; bn: BlockNumber): PowDatasetItemRef
{.gcsafe,raises: [Defect,CatchableError].} =
## Return a cache derived from argument `blockNumber` ready to be used
## for the `hashimotoLight()` method.
let
key = bn.toKey
rc = pd.dataset.lruFetch(key)
if rc.isOk:
return rc.value
let
# note that `getDataSize()` and `getCacheSize()` depend on
# `key * EPOCH_LENGTH` rather than the original block number.
top = key * EPOCH_LENGTH
cache = pd.cache.get(bn)
pair = PowDatasetItemRef(
size: cache.size,
data: cache.size.calcDataset(cache.data))
pd.dataset.lruAppend(key, pair, pd.datasetMax)
proc get*(pdr: PowDatasetRef; bn: BlockNumber): PowDatasetItemRef
{.gcsafe,raises: [Defect,CatchableError].} =
## Variant of `getCache()`
pdr[].get(bn)
proc hasItem*(pd: var PowDataset; bn: BlockNumber): bool
{.gcsafe,raises: [Defect,CatchableError].} =
##Returns true if there is a cache entry for argument `bn`.
pd.dataset.hasKey(bn.toKey)
proc hasItem*(pdr: PowDatasetRef; bn: BlockNumber): bool
{.gcsafe,raises: [Defect,CatchableError].} =
## Variant of `hasItem()`
pdr[].hasItem(bn)
# -------------------------
proc stats*(pd: var PowDataset): PowDatasetStats =
## Return current cache sizes
result = (maxItems: pd.datasetMax, size: pd.dataset.len)
proc stats*(pd: PowDatasetRef): PowDatasetStats =
## Variant of `stats()`
pd[].stats
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------