877 lines
33 KiB
Nim
877 lines
33 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2020 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [Defect].}
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import
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chronicles, options, sequtils, tables,
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metrics,
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../ssz/merkleization, ../beacon_chain_db, ../state_transition, ../extras,
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../spec/[crypto, datatypes, digest, helpers, validator],
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block_pools_types
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declareCounter beacon_reorgs_total, "Total occurrences of reorganizations of the chain" # On fork choice
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declareCounter beacon_state_data_cache_hits, "dag.cachedStates hits"
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declareCounter beacon_state_data_cache_misses, "dag.cachedStates misses"
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logScope: topics = "hotdb"
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proc putBlock*(dag: var CandidateChains, blockRoot: Eth2Digest, signedBlock: SignedBeaconBlock) {.inline.} =
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dag.db.putBlock(blockRoot, signedBlock)
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proc updateStateData*(
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dag: CandidateChains, state: var StateData, bs: BlockSlot) {.gcsafe.}
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template withState*(
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dag: CandidateChains, cache: var StateData, blockSlot: BlockSlot, body: untyped): untyped =
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## Helper template that updates state to a particular BlockSlot - usage of
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## cache is unsafe outside of block.
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## TODO async transformations will lead to a race where cache gets updated
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## while waiting for future to complete - catch this here somehow?
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updateStateData(dag, cache, blockSlot)
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template hashedState(): HashedBeaconState {.inject, used.} = cache.data
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template state(): BeaconState {.inject, used.} = cache.data.data
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template blck(): BlockRef {.inject, used.} = cache.blck
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template root(): Eth2Digest {.inject, used.} = cache.data.root
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body
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func parent*(bs: BlockSlot): BlockSlot =
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## Return a blockslot representing the previous slot, using the parent block
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## if the current slot had a block
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if bs.slot == Slot(0):
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BlockSlot(blck: nil, slot: Slot(0))
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else:
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BlockSlot(
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blck: if bs.slot > bs.blck.slot: bs.blck else: bs.blck.parent,
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slot: bs.slot - 1
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)
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func populateEpochCache*(state: BeaconState, epoch: Epoch): EpochRef =
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result = (EpochRef)(
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epoch: state.slot.compute_epoch_at_slot,
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shuffled_active_validator_indices:
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get_shuffled_active_validator_indices(state, epoch))
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func link*(parent, child: BlockRef) =
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doAssert (not (parent.root == Eth2Digest() or child.root == Eth2Digest())),
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"blocks missing root!"
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doAssert parent.root != child.root, "self-references not allowed"
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child.parent = parent
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parent.children.add(child)
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func isAncestorOf*(a, b: BlockRef): bool =
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var b = b
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var depth = 0
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const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
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while true:
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if a == b: return true
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# for now, use an assert for block chain length since a chain this long
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# indicates a circular reference here..
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doAssert depth < maxDepth
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depth += 1
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if a.slot >= b.slot or b.parent.isNil:
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return false
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doAssert b.slot > b.parent.slot
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b = b.parent
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func getAncestorAt*(blck: BlockRef, slot: Slot): BlockRef =
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## Return the most recent block as of the time at `slot` that not more recent
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## than `blck` itself
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var blck = blck
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var depth = 0
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const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
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while true:
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if blck.slot <= slot:
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return blck
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if blck.parent.isNil:
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return nil
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doAssert depth < maxDepth
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depth += 1
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blck = blck.parent
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func get_ancestor*(blck: BlockRef, slot: Slot): BlockRef =
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## https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/fork-choice.md#get_ancestor
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## Return ancestor at slot, or nil if queried block is older
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var blck = blck
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var depth = 0
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const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
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while true:
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if blck.slot == slot:
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return blck
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if blck.slot < slot:
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return nil
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if blck.parent.isNil:
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return nil
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doAssert depth < maxDepth
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depth += 1
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blck = blck.parent
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func atSlot*(blck: BlockRef, slot: Slot): BlockSlot =
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## Return a BlockSlot at a given slot, with the block set to the closest block
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## available. If slot comes from before the block, a suitable block ancestor
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## will be used, else blck is returned as if all slots after it were empty.
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## This helper is useful when imagining what the chain looked like at a
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## particular moment in time, or when imagining what it will look like in the
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## near future if nothing happens (such as when looking ahead for the next
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## block proposal)
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BlockSlot(blck: blck.getAncestorAt(slot), slot: slot)
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func getEpochInfo*(blck: BlockRef, state: BeaconState): EpochRef =
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# This is the only intended mechanism by which to get an EpochRef
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let
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state_epoch = state.slot.compute_epoch_at_slot
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matching_epochinfo = blck.epochsInfo.filterIt(it.epoch == state_epoch)
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if matching_epochinfo.len == 0:
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let cache = populateEpochCache(state, state_epoch)
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blck.epochsInfo.add(cache)
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trace "candidate_chains.skipAndUpdateState(): back-filling parent.epochInfo",
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state_slot = state.slot
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cache
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elif matching_epochinfo.len == 1:
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matching_epochinfo[0]
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else:
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raiseAssert "multiple EpochRefs per epoch per BlockRef invalid"
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func getEpochCache*(blck: BlockRef, state: BeaconState): StateCache =
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let epochInfo = getEpochInfo(blck, state)
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result = get_empty_per_epoch_cache()
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result.shuffled_active_validator_indices[
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state.slot.compute_epoch_at_slot] =
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epochInfo.shuffled_active_validator_indices
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func init(T: type BlockRef, root: Eth2Digest, slot: Slot): BlockRef =
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BlockRef(
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root: root,
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slot: slot
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)
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func init*(T: type BlockRef, root: Eth2Digest, blck: BeaconBlock): BlockRef =
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BlockRef.init(root, blck.slot)
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proc init*(T: type CandidateChains, db: BeaconChainDB,
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updateFlags: UpdateFlags = {}): CandidateChains =
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# TODO we require that the db contains both a head and a tail block -
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# asserting here doesn't seem like the right way to go about it however..
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let
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tailBlockRoot = db.getTailBlock()
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headBlockRoot = db.getHeadBlock()
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doAssert tailBlockRoot.isSome(), "Missing tail block, database corrupt?"
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doAssert headBlockRoot.isSome(), "Missing head block, database corrupt?"
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let
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tailRoot = tailBlockRoot.get()
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tailBlock = db.getBlock(tailRoot).get()
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tailRef = BlockRef.init(tailRoot, tailBlock.message)
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headRoot = headBlockRoot.get()
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var
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blocks = {tailRef.root: tailRef}.toTable()
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headRef: BlockRef
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if headRoot != tailRoot:
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var curRef: BlockRef
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for root, blck in db.getAncestors(headRoot):
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if root == tailRef.root:
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doAssert(not curRef.isNil)
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link(tailRef, curRef)
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curRef = curRef.parent
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break
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let newRef = BlockRef.init(root, blck.message)
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if curRef == nil:
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curRef = newRef
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headRef = newRef
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else:
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link(newRef, curRef)
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curRef = curRef.parent
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blocks[curRef.root] = curRef
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trace "Populating block dag", key = curRef.root, val = curRef
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doAssert curRef == tailRef,
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"head block does not lead to tail, database corrupt?"
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else:
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headRef = tailRef
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var
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bs = headRef.atSlot(headRef.slot)
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tmpState = (ref StateData)()
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# Now that we have a head block, we need to find the most recent state that
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# we have saved in the database
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while bs.blck != nil:
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let root = db.getStateRoot(bs.blck.root, bs.slot)
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if root.isSome():
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# TODO load StateData from BeaconChainDB
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# We save state root separately for empty slots which means we might
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# sometimes not find a state even though we saved its state root
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if db.getState(root.get(), tmpState.data.data, noRollback):
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tmpState.data.root = root.get()
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tmpState.blck = bs.blck
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break
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bs = bs.parent() # Iterate slot by slot in case there's a gap!
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if tmpState.blck == nil:
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warn "No state found in head history, database corrupt?"
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# TODO Potentially we could recover from here instead of crashing - what
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# would be a good recovery model?
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raiseAssert "No state found in head history, database corrupt?"
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# We presently save states on the epoch boundary - it means that the latest
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# state we loaded might be older than head block - nonetheless, it will be
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# from the same epoch as the head, thus the finalized and justified slots are
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# the same - these only change on epoch boundaries.
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let
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finalizedSlot =
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tmpState.data.data.finalized_checkpoint.epoch.compute_start_slot_at_epoch()
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finalizedHead = headRef.atSlot(finalizedSlot)
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justifiedSlot =
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tmpState.data.data.current_justified_checkpoint.epoch.compute_start_slot_at_epoch()
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justifiedHead = headRef.atSlot(justifiedSlot)
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head = Head(blck: headRef, justified: justifiedHead)
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doAssert justifiedHead.slot >= finalizedHead.slot,
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"justified head comes before finalized head - database corrupt?"
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let res = CandidateChains(
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blocks: blocks,
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tail: tailRef,
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head: head,
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finalizedHead: finalizedHead,
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db: db,
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heads: @[head],
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headState: tmpState[],
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justifiedState: tmpState[], # This is wrong but we'll update it below
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tmpState: tmpState[],
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# The only allowed flag right now is verifyFinalization, as the others all
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# allow skipping some validation.
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updateFlags: {verifyFinalization} * updateFlags
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)
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doAssert res.updateFlags in [{}, {verifyFinalization}]
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res.updateStateData(res.justifiedState, justifiedHead)
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res.updateStateData(res.headState, headRef.atSlot(headRef.slot))
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info "Block dag initialized",
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head = head.blck, justifiedHead, finalizedHead, tail = tailRef,
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totalBlocks = blocks.len
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res
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proc getState(
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dag: CandidateChains, db: BeaconChainDB, stateRoot: Eth2Digest, blck: BlockRef,
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output: var StateData): bool =
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let outputAddr = unsafeAddr output # local scope
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func restore(v: var BeaconState) =
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if outputAddr == (unsafeAddr dag.headState):
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# TODO seeing the headState in the restore shouldn't happen - we load
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# head states only when updating the head position, and by that time
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# the database will have gone through enough sanity checks that
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# SSZ exceptions shouldn't happen, which is when restore happens.
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# Nonetheless, this is an ugly workaround that needs to go away
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doAssert false, "Cannot alias headState"
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outputAddr[] = dag.headState
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if not db.getState(stateRoot, output.data.data, restore):
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return false
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output.blck = blck
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output.data.root = stateRoot
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true
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func getStateCacheIndex(dag: CandidateChains, blockRoot: Eth2Digest, slot: Slot): int =
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for i, cachedState in dag.cachedStates:
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let (cacheBlockRoot, cacheSlot, state) = cachedState
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if cacheBlockRoot == blockRoot and cacheSlot == slot:
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return i
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-1
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proc putState*(dag: CandidateChains, state: HashedBeaconState, blck: BlockRef) =
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# TODO we save state at every epoch start but never remove them - we also
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# potentially save multiple states per slot if reorgs happen, meaning
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# we could easily see a state explosion
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logScope: pcs = "save_state_at_epoch_start"
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var rootWritten = false
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if state.data.slot != blck.slot:
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# This is a state that was produced by a skip slot for which there is no
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# block - we'll save the state root in the database in case we need to
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# replay the skip
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dag.db.putStateRoot(blck.root, state.data.slot, state.root)
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rootWritten = true
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if state.data.slot.isEpoch:
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if not dag.db.containsState(state.root):
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info "Storing state",
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blck = shortLog(blck),
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stateSlot = shortLog(state.data.slot),
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stateRoot = shortLog(state.root),
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cat = "caching"
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dag.db.putState(state.root, state.data)
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if not rootWritten:
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dag.db.putStateRoot(blck.root, state.data.slot, state.root)
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# Need to be able to efficiently access states for both attestation
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# aggregation and to process block proposals going back to the last
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# finalized slot. Ideally to avoid potential combinatiorial forking
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# storage and/or memory constraints could CoW, up to and including,
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# in particular, hash_tree_root() which is expensive to do 30 times
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# since the previous epoch, to efficiently state_transition back to
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# desired slot. However, none of that's in place, so there are both
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# expensive, repeated BeaconState copies as well as computationally
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# time-consuming-near-end-of-epoch hash tree roots. The latter are,
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# effectively, naïvely O(n^2) in slot number otherwise, so when the
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# slots become in the mid-to-high-20s it's spending all its time in
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# pointlessly repeated calculations of prefix-state-transitions. An
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# intermediate time/memory workaround involves storing only mapping
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# between BlockRefs, or BlockSlots, and the BeaconState tree roots,
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# but that still involves tens of megabytes worth of copying, along
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# with the concomitant memory allocator and GC load. Instead, use a
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# more memory-intensive (but more conceptually straightforward, and
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# faster) strategy to just store, for the most recent slots.
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let stateCacheIndex = dag.getStateCacheIndex(blck.root, state.data.slot)
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if stateCacheIndex == -1:
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# Could use a deque or similar, but want simpler structure, and the data
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# items are small and few.
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const MAX_CACHE_SIZE = 32
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insert(dag.cachedStates, (blck.root, state.data.slot, newClone(state)))
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while dag.cachedStates.len > MAX_CACHE_SIZE:
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discard dag.cachedStates.pop()
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let cacheLen = dag.cachedStates.len
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trace "CandidateChains.putState(): state cache updated", cacheLen
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doAssert cacheLen > 0 and cacheLen <= MAX_CACHE_SIZE
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func getRef*(dag: CandidateChains, root: Eth2Digest): BlockRef =
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## Retrieve a resolved block reference, if available
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dag.blocks.getOrDefault(root, nil)
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func getBlockRange*(
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dag: CandidateChains, startSlot: Slot, skipStep: Natural,
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output: var openArray[BlockRef]): Natural =
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## This function populates an `output` buffer of blocks
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## with a slots ranging from `startSlot` up to, but not including,
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## `startSlot + skipStep * output.len`, skipping any slots that don't have
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## a block.
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##
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## Blocks will be written to `output` from the end without gaps, even if
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## a block is missing in a particular slot. The return value shows how
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## many slots were missing blocks - to iterate over the result, start
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## at this index.
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##
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## If there were no blocks in the range, `output.len` will be returned.
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let count = output.len
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trace "getBlockRange entered",
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head = shortLog(dag.head.blck.root), count, startSlot, skipStep
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let
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skipStep = max(1, skipStep) # Treat 0 step as 1
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endSlot = startSlot + uint64(count * skipStep)
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var
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b = dag.head.blck.atSlot(endSlot)
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o = count
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for i in 0..<count:
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for j in 0..<skipStep:
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b = b.parent
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if b.blck.slot == b.slot:
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dec o
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output[o] = b.blck
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# Make sure the given input is cleared, just in case
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for i in 0..<o:
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output[i] = nil
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o # Return the index of the first non-nil item in the output
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func getBlockBySlot*(dag: CandidateChains, slot: Slot): BlockRef =
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## Retrieves the first block in the current canonical chain
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## with slot number less or equal to `slot`.
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dag.head.blck.atSlot(slot).blck
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func getBlockByPreciseSlot*(dag: CandidateChains, slot: Slot): BlockRef =
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## Retrieves a block from the canonical chain with a slot
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## number equal to `slot`.
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let found = dag.getBlockBySlot(slot)
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if found.slot != slot: found else: nil
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proc get*(dag: CandidateChains, blck: BlockRef): BlockData =
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## Retrieve the associated block body of a block reference
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doAssert (not blck.isNil), "Trying to get nil BlockRef"
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let data = dag.db.getBlock(blck.root)
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doAssert data.isSome, "BlockRef without backing data, database corrupt?"
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BlockData(data: data.get(), refs: blck)
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proc get*(dag: CandidateChains, root: Eth2Digest): Option[BlockData] =
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## Retrieve a resolved block reference and its associated body, if available
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let refs = dag.getRef(root)
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if not refs.isNil:
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some(dag.get(refs))
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else:
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none(BlockData)
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proc skipAndUpdateState(
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dag: CandidateChains,
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state: var HashedBeaconState, blck: BlockRef, slot: Slot, save: bool) =
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while state.data.slot < slot:
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# Process slots one at a time in case afterUpdate needs to see empty states
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# TODO when replaying, we already do this query when loading the ancestors -
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# save and reuse
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# TODO possibly we should keep this in memory for the hot blocks
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let nextStateRoot = dag.db.getStateRoot(blck.root, state.data.slot + 1)
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var stateCache = getEpochCache(blck, state.data)
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advance_slot(state, nextStateRoot, dag.updateFlags, stateCache)
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if save:
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dag.putState(state, blck)
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proc skipAndUpdateState(
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dag: CandidateChains,
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state: var StateData, blck: BlockData, flags: UpdateFlags, save: bool): bool =
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dag.skipAndUpdateState(
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state.data, blck.refs, blck.data.message.slot - 1, save)
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var statePtr = unsafeAddr state # safe because `restore` is locally scoped
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func restore(v: var HashedBeaconState) =
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doAssert (addr(statePtr.data) == addr v)
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statePtr[] = dag.headState
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var stateCache = getEpochCache(blck.refs, state.data.data)
|
|
let ok = state_transition(
|
|
state.data, blck.data, stateCache, flags + dag.updateFlags, restore)
|
|
|
|
if ok and save:
|
|
dag.putState(state.data, blck.refs)
|
|
|
|
ok
|
|
|
|
proc rewindState(dag: CandidateChains, state: var StateData, bs: BlockSlot):
|
|
seq[BlockData] =
|
|
logScope: pcs = "replay_state"
|
|
|
|
var ancestors = @[dag.get(bs.blck)]
|
|
# Common case: the last block applied is the parent of the block to apply:
|
|
if not bs.blck.parent.isNil and state.blck.root == bs.blck.parent.root and
|
|
state.data.data.slot < bs.blck.slot:
|
|
return ancestors
|
|
|
|
# It appears that the parent root of the proposed new block is different from
|
|
# what we expected. We will have to rewind the state to a point along the
|
|
# chain of ancestors of the new block. We will do this by loading each
|
|
# successive parent block and checking if we can find the corresponding state
|
|
# in the database.
|
|
var
|
|
stateRoot = block:
|
|
let tmp = dag.db.getStateRoot(bs.blck.root, bs.slot)
|
|
if tmp.isSome() and dag.db.containsState(tmp.get()):
|
|
tmp
|
|
else:
|
|
# State roots are sometimes kept in database even though state is not
|
|
err(Opt[Eth2Digest])
|
|
curBs = bs
|
|
|
|
while stateRoot.isNone():
|
|
let parBs = curBs.parent()
|
|
if parBs.blck.isNil:
|
|
break # Bug probably!
|
|
|
|
if parBs.blck != curBs.blck:
|
|
ancestors.add(dag.get(parBs.blck))
|
|
|
|
# TODO investigate replacing with getStateCached, by refactoring whole
|
|
# function. Empirically, this becomes pretty rare once good caches are
|
|
# used in the front-end.
|
|
let idx = dag.getStateCacheIndex(parBs.blck.root, parBs.slot)
|
|
if idx >= 0:
|
|
state.data = dag.cachedStates[idx].state[]
|
|
let ancestor = ancestors.pop()
|
|
state.blck = ancestor.refs
|
|
|
|
beacon_state_data_cache_hits.inc()
|
|
trace "Replaying state transitions via in-memory cache",
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
ancestorStateRoot = shortLog(ancestor.data.message.state_root),
|
|
ancestorStateSlot = shortLog(state.data.data.slot),
|
|
slot = shortLog(bs.slot),
|
|
blockRoot = shortLog(bs.blck.root),
|
|
ancestors = ancestors.len,
|
|
cat = "replay_state"
|
|
|
|
return ancestors
|
|
|
|
beacon_state_data_cache_misses.inc()
|
|
if (let tmp = dag.db.getStateRoot(parBs.blck.root, parBs.slot); tmp.isSome()):
|
|
if dag.db.containsState(tmp.get):
|
|
stateRoot = tmp
|
|
break
|
|
|
|
curBs = parBs
|
|
|
|
if stateRoot.isNone():
|
|
# TODO this should only happen if the database is corrupt - we walked the
|
|
# list of parent blocks and couldn't find a corresponding state in the
|
|
# database, which should never happen (at least we should have the
|
|
# tail state in there!)
|
|
error "Couldn't find ancestor state root!",
|
|
blockRoot = shortLog(bs.blck.root),
|
|
blockSlot = shortLog(bs.blck.slot),
|
|
slot = shortLog(bs.slot),
|
|
cat = "crash"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
let
|
|
ancestor = ancestors.pop()
|
|
root = stateRoot.get()
|
|
found = dag.getState(dag.db, root, ancestor.refs, state)
|
|
|
|
if not found:
|
|
# TODO this should only happen if the database is corrupt - we walked the
|
|
# list of parent blocks and couldn't find a corresponding state in the
|
|
# database, which should never happen (at least we should have the
|
|
# tail state in there!)
|
|
error "Couldn't find ancestor state or block parent missing!",
|
|
blockRoot = shortLog(bs.blck.root),
|
|
blockSlot = shortLog(bs.blck.slot),
|
|
slot = shortLog(bs.slot),
|
|
cat = "crash"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
trace "Replaying state transitions",
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
ancestorStateRoot = shortLog(ancestor.data.message.state_root),
|
|
ancestorStateSlot = shortLog(state.data.data.slot),
|
|
slot = shortLog(bs.slot),
|
|
blockRoot = shortLog(bs.blck.root),
|
|
ancestors = ancestors.len,
|
|
cat = "replay_state"
|
|
|
|
ancestors
|
|
|
|
proc getStateDataCached(dag: CandidateChains, state: var StateData, bs: BlockSlot): bool =
|
|
# This pointedly does not run rewindState or state_transition, but otherwise
|
|
# mostly matches updateStateData(...), because it's too expensive to run the
|
|
# rewindState(...)/skipAndUpdateState(...)/state_transition(...) procs, when
|
|
# each hash_tree_root(...) consumes a nontrivial fraction of a second.
|
|
when false:
|
|
# For debugging/development purposes to assess required lookback window for
|
|
# any given use case.
|
|
doAssert state.data.data.slot <= bs.slot + 4
|
|
|
|
let idx = dag.getStateCacheIndex(bs.blck.root, bs.slot)
|
|
if idx >= 0:
|
|
state.data = dag.cachedStates[idx].state[]
|
|
state.blck = bs.blck
|
|
beacon_state_data_cache_hits.inc()
|
|
return true
|
|
|
|
# In-memory caches didn't hit. Try main blockpool database. This is slower
|
|
# than the caches due to SSZ (de)serializing and disk I/O, so prefer them.
|
|
beacon_state_data_cache_misses.inc()
|
|
if (let tmp = dag.db.getStateRoot(bs.blck.root, bs.slot); tmp.isSome()):
|
|
return dag.getState(dag.db, tmp.get(), bs.blck, state)
|
|
|
|
false
|
|
|
|
proc updateStateData*(dag: CandidateChains, state: var StateData, bs: BlockSlot) =
|
|
## Rewind or advance state such that it matches the given block and slot -
|
|
## this may include replaying from an earlier snapshot if blck is on a
|
|
## different branch or has advanced to a higher slot number than slot
|
|
## If slot is higher than blck.slot, replay will fill in with empty/non-block
|
|
## slots, else it is ignored
|
|
|
|
# We need to check the slot because the state might have moved forwards
|
|
# without blocks
|
|
if state.blck.root == bs.blck.root and state.data.data.slot <= bs.slot:
|
|
if state.data.data.slot != bs.slot:
|
|
# Might be that we're moving to the same block but later slot
|
|
dag.skipAndUpdateState(state.data, bs.blck, bs.slot, true)
|
|
|
|
return # State already at the right spot
|
|
|
|
if dag.getStateDataCached(state, bs):
|
|
return
|
|
|
|
let ancestors = rewindState(dag, state, bs)
|
|
|
|
# If we come this far, we found the state root. The last block on the stack
|
|
# is the one that produced this particular state, so we can pop it
|
|
# TODO it might be possible to use the latest block hashes from the state to
|
|
# do this more efficiently.. whatever!
|
|
|
|
# Time to replay all the blocks between then and now. We skip one because
|
|
# it's the one that we found the state with, and it has already been
|
|
# applied. Pathologically quadratic in slot number, naïvely.
|
|
for i in countdown(ancestors.len - 1, 0):
|
|
# Because the ancestors are in the database, there's no need to persist them
|
|
# again. Also, because we're applying blocks that were loaded from the
|
|
# database, we can skip certain checks that have already been performed
|
|
# before adding the block to the database. In particular, this means that
|
|
# no state root calculation will take place here, because we can load
|
|
# the final state root from the block itself.
|
|
let ok =
|
|
dag.skipAndUpdateState(
|
|
state, ancestors[i],
|
|
{skipBlsValidation, skipMerkleValidation, skipStateRootValidation},
|
|
false)
|
|
doAssert ok, "Blocks in database should never fail to apply.."
|
|
|
|
# We save states here - blocks were guaranteed to have passed through the save
|
|
# function once at least, but not so for empty slots!
|
|
dag.skipAndUpdateState(state.data, bs.blck, bs.slot, true)
|
|
|
|
state.blck = bs.blck
|
|
|
|
proc loadTailState*(dag: CandidateChains): StateData =
|
|
## Load the state associated with the current tail in the dag
|
|
let stateRoot = dag.db.getBlock(dag.tail.root).get().message.state_root
|
|
let found = dag.getState(dag.db, stateRoot, dag.tail, result)
|
|
# TODO turn into regular error, this can happen
|
|
doAssert found, "Failed to load tail state, database corrupt?"
|
|
|
|
proc delState(dag: CandidateChains, bs: BlockSlot) =
|
|
# Delete state state and mapping for a particular block+slot
|
|
if (let root = dag.db.getStateRoot(bs.blck.root, bs.slot); root.isSome()):
|
|
dag.db.delState(root.get())
|
|
|
|
proc updateHead*(dag: CandidateChains, newHead: BlockRef) =
|
|
## Update what we consider to be the current head, as given by the fork
|
|
## choice.
|
|
## The choice of head affects the choice of finalization point - the order
|
|
## of operations naturally becomes important here - after updating the head,
|
|
## blocks that were once considered potential candidates for a tree will
|
|
## now fall from grace, or no longer be considered resolved.
|
|
doAssert newHead.parent != nil or newHead.slot == 0
|
|
logScope: pcs = "fork_choice"
|
|
|
|
if dag.head.blck == newHead:
|
|
info "No head block update",
|
|
head = shortLog(newHead),
|
|
cat = "fork_choice"
|
|
|
|
return
|
|
|
|
let
|
|
lastHead = dag.head
|
|
dag.db.putHeadBlock(newHead.root)
|
|
|
|
# Start off by making sure we have the right state
|
|
updateStateData(
|
|
dag, dag.headState, BlockSlot(blck: newHead, slot: newHead.slot))
|
|
|
|
let
|
|
justifiedSlot = dag.headState.data.data
|
|
.current_justified_checkpoint
|
|
.epoch
|
|
.compute_start_slot_at_epoch()
|
|
justifiedBS = newHead.atSlot(justifiedSlot)
|
|
|
|
dag.head = Head(blck: newHead, justified: justifiedBS)
|
|
updateStateData(dag, dag.justifiedState, justifiedBS)
|
|
|
|
# TODO isAncestorOf may be expensive - too expensive?
|
|
if not lastHead.blck.isAncestorOf(newHead):
|
|
info "Updated head block (new parent)",
|
|
lastHead = shortLog(lastHead.blck),
|
|
headParent = shortLog(newHead.parent),
|
|
stateRoot = shortLog(dag.headState.data.root),
|
|
headBlock = shortLog(dag.headState.blck),
|
|
stateSlot = shortLog(dag.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(dag.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(dag.headState.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
# A reasonable criterion for "reorganizations of the chain"
|
|
beacon_reorgs_total.inc()
|
|
else:
|
|
info "Updated head block",
|
|
stateRoot = shortLog(dag.headState.data.root),
|
|
headBlock = shortLog(dag.headState.blck),
|
|
stateSlot = shortLog(dag.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(dag.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(dag.headState.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
let
|
|
finalizedEpochStartSlot =
|
|
dag.headState.data.data.finalized_checkpoint.epoch.
|
|
compute_start_slot_at_epoch()
|
|
# TODO there might not be a block at the epoch boundary - what then?
|
|
finalizedHead = newHead.atSlot(finalizedEpochStartSlot)
|
|
|
|
doAssert (not finalizedHead.blck.isNil),
|
|
"Block graph should always lead to a finalized block"
|
|
|
|
if finalizedHead != dag.finalizedHead:
|
|
block: # Remove states, walking slot by slot
|
|
discard
|
|
# TODO this is very aggressive - in theory all our operations start at
|
|
# the finalized block so all states before that can be wiped..
|
|
# TODO this is disabled for now because the logic for initializing the
|
|
# block dag and potentially a few other places depend on certain
|
|
# states (like the tail state) being present. It's also problematic
|
|
# because it is not clear what happens when tail and finalized states
|
|
# happen on an empty slot..
|
|
# var cur = finalizedHead
|
|
# while cur != dag.finalizedHead:
|
|
# cur = cur.parent
|
|
# dag.delState(cur)
|
|
|
|
block: # Clean up block refs, walking block by block
|
|
var cur = finalizedHead.blck
|
|
while cur != dag.finalizedHead.blck:
|
|
# Finalization means that we choose a single chain as the canonical one -
|
|
# it also means we're no longer interested in any branches from that chain
|
|
# up to the finalization point.
|
|
# The new finalized head should not be cleaned! We start at its parent and
|
|
# clean everything including the old finalized head.
|
|
cur = cur.parent
|
|
|
|
# TODO what about attestations? we need to drop those too, though they
|
|
# *should* be pretty harmless
|
|
if cur.parent != nil: # This happens for the genesis / tail block
|
|
for child in cur.parent.children:
|
|
if child != cur:
|
|
# TODO also remove states associated with the unviable forks!
|
|
# TODO the easiest thing to do here would probably be to use
|
|
# dag.heads to find unviable heads, then walk those chains
|
|
# and remove everything.. currently, if there's a child with
|
|
# children of its own, those children will not be pruned
|
|
# correctly from the database
|
|
dag.blocks.del(child.root)
|
|
dag.db.delBlock(child.root)
|
|
cur.parent.children = @[cur]
|
|
|
|
dag.finalizedHead = finalizedHead
|
|
|
|
let hlen = dag.heads.len
|
|
for i in 0..<hlen:
|
|
let n = hlen - i - 1
|
|
if not dag.finalizedHead.blck.isAncestorOf(dag.heads[n].blck):
|
|
# Any heads that are not derived from the newly finalized block are no
|
|
# longer viable candidates for future head selection
|
|
dag.heads.del(n)
|
|
|
|
info "Finalized block",
|
|
finalizedHead = shortLog(finalizedHead),
|
|
head = shortLog(newHead),
|
|
heads = dag.heads.len,
|
|
cat = "fork_choice"
|
|
|
|
# TODO prune everything before weak subjectivity period
|
|
|
|
func latestJustifiedBlock*(dag: CandidateChains): BlockSlot =
|
|
## Return the most recent block that is justified and at least as recent
|
|
## as the latest finalized block
|
|
|
|
doAssert dag.heads.len > 0,
|
|
"We should have at least the genesis block in heads"
|
|
doAssert (not dag.head.blck.isNil()),
|
|
"Genesis block will be head, if nothing else"
|
|
|
|
# Prefer stability: use justified block from current head to break ties!
|
|
result = dag.head.justified
|
|
for head in dag.heads[1 ..< ^0]:
|
|
if head.justified.slot > result.slot:
|
|
result = head.justified
|
|
|
|
proc isInitialized*(T: type CandidateChains, db: BeaconChainDB): bool =
|
|
let
|
|
headBlockRoot = db.getHeadBlock()
|
|
tailBlockRoot = db.getTailBlock()
|
|
|
|
if not (headBlockRoot.isSome() and tailBlockRoot.isSome()):
|
|
return false
|
|
|
|
let
|
|
headBlock = db.getBlock(headBlockRoot.get())
|
|
tailBlock = db.getBlock(tailBlockRoot.get())
|
|
|
|
if not (headBlock.isSome() and tailBlock.isSome()):
|
|
return false
|
|
|
|
if not db.containsState(tailBlock.get().message.state_root):
|
|
return false
|
|
|
|
return true
|
|
|
|
proc preInit*(
|
|
T: type CandidateChains, db: BeaconChainDB, state: BeaconState,
|
|
signedBlock: SignedBeaconBlock) =
|
|
# write a genesis state, the way the CandidateChains expects it to be stored in
|
|
# database
|
|
# TODO probably should just init a blockpool with the freshly written
|
|
# state - but there's more refactoring needed to make it nice - doing
|
|
# a minimal patch for now..
|
|
let
|
|
blockRoot = hash_tree_root(signedBlock.message)
|
|
|
|
doAssert signedBlock.message.state_root == hash_tree_root(state)
|
|
notice "New database from snapshot",
|
|
blockRoot = shortLog(blockRoot),
|
|
stateRoot = shortLog(signedBlock.message.state_root),
|
|
fork = state.fork,
|
|
validators = state.validators.len(),
|
|
cat = "initialization"
|
|
|
|
db.putState(state)
|
|
db.putBlock(signedBlock)
|
|
db.putTailBlock(blockRoot)
|
|
db.putHeadBlock(blockRoot)
|
|
db.putStateRoot(blockRoot, state.slot, signedBlock.message.state_root)
|
|
|
|
proc getProposer*(
|
|
dag: CandidateChains, head: BlockRef, slot: Slot):
|
|
Option[(ValidatorIndex, ValidatorPubKey)] =
|
|
dag.withState(dag.tmpState, head.atSlot(slot)):
|
|
var cache = get_empty_per_epoch_cache()
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.3/specs/phase0/validator.md#validator-assignments
|
|
let proposerIdx = get_beacon_proposer_index(state, cache)
|
|
if proposerIdx.isNone:
|
|
warn "Missing proposer index",
|
|
slot=slot,
|
|
epoch=slot.compute_epoch_at_slot,
|
|
num_validators=state.validators.len,
|
|
active_validators=
|
|
get_active_validator_indices(state, slot.compute_epoch_at_slot),
|
|
balances=state.balances
|
|
return
|
|
|
|
return some((proposerIdx.get(), state.validators[proposerIdx.get()].pubkey))
|