1161 lines
45 KiB
Nim
1161 lines
45 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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bitops, chronicles, options, tables,
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stew/results, ssz, beacon_chain_db, state_transition, extras, eth/db/kvstore,
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beacon_node_types, metrics,
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spec/[crypto, datatypes, digest, helpers, validator]
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declareCounter beacon_reorgs_total, "Total occurrences of reorganizations of the chain" # On fork choice
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logScope: topics = "blkpool"
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proc updateStateData*(
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pool: BlockPool, state: var StateData, bs: BlockSlot) {.gcsafe.}
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proc add*(
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pool: var BlockPool, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock): BlockRef {.gcsafe.}
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template withState*(
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pool: BlockPool, 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(pool, 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 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 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 BlockPool, db: BeaconChainDB): BlockPool =
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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 pool", 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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let loaded = db.getState(root.get(), tmpState.data.data, noRollback)
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if not loaded:
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# TODO We don't write state root and state atomically, so we need to be
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# lenient here in case of dirty shutdown - transactions would be
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# nice!
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warn "State root, but no state - database corrupt?",
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stateRoot = root.get(), blockRoot = bs.blck.root, blockSlot = bs.slot
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continue
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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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justifiedBlock = db.getBlock(justifiedHead.blck.root).get()
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justifiedStateRoot = justifiedBlock.message.state_root
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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 = BlockPool(
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pending: initTable[Eth2Digest, SignedBeaconBlock](),
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missing: initTable[Eth2Digest, MissingBlock](),
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cachedStates: [
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newTable[tuple[a: Eth2Digest, b: Slot], StateData](),
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newTable[tuple[a: Eth2Digest, b: Slot], StateData]()
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],
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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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)
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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 pool 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 addResolvedBlock(
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pool: var BlockPool, state: BeaconState, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock, parent: BlockRef): BlockRef =
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logScope: pcs = "block_resolution"
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doAssert state.slot == signedBlock.message.slot, "state must match block"
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let blockRef = BlockRef.init(blockRoot, signedBlock.message)
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link(parent, blockRef)
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pool.blocks[blockRoot] = blockRef
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trace "Populating block pool", key = blockRoot, val = blockRef
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# Resolved blocks should be stored in database
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pool.db.putBlock(blockRoot, signedBlock)
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# This block *might* have caused a justification - make sure we stow away
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# that information:
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let justifiedSlot =
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state.current_justified_checkpoint.epoch.compute_start_slot_at_epoch()
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var foundHead: Option[Head]
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for head in pool.heads.mitems():
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if head.blck.isAncestorOf(blockRef):
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if head.justified.slot != justifiedSlot:
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head.justified = blockRef.atSlot(justifiedSlot)
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head.blck = blockRef
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foundHead = some(head)
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break
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if foundHead.isNone():
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foundHead = some(Head(
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blck: blockRef,
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justified: blockRef.atSlot(justifiedSlot)))
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pool.heads.add(foundHead.get())
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info "Block resolved",
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blck = shortLog(signedBlock.message),
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blockRoot = shortLog(blockRoot),
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justifiedHead = foundHead.get().justified,
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heads = pool.heads.len(),
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cat = "filtering"
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# Now that we have the new block, we should see if any of the previously
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# unresolved blocks magically become resolved
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# TODO there are more efficient ways of doing this that don't risk
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# running out of stack etc
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# TODO This code is convoluted because when there are more than ~1.5k
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# blocks being synced, there's a stack overflow as `add` gets called
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# for the whole chain of blocks. Instead we use this ugly field in `pool`
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# which could be avoided by refactoring the code
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if not pool.inAdd:
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pool.inAdd = true
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defer: pool.inAdd = false
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var keepGoing = true
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while keepGoing:
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let retries = pool.pending
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for k, v in retries:
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discard pool.add(k, v)
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# Keep going for as long as the pending pool is shrinking
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# TODO inefficient! so what?
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keepGoing = pool.pending.len < retries.len
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blockRef
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proc getState(
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pool: BlockPool, 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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proc rollback(v: var BeaconState) =
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if outputAddr == (unsafeAddr pool.headState):
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# TODO seeing the headState in the rollback 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 rollback 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[] = pool.headState
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if not db.getState(stateRoot, output.data.data, rollback):
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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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proc putState(pool: BlockPool, 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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let epochParity = state.data.slot.compute_epoch_at_slot.uint64 mod 2
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if state.data.slot mod SLOTS_PER_EPOCH == 0:
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if not pool.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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pool.db.putState(state.root, state.data)
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# TODO this should be atomic with the above write..
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pool.db.putStateRoot(blck.root, state.data.slot, state.root)
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# Because state.data.slot mod SLOTS_PER_EPOCH == 0, wrap back to last
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# time this was the case i.e. last currentCache. The opposite parity,
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# by contrast, has just finished filling from the previous epoch. The
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# resulting lookback window is thus >= SLOTS_PER_EPOCH in size, while
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# bounded from above by 2*SLOTS_PER_EPOCH.
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pool.cachedStates[epochParity] =
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newTable[tuple[a: Eth2Digest, b: Slot], StateData]()
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else:
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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. Keep a
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# block's StateData of odd-numbered epoch in bucket 1, whilst evens
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# land in bucket 0 (which is handed back to GC in if branch). There
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# still is a possibility of combinatorial explosion, but this only,
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# by a constant-factor, worsens things. TODO the actual solution's,
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# eventually, to switch to CoW and/or ref objects for state and the
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# hash_tree_root processing.
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let key = (a: blck.root, b: state.data.slot)
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if key notin pool.cachedStates[epochParity]:
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# Avoid constructing StateData if not necessary
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pool.cachedStates[epochParity][key] = StateData(data: state, blck: blck)
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proc add*(
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pool: var BlockPool, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock): BlockRef {.gcsafe.} =
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## return the block, if resolved...
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## the state parameter may be updated to include the given block, if
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## everything checks out
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# TODO reevaluate passing the state in like this
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let blck = signedBlock.message
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doAssert blockRoot == hash_tree_root(blck)
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logScope: pcs = "block_addition"
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# Already seen this block??
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pool.blocks.withValue(blockRoot, blockRef):
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debug "Block already exists",
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blck = shortLog(blck),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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return blockRef[]
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pool.missing.del(blockRoot)
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# If the block we get is older than what we finalized already, we drop it.
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# One way this can happen is that we start resolving a block and finalization
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# happens in the meantime - the block we requested will then be stale
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# by the time it gets here.
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if blck.slot <= pool.finalizedHead.slot:
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debug "Old block, dropping",
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blck = shortLog(blck),
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finalizedHead = shortLog(pool.finalizedHead),
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tail = shortLog(pool.tail),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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return
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let parent = pool.blocks.getOrDefault(blck.parent_root)
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if parent != nil:
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if parent.slot >= blck.slot:
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# TODO Malicious block? inform peer pool?
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notice "Invalid block slot",
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blck = shortLog(blck),
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blockRoot = shortLog(blockRoot),
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parentBlock = shortLog(parent)
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return
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# The block might have been in either of pending or missing - we don't want
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# any more work done on its behalf
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pool.pending.del(blockRoot)
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# The block is resolved, now it's time to validate it to ensure that the
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# blocks we add to the database are clean for the given state
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# TODO if the block is from the future, we should not be resolving it (yet),
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# but maybe we should use it as a hint that our clock is wrong?
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updateStateData(pool, pool.tmpState, BlockSlot(blck: parent, slot: blck.slot - 1))
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let
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poolPtr = unsafeAddr pool # safe because restore is short-lived
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proc restore(v: var HashedBeaconState) =
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# TODO address this ugly workaround - there should probably be a
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# `state_transition` that takes a `StateData` instead and updates
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# the block as well
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doAssert v.addr == addr poolPtr.tmpState.data
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poolPtr.tmpState = poolPtr.headState
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if not state_transition(pool.tmpState.data, signedBlock, {}, restore):
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# TODO find a better way to log all this block data
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notice "Invalid block",
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blck = shortLog(blck),
|
|
blockRoot = shortLog(blockRoot),
|
|
cat = "filtering"
|
|
|
|
return
|
|
# Careful, tmpState.data has been updated but not blck - we need to create
|
|
# the BlockRef first!
|
|
pool.tmpState.blck = pool.addResolvedBlock(
|
|
pool.tmpState.data.data, blockRoot, signedBlock, parent)
|
|
pool.putState(pool.tmpState.data, pool.tmpState.blck)
|
|
|
|
return pool.tmpState.blck
|
|
|
|
# TODO already checked hash though? main reason to keep this is because
|
|
# the pending pool calls this function back later in a loop, so as long
|
|
# as pool.add(...) requires a SignedBeaconBlock, easier to keep them in
|
|
# pending too.
|
|
pool.pending[blockRoot] = signedBlock
|
|
|
|
# TODO possibly, it makes sense to check the database - that would allow sync
|
|
# to simply fill up the database with random blocks the other clients
|
|
# think are useful - but, it would also risk filling the database with
|
|
# junk that's not part of the block graph
|
|
|
|
if blck.parent_root in pool.missing or
|
|
blck.parent_root in pool.pending:
|
|
return
|
|
|
|
# This is an unresolved block - put its parent on the missing list for now...
|
|
# TODO if we receive spam blocks, one heurestic to implement might be to wait
|
|
# for a couple of attestations to appear before fetching parents - this
|
|
# would help prevent using up network resources for spam - this serves
|
|
# two purposes: one is that attestations are likely to appear for the
|
|
# block only if it's valid / not spam - the other is that malicious
|
|
# validators that are not proposers can sign invalid blocks and send
|
|
# them out without penalty - but signing invalid attestations carries
|
|
# a risk of being slashed, making attestations a more valuable spam
|
|
# filter.
|
|
# TODO when we receive the block, we don't know how many others we're missing
|
|
# from that branch, so right now, we'll just do a blind guess
|
|
let parentSlot = blck.slot - 1
|
|
|
|
pool.missing[blck.parent_root] = MissingBlock(
|
|
slots:
|
|
# The block is at least two slots ahead - try to grab whole history
|
|
if parentSlot > pool.head.blck.slot:
|
|
parentSlot - pool.head.blck.slot
|
|
else:
|
|
# It's a sibling block from a branch that we're missing - fetch one
|
|
# epoch at a time
|
|
max(1.uint64, SLOTS_PER_EPOCH.uint64 -
|
|
(parentSlot.uint64 mod SLOTS_PER_EPOCH.uint64))
|
|
)
|
|
|
|
debug "Unresolved block (parent missing)",
|
|
blck = shortLog(blck),
|
|
blockRoot = shortLog(blockRoot),
|
|
pending = pool.pending.len,
|
|
missing = pool.missing.len,
|
|
cat = "filtering"
|
|
|
|
func getRef*(pool: BlockPool, root: Eth2Digest): BlockRef =
|
|
## Retrieve a resolved block reference, if available
|
|
pool.blocks.getOrDefault(root, nil)
|
|
|
|
proc getBlockRange*(
|
|
pool: BlockPool, startSlot: Slot, skipStep: Natural,
|
|
output: var openArray[BlockRef]): Natural =
|
|
## This function populates an `output` buffer of blocks
|
|
## with a slots ranging from `startSlot` up to, but not including,
|
|
## `startSlot + skipStep * output.len`, skipping any slots that don't have
|
|
## a block.
|
|
##
|
|
## Blocks will be written to `output` from the end without gaps, even if
|
|
## a block is missing in a particular slot. The return value shows how
|
|
## many slots were missing blocks - to iterate over the result, start
|
|
## at this index.
|
|
##
|
|
## If there were no blocks in the range, `output.len` will be returned.
|
|
let count = output.len
|
|
trace "getBlockRange entered",
|
|
head = shortLog(pool.head.blck.root), count, startSlot, skipStep
|
|
|
|
let
|
|
skipStep = max(1, skipStep) # Treat 0 step as 1
|
|
endSlot = startSlot + uint64(count * skipStep)
|
|
|
|
var
|
|
b = pool.head.blck.atSlot(endSlot)
|
|
o = count
|
|
for i in 0..<count:
|
|
for j in 0..<skipStep:
|
|
b = b.parent
|
|
if b.blck.slot == b.slot:
|
|
dec o
|
|
output[o] = b.blck
|
|
|
|
# Make sure the given input is cleared, just in case
|
|
for i in 0..<o:
|
|
output[i] = nil
|
|
|
|
o # Return the index of the first non-nil item in the output
|
|
|
|
func getBlockBySlot*(pool: BlockPool, slot: Slot): BlockRef =
|
|
## Retrieves the first block in the current canonical chain
|
|
## with slot number less or equal to `slot`.
|
|
pool.head.blck.atSlot(slot).blck
|
|
|
|
func getBlockByPreciseSlot*(pool: BlockPool, slot: Slot): BlockRef =
|
|
## Retrieves a block from the canonical chain with a slot
|
|
## number equal to `slot`.
|
|
let found = pool.getBlockBySlot(slot)
|
|
if found.slot != slot: found else: nil
|
|
|
|
proc get*(pool: BlockPool, blck: BlockRef): BlockData =
|
|
## Retrieve the associated block body of a block reference
|
|
doAssert (not blck.isNil), "Trying to get nil BlockRef"
|
|
|
|
let data = pool.db.getBlock(blck.root)
|
|
doAssert data.isSome, "BlockRef without backing data, database corrupt?"
|
|
|
|
BlockData(data: data.get(), refs: blck)
|
|
|
|
proc get*(pool: BlockPool, root: Eth2Digest): Option[BlockData] =
|
|
## Retrieve a resolved block reference and its associated body, if available
|
|
let refs = pool.getRef(root)
|
|
|
|
if not refs.isNil:
|
|
some(pool.get(refs))
|
|
else:
|
|
none(BlockData)
|
|
|
|
func getOrResolve*(pool: var BlockPool, root: Eth2Digest): BlockRef =
|
|
## Fetch a block ref, or nil if not found (will be added to list of
|
|
## blocks-to-resolve)
|
|
result = pool.getRef(root)
|
|
|
|
if result.isNil:
|
|
pool.missing[root] = MissingBlock(slots: 1)
|
|
|
|
func checkMissing*(pool: var BlockPool): seq[FetchRecord] =
|
|
## Return a list of blocks that we should try to resolve from other client -
|
|
## to be called periodically but not too often (once per slot?)
|
|
var done: seq[Eth2Digest]
|
|
|
|
for k, v in pool.missing.mpairs():
|
|
if v.tries > 8:
|
|
done.add(k)
|
|
else:
|
|
inc v.tries
|
|
|
|
for k in done:
|
|
# TODO Need to potentially remove from pool.pending - this is currently a
|
|
# memory leak here!
|
|
pool.missing.del(k)
|
|
|
|
# simple (simplistic?) exponential backoff for retries..
|
|
for k, v in pool.missing.pairs():
|
|
if v.tries.popcount() == 1:
|
|
result.add(FetchRecord(root: k, historySlots: v.slots))
|
|
|
|
proc skipAndUpdateState(
|
|
pool: BlockPool,
|
|
state: var HashedBeaconState, blck: BlockRef, slot: Slot) =
|
|
while state.data.slot < slot:
|
|
# Process slots one at a time in case afterUpdate needs to see empty states
|
|
process_slots(state, state.data.slot + 1)
|
|
pool.putState(state, blck)
|
|
|
|
proc skipAndUpdateState(
|
|
pool: BlockPool,
|
|
state: var StateData, blck: BlockData, flags: UpdateFlags): bool =
|
|
|
|
pool.skipAndUpdateState(state.data, blck.refs, blck.data.message.slot - 1)
|
|
|
|
var statePtr = unsafeAddr state # safe because `rollback` is locally scoped
|
|
proc rollback(v: var HashedBeaconState) =
|
|
doAssert (addr(statePtr.data) == addr v)
|
|
statePtr[] = pool.headState
|
|
|
|
let ok = state_transition(state.data, blck.data, flags, rollback)
|
|
if ok:
|
|
pool.putState(state.data, blck.refs)
|
|
|
|
ok
|
|
|
|
proc rewindState(pool: BlockPool, state: var StateData, bs: BlockSlot):
|
|
seq[BlockData] =
|
|
logScope: pcs = "replay_state"
|
|
|
|
var ancestors = @[pool.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 = pool.db.getStateRoot(bs.blck.root, bs.slot)
|
|
curBs = bs
|
|
|
|
# TODO this can happen when state root is saved but state is gone - this would
|
|
# indicate a corrupt database, but since we're not atomically
|
|
# writing and deleting state+root mappings in a single transaction, it's
|
|
# likely to happen and we guard against it here.
|
|
if stateRoot.isSome() and not pool.db.containsState(stateRoot.get()):
|
|
stateRoot.err()
|
|
|
|
while stateRoot.isNone():
|
|
let parBs = curBs.parent()
|
|
if parBs.blck.isNil:
|
|
break # Bug probably!
|
|
|
|
if parBs.blck != curBs.blck:
|
|
ancestors.add(pool.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.
|
|
for cachedState in pool.cachedStates:
|
|
let key = (a: parBs.blck.root, b: parBs.slot)
|
|
|
|
try:
|
|
state = cachedState[key]
|
|
except KeyError:
|
|
continue
|
|
let ancestor = ancestors.pop()
|
|
when false:
|
|
doAssert state.blck == ancestor.refs
|
|
|
|
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
|
|
|
|
if (let tmp = pool.db.getStateRoot(parBs.blck.root, parBs.slot); tmp.isSome()):
|
|
if pool.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 = pool.getState(pool.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(pool: BlockPool, 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.
|
|
for poolStateCache in pool.cachedStates:
|
|
try:
|
|
state = poolStateCache[(a: bs.blck.root, b: bs.slot)]
|
|
return true
|
|
except KeyError:
|
|
discard
|
|
|
|
# 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.
|
|
if (let tmp = pool.db.getStateRoot(bs.blck.root, bs.slot); tmp.isSome()):
|
|
doAssert pool.getState(pool.db, tmp.get(), bs.blck, state)
|
|
return true
|
|
|
|
false
|
|
|
|
proc updateStateData*(pool: BlockPool, 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
|
|
pool.skipAndUpdateState(state.data, bs.blck, bs.slot)
|
|
|
|
return # State already at the right spot
|
|
|
|
if pool.getStateDataCached(state, bs):
|
|
return
|
|
|
|
let ancestors = rewindState(pool, 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):
|
|
let ok =
|
|
pool.skipAndUpdateState(
|
|
state, ancestors[i],
|
|
{skipBlsValidation, skipMerkleValidation, skipStateRootValidation})
|
|
doAssert ok, "Blocks in database should never fail to apply.."
|
|
|
|
pool.skipAndUpdateState(state.data, bs.blck, bs.slot)
|
|
|
|
state.blck = bs.blck
|
|
|
|
proc loadTailState*(pool: BlockPool): StateData =
|
|
## Load the state associated with the current tail in the pool
|
|
let stateRoot = pool.db.getBlock(pool.tail.root).get().message.state_root
|
|
let found = pool.getState(pool.db, stateRoot, pool.tail, result)
|
|
# TODO turn into regular error, this can happen
|
|
doAssert found, "Failed to load tail state, database corrupt?"
|
|
|
|
proc delState(pool: BlockPool, bs: BlockSlot) =
|
|
# Delete state state and mapping for a particular block+slot
|
|
if (let root = pool.db.getStateRoot(bs.blck.root, bs.slot); root.isSome()):
|
|
pool.db.delState(root.get())
|
|
pool.db.delStateRoot(bs.blck.root, bs.slot)
|
|
|
|
proc updateHead*(pool: BlockPool, 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 pool.head.blck == newHead:
|
|
info "No head block update",
|
|
head = shortLog(newHead),
|
|
cat = "fork_choice"
|
|
|
|
return
|
|
|
|
let
|
|
lastHead = pool.head
|
|
pool.db.putHeadBlock(newHead.root)
|
|
|
|
# Start off by making sure we have the right state
|
|
updateStateData(
|
|
pool, pool.headState, BlockSlot(blck: newHead, slot: newHead.slot))
|
|
|
|
let
|
|
justifiedSlot = pool.headState.data.data
|
|
.current_justified_checkpoint
|
|
.epoch
|
|
.compute_start_slot_at_epoch()
|
|
justifiedBS = newHead.atSlot(justifiedSlot)
|
|
|
|
pool.head = Head(blck: newHead, justified: justifiedBS)
|
|
updateStateData(pool, pool.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(pool.headState.data.root),
|
|
headBlock = shortLog(pool.headState.blck),
|
|
stateSlot = shortLog(pool.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(pool.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(pool.headState.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
# A reasonable criterion for "reorganizations of the chain"
|
|
try:
|
|
beacon_reorgs_total.inc()
|
|
except Exception as e: # TODO https://github.com/status-im/nim-metrics/pull/22
|
|
trace "Couldn't update metrics", msg = e.msg
|
|
else:
|
|
info "Updated head block",
|
|
stateRoot = shortLog(pool.headState.data.root),
|
|
headBlock = shortLog(pool.headState.blck),
|
|
stateSlot = shortLog(pool.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(pool.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(pool.headState.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
let
|
|
finalizedEpochStartSlot =
|
|
pool.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 != pool.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 pool 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 != pool.finalizedHead:
|
|
# cur = cur.parent
|
|
# pool.delState(cur)
|
|
|
|
block: # Clean up block refs, walking block by block
|
|
var cur = finalizedHead.blck
|
|
while cur != pool.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
|
|
# pool.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
|
|
pool.blocks.del(child.root)
|
|
pool.db.delBlock(child.root)
|
|
cur.parent.children = @[cur]
|
|
|
|
pool.finalizedHead = finalizedHead
|
|
|
|
let hlen = pool.heads.len
|
|
for i in 0..<hlen:
|
|
let n = hlen - i - 1
|
|
if not pool.finalizedHead.blck.isAncestorOf(pool.heads[n].blck):
|
|
# Any heads that are not derived from the newly finalized block are no
|
|
# longer viable candidates for future head selection
|
|
pool.heads.del(n)
|
|
|
|
info "Finalized block",
|
|
finalizedHead = shortLog(finalizedHead),
|
|
head = shortLog(newHead),
|
|
heads = pool.heads.len,
|
|
cat = "fork_choice"
|
|
|
|
# TODO prune everything before weak subjectivity period
|
|
|
|
func latestJustifiedBlock*(pool: BlockPool): BlockSlot =
|
|
## Return the most recent block that is justified and at least as recent
|
|
## as the latest finalized block
|
|
|
|
doAssert pool.heads.len > 0,
|
|
"We should have at least the genesis block in heaads"
|
|
doAssert (not pool.head.blck.isNil()),
|
|
"Genesis block will be head, if nothing else"
|
|
|
|
# Prefer stability: use justified block from current head to break ties!
|
|
result = pool.head.justified
|
|
for head in pool.heads[1 ..< ^0]:
|
|
if head.justified.slot > result.slot:
|
|
result = head.justified
|
|
|
|
proc isInitialized*(T: type BlockPool, 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 BlockPool, db: BeaconChainDB, state: BeaconState,
|
|
signedBlock: SignedBeaconBlock) =
|
|
# write a genesis state, the way the BlockPool 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*(pool: BlockPool, head: BlockRef, slot: Slot): Option[ValidatorPubKey] =
|
|
pool.withState(pool.tmpState, head.atSlot(slot)):
|
|
var cache = get_empty_per_epoch_cache()
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/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(state.validators[proposerIdx.get()].pubkey)
|
|
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/p2p-interface.md#global-topics
|
|
proc isValidBeaconBlock*(pool: var BlockPool,
|
|
signed_beacon_block: SignedBeaconBlock, current_slot: Slot,
|
|
flags: UpdateFlags): bool =
|
|
# In general, checks are ordered from cheap to expensive. Especially, crypto
|
|
# verification could be quite a bit more expensive than the rest. This is an
|
|
# externally easy-to-invoke function by tossing network packets at the node.
|
|
|
|
# The block is not from a future slot
|
|
# TODO allow `MAXIMUM_GOSSIP_CLOCK_DISPARITY` leniency, especially towards
|
|
# seemingly future slots.
|
|
if not (signed_beacon_block.message.slot <= current_slot):
|
|
debug "isValidBeaconBlock: block is from a future slot",
|
|
signed_beacon_block_message_slot = signed_beacon_block.message.slot,
|
|
current_slot = current_slot
|
|
return false
|
|
|
|
# The block is from a slot greater than the latest finalized slot (with a
|
|
# MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e. validate that
|
|
# signed_beacon_block.message.slot >
|
|
# compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)
|
|
if not (signed_beacon_block.message.slot > pool.finalizedHead.slot):
|
|
debug "isValidBeaconBlock: block is not from a slot greater than the latest finalized slot"
|
|
return false
|
|
|
|
# The block is the first block with valid signature received for the proposer
|
|
# for the slot, signed_beacon_block.message.slot.
|
|
#
|
|
# While this condition is similar to the proposer slashing condition at
|
|
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/validator.md#proposer-slashing
|
|
# it's not identical, and this check does not address slashing:
|
|
#
|
|
# (1) The beacon blocks must be conflicting, i.e. different, for the same
|
|
# slot and proposer. This check also catches identical blocks.
|
|
#
|
|
# (2) By this point in the function, it's not been checked whether they're
|
|
# signed yet. As in general, expensive checks should be deferred, this
|
|
# would add complexity not directly relevant this function.
|
|
#
|
|
# (3) As evidenced by point (1), the similarity in the validation condition
|
|
# and slashing condition, while not coincidental, aren't similar enough
|
|
# to combine, as one or the other might drift.
|
|
#
|
|
# (4) Furthermore, this function, as much as possible, simply returns a yes
|
|
# or no answer, without modifying other state for p2p network interface
|
|
# validation. Complicating this interface, for the sake of sharing only
|
|
# couple lines of code, wouldn't be worthwhile.
|
|
#
|
|
# TODO might check unresolved/orphaned blocks too, and this might not see all
|
|
# blocks at a given slot (though, in theory, those get checked elsewhere), or
|
|
# adding metrics that count how often these conditions occur.
|
|
let
|
|
slotBlockRef = getBlockBySlot(pool, signed_beacon_block.message.slot)
|
|
|
|
if not slotBlockRef.isNil:
|
|
let blck = pool.get(slotBlockRef).data
|
|
if blck.message.proposer_index ==
|
|
signed_beacon_block.message.proposer_index and
|
|
blck.message.slot == signed_beacon_block.message.slot and
|
|
blck.signature.toRaw() != signed_beacon_block.signature.toRaw():
|
|
debug "isValidBeaconBlock: block isn't first block with valid signature received for the proposer",
|
|
signed_beacon_block_message_slot = signed_beacon_block.message.slot,
|
|
blckRef = slotBlockRef,
|
|
received_block = shortLog(signed_beacon_block.message),
|
|
existing_block = shortLog(pool.get(slotBlockRef).data.message)
|
|
return false
|
|
|
|
# If this block doesn't have a parent we know about, we can't/don't really
|
|
# trace it back to a known-good state/checkpoint to verify its prevenance;
|
|
# while one could getOrResolve to queue up searching for missing parent it
|
|
# might not be the best place. As much as feasible, this function aims for
|
|
# answering yes/no, not queuing other action or otherwise altering state.
|
|
let parent_ref = pool.getRef(signed_beacon_block.message.parent_root)
|
|
if parent_ref.isNil:
|
|
# This doesn't mean a block is forever invalid, only that we haven't seen
|
|
# its ancestor blocks yet. While that means for now it should be blocked,
|
|
# at least, from libp2p propagation, it shouldn't be ignored. TODO, if in
|
|
# the future this block moves from pending to being resolved, consider if
|
|
# it's worth broadcasting it then.
|
|
|
|
# Pending pool gets checked via `BlockPool.add(...)` later, and relevant
|
|
# checks are performed there. In usual paths beacon_node adds blocks via
|
|
# BlockPool.add(...) directly, with no additional validity checks. TODO,
|
|
# not specific to this, but by the pending pool keying on the htr of the
|
|
# BeaconBlock, not SignedBeaconBlock, opens up certain spoofing attacks.
|
|
pool.pending[hash_tree_root(signed_beacon_block.message)] =
|
|
signed_beacon_block
|
|
return false
|
|
|
|
# The proposer signature, signed_beacon_block.signature, is valid with
|
|
# respect to the proposer_index pubkey.
|
|
let bs =
|
|
BlockSlot(blck: parent_ref, slot: pool.get(parent_ref).data.message.slot)
|
|
pool.withState(pool.tmpState, bs):
|
|
let
|
|
blockRoot = hash_tree_root(signed_beacon_block.message)
|
|
domain = get_domain(pool.headState.data.data, DOMAIN_BEACON_PROPOSER,
|
|
compute_epoch_at_slot(signed_beacon_block.message.slot))
|
|
signing_root = compute_signing_root(blockRoot, domain)
|
|
proposer_index = signed_beacon_block.message.proposer_index
|
|
|
|
if proposer_index >= pool.headState.data.data.validators.len.uint64:
|
|
return false
|
|
if not blsVerify(pool.headState.data.data.validators[proposer_index].pubkey,
|
|
signing_root.data, signed_beacon_block.signature):
|
|
debug "isValidBeaconBlock: block failed signature verification"
|
|
return false
|
|
|
|
true
|