# beacon_chain # Copyright (c) 2018-2022 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0). # at your option. This file may not be copied, modified, or distributed except according to those terms. {.push raises: [Defect].} import chronicles, ../spec/forks export chronicles, forks type BlockRef* = ref object ## Node in object graph guaranteed to lead back to tail block, and to have ## a corresponding entry in database. ## ## All blocks identified by a `BlockRef` are valid per the state transition ## rules and that at some point were candidates for head selection. The ## ChainDAG offers stronger guarantees: it only returns `BlockRef` instances ## that are rooted in the currently finalized chain - however, these ## guarantees are valid only until the next head update - in particular, ## they are not valid across `await` calls. ## ## Block graph forms a tree - in particular, there are no cycles. bid*: BlockId ##\ ## Root that can be used to retrieve block data from database parent*: BlockRef ##\ ## Not nil, except for the tail BlockSlot* = object ## Unique identifier for a particular fork and time in the block chain - ## normally, there's a block for every slot, but in the case a block is not ## produced, the chain progresses anyway, producing a new state for every ## slot. blck*: BlockRef slot*: Slot ##\ ## Slot time for this BlockSlot which may differ from blck.slot when time ## has advanced without blocks template root*(blck: BlockRef): Eth2Digest = blck.bid.root template slot*(blck: BlockRef): Slot = blck.bid.slot func init*(T: type BlockRef, root: Eth2Digest, slot: Slot): BlockRef = BlockRef( bid: BlockId(root: root, slot: slot) ) func init*(T: type BlockRef, root: Eth2Digest, blck: SomeForkyBeaconBlock): BlockRef = BlockRef.init(root, blck.slot) func parent*(bs: BlockSlot): BlockSlot = ## Return a blockslot representing the previous slot, using the parent block ## if the current slot had a block if bs.slot == Slot(0): BlockSlot(blck: nil, slot: Slot(0)) else: BlockSlot( blck: if bs.slot > bs.blck.slot: bs.blck else: bs.blck.parent, slot: bs.slot - 1 ) func parentOrSlot*(bs: BlockSlot): BlockSlot = ## Return a blockslot representing the previous slot, using the parent block ## with the current slot if the current had a block if bs.blck.isNil(): BlockSlot(blck: nil, slot: Slot(0)) elif bs.slot == bs.blck.slot: BlockSlot(blck: bs.blck.parent, slot: bs.slot) else: BlockSlot(blck: bs.blck, slot: bs.slot - 1) func getDepth*(a, b: BlockRef): tuple[ancestor: bool, depth: int] = var b = b var depth = 0 const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int) while true: if a == b: return (true, depth) # for now, use an assert for block chain length since a chain this long # indicates a circular reference here.. doAssert depth < maxDepth depth += 1 if a.slot >= b.slot or b.parent.isNil: return (false, depth) doAssert b.slot > b.parent.slot b = b.parent func isAncestorOf*(a, b: BlockRef): bool = let (isAncestor, _) = getDepth(a, b) isAncestor func link*(parent, child: BlockRef) = doAssert (not (parent.root.isZero or child.root.isZero)), "blocks missing root!" doAssert parent.root != child.root, "self-references not allowed" child.parent = parent func get_ancestor*(blck: BlockRef, slot: Slot, maxDepth = 100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int): BlockRef = ## https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/phase0/fork-choice.md#get_ancestor ## Return the most recent block as of the time at `slot` that not more recent ## than `blck` itself if isNil(blck): return nil var blck = blck var depth = 0 while true: if blck.slot <= slot: return blck if isNil(blck.parent): return nil doAssert depth < maxDepth depth += 1 blck = blck.parent func atSlot*(blck: BlockRef, slot: Slot): BlockSlot = ## Return a BlockSlot at a given slot, with the block set to the closest block ## available. If slot comes from before the block, a suitable block ancestor ## will be used, else blck is returned as if all slots after it were empty. ## This helper is useful when imagining what the chain looked like at a ## particular moment in time, or when imagining what it will look like in the ## near future if nothing happens (such as when looking ahead for the next ## block proposal) BlockSlot(blck: blck.get_ancestor(slot), slot: slot) func atSlot*(blck: BlockRef): BlockSlot = blck.atSlot(blck.slot) func atEpochStart*(blck: BlockRef, epoch: Epoch): BlockSlot = ## Return the BlockSlot corresponding to the first slot in the given epoch atSlot(blck, epoch.start_slot()) func atSlotEpoch*(blck: BlockRef, epoch: Epoch): BlockSlot = ## Return the last block that was included in the chain leading ## up to the given epoch - this amounts to the state at the time ## when epoch processing for `epoch` has been done, but no block ## has yet been applied if epoch == GENESIS_EPOCH: blck.atEpochStart(epoch) else: let start = epoch.start_slot() tmp = blck.atSlot(start - 1) if isNil(tmp.blck): BlockSlot() else: tmp.blck.atSlot(start) func toBlockSlotId*(bs: BlockSlot): Opt[BlockSlotId] = if isNil(bs.blck): err() else: ok BlockSlotId.init(bs.blck.bid, bs.slot) func isProposed*(blck: BlockRef, slot: Slot): bool = ## Return true if `blck` was proposed in the given slot not isNil(blck) and blck.bid.isProposed(slot) func isProposed*(bs: BlockSlot): bool = ## Return true if `bs` represents the proposed block (as opposed to an empty ## slot) bs.blck.isProposed(bs.slot) func shortLog*(v: BlockRef): string = # epoch:root when logging epoch, root:slot when logging slot! if v.isNil(): "nil:0" else: shortLog(v.bid) func shortLog*(v: BlockSlot): string = # epoch:root when logging epoch, root:slot when logging slot! if isNil(v.blck): "nil:0@" & $v.slot elif v.blck.slot == v.slot: shortLog(v.blck) else: # There was a gap - log it shortLog(v.blck) & "@" & $v.slot chronicles.formatIt BlockSlot: shortLog(it) chronicles.formatIt BlockRef: shortLog(it)