228 lines
7.6 KiB
Nim
228 lines
7.6 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2022 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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when (NimMajor, NimMinor) < (1, 4):
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{.push raises: [Defect].}
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else:
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{.push raises: [].}
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import
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chronicles,
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../spec/datatypes/[phase0, altair, bellatrix],
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../spec/forks
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# TODO remove once forks re-exports these
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from ../spec/datatypes/capella import SomeBeaconBlock, TrustedBeaconBlock
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export chronicles, forks
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type
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BlockRef* = ref object
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## Node in object graph guaranteed to lead back to finalized head, and to
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## have a corresponding entry in database.
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##
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## All blocks identified by a `BlockRef` are valid per the state transition
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## rules and that at some point were candidates for head selection. The
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## ChainDAG offers stronger guarantees: it only returns `BlockRef` instances
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## that are rooted in the currently finalized chain - however, these
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## guarantees are valid only until the next head update - in particular,
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## they are not valid across `await` calls.
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##
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## Block graph forms a tree - in particular, there are no cycles.
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bid*: BlockId ##\
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## Root that can be used to retrieve block data from database
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executionBlockRoot*: Option[Eth2Digest]
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parent*: BlockRef ##\
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## Not nil, except for the finalized head
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BlockSlot* = object
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## Unique identifier for a particular fork and time in the block chain -
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## normally, there's a block for every slot, but in the case a block is not
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## produced, the chain progresses anyway, producing a new state for every
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## slot.
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blck*: BlockRef
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slot*: Slot ##\
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## Slot time for this BlockSlot which may differ from blck.slot when time
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## has advanced without blocks
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template root*(blck: BlockRef): Eth2Digest = blck.bid.root
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template slot*(blck: BlockRef): Slot = blck.bid.slot
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func init*(
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T: type BlockRef, root: Eth2Digest,
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executionPayloadRoot: Option[Eth2Digest], slot: Slot): BlockRef =
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BlockRef(
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bid: BlockId(root: root, slot: slot),
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executionBlockRoot: executionPayloadRoot)
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func init*(
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T: type BlockRef, root: Eth2Digest,
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blck: phase0.SomeBeaconBlock | altair.SomeBeaconBlock |
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phase0.TrustedBeaconBlock | altair.TrustedBeaconBlock): BlockRef =
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BlockRef.init(root, some ZERO_HASH, blck.slot)
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func init*(
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T: type BlockRef, root: Eth2Digest,
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blck: bellatrix.SomeBeaconBlock | bellatrix.TrustedBeaconBlock |
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capella.SomeBeaconBlock | capella.TrustedBeaconBlock): BlockRef =
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BlockRef.init(
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root, some Eth2Digest(blck.body.execution_payload.block_hash), blck.slot)
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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 parentOrSlot*(bs: BlockSlot): BlockSlot =
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## Return a blockslot representing the previous slot, using the parent block
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## with the current slot if the current had a block
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if bs.blck.isNil():
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BlockSlot(blck: nil, slot: Slot(0))
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elif bs.slot == bs.blck.slot:
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BlockSlot(blck: bs.blck.parent, slot: bs.slot)
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else:
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BlockSlot(blck: bs.blck, slot: bs.slot - 1)
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func getDepth*(a, b: BlockRef): tuple[ancestor: bool, depth: int] =
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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:
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return (true, depth)
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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, depth)
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doAssert b.slot > b.parent.slot
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b = b.parent
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func isAncestorOf*(a, b: BlockRef): bool =
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let (isAncestor, _) = getDepth(a, b)
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isAncestor
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func link*(parent, child: BlockRef) =
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doAssert (not (parent.root.isZero or child.root.isZero)),
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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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func get_ancestor*(blck: BlockRef, slot: Slot,
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maxDepth = 100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int):
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BlockRef =
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## https://github.com/ethereum/consensus-specs/blob/v1.2.0/specs/phase0/fork-choice.md#get_ancestor
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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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if isNil(blck): return nil
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var blck = blck
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var depth = 0
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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 isNil(blck.parent):
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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.get_ancestor(slot), slot: slot)
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func atSlot*(blck: BlockRef): BlockSlot =
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blck.atSlot(blck.slot)
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func atEpochStart*(blck: BlockRef, epoch: Epoch): BlockSlot =
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## Return the BlockSlot corresponding to the first slot in the given epoch
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atSlot(blck, epoch.start_slot())
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func atSlotEpoch*(blck: BlockRef, epoch: Epoch): BlockSlot =
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## Return the last block that was included in the chain leading
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## up to the given epoch - this amounts to the state at the time
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## when epoch processing for `epoch` has been done, but no block
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## has yet been applied
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if epoch == GENESIS_EPOCH:
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blck.atEpochStart(epoch)
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else:
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let
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start = epoch.start_slot()
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tmp = blck.atSlot(start - 1)
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if isNil(tmp.blck):
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BlockSlot()
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else:
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tmp.blck.atSlot(start)
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func atCheckpoint*(blck: BlockRef, checkpoint: Checkpoint): Opt[BlockSlot] =
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## Rewind from `blck` to the given `checkpoint` iff it is an ancestor
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let target = blck.atSlot(checkpoint.epoch.start_slot)
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if target.blck == nil:
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return err()
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if target.blck.root != checkpoint.root:
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return err()
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ok target
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func toBlockSlotId*(bs: BlockSlot): Opt[BlockSlotId] =
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if isNil(bs.blck):
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err()
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else:
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ok BlockSlotId.init(bs.blck.bid, bs.slot)
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func isProposed*(blck: BlockRef, slot: Slot): bool =
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## Return true if `blck` was proposed in the given slot
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not isNil(blck) and blck.bid.isProposed(slot)
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func isProposed*(bs: BlockSlot): bool =
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## Return true if `bs` represents the proposed block (as opposed to an empty
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## slot)
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bs.blck.isProposed(bs.slot)
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func shortLog*(v: BlockRef): string =
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# epoch:root when logging epoch, root:slot when logging slot!
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if v.isNil():
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"nil:0"
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else:
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shortLog(v.bid)
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func shortLog*(v: BlockSlot): string =
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# epoch:root when logging epoch, root:slot when logging slot!
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if isNil(v.blck):
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"nil:0@" & $v.slot
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elif v.blck.slot == v.slot:
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shortLog(v.blck)
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else: # There was a gap - log it
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shortLog(v.blck) & "@" & $v.slot
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chronicles.formatIt BlockSlot: shortLog(it)
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chronicles.formatIt BlockRef: shortLog(it)
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