nimbus-eth2/beacon_chain/consensus_object_pools/block_dag.nim

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# beacon_chain
# Copyright (c) 2018-2024 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: [].}
import
chronicles,
../spec/datatypes/[phase0, altair, bellatrix],
chaindag: don't keep backfill block table in memory (#3429) This PR names and documents the concept of the archive: a range of slots for which we have degraded functionality in terms of historical access - in particular: * we don't support rewinding to states in this range * we don't keep an in-memory representation of the block dag The archive de-facto exists in a trusted-node-synced node, but this PR gives it a name and drops the in-memory digest index. In order to satisfy `GetBlocksByRange` requests, we ensure that we have blocks for the entire archive period via backfill. Future versions may relax this further, adding a "pre-archive" period that is fully pruned. During by-slot searches in the archive (both for libp2p and rest requests), an extra database lookup is used to covert the given `slot` to a `root` - future versions will avoid this using era files which natively are indexed by `slot`. That said, the lookup is quite fast compared to the actual block loading given how trivial the table is - it's hard to measure, even. A collateral benefit of this PR is that checkpoint-synced nodes will see 100-200MB memory usage savings, thanks to the dropped in-memory cache - future pruning work will bring this benefit to full nodes as well. * document chaindag storage architecture and assumptions * look up parent using block id instead of full block in clearance (future-proofing the code against a future in which blocks come from era files) * simplify finalized block init, always writing the backfill portion to db at startup (to ensure lookups work as expected) * preallocate some extra memory for finalized blocks, to avoid immediate realloc
2022-02-26 18:16:19 +00:00
../spec/forks
from ../spec/datatypes/capella import SomeBeaconBlock, TrustedBeaconBlock
2023-02-25 01:03:34 +00:00
from ../spec/datatypes/deneb import SomeBeaconBlock, TrustedBeaconBlock
chaindag: don't keep backfill block table in memory (#3429) This PR names and documents the concept of the archive: a range of slots for which we have degraded functionality in terms of historical access - in particular: * we don't support rewinding to states in this range * we don't keep an in-memory representation of the block dag The archive de-facto exists in a trusted-node-synced node, but this PR gives it a name and drops the in-memory digest index. In order to satisfy `GetBlocksByRange` requests, we ensure that we have blocks for the entire archive period via backfill. Future versions may relax this further, adding a "pre-archive" period that is fully pruned. During by-slot searches in the archive (both for libp2p and rest requests), an extra database lookup is used to covert the given `slot` to a `root` - future versions will avoid this using era files which natively are indexed by `slot`. That said, the lookup is quite fast compared to the actual block loading given how trivial the table is - it's hard to measure, even. A collateral benefit of this PR is that checkpoint-synced nodes will see 100-200MB memory usage savings, thanks to the dropped in-memory cache - future pruning work will bring this benefit to full nodes as well. * document chaindag storage architecture and assumptions * look up parent using block id instead of full block in clearance (future-proofing the code against a future in which blocks come from era files) * simplify finalized block init, always writing the backfill portion to db at startup (to ensure lookups work as expected) * preallocate some extra memory for finalized blocks, to avoid immediate realloc
2022-02-26 18:16:19 +00:00
export chronicles, forks
type
BlockRef* = ref object
## Node in object graph guaranteed to lead back to finalized head, 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
executionBlockHash*: Opt[Eth2Digest]
executionValid*: bool
parent*: BlockRef ##\
## Not nil, except for the finalized head
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,
executionBlockHash: Opt[Eth2Digest], executionValid: bool, slot: Slot):
BlockRef =
BlockRef(
bid: BlockId(root: root, slot: slot),
executionBlockHash: executionBlockHash, executionValid: executionValid)
func init*(
T: type BlockRef, root: Eth2Digest, executionValid: bool,
blck: phase0.SomeBeaconBlock | altair.SomeBeaconBlock |
phase0.TrustedBeaconBlock | altair.TrustedBeaconBlock): BlockRef =
# Use same formal parameters for simplicity, but it's impossible for these
# blocks to be optimistic.
BlockRef.init(root, Opt.some ZERO_HASH, executionValid = true, blck.slot)
func init*(
T: type BlockRef, root: Eth2Digest, executionValid: bool,
blck: bellatrix.SomeBeaconBlock | bellatrix.TrustedBeaconBlock |
capella.SomeBeaconBlock | capella.TrustedBeaconBlock |
deneb.SomeBeaconBlock | deneb.TrustedBeaconBlock |
electra.SomeBeaconBlock | electra.TrustedBeaconBlock): BlockRef =
BlockRef.init(
root, Opt.some Eth2Digest(blck.body.execution_payload.block_hash),
executionValid =
executionValid or blck.body.execution_payload.block_hash == ZERO_HASH,
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)
# This is used to detect internal inconsistencies, e.g., circular references.
# Note that `BlockRef` is only used for the non-finalized chain segment.
const defaultMaxDepth = 1'i64 shl 24 # More than enough for years
func getDepth*(a, b: BlockRef): tuple[ancestor: bool, depth: int] =
var b = b
var depth = 0
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 < defaultMaxDepth
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 = defaultMaxDepth): BlockRef =
## https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.5/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 atCheckpoint*(blck: BlockRef, checkpoint: Checkpoint): Opt[BlockSlot] =
## Rewind from `blck` to the given `checkpoint` iff it is an ancestor
let target = blck.atSlot(checkpoint.epoch.start_slot)
if target.blck == nil:
return err()
if target.blck.root != checkpoint.root:
return err()
ok target
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)