nimbus-eth2/beacon_chain/block_pools/quarantine.nim

93 lines
3.2 KiB
Nim

# beacon_chain
# Copyright (c) 2018-2020 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.
import
chronicles, tables, options,
stew/bitops2,
metrics,
../spec/[datatypes, digest],
block_pools_types
export options, block_pools_types
logScope:
topics = "quarant"
{.push raises: [Defect].}
func checkMissing*(quarantine: var QuarantineRef): 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 quarantine.missing.mpairs():
if v.tries > 8:
done.add(k)
else:
inc v.tries
for k in done:
# TODO Need to potentially remove from quarantine.pending - this is currently a
# memory leak here!
quarantine.missing.del(k)
# simple (simplistic?) exponential backoff for retries..
for k, v in quarantine.missing.pairs():
if countOnes(v.tries.uint64) == 1:
result.add(FetchRecord(root: k))
func addMissing*(quarantine: var QuarantineRef, root: Eth2Digest) =
## Schedule the download a the given block
if root notin quarantine.orphans:
# If the block is in orphans, we no longer need it
discard quarantine.missing.hasKeyOrPut(root, MissingBlock())
func removeOldBlocks(quarantine: var QuarantineRef, dag: ChainDAGRef) =
var oldBlocks: seq[Eth2Digest]
for k, v in quarantine.orphans.pairs():
if v.message.slot <= dag.finalizedHead.slot:
oldBlocks.add k
for k in oldBlocks:
quarantine.orphans.del k
func clearQuarantine*(quarantine: var QuarantineRef) =
quarantine.orphans.clear()
quarantine.missing.clear()
func add*(quarantine: var QuarantineRef, dag: ChainDAGRef,
signedBlock: SignedBeaconBlock): bool =
## Adds block to quarantine's `orphans` and `missing` lists.
# Typically, blocks will arrive in mostly topological order, with some
# out-of-order block pairs. Therefore, it is unhelpful to use either a
# FIFO or LIFO discpline, and since by definition each block gets used
# either 0 or 1 times it's not a cache either. Instead, stop accepting
# new blocks, and rely on syncing to cache up again if necessary. When
# using forward sync, blocks only arrive in an order not requiring the
# quarantine.
#
# For typical use cases, this need not be large, as they're two or three
# blocks arriving out of order due to variable network delays. As blocks
# for future slots are rejected before reaching quarantine, this usually
# will be a block for the last couple of slots for which the parent is a
# likely imminent arrival.
const MAX_QUARANTINE_ORPHANS = 10
quarantine.removeOldBlocks(dag)
if quarantine.orphans.len >= MAX_QUARANTINE_ORPHANS:
return false
quarantine.orphans[signedBlock.root] = signedBlock
quarantine.missing.del(signedBlock.root)
quarantine.addMissing(signedBlock.message.parent_root)
true