321 lines
11 KiB
Nim
321 lines
11 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2023 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: [].}
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import
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std/[algorithm, options, tables],
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stew/bitops2,
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../spec/forks
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export tables, forks
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const
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MaxMissingItems = 1024
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## Arbitrary
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MaxOrphans = SLOTS_PER_EPOCH * 3
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## Enough for finalization in an alternative fork
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MaxBlobless = SLOTS_PER_EPOCH
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## Arbitrary
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MaxUnviables = 16 * 1024
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## About a day of blocks - most likely not needed but it's quite cheap..
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type
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MissingBlock* = object
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tries*: int
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FetchRecord* = object
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root*: Eth2Digest
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Quarantine* = object
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## Keeps track of unvalidated blocks coming from the network
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## and that cannot yet be added to the chain
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##
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## This only stores blocks that cannot be linked to the
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## ChainDAGRef DAG due to missing ancestor(s).
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##
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## Trivially invalid blocks may be dropped before reaching this stage.
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orphans*: Table[(Eth2Digest, ValidatorSig), ForkedSignedBeaconBlock]
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## Blocks that we don't have a parent for - when we resolve the
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## parent, we can proceed to resolving the block as well - we
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## index this by root and signature such that a block with
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## invalid signature won't cause a block with a valid signature
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## to be dropped. An orphan block may also be "blobless" (see
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## below) - if so, upon resolving the parent, it should be
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## added to the blobless table, after verifying its signature.
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blobless*: Table[Eth2Digest, deneb.SignedBeaconBlock]
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## Blocks that we don't have blobs for. When we have received
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## all blobs for this block, we can proceed to resolving the
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## block as well. A blobless block inserted into this table must
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## have a resolved parent (i.e., it is not an orphan).
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unviable*: OrderedTable[Eth2Digest, tuple[]]
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## Unviable blocks are those that come from a history that does not
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## include the finalized checkpoint we're currently following, and can
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## therefore never be included in our canonical chain - we keep their hash
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## around so that we can avoid cluttering the orphans table with their
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## descendants - the ChainDAG only keeps track blocks that make up the
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## valid and canonical history.
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##
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## Entries are evicted in FIFO order - recent entries are more likely to
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## appear again in attestations and blocks - however, the unviable block
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## table is not a complete directory of all unviable blocks circulating -
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## only those we have observed, been able to verify as unviable and fit
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## in this cache.
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missing*: Table[Eth2Digest, MissingBlock]
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## Roots of blocks that we would like to have (either parent_root of
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## unresolved blocks or block roots of attestations)
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func init*(T: type Quarantine): T =
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T()
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func checkMissing*(quarantine: var Quarantine): seq[FetchRecord] =
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## Return a list of blocks that we should try to resolve from other client -
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## to be called periodically but not too often (once per slot?)
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var done: seq[Eth2Digest]
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for k, v in quarantine.missing.mpairs():
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if v.tries > 8:
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done.add(k)
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else:
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inc v.tries
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for k in done:
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quarantine.missing.del(k)
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# simple (simplistic?) exponential backoff for retries..
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for k, v in quarantine.missing:
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if countOnes(v.tries.uint64) == 1:
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result.add(FetchRecord(root: k))
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# TODO stew/sequtils2
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template anyIt(s, pred: untyped): bool =
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# https://github.com/nim-lang/Nim/blob/v1.6.10/lib/pure/collections/sequtils.nim#L753-L775
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# without the items(...)
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var result = false
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for it {.inject.} in s:
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if pred:
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result = true
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break
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result
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func addMissing*(quarantine: var Quarantine, root: Eth2Digest) =
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## Schedule the download a the given block
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if quarantine.missing.len >= MaxMissingItems:
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return
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if root in quarantine.unviable:
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# Won't get anywhere with this block
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return
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# It's not really missing if we're keeping it in the quarantine
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if anyIt(quarantine.orphans.keys, it[0] == root):
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return
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# Add if it's not there, but don't update missing counter
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discard quarantine.missing.hasKeyOrPut(root, MissingBlock())
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func removeOrphan*(
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quarantine: var Quarantine, signedBlock: ForkySignedBeaconBlock) =
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quarantine.orphans.del((signedBlock.root, signedBlock.signature))
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func removeBlobless*(
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quarantine: var Quarantine, signedBlock: ForkySignedBeaconBlock) =
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quarantine.blobless.del(signedBlock.root)
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func isViable(
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finalizedSlot: Slot, slot: Slot): bool =
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# The orphan must be newer than the finalization point so that its parent
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# either is the finalized block or more recent
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slot > finalizedSlot
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func cleanupUnviable(quarantine: var Quarantine) =
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while quarantine.unviable.len() >= MaxUnviables:
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var toDel: Eth2Digest
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for k in quarantine.unviable.keys():
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toDel = k
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break # Cannot modify while for-looping
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quarantine.unviable.del(toDel)
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func removeUnviableOrphanTree(quarantine: var Quarantine,
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toCheck: var seq[Eth2Digest],
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tbl: var Table[(Eth2Digest, ValidatorSig),
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ForkedSignedBeaconBlock]):
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seq[Eth2Digest] =
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# Remove the tree of orphans whose ancestor is unviable - they are now also
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# unviable! This helps avoiding junk in the quarantine, because we don't keep
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# unviable parents in the DAG and there's no way to tell an orphan from an
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# unviable block without the parent.
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var
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toRemove: seq[(Eth2Digest, ValidatorSig)] # Can't modify while iterating
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checked: seq[Eth2Digest]
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while toCheck.len > 0:
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let root = toCheck.pop()
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if root notin checked:
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checked.add(root)
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for k, v in tbl.mpairs():
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let blockRoot = getForkedBlockField(v, parent_root)
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if blockRoot == root:
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toCheck.add(k[0])
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toRemove.add(k)
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elif k[0] == root:
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toRemove.add(k)
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for k in toRemove:
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tbl.del k
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quarantine.unviable[k[0]] = ()
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toRemove.setLen(0)
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checked
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func removeUnviableBloblessTree(quarantine: var Quarantine,
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toCheck: var seq[Eth2Digest],
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tbl: var Table[Eth2Digest,
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deneb.SignedBeaconBlock]) =
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var
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toRemove: seq[Eth2Digest] # Can't modify while iterating
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while toCheck.len > 0:
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let root = toCheck.pop()
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for k, v in tbl.mpairs():
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let blockRoot = v.message.parent_root
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if blockRoot == root:
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toCheck.add(k)
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toRemove.add(k)
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elif k == root:
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toRemove.add(k)
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for k in toRemove:
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tbl.del k
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quarantine.unviable[k] = ()
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toRemove.setLen(0)
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func addUnviable*(quarantine: var Quarantine, root: Eth2Digest) =
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if root in quarantine.unviable:
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return
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quarantine.cleanupUnviable()
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var toCheck = @[root]
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var checked = quarantine.removeUnviableOrphanTree(toCheck, quarantine.orphans)
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quarantine.removeUnviableBloblessTree(checked, quarantine.blobless)
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quarantine.unviable[root] = ()
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func cleanupOrphans(quarantine: var Quarantine, finalizedSlot: Slot) =
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var toDel: seq[(Eth2Digest, ValidatorSig)]
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for k, v in quarantine.orphans:
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if not isViable(finalizedSlot, getForkedBlockField(v, slot)):
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toDel.add k
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for k in toDel:
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quarantine.addUnviable k[0]
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quarantine.orphans.del k
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func cleanupBlobless(quarantine: var Quarantine, finalizedSlot: Slot) =
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var toDel: seq[Eth2Digest]
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for k, v in quarantine.blobless:
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if not isViable(finalizedSlot, v.message.slot):
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toDel.add k
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for k in toDel:
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quarantine.addUnviable k
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quarantine.blobless.del k
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func clearAfterReorg*(quarantine: var Quarantine) =
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## Clear missing and orphans to start with a fresh slate in case of a reorg
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## Unviables remain unviable and are not cleared.
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quarantine.missing.reset()
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quarantine.orphans.reset()
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# Typically, blocks will arrive in mostly topological order, with some
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# out-of-order block pairs. Therefore, it is unhelpful to use either a
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# FIFO or LIFO discpline, and since by definition each block gets used
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# either 0 or 1 times it's not a cache either. Instead, stop accepting
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# new blocks, and rely on syncing to cache up again if necessary.
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#
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# For typical use cases, this need not be large, as they're two or three
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# blocks arriving out of order due to variable network delays. As blocks
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# for future slots are rejected before reaching quarantine, this usually
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# will be a block for the last couple of slots for which the parent is a
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# likely imminent arrival.
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func addOrphan*(
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quarantine: var Quarantine, finalizedSlot: Slot,
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signedBlock: ForkedSignedBeaconBlock): bool =
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## Adds block to quarantine's `orphans` and `missing` lists.
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if not isViable(finalizedSlot, getForkedBlockField(signedBlock, slot)):
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quarantine.addUnviable(signedBlock.root)
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return false
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quarantine.cleanupOrphans(finalizedSlot)
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let parent_root = getForkedBlockField(signedBlock, parent_root)
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if parent_root in quarantine.unviable:
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quarantine.unviable[signedBlock.root] = ()
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return true
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# Even if the quarantine is full, we need to schedule its parent for
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# downloading or we'll never get to the bottom of things
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quarantine.addMissing(parent_root)
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if quarantine.orphans.lenu64 >= MaxOrphans:
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return false
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quarantine.orphans[(signedBlock.root, signedBlock.signature)] = signedBlock
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quarantine.missing.del(signedBlock.root)
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true
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iterator pop*(quarantine: var Quarantine, root: Eth2Digest):
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ForkedSignedBeaconBlock =
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# Pop orphans whose parent is the block identified by `root`
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var toRemove: seq[(Eth2Digest, ValidatorSig)]
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defer: # Run even if iterator is not carried to termination
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for k in toRemove:
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quarantine.orphans.del k
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for k, v in quarantine.orphans.mpairs():
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if getForkedBlockField(v, parent_root) == root:
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toRemove.add(k)
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yield v
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proc addBlobless*(
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quarantine: var Quarantine, finalizedSlot: Slot,
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signedBlock: deneb.SignedBeaconBlock): bool =
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if not isViable(finalizedSlot, signedBlock.message.slot):
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quarantine.addUnviable(signedBlock.root)
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return false
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quarantine.cleanupBlobless(finalizedSlot)
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if quarantine.blobless.lenu64 >= MaxBlobless:
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return false
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quarantine.blobless[signedBlock.root] = signedBlock
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quarantine.missing.del(signedBlock.root)
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true
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func popBlobless*(quarantine: var Quarantine, root: Eth2Digest):
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Option[deneb.SignedBeaconBlock] =
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var blck: deneb.SignedBeaconBlock
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if quarantine.blobless.pop(root, blck):
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return some(blck)
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else:
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return none(deneb.SignedBeaconBlock)
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iterator peekBlobless*(quarantine: var Quarantine): deneb.SignedBeaconBlock =
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for k, v in quarantine.blobless.mpairs():
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yield v
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