129 lines
4.5 KiB
Nim
129 lines
4.5 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2020 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: [Defect].}
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import
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std/[tables, options],
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chronicles,
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stew/bitops2,
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eth/keys,
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../spec/[crypto, datatypes, digest],
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./block_pools_types
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export options, block_pools_types
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logScope:
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topics = "quarant"
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func init*(T: type QuarantineRef, rng: ref BrHmacDrbgContext): T =
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result = T()
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result.rng = rng
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func checkMissing*(quarantine: var QuarantineRef): 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.pairs():
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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/version-1-2/lib/pure/collections/sequtils.nim#L682-L704
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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 containsOrphan*(
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quarantine: QuarantineRef, signedBlock: SignedBeaconBlock): bool =
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(signedBlock.root, signedBlock.signature) in quarantine.orphans
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func addMissing*(quarantine: var QuarantineRef, root: Eth2Digest) =
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## Schedule the download a the given block
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# Can only request by root, not by signature, so partial match suffices
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if not anyIt(quarantine.orphans.keys, it[0] == root):
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# If the block is in orphans, we no longer need it
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discard quarantine.missing.hasKeyOrPut(root, MissingBlock())
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func removeOrphan*(
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quarantine: var QuarantineRef, signedBlock: SignedBeaconBlock) =
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quarantine.orphans.del((signedBlock.root, signedBlock.signature))
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func isViableOrphan(dag: ChainDAGRef, signedBlock: SignedBeaconBlock): 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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signedBlock.message.slot > dag.finalizedHead.slot
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func removeOldBlocks(quarantine: var QuarantineRef, dag: ChainDAGRef) =
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var oldBlocks: seq[(Eth2Digest, ValidatorSig)]
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for k, v in quarantine.orphans.pairs():
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if not isViableOrphan(dag, v):
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oldBlocks.add k
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for k in oldBlocks:
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quarantine.orphans.del k
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func clearQuarantine*(quarantine: var QuarantineRef) =
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quarantine.orphans.clear()
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quarantine.missing.clear()
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func add*(quarantine: var QuarantineRef, dag: ChainDAGRef,
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signedBlock: SignedBeaconBlock): bool =
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## Adds block to quarantine's `orphans` and `missing` lists.
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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. When
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# using forward sync, blocks only arrive in an order not requiring the
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# quarantine.
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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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# Since we start forward sync when about one epoch is missing, that's as
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# good a number as any.
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const MAX_QUARANTINE_ORPHANS = SLOTS_PER_EPOCH
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if not isViableOrphan(dag, signedBlock):
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return false
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quarantine.removeOldBlocks(dag)
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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(signedBlock.message.parent_root)
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if quarantine.orphans.lenu64 >= MAX_QUARANTINE_ORPHANS:
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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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