831 lines
30 KiB
Nim
831 lines
30 KiB
Nim
import
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bitops, chronicles, options, tables,
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ssz, beacon_chain_db, state_transition, extras,
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beacon_node_types, metrics,
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spec/[crypto, datatypes, digest, helpers]
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declareCounter beacon_reorgs_total, "Total occurrences of reorganizations of the chain" # On fork choice
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logScope: topics = "blkpool"
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func parent*(bs: BlockSlot): BlockSlot =
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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 link(parent, child: BlockRef) =
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doAssert (not (parent.root == Eth2Digest() or child.root == Eth2Digest())),
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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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parent.children.add(child)
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func isAncestorOf*(a, b: BlockRef): bool =
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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: return true
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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
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doAssert b.slot > b.parent.slot
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b = b.parent
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func init*(T: type BlockRef, root: Eth2Digest, slot: Slot): BlockRef =
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BlockRef(
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root: root,
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slot: slot
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)
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func init*(T: type BlockRef, root: Eth2Digest, blck: BeaconBlock): BlockRef =
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BlockRef.init(root, blck.slot)
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func findAncestorBySlot*(blck: BlockRef, slot: Slot): BlockSlot =
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## Find the first ancestor that has a slot number less than or equal to `slot`
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doAssert(not blck.isNil)
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var ret = blck
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while ret.parent != nil and ret.slot > slot:
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ret = ret.parent
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BlockSlot(blck: ret, slot: slot)
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proc init*(T: type BlockPool, db: BeaconChainDB): BlockPool =
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# TODO we require that the db contains both a head and a tail block -
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# asserting here doesn't seem like the right way to go about it however..
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let
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tailBlockRoot = db.getTailBlock()
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headBlockRoot = db.getHeadBlock()
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doAssert tailBlockRoot.isSome(), "Missing tail block, database corrupt?"
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doAssert headBlockRoot.isSome(), "Missing head block, database corrupt?"
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let
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tailRoot = tailBlockRoot.get()
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tailBlock = db.getBlock(tailRoot).get()
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tailRef = BlockRef.init(tailRoot, tailBlock.message)
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headRoot = headBlockRoot.get()
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var
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blocks = {tailRef.root: tailRef}.toTable()
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latestStateRoot = Option[Eth2Digest]()
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headRef: BlockRef
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if headRoot != tailRoot:
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var curRef: BlockRef
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for root, blck in db.getAncestors(headRoot):
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if root == tailRef.root:
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doAssert(not curRef.isNil)
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link(tailRef, curRef)
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curRef = curRef.parent
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break
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let newRef = BlockRef.init(root, blck.message)
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if curRef == nil:
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curRef = newRef
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headRef = newRef
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else:
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link(newRef, curRef)
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curRef = curRef.parent
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blocks[curRef.root] = curRef
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trace "Populating block pool", key = curRef.root, val = curRef
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if latestStateRoot.isNone() and db.containsState(blck.message.state_root):
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latestStateRoot = some(blck.message.state_root)
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doAssert curRef == tailRef,
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"head block does not lead to tail, database corrupt?"
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else:
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headRef = tailRef
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var blocksBySlot = initTable[Slot, seq[BlockRef]]()
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for _, b in tables.pairs(blocks):
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let slot = db.getBlock(b.root).get().message.slot
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blocksBySlot.mgetOrPut(slot, @[]).add(b)
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let
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# The head state is necessary to find out what we considered to be the
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# finalized epoch last time we saved something.
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headStateRoot =
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if latestStateRoot.isSome():
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latestStateRoot.get()
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else:
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db.getBlock(tailRef.root).get().message.state_root
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# TODO right now, because we save a state at every epoch, this *should*
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# be the latest justified state or newer, meaning it's enough for
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# establishing what we consider to be the finalized head. This logic
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# will need revisiting however
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headState = db.getState(headStateRoot).get()
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finalizedHead =
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headRef.findAncestorBySlot(
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headState.finalized_checkpoint.epoch.compute_start_slot_at_epoch())
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justifiedSlot =
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headState.current_justified_checkpoint.epoch.compute_start_slot_at_epoch()
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justifiedHead = headRef.findAncestorBySlot(justifiedSlot)
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head = Head(blck: headRef, justified: justifiedHead)
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doAssert justifiedHead.slot >= finalizedHead.slot,
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"justified head comes before finalized head - database corrupt?"
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debug "Block pool initialized",
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head = head.blck, finalizedHead, tail = tailRef,
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totalBlocks = blocks.len, totalKnownSlots = blocksBySlot.len
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BlockPool(
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pending: initTable[Eth2Digest, SignedBeaconBlock](),
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missing: initTable[Eth2Digest, MissingBlock](),
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blocks: blocks,
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blocksBySlot: blocksBySlot,
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tail: tailRef,
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head: head,
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finalizedHead: finalizedHead,
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db: db,
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heads: @[head]
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)
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proc addSlotMapping(pool: BlockPool, br: BlockRef) =
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proc addIfMissing(s: var seq[BlockRef], v: BlockRef) =
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if v notin s:
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s.add(v)
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pool.blocksBySlot.mgetOrPut(br.slot, @[]).addIfMissing(br)
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proc delSlotMapping(pool: BlockPool, br: BlockRef) =
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var blks = pool.blocksBySlot.getOrDefault(br.slot)
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if blks.len != 0:
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let i = blks.find(br)
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if i >= 0: blks.del(i)
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if blks.len == 0:
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pool.blocksBySlot.del(br.slot)
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else:
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pool.blocksBySlot[br.slot] = blks
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proc updateStateData*(
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pool: BlockPool, state: var StateData, bs: BlockSlot) {.gcsafe.}
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proc add*(
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pool: var BlockPool, state: var StateData, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock): BlockRef {.gcsafe.}
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proc addResolvedBlock(
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pool: var BlockPool, state: var StateData, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock, parent: BlockRef): BlockRef =
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logScope: pcs = "block_resolution"
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let blockRef = BlockRef.init(blockRoot, signedBlock.message)
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link(parent, blockRef)
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pool.blocks[blockRoot] = blockRef
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trace "Populating block pool", key = blockRoot, val = blockRef
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pool.addSlotMapping(blockRef)
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# Resolved blocks should be stored in database
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pool.db.putBlock(blockRoot, signedBlock)
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# TODO this is a bit ugly - we update state.data outside of this function then
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# set the rest here - need a blockRef to update it. Clean this up -
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# hopefully it won't be necessary by the time hash caching and the rest
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# is done..
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doAssert state.data.data.slot == blockRef.slot
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state.blck = blockRef
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# This block *might* have caused a justification - make sure we stow away
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# that information:
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let justifiedSlot =
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state.data.data.current_justified_checkpoint.epoch.compute_start_slot_at_epoch()
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var foundHead: Option[Head]
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for head in pool.heads.mitems():
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if head.blck.isAncestorOf(blockRef):
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if head.justified.slot != justifiedSlot:
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head.justified = blockRef.findAncestorBySlot(justifiedSlot)
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head.blck = blockRef
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foundHead = some(head)
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break
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if foundHead.isNone():
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foundHead = some(Head(
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blck: blockRef,
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justified: blockRef.findAncestorBySlot(justifiedSlot)))
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pool.heads.add(foundHead.get())
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info "Block resolved",
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blck = shortLog(signedBlock.message),
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blockRoot = shortLog(blockRoot),
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justifiedRoot = shortLog(foundHead.get().justified.blck.root),
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justifiedSlot = shortLog(foundHead.get().justified.slot),
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cat = "filtering"
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# Now that we have the new block, we should see if any of the previously
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# unresolved blocks magically become resolved
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# TODO there are more efficient ways of doing this that don't risk
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# running out of stack etc
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# TODO This code is convoluted because when there are more than ~1.5k
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# blocks being synced, there's a stack overflow as `add` gets called
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# for the whole chain of blocks. Instead we use this ugly field in `pool`
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# which could be avoided by refactoring the code
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if not pool.inAdd:
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pool.inAdd = true
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defer: pool.inAdd = false
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var keepGoing = true
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while keepGoing:
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let retries = pool.pending
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for k, v in retries:
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discard pool.add(state, k, v)
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# Keep going for as long as the pending pool is shrinking
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# TODO inefficient! so what?
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keepGoing = pool.pending.len < retries.len
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blockRef
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proc add*(
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pool: var BlockPool, state: var StateData, blockRoot: Eth2Digest,
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signedBlock: SignedBeaconBlock): BlockRef {.gcsafe.} =
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## return the block, if resolved...
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## the state parameter may be updated to include the given block, if
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## everything checks out
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# TODO reevaluate passing the state in like this
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let blck = signedBlock.message
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doAssert blockRoot == hash_tree_root(blck)
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logScope: pcs = "block_addition"
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# Already seen this block??
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if blockRoot in pool.blocks:
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debug "Block already exists",
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blck = shortLog(blck),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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return pool.blocks[blockRoot]
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pool.missing.del(blockRoot)
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# If the block we get is older than what we finalized already, we drop it.
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# One way this can happen is that we start resolving a block and finalization
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# happens in the meantime - the block we requested will then be stale
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# by the time it gets here.
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if blck.slot <= pool.finalizedHead.slot:
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debug "Old block, dropping",
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blck = shortLog(blck),
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tailSlot = shortLog(pool.tail.slot),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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return
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let parent = pool.blocks.getOrDefault(blck.parent_root)
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if parent != nil:
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# The block might have been in either of these - we don't want any more
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# work done on its behalf
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pool.pending.del(blockRoot)
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# The block is resolved, now it's time to validate it to ensure that the
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# blocks we add to the database are clean for the given state
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# TODO if the block is from the future, we should not be resolving it (yet),
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# but maybe we should use it as a hint that our clock is wrong?
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updateStateData(pool, state, BlockSlot(blck: parent, slot: blck.slot - 1))
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if not state_transition(state.data, blck, {}):
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# TODO find a better way to log all this block data
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notice "Invalid block",
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blck = shortLog(blck),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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return
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return pool.addResolvedBlock(state, blockRoot, signedBlock, parent)
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# TODO already checked hash though? main reason to keep this is because
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# the pending pool calls this function back later in a loop, so as long
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# as pool.add(...) requires a SignedBeaconBlock, easier to keep them in
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# pending too.
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pool.pending[blockRoot] = signedBlock
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# TODO possibly, it makes sense to check the database - that would allow sync
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# to simply fill up the database with random blocks the other clients
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# think are useful - but, it would also risk filling the database with
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# junk that's not part of the block graph
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if blck.parent_root in pool.missing or
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blck.parent_root in pool.pending:
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return
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# This is an unresolved block - put its parent on the missing list for now...
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# TODO if we receive spam blocks, one heurestic to implement might be to wait
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# for a couple of attestations to appear before fetching parents - this
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# would help prevent using up network resources for spam - this serves
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# two purposes: one is that attestations are likely to appear for the
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# block only if it's valid / not spam - the other is that malicious
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# validators that are not proposers can sign invalid blocks and send
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# them out without penalty - but signing invalid attestations carries
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# a risk of being slashed, making attestations a more valuable spam
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# filter.
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# TODO when we receive the block, we don't know how many others we're missing
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# from that branch, so right now, we'll just do a blind guess
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debug "Unresolved block (parent missing)",
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blck = shortLog(blck),
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blockRoot = shortLog(blockRoot),
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cat = "filtering"
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let parentSlot = blck.slot - 1
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pool.missing[blck.parent_root] = MissingBlock(
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slots:
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# The block is at least two slots ahead - try to grab whole history
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if parentSlot > pool.head.blck.slot:
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parentSlot - pool.head.blck.slot
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else:
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# It's a sibling block from a branch that we're missing - fetch one
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# epoch at a time
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max(1.uint64, SLOTS_PER_EPOCH.uint64 -
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(parentSlot.uint64 mod SLOTS_PER_EPOCH.uint64))
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)
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func getRef*(pool: BlockPool, root: Eth2Digest): BlockRef =
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## Retrieve a resolved block reference, if available
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pool.blocks.getOrDefault(root, nil)
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proc getBlockRange*(pool: BlockPool, headBlock: Eth2Digest,
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startSlot: Slot, skipStep: Natural,
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output: var openarray[BlockRef]): Natural =
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## This function populates an `output` buffer of blocks
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## with a range starting from `startSlot` and skipping
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## every `skipTest` number of blocks.
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##
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## Please note that the function may not necessarily
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## populate the entire buffer. The values will be written
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## in a way such that the last block is placed at the end
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## of the buffer while the first indices of the buffer
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## may remain unwritten.
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##
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## The result value of the function will be the index of
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## the first block in the resulting buffer. If no values
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## were written to the buffer, the result will be equal to
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## `buffer.len`. In other words, you can use the function
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## like this:
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##
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## var buffer: array[N, BlockRef]
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## let startPos = pool.getBlockRange(headBlock, startSlot, skipStep, buffer)
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## for i in startPos ..< buffer.len:
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## echo buffer[i].slot
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##
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result = output.len
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trace "getBlockRange entered", headBlock, startSlot, skipStep
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var b = pool.getRef(headBlock)
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if b == nil:
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trace "head block not found", headBlock
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return
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trace "head block found", headBlock = b
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if b.slot < startSlot:
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trace "head block is older than startSlot", headBlockSlot = b.slot, startSlot
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return
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template skip(n: int) =
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let targetSlot = b.slot - Slot(n)
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while b.slot > targetSlot:
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if b.parent == nil:
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trace "stopping at parentless block", slot = b.slot, root = b.root
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return
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trace "skipping block", nextBlock = b.parent
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b = b.parent
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# We must compute the last block that is eligible for inclusion
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# in the results. This will be a block with a slot number that's
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# aligned to the stride of the requested block range, so we first
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# compute the steps needed to get to an aligned position:
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var blocksToSkip = b.slot.int mod skipStep
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let alignedHeadSlot = b.slot.int - blocksToSkip
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# Then we see if this aligned position is within our wanted
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# range. If it's outside it, we must skip more blocks:
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let lastWantedSlot = startSlot.int + (output.len - 1) * skipStep
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if alignedHeadSlot > lastWantedSlot:
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blocksToSkip += (alignedHeadSlot - lastWantedSlot)
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# Finally, we skip the computed number of blocks
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trace "aligning head", blocksToSkip
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skip blocksToSkip
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# From here, we can just write out the requested block range:
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while b != nil and b.slot >= startSlot and result > 0:
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dec result
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output[result] = b
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trace "getBlockRange result", position = result, blockSlot = b.slot
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skip skipStep
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proc get*(pool: BlockPool, blck: BlockRef): BlockData =
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## Retrieve the associated block body of a block reference
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doAssert (not blck.isNil), "Trying to get nil BlockRef"
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let data = pool.db.getBlock(blck.root)
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doAssert data.isSome, "BlockRef without backing data, database corrupt?"
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BlockData(data: data.get(), refs: blck)
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proc get*(pool: BlockPool, root: Eth2Digest): Option[BlockData] =
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## Retrieve a resolved block reference and its associated body, if available
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let refs = pool.getRef(root)
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if not refs.isNil:
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some(pool.get(refs))
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else:
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none(BlockData)
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func getOrResolve*(pool: var BlockPool, root: Eth2Digest): BlockRef =
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## Fetch a block ref, or nil if not found (will be added to list of
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## blocks-to-resolve)
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result = pool.getRef(root)
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if result.isNil:
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pool.missing[root] = MissingBlock(slots: 1)
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iterator blockRootsForSlot*(pool: BlockPool, slot: Slot): Eth2Digest =
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for br in pool.blocksBySlot.getOrDefault(slot, @[]):
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yield br.root
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func checkMissing*(pool: var BlockPool): 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 pool.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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# TODO Need to potentially remove from pool.pending - this is currently a
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# memory leak here!
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pool.missing.del(k)
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# simple (simplistic?) exponential backoff for retries..
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for k, v in pool.missing.pairs():
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if v.tries.popcount() == 1:
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result.add(FetchRecord(root: k, historySlots: v.slots))
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proc skipAndUpdateState(
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state: var HashedBeaconState, blck: BeaconBlock, flags: UpdateFlags,
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afterUpdate: proc (state: HashedBeaconState)): bool =
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process_slots(state, blck.slot - 1)
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afterUpdate(state)
|
|
|
|
let ok = state_transition(state, blck, flags)
|
|
|
|
afterUpdate(state)
|
|
|
|
ok
|
|
|
|
proc maybePutState(pool: BlockPool, state: HashedBeaconState, blck: BlockRef) =
|
|
# TODO we save state at every epoch start but never remove them - we also
|
|
# potentially save multiple states per slot if reorgs happen, meaning
|
|
# we could easily see a state explosion
|
|
# TODO this is out of sync with epoch def now, I think -- (slot + 1) mod foo.
|
|
logScope: pcs = "save_state_at_epoch_start"
|
|
|
|
|
|
if state.data.slot mod SLOTS_PER_EPOCH == 0:
|
|
if not pool.db.containsState(state.root):
|
|
info "Storing state",
|
|
stateSlot = shortLog(state.data.slot),
|
|
stateRoot = shortLog(state.root),
|
|
cat = "caching"
|
|
pool.db.putState(state.root, state.data)
|
|
# TODO this should be atomic with the above write..
|
|
pool.db.putStateRoot(blck.root, state.data.slot, state.root)
|
|
|
|
proc rewindState(pool: BlockPool, state: var StateData, bs: BlockSlot):
|
|
seq[BlockData] =
|
|
logScope: pcs = "replay_state"
|
|
|
|
var ancestors = @[pool.get(bs.blck)]
|
|
# Common case: the last block applied is the parent of the block to apply:
|
|
if not bs.blck.parent.isNil and state.blck.root == bs.blck.parent.root and
|
|
state.data.data.slot < bs.slot:
|
|
return ancestors
|
|
|
|
# It appears that the parent root of the proposed new block is different from
|
|
# what we expected. We will have to rewind the state to a point along the
|
|
# chain of ancestors of the new block. We will do this by loading each
|
|
# successive parent block and checking if we can find the corresponding state
|
|
# in the database.
|
|
|
|
var
|
|
stateRoot = pool.db.getStateRoot(bs.blck.root, bs.slot)
|
|
curBs = bs
|
|
while stateRoot.isNone():
|
|
let parBs = curBs.parent()
|
|
if parBs.blck.isNil:
|
|
break # Bug probably!
|
|
|
|
if parBs.blck != curBs.blck:
|
|
ancestors.add(pool.get(parBs.blck))
|
|
|
|
if (let tmp = pool.db.getStateRoot(parBs.blck.root, parBs.slot); tmp.isSome()):
|
|
if pool.db.containsState(tmp.get):
|
|
stateRoot = tmp
|
|
break
|
|
|
|
curBs = parBs
|
|
|
|
if stateRoot.isNone():
|
|
# TODO this should only happen if the database is corrupt - we walked the
|
|
# list of parent blocks and couldn't find a corresponding state in the
|
|
# database, which should never happen (at least we should have the
|
|
# tail state in there!)
|
|
error "Couldn't find ancestor state root!",
|
|
blockRoot = shortLog(bs.blck.root),
|
|
cat = "crash"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
let
|
|
ancestor = ancestors[^1]
|
|
ancestorState = pool.db.getState(stateRoot.get())
|
|
|
|
if ancestorState.isNone():
|
|
# TODO this should only happen if the database is corrupt - we walked the
|
|
# list of parent blocks and couldn't find a corresponding state in the
|
|
# database, which should never happen (at least we should have the
|
|
# tail state in there!)
|
|
error "Couldn't find ancestor state or block parent missing!",
|
|
blockRoot = shortLog(bs.blck.root),
|
|
cat = "crash"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
trace "Replaying state transitions",
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
ancestorStateRoot = shortLog(ancestor.data.state_root),
|
|
ancestorStateSlot = shortLog(ancestorState.get().slot),
|
|
slot = shortLog(bs.slot),
|
|
blockRoot = shortLog(bs.blck.root),
|
|
ancestors = ancestors.len,
|
|
cat = "replay_state"
|
|
|
|
state.data.data = ancestorState.get()
|
|
state.data.root = stateRoot.get()
|
|
state.blck = ancestor.refs
|
|
|
|
ancestors
|
|
|
|
proc updateStateData*(pool: BlockPool, state: var StateData, bs: BlockSlot) =
|
|
## Rewind or advance state such that it matches the given block and slot -
|
|
## this may include replaying from an earlier snapshot if blck is on a
|
|
## different branch or has advanced to a higher slot number than slot
|
|
## If slot is higher than blck.slot, replay will fill in with empty/non-block
|
|
## slots, else it is ignored
|
|
|
|
# We need to check the slot because the state might have moved forwards
|
|
# without blocks
|
|
if state.blck.root == bs.blck.root and state.data.data.slot <= bs.slot:
|
|
if state.data.data.slot != bs.slot:
|
|
# Might be that we're moving to the same block but later slot
|
|
process_slots(state.data, bs.slot)
|
|
pool.maybePutState(state.data, bs.blck)
|
|
|
|
return # State already at the right spot
|
|
|
|
let ancestors = rewindState(pool, state, bs)
|
|
|
|
# If we come this far, we found the state root. The last block on the stack
|
|
# is the one that produced this particular state, so we can pop it
|
|
# TODO it might be possible to use the latest block hashes from the state to
|
|
# do this more efficiently.. whatever!
|
|
|
|
# Time to replay all the blocks between then and now. We skip one because
|
|
# it's the one that we found the state with, and it has already been
|
|
# applied
|
|
for i in countdown(ancestors.len - 2, 0):
|
|
let ok =
|
|
skipAndUpdateState(state.data, ancestors[i].data.message, {skipValidation}) do(
|
|
state: HashedBeaconState):
|
|
pool.maybePutState(state, ancestors[i].refs)
|
|
doAssert ok, "Blocks in database should never fail to apply.."
|
|
|
|
# TODO check if this triggers rest of state transition, or should
|
|
process_slots(state.data, bs.slot)
|
|
pool.maybePutState(state.data, bs.blck)
|
|
|
|
state.blck = bs.blck
|
|
|
|
proc loadTailState*(pool: BlockPool): StateData =
|
|
## Load the state associated with the current tail in the pool
|
|
let stateRoot = pool.db.getBlock(pool.tail.root).get().message.state_root
|
|
StateData(
|
|
data: HashedBeaconState(
|
|
data: pool.db.getState(stateRoot).get(),
|
|
root: stateRoot),
|
|
blck: pool.tail
|
|
)
|
|
|
|
proc delBlockAndState(pool: BlockPool, blockRoot: Eth2Digest) =
|
|
if (let blk = pool.db.getBlock(blockRoot); blk.isSome):
|
|
pool.db.delState(blk.get.message.stateRoot)
|
|
pool.db.delBlock(blockRoot)
|
|
|
|
proc delFinalizedStateIfNeeded(pool: BlockPool, b: BlockRef) =
|
|
# Delete finalized state for block `b` from the database, that doesn't need
|
|
# to be kept for replaying.
|
|
# TODO: Currently the protocol doesn't provide a way to request states,
|
|
# so we don't need any of the finalized states, and thus remove all of them
|
|
# (except the most recent)
|
|
if (let blk = pool.db.getBlock(b.root); blk.isSome):
|
|
pool.db.delState(blk.get.message.stateRoot)
|
|
|
|
proc setTailBlock(pool: BlockPool, newTail: BlockRef) =
|
|
## Advance tail block, pruning all the states and blocks with older slots
|
|
let oldTail = pool.tail
|
|
let fromSlot = oldTail.slot.uint64
|
|
let toSlot = newTail.slot.uint64 - 1
|
|
assert(toSlot > fromSlot)
|
|
for s in fromSlot .. toSlot:
|
|
for b in pool.blocksBySlot.getOrDefault(s.Slot, @[]):
|
|
pool.delBlockAndState(b.root)
|
|
b.children = @[]
|
|
b.parent = nil
|
|
pool.blocks.del(b.root)
|
|
pool.pending.del(b.root)
|
|
pool.missing.del(b.root)
|
|
|
|
pool.blocksBySlot.del(s.Slot)
|
|
|
|
pool.db.putTailBlock(newTail.root)
|
|
pool.tail = newTail
|
|
pool.addSlotMapping(newTail)
|
|
info "Tail block updated",
|
|
slot = newTail.slot,
|
|
root = shortLog(newTail.root)
|
|
|
|
proc updateHead*(pool: BlockPool, state: var StateData, blck: BlockRef) =
|
|
## Update what we consider to be the current head, as given by the fork
|
|
## choice.
|
|
## The choice of head affects the choice of finalization point - the order
|
|
## of operations naturally becomes important here - after updating the head,
|
|
## blocks that were once considered potential candidates for a tree will
|
|
## now fall from grace, or no longer be considered resolved.
|
|
doAssert blck.parent != nil or blck.slot == 0
|
|
logScope: pcs = "fork_choice"
|
|
|
|
if pool.head.blck == blck:
|
|
info "No head block update",
|
|
headBlockRoot = shortLog(blck.root),
|
|
headBlockSlot = shortLog(blck.slot),
|
|
cat = "fork_choice"
|
|
|
|
return
|
|
|
|
let
|
|
lastHead = pool.head
|
|
pool.db.putHeadBlock(blck.root)
|
|
|
|
# Start off by making sure we have the right state
|
|
updateStateData(pool, state, BlockSlot(blck: blck, slot: blck.slot))
|
|
let justifiedSlot = state.data.data
|
|
.current_justified_checkpoint
|
|
.epoch
|
|
.compute_start_slot_at_epoch()
|
|
pool.head = Head(blck: blck, justified: blck.findAncestorBySlot(justifiedSlot))
|
|
|
|
if lastHead.blck != blck.parent:
|
|
info "Updated head block (new parent)",
|
|
lastHeadRoot = shortLog(lastHead.blck.root),
|
|
parentRoot = shortLog(blck.parent.root),
|
|
stateRoot = shortLog(state.data.root),
|
|
headBlockRoot = shortLog(state.blck.root),
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
justifiedEpoch = shortLog(state.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(state.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
# A reasonable criterion for "reorganizations of the chain"
|
|
# TODO if multiple heads have gotten skipped, could fire at
|
|
# spurious times - for example when multiple blocks have been added between
|
|
# head updates
|
|
beacon_reorgs_total.inc()
|
|
else:
|
|
info "Updated head block",
|
|
stateRoot = shortLog(state.data.root),
|
|
headBlockRoot = shortLog(state.blck.root),
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
justifiedEpoch = shortLog(state.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(state.data.data.finalized_checkpoint.epoch),
|
|
cat = "fork_choice"
|
|
|
|
let
|
|
finalizedEpochStartSlot = state.data.data.finalized_checkpoint.epoch.compute_start_slot_at_epoch()
|
|
# TODO there might not be a block at the epoch boundary - what then?
|
|
finalizedHead = blck.findAncestorBySlot(finalizedEpochStartSlot)
|
|
|
|
doAssert (not finalizedHead.blck.isNil),
|
|
"Block graph should always lead to a finalized block"
|
|
|
|
if finalizedHead != pool.finalizedHead:
|
|
info "Finalized block",
|
|
finalizedBlockRoot = shortLog(finalizedHead.blck.root),
|
|
finalizedBlockSlot = shortLog(finalizedHead.slot),
|
|
headBlockRoot = shortLog(blck.root),
|
|
headBlockSlot = shortLog(blck.slot),
|
|
cat = "fork_choice"
|
|
|
|
pool.finalizedHead = finalizedHead
|
|
|
|
var cur = finalizedHead.blck
|
|
while cur != pool.finalizedHead.blck:
|
|
# Finalization means that we choose a single chain as the canonical one -
|
|
# it also means we're no longer interested in any branches from that chain
|
|
# up to the finalization point
|
|
|
|
# TODO technically, if we remove from children the gc should free the block
|
|
# because it should become orphaned, via mark&sweep if nothing else,
|
|
# though this needs verification
|
|
# TODO what about attestations? we need to drop those too, though they
|
|
# *should* be pretty harmless
|
|
# TODO remove from database as well.. here, or using some GC-like setup
|
|
# that periodically cleans it up?
|
|
for child in cur.parent.children:
|
|
if child != cur:
|
|
pool.blocks.del(child.root)
|
|
pool.delBlockAndState(child.root)
|
|
pool.delSlotMapping(child)
|
|
else:
|
|
pool.delFinalizedStateIfNeeded(child)
|
|
cur.parent.children = @[cur]
|
|
cur = cur.parent
|
|
|
|
let hlen = pool.heads.len
|
|
for i in 0..<hlen:
|
|
let n = hlen - i - 1
|
|
if pool.heads[n].blck.slot < pool.finalizedHead.blck.slot:
|
|
# By definition, the current head should be newer than the finalized
|
|
# head, so we'll never delete it here
|
|
pool.heads.del(n)
|
|
|
|
# Calculate new tail block and set it
|
|
# New tail should be WEAK_SUBJECTIVITY_PERIOD * 2 older than finalizedHead
|
|
const tailSlotInterval = WEAK_SUBJECTVITY_PERIOD * 2
|
|
if finalizedEpochStartSlot - GENESIS_SLOT > tailSlotInterval:
|
|
let tailSlot = finalizedEpochStartSlot - tailSlotInterval
|
|
let newTail = finalizedHead.blck.findAncestorBySlot(tailSlot)
|
|
pool.setTailBlock(newTail.blck)
|
|
|
|
func latestJustifiedBlock*(pool: BlockPool): BlockSlot =
|
|
## Return the most recent block that is justified and at least as recent
|
|
## as the latest finalized block
|
|
|
|
doAssert pool.heads.len > 0,
|
|
"We should have at least the genesis block in heaads"
|
|
doAssert (not pool.head.blck.isNil()),
|
|
"Genesis block will be head, if nothing else"
|
|
|
|
# Prefer stability: use justified block from current head to break ties!
|
|
result = pool.head.justified
|
|
for head in pool.heads[1 ..< ^0]:
|
|
if head.justified.slot > result.slot:
|
|
result = head.justified
|
|
|
|
proc preInit*(
|
|
T: type BlockPool, db: BeaconChainDB, state: BeaconState,
|
|
signedBlock: SignedBeaconBlock) =
|
|
# write a genesis state, the way the BlockPool expects it to be stored in
|
|
# database
|
|
# TODO probably should just init a blockpool with the freshly written
|
|
# state - but there's more refactoring needed to make it nice - doing
|
|
# a minimal patch for now..
|
|
let
|
|
blockRoot = hash_tree_root(signedBlock.message)
|
|
|
|
notice "New database from snapshot",
|
|
blockRoot = shortLog(blockRoot),
|
|
stateRoot = shortLog(signedBlock.message.state_root),
|
|
fork = state.fork,
|
|
validators = state.validators.len(),
|
|
cat = "initialization"
|
|
|
|
db.putState(state)
|
|
db.putBlock(signedBlock)
|
|
db.putTailBlock(blockRoot)
|
|
db.putHeadBlock(blockRoot)
|
|
db.putStateRoot(
|
|
blockRoot, signedBlock.message.slot, signedBlock.message.state_root)
|