891 lines
32 KiB
Nim
891 lines
32 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.
|
|
|
|
{.push raises: [Defect].}
|
|
|
|
import
|
|
# Standard libraries
|
|
chronicles, options, sequtils, tables, sets,
|
|
# Status libraries
|
|
metrics,
|
|
# Internals
|
|
../ssz/merkleization, ../beacon_chain_db, ../extras,
|
|
../spec/[
|
|
crypto, datatypes, digest, helpers, validator, state_transition,
|
|
beaconstate],
|
|
block_pools_types
|
|
|
|
declareCounter beacon_reorgs_total, "Total occurrences of reorganizations of the chain" # On fork choice
|
|
declareCounter beacon_state_data_cache_hits, "dag.cachedStates hits"
|
|
declareCounter beacon_state_data_cache_misses, "dag.cachedStates misses"
|
|
|
|
logScope: topics = "hotdb"
|
|
|
|
proc putBlock*(
|
|
dag: var CandidateChains, signedBlock: SignedBeaconBlock) =
|
|
dag.db.putBlock(signedBlock)
|
|
|
|
proc updateStateData*(
|
|
dag: CandidateChains, state: var StateData, bs: BlockSlot,
|
|
matchEpoch: bool = false) {.gcsafe.}
|
|
|
|
template withState*(
|
|
dag: CandidateChains, cache: var StateData, blockSlot: BlockSlot, body: untyped): untyped =
|
|
## Helper template that updates state to a particular BlockSlot - usage of
|
|
## cache is unsafe outside of block.
|
|
## TODO async transformations will lead to a race where cache gets updated
|
|
## while waiting for future to complete - catch this here somehow?
|
|
|
|
updateStateData(dag, cache, blockSlot)
|
|
|
|
template hashedState(): HashedBeaconState {.inject, used.} = cache.data
|
|
template state(): BeaconState {.inject, used.} = cache.data.data
|
|
template blck(): BlockRef {.inject, used.} = cache.blck
|
|
template root(): Eth2Digest {.inject, used.} = cache.data.root
|
|
|
|
body
|
|
|
|
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 populateEpochCache(state: BeaconState): EpochRef =
|
|
let epoch = state.get_current_epoch()
|
|
EpochRef(
|
|
epoch: epoch,
|
|
shuffled_active_validator_indices:
|
|
get_shuffled_active_validator_indices(state, epoch))
|
|
|
|
func link*(parent, child: BlockRef) =
|
|
doAssert (not (parent.root == Eth2Digest() or child.root == Eth2Digest())),
|
|
"blocks missing root!"
|
|
doAssert parent.root != child.root, "self-references not allowed"
|
|
|
|
child.parent = parent
|
|
|
|
func isAncestorOf*(a, b: BlockRef): bool =
|
|
var b = b
|
|
var depth = 0
|
|
const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
|
|
while true:
|
|
if a == b: return true
|
|
|
|
# for now, use an assert for block chain length since a chain this long
|
|
# indicates a circular reference here..
|
|
doAssert depth < maxDepth
|
|
depth += 1
|
|
|
|
if a.slot >= b.slot or b.parent.isNil:
|
|
return false
|
|
|
|
doAssert b.slot > b.parent.slot
|
|
b = b.parent
|
|
|
|
func getAncestorAt*(blck: BlockRef, slot: Slot): BlockRef =
|
|
## Return the most recent block as of the time at `slot` that not more recent
|
|
## than `blck` itself
|
|
|
|
var blck = blck
|
|
|
|
var depth = 0
|
|
const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
|
|
|
|
while true:
|
|
if blck.slot <= slot:
|
|
return blck
|
|
|
|
if blck.parent.isNil:
|
|
return nil
|
|
|
|
doAssert depth < maxDepth
|
|
depth += 1
|
|
|
|
blck = blck.parent
|
|
|
|
func get_ancestor*(blck: BlockRef, slot: Slot): BlockRef =
|
|
## https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/fork-choice.md#get_ancestor
|
|
## Return ancestor at slot, or nil if queried block is older
|
|
var blck = blck
|
|
|
|
var depth = 0
|
|
const maxDepth = (100'i64 * 365 * 24 * 60 * 60 div SECONDS_PER_SLOT.int)
|
|
|
|
while true:
|
|
if blck.slot == slot:
|
|
return blck
|
|
|
|
if blck.slot < slot:
|
|
return nil
|
|
|
|
if blck.parent.isNil:
|
|
return nil
|
|
|
|
doAssert depth < maxDepth
|
|
depth += 1
|
|
|
|
blck = blck.parent
|
|
|
|
iterator get_ancestors_in_epoch(blockSlot: BlockSlot): BlockSlot =
|
|
let min_slot =
|
|
blockSlot.slot.compute_epoch_at_slot.compute_start_slot_at_epoch
|
|
var blockSlot = blockSlot
|
|
|
|
while true:
|
|
for slot in countdown(blockSlot.slot, max(blockSlot.blck.slot, min_slot)):
|
|
yield BlockSlot(blck: blockSlot.blck, slot: slot)
|
|
|
|
if blockSlot.blck.parent.isNil or blockSlot.blck.slot <= min_slot:
|
|
break
|
|
|
|
doAssert blockSlot.blck.slot > blockSlot.blck.parent.slot
|
|
blockSlot =
|
|
BlockSlot(blck: blockSlot.blck.parent, slot: blockSlot.blck.slot - 1)
|
|
|
|
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.getAncestorAt(slot), slot: slot)
|
|
|
|
func getEpochInfo*(blck: BlockRef, state: BeaconState): EpochRef =
|
|
# This is the only intended mechanism by which to get an EpochRef
|
|
let
|
|
state_epoch = state.get_current_epoch()
|
|
matching_epochinfo = blck.epochsInfo.filterIt(it.epoch == state_epoch)
|
|
|
|
if matching_epochinfo.len == 0:
|
|
let cache = populateEpochCache(state)
|
|
|
|
# Don't use BlockRef caching as far as the epoch where the active
|
|
# validator indices can diverge.
|
|
if (compute_activation_exit_epoch(blck.slot.compute_epoch_at_slot) >
|
|
state_epoch):
|
|
blck.epochsInfo.add(cache)
|
|
trace "candidate_chains.getEpochInfo: back-filling parent.epochInfo",
|
|
state_slot = state.slot
|
|
cache
|
|
elif matching_epochinfo.len == 1:
|
|
matching_epochinfo[0]
|
|
else:
|
|
raiseAssert "multiple EpochRefs per epoch per BlockRef invalid"
|
|
|
|
func getEpochCache*(blck: BlockRef, state: BeaconState): StateCache =
|
|
let epochInfo = getEpochInfo(blck, state)
|
|
result = StateCache()
|
|
result.shuffled_active_validator_indices[state.get_current_epoch()] =
|
|
epochInfo.shuffled_active_validator_indices
|
|
|
|
func init(T: type BlockRef, root: Eth2Digest, slot: Slot): BlockRef =
|
|
BlockRef(
|
|
root: root,
|
|
slot: slot
|
|
)
|
|
|
|
func init*(T: type BlockRef, root: Eth2Digest, blck: SomeBeaconBlock): BlockRef =
|
|
BlockRef.init(root, blck.slot)
|
|
|
|
proc init*(T: type CandidateChains,
|
|
preset: RuntimePreset,
|
|
db: BeaconChainDB,
|
|
updateFlags: UpdateFlags = {}): CandidateChains =
|
|
# TODO we require that the db contains both a head and a tail block -
|
|
# asserting here doesn't seem like the right way to go about it however..
|
|
|
|
let
|
|
tailBlockRoot = db.getTailBlock()
|
|
headBlockRoot = db.getHeadBlock()
|
|
|
|
doAssert tailBlockRoot.isSome(), "Missing tail block, database corrupt?"
|
|
doAssert headBlockRoot.isSome(), "Missing head block, database corrupt?"
|
|
|
|
let
|
|
tailRoot = tailBlockRoot.get()
|
|
tailBlock = db.getBlock(tailRoot).get()
|
|
tailRef = BlockRef.init(tailRoot, tailBlock.message)
|
|
headRoot = headBlockRoot.get()
|
|
|
|
var
|
|
blocks = {tailRef.root: tailRef}.toTable()
|
|
headRef: BlockRef
|
|
|
|
if headRoot != tailRoot:
|
|
var curRef: BlockRef
|
|
|
|
for blck in db.getAncestors(headRoot):
|
|
if blck.root == tailRef.root:
|
|
doAssert(not curRef.isNil)
|
|
link(tailRef, curRef)
|
|
curRef = curRef.parent
|
|
break
|
|
|
|
let newRef = BlockRef.init(blck.root, blck.message)
|
|
if curRef == nil:
|
|
curRef = newRef
|
|
headRef = newRef
|
|
else:
|
|
link(newRef, curRef)
|
|
curRef = curRef.parent
|
|
blocks[curRef.root] = curRef
|
|
trace "Populating block dag", key = curRef.root, val = curRef
|
|
|
|
doAssert curRef == tailRef,
|
|
"head block does not lead to tail, database corrupt?"
|
|
else:
|
|
headRef = tailRef
|
|
|
|
var
|
|
bs = headRef.atSlot(headRef.slot)
|
|
tmpState = (ref StateData)()
|
|
|
|
# Now that we have a head block, we need to find the most recent state that
|
|
# we have saved in the database
|
|
while bs.blck != nil:
|
|
let root = db.getStateRoot(bs.blck.root, bs.slot)
|
|
if root.isSome():
|
|
# TODO load StateData from BeaconChainDB
|
|
# We save state root separately for empty slots which means we might
|
|
# sometimes not find a state even though we saved its state root
|
|
if db.getState(root.get(), tmpState.data.data, noRollback):
|
|
tmpState.data.root = root.get()
|
|
tmpState.blck = bs.blck
|
|
|
|
break
|
|
|
|
bs = bs.parent() # Iterate slot by slot in case there's a gap!
|
|
|
|
if tmpState.blck == nil:
|
|
warn "No state found in head history, database corrupt?"
|
|
# TODO Potentially we could recover from here instead of crashing - what
|
|
# would be a good recovery model?
|
|
raiseAssert "No state found in head history, database corrupt?"
|
|
|
|
# We presently save states on the epoch boundary - it means that the latest
|
|
# state we loaded might be older than head block - nonetheless, it will be
|
|
# from the same epoch as the head, thus the finalized and justified slots are
|
|
# the same - these only change on epoch boundaries.
|
|
let
|
|
finalizedSlot =
|
|
tmpState.data.data.finalized_checkpoint.epoch.compute_start_slot_at_epoch()
|
|
finalizedHead = headRef.atSlot(finalizedSlot)
|
|
justifiedSlot =
|
|
tmpState.data.data.current_justified_checkpoint.epoch.compute_start_slot_at_epoch()
|
|
justifiedHead = headRef.atSlot(justifiedSlot)
|
|
head = Head(blck: headRef, justified: justifiedHead)
|
|
|
|
doAssert justifiedHead.slot >= finalizedHead.slot,
|
|
"justified head comes before finalized head - database corrupt?"
|
|
|
|
let res = CandidateChains(
|
|
blocks: blocks,
|
|
tail: tailRef,
|
|
head: head,
|
|
finalizedHead: finalizedHead,
|
|
db: db,
|
|
heads: @[head],
|
|
headState: tmpState[],
|
|
justifiedState: tmpState[], # This is wrong but we'll update it below
|
|
tmpState: tmpState[],
|
|
clearanceState: tmpState[],
|
|
balanceState: tmpState[],
|
|
|
|
# The only allowed flag right now is verifyFinalization, as the others all
|
|
# allow skipping some validation.
|
|
updateFlags: {verifyFinalization} * updateFlags,
|
|
runtimePreset: preset,
|
|
)
|
|
|
|
doAssert res.updateFlags in [{}, {verifyFinalization}]
|
|
|
|
res.updateStateData(res.justifiedState, justifiedHead)
|
|
res.updateStateData(res.headState, headRef.atSlot(headRef.slot))
|
|
res.clearanceState = res.headState
|
|
res.balanceState = res.justifiedState
|
|
|
|
info "Block dag initialized",
|
|
head = head.blck, justifiedHead, finalizedHead, tail = tailRef,
|
|
totalBlocks = blocks.len
|
|
|
|
res
|
|
|
|
proc getState(
|
|
dag: CandidateChains, db: BeaconChainDB, stateRoot: Eth2Digest, blck: BlockRef,
|
|
output: var StateData): bool =
|
|
let outputAddr = unsafeAddr output # local scope
|
|
func restore(v: var BeaconState) =
|
|
if outputAddr == (unsafeAddr dag.headState):
|
|
# TODO seeing the headState in the restore shouldn't happen - we load
|
|
# head states only when updating the head position, and by that time
|
|
# the database will have gone through enough sanity checks that
|
|
# SSZ exceptions shouldn't happen, which is when restore happens.
|
|
# Nonetheless, this is an ugly workaround that needs to go away
|
|
doAssert false, "Cannot alias headState"
|
|
|
|
assign(outputAddr[], dag.headState)
|
|
|
|
if not db.getState(stateRoot, output.data.data, restore):
|
|
return false
|
|
|
|
output.blck = blck
|
|
output.data.root = stateRoot
|
|
|
|
true
|
|
|
|
func getStateCacheIndex(
|
|
dag: CandidateChains, blockRoot: Eth2Digest, slot: Slot, matchEpoch: bool):
|
|
int =
|
|
for i, cachedState in dag.cachedStates:
|
|
let (cacheBlockRoot, cacheSlot, _) = cachedState
|
|
if cacheBlockRoot == blockRoot and (cacheSlot == slot or
|
|
(matchEpoch and
|
|
cacheSlot.compute_epoch_at_slot == slot.compute_epoch_at_slot)):
|
|
return i
|
|
|
|
-1
|
|
|
|
func putStateCache*(
|
|
dag: CandidateChains, state: HashedBeaconState, blck: BlockRef) =
|
|
# Efficiently access states for both attestation aggregation and to process
|
|
# block proposals going back to the last finalized slot.
|
|
let stateCacheIndex =
|
|
dag.getStateCacheIndex(blck.root, state.data.slot, false)
|
|
if stateCacheIndex == -1:
|
|
const MAX_CACHE_SIZE = 18
|
|
|
|
let cacheLen = dag.cachedStates.len
|
|
doAssert cacheLen <= MAX_CACHE_SIZE
|
|
|
|
let entry =
|
|
if dag.cachedStates.len == MAX_CACHE_SIZE: dag.cachedStates.pop().state
|
|
else: (ref HashedBeaconState)()
|
|
assign(entry[], state)
|
|
|
|
insert(dag.cachedStates, (blck.root, state.data.slot, entry))
|
|
trace "CandidateChains.putState(): state cache updated",
|
|
cacheLen, root = shortLog(blck.root), slot = state.data.slot
|
|
|
|
proc putState*(dag: CandidateChains, 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
|
|
logScope: pcs = "save_state_at_epoch_start"
|
|
|
|
var rootWritten = false
|
|
if state.data.slot != blck.slot:
|
|
# This is a state that was produced by a skip slot for which there is no
|
|
# block - we'll save the state root in the database in case we need to
|
|
# replay the skip
|
|
dag.db.putStateRoot(blck.root, state.data.slot, state.root)
|
|
rootWritten = true
|
|
|
|
if state.data.slot.isEpoch:
|
|
if not dag.db.containsState(state.root):
|
|
info "Storing state",
|
|
blck = shortLog(blck),
|
|
stateSlot = shortLog(state.data.slot),
|
|
stateRoot = shortLog(state.root)
|
|
|
|
dag.db.putState(state.root, state.data)
|
|
if not rootWritten:
|
|
dag.db.putStateRoot(blck.root, state.data.slot, state.root)
|
|
|
|
if state.data.slot mod 2 == 0:
|
|
putStateCache(dag, state, blck)
|
|
|
|
func getRef*(dag: CandidateChains, root: Eth2Digest): BlockRef =
|
|
## Retrieve a resolved block reference, if available
|
|
dag.blocks.getOrDefault(root, nil)
|
|
|
|
func getBlockRange*(
|
|
dag: CandidateChains, startSlot: Slot, skipStep: Natural,
|
|
output: var openArray[BlockRef]): Natural =
|
|
## This function populates an `output` buffer of blocks
|
|
## with a slots ranging from `startSlot` up to, but not including,
|
|
## `startSlot + skipStep * output.len`, skipping any slots that don't have
|
|
## a block.
|
|
##
|
|
## Blocks will be written to `output` from the end without gaps, even if
|
|
## a block is missing in a particular slot. The return value shows how
|
|
## many slots were missing blocks - to iterate over the result, start
|
|
## at this index.
|
|
##
|
|
## If there were no blocks in the range, `output.len` will be returned.
|
|
let count = output.len
|
|
trace "getBlockRange entered",
|
|
head = shortLog(dag.head.blck.root), count, startSlot, skipStep
|
|
|
|
let
|
|
skipStep = max(1, skipStep) # Treat 0 step as 1
|
|
endSlot = startSlot + uint64(count * skipStep)
|
|
|
|
var
|
|
b = dag.head.blck.atSlot(endSlot)
|
|
o = count
|
|
for i in 0..<count:
|
|
for j in 0..<skipStep:
|
|
b = b.parent
|
|
if b.blck.slot == b.slot:
|
|
dec o
|
|
output[o] = b.blck
|
|
|
|
# Make sure the given input is cleared, just in case
|
|
for i in 0..<o:
|
|
output[i] = nil
|
|
|
|
o # Return the index of the first non-nil item in the output
|
|
|
|
func getBlockBySlot*(dag: CandidateChains, slot: Slot): BlockRef =
|
|
## Retrieves the first block in the current canonical chain
|
|
## with slot number less or equal to `slot`.
|
|
dag.head.blck.atSlot(slot).blck
|
|
|
|
func getBlockByPreciseSlot*(dag: CandidateChains, slot: Slot): BlockRef =
|
|
## Retrieves a block from the canonical chain with a slot
|
|
## number equal to `slot`.
|
|
let found = dag.getBlockBySlot(slot)
|
|
if found.slot != slot: found else: nil
|
|
|
|
proc get*(dag: CandidateChains, blck: BlockRef): BlockData =
|
|
## Retrieve the associated block body of a block reference
|
|
doAssert (not blck.isNil), "Trying to get nil BlockRef"
|
|
|
|
let data = dag.db.getBlock(blck.root)
|
|
doAssert data.isSome, "BlockRef without backing data, database corrupt?"
|
|
|
|
BlockData(data: data.get(), refs: blck)
|
|
|
|
proc get*(dag: CandidateChains, root: Eth2Digest): Option[BlockData] =
|
|
## Retrieve a resolved block reference and its associated body, if available
|
|
let refs = dag.getRef(root)
|
|
|
|
if not refs.isNil:
|
|
some(dag.get(refs))
|
|
else:
|
|
none(BlockData)
|
|
|
|
proc skipAndUpdateState(
|
|
dag: CandidateChains,
|
|
state: var HashedBeaconState, blck: BlockRef, slot: Slot, save: bool) =
|
|
while state.data.slot < slot:
|
|
# Process slots one at a time in case afterUpdate needs to see empty states
|
|
var stateCache = getEpochCache(blck, state.data)
|
|
advance_slot(state, dag.updateFlags, stateCache)
|
|
|
|
if save:
|
|
dag.putState(state, blck)
|
|
|
|
proc skipAndUpdateState(
|
|
dag: CandidateChains,
|
|
state: var StateData, blck: BlockData, flags: UpdateFlags, save: bool): bool =
|
|
|
|
dag.skipAndUpdateState(
|
|
state.data, blck.refs, blck.data.message.slot - 1, save)
|
|
|
|
var statePtr = unsafeAddr state # safe because `restore` is locally scoped
|
|
func restore(v: var HashedBeaconState) =
|
|
doAssert (addr(statePtr.data) == addr v)
|
|
statePtr[] = dag.headState
|
|
|
|
var stateCache = getEpochCache(blck.refs, state.data.data)
|
|
let ok = state_transition(
|
|
dag.runtimePreset, state.data, blck.data,
|
|
stateCache, flags + dag.updateFlags, restore)
|
|
|
|
if ok and save:
|
|
dag.putState(state.data, blck.refs)
|
|
|
|
ok
|
|
|
|
proc rewindState(
|
|
dag: CandidateChains, state: var StateData, bs: BlockSlot,
|
|
matchEpoch: bool): seq[BlockRef] =
|
|
logScope:
|
|
blockSlot = shortLog(bs)
|
|
pcs = "replay_state"
|
|
|
|
var ancestors = @[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.blck.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 = block:
|
|
let tmp = dag.db.getStateRoot(bs.blck.root, bs.slot)
|
|
if tmp.isSome() and dag.db.containsState(tmp.get()):
|
|
tmp
|
|
else:
|
|
# State roots are sometimes kept in database even though state is not
|
|
err(Opt[Eth2Digest])
|
|
curBs = bs
|
|
|
|
while stateRoot.isNone():
|
|
let parBs = curBs.parent()
|
|
if parBs.blck.isNil:
|
|
break # Bug probably!
|
|
|
|
if parBs.blck != curBs.blck:
|
|
ancestors.add(parBs.blck)
|
|
|
|
# TODO investigate replacing with getStateCached, by refactoring whole
|
|
# function. Empirically, this becomes pretty rare once good caches are
|
|
# used in the front-end.
|
|
let idx = dag.getStateCacheIndex(parBs.blck.root, parBs.slot, matchEpoch)
|
|
if idx >= 0:
|
|
assign(state.data, dag.cachedStates[idx].state[])
|
|
let ancestor = ancestors.pop()
|
|
state.blck = ancestor
|
|
|
|
beacon_state_data_cache_hits.inc()
|
|
trace "Replaying state transitions via in-memory cache",
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
ancestorStateRoot = shortLog(state.data.root),
|
|
ancestors = ancestors.len
|
|
|
|
return ancestors
|
|
|
|
beacon_state_data_cache_misses.inc()
|
|
if (let tmp = dag.db.getStateRoot(parBs.blck.root, parBs.slot); tmp.isSome()):
|
|
if dag.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!)
|
|
fatal "Couldn't find ancestor state root!"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
let
|
|
ancestor = ancestors.pop()
|
|
root = stateRoot.get()
|
|
found = dag.getState(dag.db, root, ancestor, state)
|
|
|
|
if not found:
|
|
# 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!)
|
|
fatal "Couldn't find ancestor state or block parent missing!"
|
|
doAssert false, "Oh noes, we passed big bang!"
|
|
|
|
trace "Replaying state transitions",
|
|
stateSlot = shortLog(state.data.data.slot),
|
|
ancestors = ancestors.len
|
|
|
|
ancestors
|
|
|
|
proc getStateDataCached(
|
|
dag: CandidateChains, state: var StateData, bs: BlockSlot,
|
|
matchEpoch: bool): bool =
|
|
# This pointedly does not run rewindState or state_transition, but otherwise
|
|
# mostly matches updateStateData(...), because it's too expensive to run the
|
|
# rewindState(...)/skipAndUpdateState(...)/state_transition(...) procs, when
|
|
# each hash_tree_root(...) consumes a nontrivial fraction of a second.
|
|
when false:
|
|
# For debugging/development purposes to assess required lookback window for
|
|
# any given use case.
|
|
doAssert state.data.data.slot <= bs.slot + 4
|
|
|
|
let idx = dag.getStateCacheIndex(bs.blck.root, bs.slot, matchEpoch)
|
|
if idx >= 0:
|
|
assign(state.data, dag.cachedStates[idx].state[])
|
|
state.blck = bs.blck
|
|
beacon_state_data_cache_hits.inc()
|
|
return true
|
|
|
|
# In-memory caches didn't hit. Try main blockpool database. This is slower
|
|
# than the caches due to SSZ (de)serializing and disk I/O, so prefer them.
|
|
beacon_state_data_cache_misses.inc()
|
|
if (let tmp = dag.db.getStateRoot(bs.blck.root, bs.slot); tmp.isSome()):
|
|
return dag.getState(dag.db, tmp.get(), bs.blck, state)
|
|
|
|
false
|
|
|
|
template withEpochState*(
|
|
dag: CandidateChains, cache: var StateData, blockSlot: BlockSlot, body: untyped): untyped =
|
|
## Helper template that updates state to a particular BlockSlot - usage of
|
|
## cache is unsafe outside of block.
|
|
## TODO async transformations will lead to a race where cache gets updated
|
|
## while waiting for future to complete - catch this here somehow?
|
|
# TODO implement the looser constraints allowed by epoch, not precise slot target
|
|
# allow expressing preference to opt-in to looser constraints regardless
|
|
dag.withState(cache, blockSlot):
|
|
body
|
|
|
|
proc updateStateData*(
|
|
dag: CandidateChains, state: var StateData, bs: BlockSlot,
|
|
matchEpoch: bool = false) =
|
|
## 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
|
|
dag.skipAndUpdateState(state.data, bs.blck, bs.slot, true)
|
|
|
|
return # State already at the right spot
|
|
|
|
if dag.getStateDataCached(state, bs, matchEpoch):
|
|
return
|
|
|
|
let ancestors = rewindState(dag, state, bs, matchEpoch)
|
|
|
|
# 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. Pathologically quadratic in slot number, naïvely.
|
|
for i in countdown(ancestors.len - 1, 0):
|
|
# Because the ancestors are in the database, there's no need to persist them
|
|
# again. Also, because we're applying blocks that were loaded from the
|
|
# database, we can skip certain checks that have already been performed
|
|
# before adding the block to the database. In particular, this means that
|
|
# no state root calculation will take place here, because we can load
|
|
# the final state root from the block itself.
|
|
let ok =
|
|
dag.skipAndUpdateState(state, dag.get(ancestors[i]), {}, false)
|
|
doAssert ok, "Blocks in database should never fail to apply.."
|
|
|
|
# We save states here - blocks were guaranteed to have passed through the save
|
|
# function once at least, but not so for empty slots!
|
|
dag.skipAndUpdateState(state.data, bs.blck, bs.slot, true)
|
|
|
|
state.blck = bs.blck
|
|
|
|
dag.putStateCache(state.data, bs.blck)
|
|
|
|
proc loadTailState*(dag: CandidateChains): StateData =
|
|
## Load the state associated with the current tail in the dag
|
|
let stateRoot = dag.db.getBlock(dag.tail.root).get().message.state_root
|
|
let found = dag.getState(dag.db, stateRoot, dag.tail, result)
|
|
# TODO turn into regular error, this can happen
|
|
doAssert found, "Failed to load tail state, database corrupt?"
|
|
|
|
proc delState(dag: CandidateChains, bs: BlockSlot) =
|
|
# Delete state state and mapping for a particular block+slot
|
|
if (let root = dag.db.getStateRoot(bs.blck.root, bs.slot); root.isSome()):
|
|
dag.db.delState(root.get())
|
|
|
|
proc updateHead*(dag: CandidateChains, newHead: 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 newHead.parent != nil or newHead.slot == 0
|
|
logScope:
|
|
newHead = shortLog(newHead)
|
|
pcs = "fork_choice"
|
|
|
|
if dag.head.blck == newHead:
|
|
info "No head block update"
|
|
|
|
return
|
|
|
|
let
|
|
lastHead = dag.head
|
|
dag.db.putHeadBlock(newHead.root)
|
|
|
|
# Start off by making sure we have the right state
|
|
updateStateData(
|
|
dag, dag.headState, BlockSlot(blck: newHead, slot: newHead.slot))
|
|
|
|
let
|
|
justifiedSlot = dag.headState.data.data
|
|
.current_justified_checkpoint
|
|
.epoch
|
|
.compute_start_slot_at_epoch()
|
|
justifiedBS = newHead.atSlot(justifiedSlot)
|
|
|
|
dag.head = Head(blck: newHead, justified: justifiedBS)
|
|
updateStateData(dag, dag.justifiedState, justifiedBS)
|
|
|
|
# TODO isAncestorOf may be expensive - too expensive?
|
|
if not lastHead.blck.isAncestorOf(newHead):
|
|
info "Updated head block (new parent)",
|
|
lastHead = shortLog(lastHead.blck),
|
|
headParent = shortLog(newHead.parent),
|
|
stateRoot = shortLog(dag.headState.data.root),
|
|
headBlock = shortLog(dag.headState.blck),
|
|
stateSlot = shortLog(dag.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(dag.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(dag.headState.data.data.finalized_checkpoint.epoch)
|
|
|
|
# A reasonable criterion for "reorganizations of the chain"
|
|
beacon_reorgs_total.inc()
|
|
else:
|
|
info "Updated head block",
|
|
stateRoot = shortLog(dag.headState.data.root),
|
|
headBlock = shortLog(dag.headState.blck),
|
|
stateSlot = shortLog(dag.headState.data.data.slot),
|
|
justifiedEpoch = shortLog(dag.headState.data.data.current_justified_checkpoint.epoch),
|
|
finalizedEpoch = shortLog(dag.headState.data.data.finalized_checkpoint.epoch)
|
|
let
|
|
finalizedEpochStartSlot =
|
|
dag.headState.data.data.finalized_checkpoint.epoch.
|
|
compute_start_slot_at_epoch()
|
|
# TODO there might not be a block at the epoch boundary - what then?
|
|
finalizedHead = newHead.atSlot(finalizedEpochStartSlot)
|
|
|
|
doAssert (not finalizedHead.blck.isNil),
|
|
"Block graph should always lead to a finalized block"
|
|
|
|
if finalizedHead != dag.finalizedHead:
|
|
block: # Remove states, walking slot by slot
|
|
discard
|
|
# TODO this is very aggressive - in theory all our operations start at
|
|
# the finalized block so all states before that can be wiped..
|
|
# TODO this is disabled for now because the logic for initializing the
|
|
# block dag and potentially a few other places depend on certain
|
|
# states (like the tail state) being present. It's also problematic
|
|
# because it is not clear what happens when tail and finalized states
|
|
# happen on an empty slot..
|
|
# var cur = finalizedHead
|
|
# while cur != dag.finalizedHead:
|
|
# cur = cur.parent
|
|
# dag.delState(cur)
|
|
|
|
|
|
block: # Clean up block refs, walking block by block
|
|
# 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
|
|
let hlen = dag.heads.len
|
|
for i in 0..<hlen:
|
|
let n = hlen - i - 1
|
|
let head = dag.heads[n]
|
|
if finalizedHead.blck.isAncestorOf(head.blck):
|
|
continue
|
|
|
|
var cur = head.blck
|
|
while not cur.isAncestorOf(finalizedHead.blck):
|
|
# TODO empty states need to be removed also!
|
|
let stateRoot = dag.db.getStateRoot(cur.root, cur.slot)
|
|
if stateRoot.issome():
|
|
dag.db.delState(stateRoot.get())
|
|
|
|
dag.blocks.del(cur.root)
|
|
dag.db.delBlock(cur.root)
|
|
|
|
if cur.parent.isNil:
|
|
break
|
|
cur = cur.parent
|
|
|
|
dag.heads.del(n)
|
|
|
|
dag.finalizedHead = finalizedHead
|
|
|
|
info "Finalized block",
|
|
finalizedHead = shortLog(finalizedHead),
|
|
heads = dag.heads.len
|
|
|
|
# TODO prune everything before weak subjectivity period
|
|
|
|
func latestJustifiedBlock*(dag: CandidateChains): BlockSlot =
|
|
## Return the most recent block that is justified and at least as recent
|
|
## as the latest finalized block
|
|
|
|
doAssert dag.heads.len > 0,
|
|
"We should have at least the genesis block in heads"
|
|
doAssert (not dag.head.blck.isNil()),
|
|
"Genesis block will be head, if nothing else"
|
|
|
|
# Prefer stability: use justified block from current head to break ties!
|
|
result = dag.head.justified
|
|
for head in dag.heads[1 ..< ^0]:
|
|
if head.justified.slot > result.slot:
|
|
result = head.justified
|
|
|
|
proc isInitialized*(T: type CandidateChains, db: BeaconChainDB): bool =
|
|
let
|
|
headBlockRoot = db.getHeadBlock()
|
|
tailBlockRoot = db.getTailBlock()
|
|
|
|
if not (headBlockRoot.isSome() and tailBlockRoot.isSome()):
|
|
return false
|
|
|
|
let
|
|
headBlock = db.getBlock(headBlockRoot.get())
|
|
tailBlock = db.getBlock(tailBlockRoot.get())
|
|
|
|
if not (headBlock.isSome() and tailBlock.isSome()):
|
|
return false
|
|
|
|
if not db.containsState(tailBlock.get().message.state_root):
|
|
return false
|
|
|
|
true
|
|
|
|
proc preInit*(
|
|
T: type CandidateChains, db: BeaconChainDB, state: BeaconState,
|
|
signedBlock: SignedBeaconBlock) =
|
|
# write a genesis state, the way the CandidateChains 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..
|
|
doAssert signedBlock.message.state_root == hash_tree_root(state)
|
|
notice "New database from snapshot",
|
|
blockRoot = shortLog(signedBlock.root),
|
|
stateRoot = shortLog(signedBlock.message.state_root),
|
|
fork = state.fork,
|
|
validators = state.validators.len()
|
|
|
|
db.putState(state)
|
|
db.putBlock(signedBlock)
|
|
db.putTailBlock(signedBlock.root)
|
|
db.putHeadBlock(signedBlock.root)
|
|
db.putStateRoot(signedBlock.root, state.slot, signedBlock.message.state_root)
|
|
|
|
proc getProposer*(
|
|
dag: CandidateChains, head: BlockRef, slot: Slot):
|
|
Option[(ValidatorIndex, ValidatorPubKey)] =
|
|
dag.withState(dag.tmpState, head.atSlot(slot)):
|
|
var cache = StateCache()
|
|
|
|
let proposerIdx = get_beacon_proposer_index(state, cache)
|
|
if proposerIdx.isNone:
|
|
warn "Missing proposer index",
|
|
slot=slot,
|
|
epoch=slot.compute_epoch_at_slot,
|
|
num_validators=state.validators.len,
|
|
active_validators=
|
|
get_active_validator_indices(state, slot.compute_epoch_at_slot),
|
|
balances=state.balances
|
|
return
|
|
|
|
return some((proposerIdx.get(), state.validators[proposerIdx.get()].pubkey))
|