nimbus-eth2/beacon_chain/rpc/rpc_utils.nim
Jacek Sieka 05ffe7b2bf
Prune BlockRef on finalization (#3513)
Up til now, the block dag has been using `BlockRef`, a structure adapted
for a full DAG, to represent all of chain history. This is a correct and
simple design, but does not exploit the linearity of the chain once
parts of it finalize.

By pruning the in-memory `BlockRef` structure at finalization, we save,
at the time of writing, a cool ~250mb (or 25%:ish) chunk of memory
landing us at a steady state of ~750mb normal memory usage for a
validating node.

Above all though, we prevent memory usage from growing proportionally
with the length of the chain, something that would not be sustainable
over time -  instead, the steady state memory usage is roughly
determined by the validator set size which grows much more slowly. With
these changes, the core should remain sustainable memory-wise post-merge
all the way to withdrawals (when the validator set is expected to grow).

In-memory indices are still used for the "hot" unfinalized portion of
the chain - this ensure that consensus performance remains unchanged.

What changes is that for historical access, we use a db-based linear
slot index which is cache-and-disk-friendly, keeping the cost for
accessing historical data at a similar level as before, achieving the
savings at no percievable cost to functionality or performance.

A nice collateral benefit is the almost-instant startup since we no
longer load any large indicies at dag init.

The cost of this functionality instead can be found in the complexity of
having to deal with two ways of traversing the chain - by `BlockRef` and
by slot.

* use `BlockId` instead of `BlockRef` where finalized / historical data
may be required
* simplify clearance pre-advancement
* remove dag.finalizedBlocks (~50:ish mb)
* remove `getBlockAtSlot` - use `getBlockIdAtSlot` instead
* `parent` and `atSlot` for `BlockId` now require a `ChainDAGRef`
instance, unlike `BlockRef` traversal
* prune `BlockRef` parents on finality (~200:ish mb)
* speed up ChainDAG init by not loading finalized history index
* mess up light client server error handling - this need revisiting :)
2022-03-17 17:42:56 +00:00

112 lines
4.4 KiB
Nim

# beacon_chain
# Copyright (c) 2018-2021 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
std/[strutils, parseutils],
stew/byteutils,
../beacon_node, ../validators/validator_duties,
../consensus_object_pools/[block_pools_types, blockchain_dag],
../spec/datatypes/base,
../spec/[forks, helpers],
../spec/eth2_apis/[rpc_types, eth2_json_rpc_serialization]
export forks, rpc_types, eth2_json_rpc_serialization, blockchain_dag
template raiseNoAltairSupport*() =
raise (ref ValueError)(msg:
"The JSON-RPC interface does not support certain Altair operations due to changes in block structure - see https://nimbus.guide/rest-api.html for full altair support")
template withStateForStateId*(stateId: string, body: untyped): untyped =
let
bsi = node.stateIdToBlockSlotId(stateId)
template isState(state: ForkedHashedBeaconState): bool =
state.matches_block_slot(bsi.bid.root, bsi.slot)
if isState(node.dag.headState):
withStateVars(node.dag.headState):
var cache {.inject, used.}: StateCache
body
else:
let rpcState = assignClone(node.dag.headState)
node.dag.withUpdatedState(rpcState[], bsi) do:
body
do:
raise (ref CatchableError)(msg: "Trying to access pruned state")
proc parseRoot*(str: string): Eth2Digest {.raises: [Defect, ValueError].} =
Eth2Digest(data: hexToByteArray[32](str))
func checkEpochToSlotOverflow*(epoch: Epoch) {.raises: [Defect, ValueError].} =
const maxEpoch = epoch(FAR_FUTURE_SLOT)
if epoch >= maxEpoch:
raise newException(
ValueError, "Requesting epoch for which slot would overflow")
proc doChecksAndGetCurrentHead*(node: BeaconNode, slot: Slot): BlockRef {.raises: [Defect, CatchableError].} =
result = node.dag.head
if not node.isSynced(result):
raise newException(CatchableError, "Cannot fulfill request until node is synced")
# TODO for now we limit the requests arbitrarily by up to 2 epochs into the future
if result.slot + uint64(2 * SLOTS_PER_EPOCH) < slot:
raise newException(CatchableError, "Requesting way ahead of the current head")
proc doChecksAndGetCurrentHead*(node: BeaconNode, epoch: Epoch): BlockRef {.raises: [Defect, CatchableError].} =
checkEpochToSlotOverflow(epoch)
node.doChecksAndGetCurrentHead(epoch.start_slot())
proc parseSlot(slot: string): Slot {.raises: [Defect, CatchableError].} =
if slot.len == 0:
raise newException(ValueError, "Empty slot number not allowed")
var parsed: BiggestUInt
if parseBiggestUInt(slot, parsed) != slot.len:
raise newException(ValueError, "Not a valid slot number")
Slot parsed
proc getBlockSlotIdFromString*(node: BeaconNode, slot: string): BlockSlotId {.raises: [Defect, CatchableError].} =
let parsed = parseSlot(slot)
discard node.doChecksAndGetCurrentHead(parsed)
node.dag.getBlockIdAtSlot(parsed).valueOr:
raise newException(ValueError, "Block not found")
proc getBlockIdFromString*(node: BeaconNode, slot: string): BlockId {.raises: [Defect, CatchableError].} =
let parsed = parseSlot(slot)
discard node.doChecksAndGetCurrentHead(parsed)
let bsid = node.dag.getBlockIdAtSlot(parsed)
if bsid.isSome and bsid.get.isProposed():
bsid.get().bid
else:
raise (ref ValueError)(msg: "Block not found")
proc stateIdToBlockSlotId*(node: BeaconNode, stateId: string): BlockSlotId {.raises: [Defect, CatchableError].} =
case stateId:
of "head":
node.dag.head.bid.atSlot()
of "genesis":
node.dag.genesis.atSlot()
of "finalized":
node.dag.finalizedHead.toBlockSlotId().expect("not nil")
of "justified":
node.dag.head.atEpochStart(
getStateField(
node.dag.headState, current_justified_checkpoint).epoch).
toBlockSlotId().valueOr:
raise (ref ValueError)(msg: "State not found")
else:
if stateId.startsWith("0x"):
let stateRoot = parseRoot(stateId)
if stateRoot == getStateRoot(node.dag.headState):
node.dag.head.bid.atSlot()
else:
# We don't have a state root -> BlockSlot mapping
raise (ref ValueError)(msg: "State not found")
else: # Parse as slot number
node.getBlockSlotIdFromString(stateId)