Other changes:
Renamed the `EIP_4844_FORK_*` config constants to `DENEB_FORK_*` as
this matches the latest spec and it's already used in the official
Sepolia config.
When running `nimbus_light_client`, we persist the latest header from
`LightClientStore.finalized_header` in a database across restarts.
Because the data format is derived from the latest `LightClientStore`,
this could lead to data being persisted in pre-release formats.
To enable us to test later `LightClientStore` versions on devnets,
transition to a `ForkedLightClientStore` internally that is only
migrated to newer forks on-demand (instead of starting at latest).
Distinguish between those code locations that need to be updated on each
light client data format change, and those others that should generally
be fine, as long as a valid light client object is processed.
The former are tagged with static assert for `LightClientDataFork.high`.
The latter are changed to `lcDataFork > LightClientDataFork.None` to
indicate that they depend only on presence of any valid object.
Also bundled a few minor cleanups and fixes.
Also add `Forky` type for `LightClientStore` and minor fixes / cleanups.
The light client data structures were changed to accommodate additional
fields in future forks (e.g., to also hold execution data).
There is a minor change to the JSON serialization, where the `header`
properties are now nested inside a `LightClientHeader`.
The SSZ serialization remains compatible.
See https://github.com/ethereum/consensus-specs/pull/3190
and https://github.com/ethereum/beacon-APIs/pull/287
* consolidate consensus spec transition test fixtures
* include capella
* consoliate fork test fixtures
* note change in EIP-4844 process_block in alpha.2
We currently use `BlockError` for both beacon blocks and LC objects.
In light of EIP4844, we will likely also use it for blob sidecars.
To avoid confusion, renaming it to a more generic `VerifierError`,
and update its documentation to be more generic.
To avoid long lines as a followup, also renaming the `block_processor`'s
`BlockProcessingCompleted.completed`->`ProcessingStatus.completed` and
`BlockProcessingCompleted.notCompleted`->`ProcessingStatus.notCompleted`
Currently, we require genesis and a checkpoint block and state to start
from an arbitrary slot - this PR relaxes this requirement so that we can
start with a state alone.
The current trusted-node-sync algorithm works by first downloading
blocks until we find an epoch aligned non-empty slot, then downloads the
state via slot.
However, current
[proposals](https://github.com/ethereum/beacon-APIs/pull/226) for
checkpointing prefer finalized state as
the main reference - this allows more simple access control and caching
on the server side - in particular, this should help checkpoint-syncing
from sources that have a fast `finalized` state download (like infura
and teku) but are slow when accessing state via slot.
Earlier versions of Nimbus will not be able to read databases created
without a checkpoint block and genesis. In most cases, backfilling makes
the database compatible except where genesis is also missing (custom
networks).
* backfill checkpoint block from libp2p instead of checkpoint source,
when doing trusted node sync
* allow starting the client without genesis / checkpoint block
* perform epoch start slot lookahead when loading tail state, so as to
deal with the case where the epoch start slot does not have a block
* replace `--blockId` with `--state-id` in TNS command line
* when replaying, also look at the parent of the last-known-block (even
if we don't have the parent block data, we can still replay from a
"parent" state) - in particular, this clears the way for implementing
state pruning
* deprecate `--finalized-checkpoint-block` option (no longer needed)
* Allow chain dag without genesis / block
This PR enables the initialization of the dag without access to blocks
or genesis state - it is a prerequisite for implementing a number of
interesting features:
* checkpoint sync without any block download
* pruning of blocks and states
* backfill checkpoint block
Now that the 1.2.0-rc.2 spec contains the same `LightClientUpdate`
definition that Nimbus was already using before, the corresponding
SSZ test vectors can be re-enabled.
The justified and finalized `Checkpoint` are frequently passed around
together. This introduces a new `FinalityCheckpoint` data structure that
combines them into one.
Due to the large usage of this structure in fork choice, also took this
opportunity to update fork choice tests to the latest v1.2.0-rc.1 spec.
Many additional tests enabled, some need more work, e.g. EL mock blocks.
Also implemented `discard_equivocations` which was skipped in #3661,
and improved code reuse across fork choice logic while at it.
Merkle proofs tend to have long underlying type definitions, e.g.,
`array[log2trunc(NEXT_SYNC_COMMITTEE_INDEX), Eth2Digest]`. For the
ones used in the LC sync protocol, dedicated types are introduced
to improve readability. Furthermore, the `CachedLightClientBootstrap`
wrapper that solely wrapped a merkle branch is eliminated.
This updates `nim-ssz-serialization` to
`3db6cc0f282708aca6c290914488edd832971d61`.
Notable changes:
- Use `uint64` for `GeneralizedIndex`
- Add support for building merkle multiproofs
Incorporates the latest changes to the light client sync protocol based
on Devconnect AMS feedback. Note that this breaks compatibility with the
previous prototype, due to changes to data structures and endpoints.
See https://github.com/ethereum/consensus-specs/pull/2802
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 :)
One more step on the journey to reduce `BlockRef` usage across the
codebase - this one gets rid of `StateData` whose job was to keep track
of which block was last assigned to a state - these duties have now been
taken over by `latest_block_root`, a fairly recent addition that
computes this block root from state data (at a small cost that should be
insignificant)
99% mechanical change.
When syncing as a light client, different behaviour is needed to handle
the various ways how errors may occur. The existing logic for blocks can
also be applied to light client objects:
- `Invalid`: Malformed object that is clearly an error by its producer.
- `MissingParent`: More data is needed to decide applicability.
- `UnviableFork`: Object may be valid but will never apply on this fork.
- `Duplicate`: No errors were encountered but the object was not useful.
This adopts the spec sections of the pre-release proposal of the libp2p
based light client sync protocol, and also adds a test runner for the
new accompanying tests. While the release version of the light client
sync protocol contains conflicting definitions, it is currently unused,
and the code specific to the pre-release proposal is marked as such.
See https://github.com/ethereum/consensus-specs/pull/2802
The spec does not provide code for validating the `fork_version` field
of `LightClientUpdate`. However, we can use our own logic for additional
validation of that field. The spec's python test suite sets up states
that do not follow the fork schedule (e.g., that use Altair fork version
before Altair fork epoch), which complicates upstreaming this as code.
In practice, the sync committee signs `LightClientUpdate` instances at
the next slot following the block. This is not correctly reflected in
the tests, where it is signed one slot early. This patch updates the
tests to use the correct slot for the computation.
* limit by-root requests to non-finalized blocks
Presently, we keep a mapping from block root to `BlockRef` in memory -
this has simplified reasoning about the dag, but is not sustainable with
the chain growing.
We can distinguish between two cases where by-root access is useful:
* unfinalized blocks - this is where the beacon chain is operating
generally, by validating incoming data as interesting for future fork
choice decisions - bounded by the length of the unfinalized period
* finalized blocks - historical access in the REST API etc - no bounds,
really
In this PR, we limit the by-root block index to the first use case:
finalized chain data can more efficiently be addressed by slot number.
Future work includes:
* limiting the `BlockRef` horizon in general - each instance is 40
bytes+overhead which adds up - this needs further refactoring to deal
with the tail vs state problem
* persisting the finalized slot-to-hash index - this one also keeps
growing unbounded (albeit slowly)
Anyway, this PR easily shaves ~128mb of memory usage at the time of
writing.
* No longer honor `BeaconBlocksByRoot` requests outside of the
non-finalized period - previously, Nimbus would generously return any
block through this libp2p request - per the spec, finalized blocks
should be fetched via `BeaconBlocksByRange` instead.
* return `Opt[BlockRef]` instead of `nil` when blocks can't be found -
this becomes a lot more common now and thus deserves more attention
* `dag.blocks` -> `dag.forkBlocks` - this index only carries unfinalized
blocks from now - `finalizedBlocks` covers the other `BlockRef`
instances
* in backfill, verify that the last backfilled block leads back to
genesis, or panic
* add backfill timings to log
* fix missing check that `BlockRef` block can be fetched with
`getForkedBlock` reliably
* shortcut doppelganger check when feature is not enabled
* in REST/JSON-RPC, fetch blocks without involving `BlockRef`
* fix dag.blocks ref
tersec
zah
Eugene Kabanov
Etan Kissling
Jacek Sieka
Zahary Karadjov