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
When EL `newPayload` is slow (e.g., Raspberry Pi with Besu), the epoch
and shuffling caches tend to fill up with multiple copies per epoch when
processing gossip and performing validator duties close to wall slot.
The old strategy of evicting oldest epoch led to the same item being
evicted over and over, leading to blocking of over 5 minutes in extreme
cases where alternate epochs/shuffling got loaded repeatedly.
Changing the cache eviction strategy to least-recently-used seems to
improve the situation drastically. A simple implementation was selected
based on single linked-list without a hashtable.
When backfilling LC updates (`--light-client-data-import-mode=full`),
the highest participation update is computed without ensuring that the
finalized header is in the same period. Updates sharing same period for
both finalized and attested headers should be preferred.
Fixes a bug leading to suboptimal update selection.
* avoid database race-condition inconsistency after fcU `INVALID` then crash
* ensure head doesn't fall behind finalized; add more tests for head movement/reloading DAG
When the BN's head is reorged while shut down, reloading the BN will not
assign `BlockRef` to alternate branches. However, blocks from other
branches are still present in the database, leading to their descendants
incorrectly marked as `UnviableFork`. By restricting the check to blocks
that have been finalized, they should be reported as `MissingParent`
instead, eventually re-assigning a `BlockRef` to them.
Since these files may have been created in a previous run or manually,
we want to keep loading them even on nodes that don't enable the
keystore API (for example static setups)
Other changes:
* log keystore loading progressively (#3699)
* print initial fee recipient when loading validators
* log dynamic fee recipient updates
* more efficient forkchoiceUpdated usage
* await rather than asyncSpawn; ensure head update before dag.updateHead
* use action tracker rather than attached validators to check for next slot proposal; use wall slot + 1 rather than state slot + 1 to correctly check when missing blocks
* re-add two-fcU case for when newPayload not VALID
* check dynamicFeeRecipientsStore for potential proposal
* remove duplicate checks for whether next proposer
When the BN-embedded LC makes sync progress, pass the corresponding
execution block hash to the EL via `engine_forkchoiceUpdatedV1`.
This allows the EL to sync to wall slot while the chain DAG is behind.
Renamed `--light-client` to `--sync-light-client` for clarity, and
`--light-client-trusted-block-root` to `--trusted-block-root` for
consistency with `nimbus_light_client`.
Note that this does not work well in practice at this time:
- Geth sticks to the optimistic sync:
"Ignoring payload while snap syncing" (when passing the LC head)
"Forkchoice requested unknown head" (when updating to LC head)
- Nethermind syncs to LC head but does not report ancestors as VALID,
so the main forward sync is still stuck in optimistic mode:
"Pre-pivot block, ignored and returned Syncing"
To aid EL client teams in fixing those issues, having this available
as a hidden option is still useful.
The optimistic sync spec was updated since the LC based optsync module
was introduced. It is no longer necessary to wait for the justified
checkpoint to have execution enabled; instead, any block is okay to be
optimistically imported to the EL client, as long as its parent block
has execution enabled. Complex syncing logic has been removed, and the
LC optsync module will now follow gossip directly, reducing the latency
when using this module. Note that because this is now based on gossip
instead of using sync manager / request manager, that individual blocks
may be missed. However, EL clients should recover from this by fetching
missing blocks themselves.
* Harden block proposal against expired slashings/exits
When a message is signed in a phase0 domain, it can no longer be
validated under bellatrix due to the correct fork no longer being
available in the `BeaconState`.
To ensure that all slashing/exits are still valid, in this PR we re-run
the checks in the state that we're proposing for, thus hardening against
both signatures and other changes in the state that might have
invalidated the message.
* fix same message added multiple times
in case of attestation slashing of multiple validators in one go
Aligns the default retention policy for LC data with the one for blocks.
Minimum spec requirement for both blocks and LC data is ~5 months.
Additional use cases are better supported by retaining data for longer.
In order to avoid full replays when validating attestations hailing from
untaken forks, it's better to keep shufflings separate from `EpochRef`
and perform a lookahead on the shuffling when processing the block that
determines them.
This also helps performance in the case where REST clients are trying to
perform lookahead on attestation duties and decreases memory usage by
sharing shufflings between EpochRef instances of the same dependent
root.
When there is heavy forking, proposals may get missed due to including
attestations from different forks that later fail verification.
Checking attestation signatures when building blocks should fix this.
Adds the `--web3-url` launch argument to `nimbus_light_client` to enable
driving the EL with the optimistic head obtained from LC sync protocol.
This will keep issuing `newPayload` / `forkChoiceUpdated` requests for
new blocks, marking them as optimistic. `ZERO_HASH` is reported as the
finalized block for now.
Whether new blocks/attestations/etc are produced internally or received
via REST, their journey through the node is the same - to ensure that
they get the same treatment (logging, metrics, processing), this PR
moves the routing to a dedicated module and fixes several small
differences that existed before.
* `xxxValidator` -> `processMessageName` - the processor also was adding
messages to pools, so we want the name to reflect that action
* add missing "sent" metrics for some messages
* document ignore policy better - already-seen messages are not actaully
rebroadcast by libp2p
* skip redundant signature checks for internal validators consistently
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.
* merge LC db into main BN db
To treat derived LC data similar to derived state caches, merge it into
the main beacon node DB.
* shorten table names, group with lc prefix
* optimistic sync
* flag that initially loaded blocks from database might need execution block root filled in
* return optimistic status in REST calls
* refactor blockslot pruning
* ensure beacon_blocks_by_{root,range} do not provide optimistic blocks
* handle forkchoice head being pre-merge with block being postmerge
* re-enable blocking head updates on validator duties
* fix is_optimistic_candidate_block per spec; don't crash with nil future
* fix is_optimistic_candidate_block per spec; don't crash with nil future
* mark blocks sans execution payloads valid during head update
* persist LC data across restarts
With the Altair spec `LightClientUpdate` structure taking its final form
it is finally possible to persist LC data across restarts without having
to worry about data migration due to spec changes. A separate `lcdataV1`
database is created in the `caches` subdirectory to hold known LC data.
A full database with default settings (129 periods) uses <15 MB disk.
* extend LC data DB rationale
* wording
* add `isSupportedBySQLite` helper and explicit return
* remove redundant `return`
Separate LC initialization options from the main ChainDAGRef options to
allow ChainDAGRef to treat them as opaque and reduce risk for conflicts
when extending those options in the future.
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.
Adds a `--light-client-data-max-periods` option to override the number
of sync committee periods to retain light client data.
Raising it above the default enables archive nodes to serve full data.
Lowering below the default speeds up import times (still no persistence)
This updates `nim-ssz-serialization` to
`3db6cc0f282708aca6c290914488edd832971d61`.
Notable changes:
- Use `uint64` for `GeneralizedIndex`
- Add support for building merkle multiproofs
Combines the LC data configuration options (serve / importMode), the
callbacks (finality / optimistic LC update) as well as the cache storing
light client data, into a new `LightClientDataStore` structure.
Also moves the structure into a light client specific file.
* Initial commit
* Make `events` API spec compliant.
* Add `Eth-Consensus-Version` in responses.
* Bump chronos to get redirect with headers working.
* Add `is_optimistic` field and handling to syncing RestSyncInfo.
If database access errors are encountered while proccessing LC data,
track the section which was accessed without errors so that the rest
may be attempted to be re-indexed later.
The initial sync committee period follows a different finality rule than
the other ones. Instead of next sync committee finalizing as soon as the
`finalizedHead.slot >= period.start_slot` have to use Altair start slot.
For consistency with other options, use a common prefix for light client
data configuration options.
* `--serve-light-client-data` --> `--light-client-data-serve`
* `--import-light-client-data` --> `--light-client-data-import-mode`
No deprecation of the old identifiers as they were only sparingly used
and all usage can be easily updated without interferance.
When launched with `--light-client-enable` the latest blocks are fetched
and optimistic candidate blocks are passed to a callback (log for now).
This helps accelerate syncing in the future (optimistic sync).
Adds a `LightClient` instance to the beacon node as preparation to
accelerate syncing in the future (optimistic sync).
- `--light-client-enable` turns on the feature
- `--light-client-trusted-block-root` configures block to start from
If no block root is configured, light client tracks DAG `finalizedHead`.
Introduces a new library for syncing using libp2p based light client
sync protocol, and adds a new `nimbus_light_client` executable that uses
this library for syncing. The new executable emits log messages when
new beacon block headers are received, and is integrated into testing.
* SSZ `[]` -> `mitem`
* `[]` -> `item`
immutable access via mutable instance cannot rely on template
overloading, and `[]` cannot be a `func` because of special seq handling
in compiler.
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
Other changes:
* logtrace can now verify sync committee messages and contributions
* Many unnecessary use of pairs() have been removed for consistency
* Map 40x BN response codes to BeaconNodeStatus.Incompatible in the VC
* era file verification
Implement and document era file verification
* era file states now come with block applied for easier verification
* clarify conflicting version handling
* document verification requirements
* remove count from name, use start-era, end-root to discover range
* remove obsolete todo
* abstract out block root loading
Some upstream repos still need fixes, but this gets us close enough that
style hints can be enabled by default.
In general, "canonical" spellings are preferred even if they violate
nep-1 - this applies in particular to spec-related stuff like
`genesis_validators_root` which appears throughout the codebase.
`.era` files and Req/Resp protocols use framed formats - aligning the
database with these makes for less recompression work overall as gossip
is sent only once while req/resp repeats (potentially) - this also
allows efficient pruning-to-era where snappy-recompression is the major
cycle thief.
* harden validator API against pre-finalized slot requests
* check `syncHorizon` when responding to validator api requests too far
from `head`
* limit state-id based requests to one epoch ahead of `head`
* put historic data bounds on block/attestation/etc validator production API, preventing them from being used with already-finalized slots
* add validator block smoke tests
* make rest test create a new genesis with the tests running roughly in
the first epoch to allow testing a few more boundary conditions
* era: load blocks and states
Era files contain finalized history and can be thought of as an
alternative source for block and state data that allows clients to avoid
syncing this information from the P2P network - the P2P network is then
used to "top up" the client with the most recent data. They can be
freely shared in the community via whatever means (http, torrent, etc)
and serve as a permanent cold store of consensus data (and, after the
merge, execution data) for history buffs and bean counters alike.
This PR gently introduces support for loading blocks and states in two
cases: block requests from rest/p2p and frontfilling when doing
checkpoint sync.
The era files are used as a secondary source if the information is not
found in the database - compared to the database, there are a few key
differences:
* the database stores the block indexed by block root while the era file
indexes by slot - the former is used only in rest, while the latter is
used both by p2p and rest.
* when loading blocks from era files, the root is no longer trivially
available - if it is needed, it must either be computed (slow) or cached
(messy) - the good news is that for p2p requests, it is not needed
* in era files, "framed" snappy encoding is used while in the database
we store unframed snappy - for p2p2 requests, the latter requires
recompression while the former could avoid it
* front-filling is the process of using era files to replace backfilling
- in theory this front-filling could happen from any block and
front-fills with gaps could also be entertained, but our backfilling
algorithm cannot take advantage of this because there's no (simple) way
to tell it to "skip" a range.
* front-filling, as implemented, is a bit slow (10s to load mainnet): we
load the full BeaconState for every era to grab the roots of the blocks
- it would be better to partially load the state - as such, it would
also be good to be able to partially decompress snappy blobs
* lookups from REST via root are served by first looking up a block
summary in the database, then using the slot to load the block data from
the era file - however, there needs to be an option to create the
summary table from era files to fully support historical queries
To test this, `ncli_db` has an era file exporter: the files it creates
should be placed in an `era` folder next to `db` in the data directory.
What's interesting in particular about this setup is that `db` remains
as the source of truth for security purposes - it stores the latest
synced head root which in turn determines where a node "starts" its
consensus participation - the era directory however can be freely shared
between nodes / people without any (significant) security implications,
assuming the era files are consistent / not broken.
There's lots of future improvements to be had:
* we can drop the in-memory `BlockRef` index almost entirely - at this
point, resident memory usage of Nimbus should drop to a cool 500-600 mb
* we could serve era files via REST trivially: this would drop backfill
times to whatever time it takes to download the files - unlike the
current implementation that downloads block by block, downloading an era
at a time almost entirely cuts out request overhead
* we can "reasonably" recreate detailed state history from almost any
point in time, turning an O(slot) process into O(1) effectively - we'll
still need caches and indices to do this with sufficient efficiency for
the rest api, but at least it cuts the whole process down to minutes
instead of hours, for arbitrary points in time
* CI: ignore failures with Nim-1.6 (temporary)
* test fixes
Co-authored-by: Ștefan Talpalaru <stefantalpalaru@yahoo.com>
Gracefully handles the new failure modes recently introduced to the DAG
as part of https://github.com/status-im/nimbus-eth2/pull/3513
Data that is deemed to exist but fails to load leads to an error log to
avoid suppressing logic errors accidentally. In `verifyFinalization`
mode, the assertions remain active.
When eliminating orphaned forks, light client data about blocks was also
deleted when the orphaned fork was referring to a state several slots
after the block. Linking light client data pruning with block deletion
instead of state deletion fixes this problem. Light client data always
refers to blocks and their immediate post-state.
ref loop would stop one block early in this case - trying to load
everything in one loop ends up being pretty confusing..
* simplify finalizedBlocks topup by splitting it from the head loop /
query
When doing checkpoint sync, collecting light client data of known blocks
and states incorrectly assumes that `finalized_checkpoint` information
is also known. Hardens collection to only collect finalized checkpoint
data after `dag.computeEarliestLightClientSlot`.
Witout this, we end up with a massive .wal file that needs to be
checkpointed on first startup (which takes a few minutes) - it's much
more efficient to do smaller checkpoints, it turns out.
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 :)
The spec implicitly talks about the slot of a block in several places,
and keeping it readily available is useful in a number of context -
might as well put this implicitly refereneced helper in the spec code
directly
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.
* fewer deps on `BlockRef` traversal in anticipation of pruning
* allows identifying EpochRef:s by their shuffling as a first step of
* tighten error handling around missing blocks
using the zero hash for signalling "missing block" is fragile and easy
to miss - with checkpoint sync now, and pruning in the future, missing
blocks become "normal".
Light clients require full nodes to serve additional data so that they
can stay in sync with the network. This patch adds a new launch option
`--import-light-client-data` to configure what data to make available.
For now, data is only kept in memory; it is not persisted at this time.
Note that data is only locally collected, a separate patch is needed to
actually make it availble over the network. `--serve-light-client-data`
will be used for serving data, but is not functional yet outside tests.
When performing trusted node sync, historical access is limited to
states after the checkpoint.
Reindexing restores full historical access by replaying historical
blocks against the state and storing snapshots in the database.
The process can be initiated or resumed at any point in time.
`BlockId` is a type that bundles a block root with its slot number.
The type can be useful as key in tables that deal with non-finalized
blocks (not uniquely identified by slot) and also support pruning
(drop data about older blocks by slot). Instead of creating a custom
type for those use cases, this patch suggests implementing `hash` for
`BlockId` to re-use the existing type.
Can't apply a phase0 block to a later phase state and vice versa.
Since instantiation has been a topic, pre/post c file size:
```
424K @mspec@sstate_transition.nim.c
892K @mspec@sstate_transition_block.nim.c
```
```
288K @mspec@sstate_transition.nim.c
880K @mspec@sstate_transition_block.nim.c
```
This PR names and documents the concept of the archive: a range of slots
for which we have degraded functionality in terms of historical access -
in particular:
* we don't support rewinding to states in this range
* we don't keep an in-memory representation of the block dag
The archive de-facto exists in a trusted-node-synced node, but this PR
gives it a name and drops the in-memory digest index.
In order to satisfy `GetBlocksByRange` requests, we ensure that we have
blocks for the entire archive period via backfill. Future versions may
relax this further, adding a "pre-archive" period that is fully pruned.
During by-slot searches in the archive (both for libp2p and rest
requests), an extra database lookup is used to covert the given `slot`
to a `root` - future versions will avoid this using era files which
natively are indexed by `slot`. That said, the lookup is quite
fast compared to the actual block loading given how trivial the table
is - it's hard to measure, even.
A collateral benefit of this PR is that checkpoint-synced nodes will see
100-200MB memory usage savings, thanks to the dropped in-memory cache -
future pruning work will bring this benefit to full nodes as well.
* document chaindag storage architecture and assumptions
* look up parent using block id instead of full block in clearance
(future-proofing the code against a future in which blocks come from era
files)
* simplify finalized block init, always writing the backfill portion to
db at startup (to ensure lookups work as expected)
* preallocate some extra memory for finalized blocks, to avoid immediate
realloc
https://github.com/ethereum/consensus-specs/pull/2225 removed an ignore
rule that would filter out duplicate aggregates from gossip publishing -
however, this causes increased bandwidth and CPU usage as discussed in
https://github.com/ethereum/consensus-specs/issues/2183 - the intent is
to revert the removal and reinstate the rule.
This PR implements ignore filtering which cuts down on CPU usage (fewer
aggregates to validate) and bandwidth usage (less fanout of duplicates)
- as #2225 points out, this may lead to a small increase in IHAVE
messages.
Streamline lookup with Forky and BeaconBlockFork (then we can do the
same for era)
We use type to avoid conditionals, as fork is often already known at a
"higher" level.
* load blockid before loading block by root - this is needed to map root
to slot and will eventually be done via block summary table for "old"
blocks
Co-authored-by: tersec <tersec@users.noreply.github.com>
* clean up / document init
* drop `immutable_validators` data (pre-altair)
* document versions where data is first added
* avoid needlessly loading genesis block data on startup
* add a few more internal database consistency checks
* remove duplicate state root lookup on state load
* comment
When node is restarted before backfill has started but after some blocks
have finalized with forward sync, we would not start the backfill.
* also clean up one last `SomeSome`
tersec
Jacek Sieka
Etan Kissling
zah
Miran
Eugene Kabanov
zah