When using checkpoint sync, only checkpoint state is available, block is
not downloaded and backfilled later.
`dag.backfill` tracks latest filled `slot`, and latest `parent_root` for
which no block has been synced yet.
In checkpoint sync, this assumption is broken, because there, the start
`dag.backfill.slot` is set based on checkpoint state slot, and the block
is also not available.
However, sync manager in backward mode also requests `dag.backfill.slot`
and `block_clearance` then backfills the checkpoint block once it is
synced. But, there is no guarantee that a peer ever sends us that block.
They could send us all parent blocks and solely omit the checkpoint
block itself. In that situation, we would accept the parent blocks and
advance `dag.backfill`, and subsequently never request the checkpoint
block again, resulting in gap inside blocks DB that is never filled.
To mitigate that, the assumption is restored that `dag.backfill.slot`
is the latest filled `slot`, and `dag.backfill.parent_root` is the next
block that needs to be synced. By setting `slot` to `tail.slot + 1` and
`parent_root` to `tail.root`, we put a fake summary into `dag.backfill`
so that `block_clearance` only proceeds once checkpoint block exists.
After checkpoint sync, historical block IDs cannot yet be queried.
However, they are needed to compute dependent roots of `ShufflingRef`.
To allow lookup, enable `getBlockIdAtSlot` to answer from compatible
states in memory; as long as they descend from the finalized checkpoint
and the requested slot is sufficiently recent, `block_roots` contains
everything to recover `BlockSlotId` up to `SLOTS_PER_HISTORICAL_ROOT`.
This is similar to how `attester_dependent_root` etc. are computed.
This accelerates the first couple minutes of checkpoint sync on Mainnet,
especially the time until finality advances past the synced checkpoint.
When the BN exits after writing new `head` to database, but before
completing the `updateFinalizedBlocks` call, the database is slightly
inconsistent due to the partial write. We currently fail to start up
after that. Fix that by catching up on partial `updateFinalizedBlocks`
tasks on start up, and add a test for this edge case.
Simplify best `LightClientUpdate` collection by tracking only canonical
data instead of tracking the best update across all branches within the
sync committee period.
- https://github.com/ethereum/consensus-specs/pull/3553
* ShufflingRef approach to next-epoch validator duty calculation/prediction
* refactor action_tracker.updateActions to take ShufflingRef + beacon_proposers; refactor maybeUpdateActionTrackerNextEpoch to be separate and reused function; add actual fallback logic
* document one possible set of conditions
* check epoch participation flags and inactivity scores to ensure no penalties and MAX_EFFECTIVE_BALANCE to ensure rewards don't matter
* correctly (un)shuffle each proposer index
* remove debugging assertion
For symmetry with `forkyState` when using `withState`, and to avoid
problems with shadowing of `blck` when using `withBlck` in `template`,
also rename the injected `blck` to `forkyBlck`.
- https://github.com/nim-lang/Nim/issues/22698
Split up the `ShufflingRef` acceleration logic into generically usable
parts and attester shuffling specific parts. The generic parts could be
used to accelerate other purposes, e.g., REST `/states/xxx/randao` API.
To enable additional use cases, e.g., `/states/###/randao` beacon API,
`ShufflingRef` acceleration logic needs to be able to operate on parts
of the DAG that do not have `BlockRef`. Changing `commonAncestor` to
act on `BlockId` instead of `BlockRef` is a step toward that and also
simplifies the logic some more.
Post-merge blocks contain all information to directly obtain RANDAO
without having to load any additional info. Take advantage of that to
further accelerate `ShufflingRef` computation. Note that it is still
necessary to verify that `blck` / `state` share a sufficiently recent
ancestor for the purpose of computing attester shufflings.
- new: 243.71s, 239.67s, 237.32s, 238.36s, 239.57s
- old: 251.33s, 234.29s, 249.28s, 237.03s, 236.78s
Current RANDAO recovery logic is quite complex as it optimizes for the
minimum amount of database reads. Loading blocks isn't the bottleneck
though, so rather make the implementation more concise by avoiding the
complex strategy planning step. Note that this also prepares for an even
faster implementation for post-merge blocks in the future that extracts
RANDAO from `ExecutionPayload` directly if available, so even in cases
where efficiency is slightly lower, only historical data is affected.
`time nim c -r tests/test_blockchain_dag` (cached binary):
- new: 145.45s, 133.59s, 144.65s, 127.69s, 136.14s
- old: 149.15s, 150.84s, 135.77s, 137.49s, 133.89s
* early exit `commonAncestor` when comparing with `finalizedHead`
As all `BlockRef` lead to `finalizedHead` (`parent == nil`),
can shortcut in that situation and immediately return `finalizedHead`
if passed as one of the arguments.
* typo in comment
* add test from #5152
Co-authored-by: tersec <tersec@users.noreply.github.com>
* add note about test complexity
* regenerate test summary
---------
Co-authored-by: tersec <tersec@users.noreply.github.com>
These tables can't be deleted from (read-only) and would be too slow to
delete from anyway due to the inefficient storage format in use.
* slow down startup clearing too
* remove unused del function
* replace optimisticRoots table with field in BlockRef
* copyright year
* mark finalized blocks as verified on load
* Update beacon_chain/consensus_object_pools/block_dag.nim
Co-authored-by: Etan Kissling <etan@status.im>
* expand non-optimistic block checking to all pre-merge blocks; refactor markBlockVerified to use BlockRef rather than block root and remove superfluous caller in newPayload path replaced by addResolvedHeadBlock BlockRef construction
* don't treat finalized block specially; VALID status is sticky
---------
Co-authored-by: Etan Kissling <etan@status.im>
When an uncached `ShufflingRef` is requested, we currently replay state
which can take several seconds. Acceleration is possible by:
1. Start from any state with locked-in `get_active_validator_indices`.
Any blocks / slots applied to such a state can only affect that
result for future epochs, so are viable for querying target epoch.
`compute_activation_exit_epoch(state.slot.epoch) > target.epoch`
2. Determine highest common ancestor among `state` and `target.blck`.
At the ancestor slot, same rules re `get_active_validator_indices`.
`compute_activation_exit_epoch(ancestorSlot.epoch) > target.epoch`
3. We now have a `state` that shares history with `target.blck` up
through a common ancestor slot. Any blocks / slots that the `state`
contains, which are not part of the `target.blck` history, affect
`get_active_validator_indices` at epochs _after_ `target.epoch`.
4. Select `state.randao_mixes[N]` that is closest to common ancestor.
Either direction is fine (above / below ancestor).
5. From that RANDAO mix, mix in / out all RANDAO reveals from blocks
in-between. This is just an XOR operation, so fully reversible.
`mix = mix xor SHA256(blck.message.body.randao_reveal)`
6. Compute the attester dependent slot from `target.epoch`.
`if epoch >= 2: (target.epoch - 1).start_slot - 1 else: GENESIS_SLOT`
7. Trace back from `target.blck` to the attester dependent slot.
We now have the destination for which we want to obtain RANDAO.
8. Mix in all RANDAO reveals from blocks up through the `dependentBlck`.
Same method, no special handling necessary for epoch transitions.
9. Combine `get_active_validator_indices` from `state` at `target.epoch`
with the recovered RANDAO value at `dependentBlck` to obtain the
requested shuffling, and construct the `ShufflingRef` without replay.
* more tests and simplify logic
* test with different number of deposits per branch
* Update beacon_chain/consensus_object_pools/blockchain_dag.nim
Co-authored-by: Jacek Sieka <jacek@status.im>
* `commonAncestor` tests
* lint
---------
Co-authored-by: Jacek Sieka <jacek@status.im>
* Incremental pruning
When turning on pruning the first time the current pruning algorithm
will prune the full database at startup. This delays restart
unnecessarily, since all of the pruned space is not needed at once.
This PR introduces incremental pruning such that we will never prune
more than 32 blocks or the sync speed, whichever is higher.
This mode is expected to become default in a follow-up release.
Etan Kissling
tersec
Jacek Sieka
Eugene Kabanov