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>
* Support for driving multiple EL nodes from a single Nimbus BN
Full list of changes:
* Eth1Monitor has been renamed to ELManager to match its current
responsibilities better.
* The ELManager is no longer optional in the code (it won't have
a nil value under any circumstances).
* The support for subscribing for headers was removed as it only
worked with WebSockets and contributed significant complexity
while bringing only a very minor advantage.
* The `--web3-url` parameter has been deprecated in favor of a
new `--el` parameter. The new parameter has a reasonable default
value and supports specifying a different JWT for each connection.
Each connection can also be configured with a different set of
responsibilities (e.g. download deposits, validate blocks and/or
produce blocks). On the command-line, these properties can be
configured through URL properties stored in the #anchor part of
the URL. In TOML files, they come with a very natural syntax
(althrough the URL scheme is also supported).
* The previously scattered EL-related state and logic is now moved
to `eth1_monitor.nim` (this module will be renamed to `el_manager.nim`
in a follow-up commit). State is assigned properly either to the
`ELManager` or the to individual `ELConnection` objects where
appropriate.
The ELManager executes all Engine API requests against all attached
EL nodes, in parallel. It compares their results and if there is a
disagreement regarding the validity of a certain payload, this is
detected and the beacon node is protected from publishing a block
with a potential execution layer consensus bug in it.
The BN provides metrics per EL node for the number of successful or
failed requests for each type Engine API requests. If an EL node
goes offline and connectivity is resoted later, we report the
problem and the remedy in edge-triggered fashion.
* More progress towards implementing Deneb block production in the VC
and comparing the value of blocks produced by the EL and the builder
API.
* Adds a Makefile target for the zhejiang testnet
* clean up some Nim 1.2 workarounds
* re-add notes about JS backend
* another proc/noSideEffect -> func
* revert ncli/ncli_common.nim changes; 19969 evidently wasn't backported to 1.6
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
In a future fork, light client data will be extended with execution info
to support more use cases. To anticipate such an upgrade, introduce
`Forky` and `Forked` types, and ready the database schema.
Because the mapping of sync committee periods to fork versions is not
necessarily unique (fork schedule not in sync with period boundaries),
an additional column is added to `period` -> `LightClientUpdate` table.
When the EL/Builder fails to produce an execution payload, we fall back
to an empty `ExecutionPayload`. Even though it contains no transactions
it should refer to the configured fee recipient. This is useful for
privacy reasons (do not reveal the reason for the empty payload) and for
compliance with additional fee recipient rules by staking pools.
