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66eca1a882
## Proposed Changes
This PR has two aims: to speed up attestation packing in the op pool, and to fix bugs in the verification of attester slashings, proposer slashings and voluntary exits. The changes are bundled into a single database schema upgrade (v12).
Attestation packing is sped up by removing several inefficiencies:
- No more recalculation of `attesting_indices` during packing.
- No (unnecessary) examination of the `ParticipationFlags`: a bitfield suffices. See `RewardCache`.
- No re-checking of attestation validity during packing: the `AttestationMap` provides attestations which are "correct by construction" (I have checked this using Hydra).
- No SSZ re-serialization for the clunky `AttestationId` type (it can be removed in a future release).
So far the speed-up seems to be roughly 2-10x, from 500ms down to 50-100ms.
Verification of attester slashings, proposer slashings and voluntary exits is fixed by:
- Tracking the `ForkVersion`s that were used to verify each message inside the `SigVerifiedOp`. This allows us to quickly re-verify that they match the head state's opinion of what the `ForkVersion` should be at the epoch(s) relevant to the message.
- Storing the `SigVerifiedOp` on disk rather than the raw operation. This allows us to continue track the fork versions after a reboot.
This is mostly contained in this commit 52bb1840ae5c4356a8fc3a51e5df23ed65ed2c7f.
## Additional Info
The schema upgrade uses the justified state to re-verify attestations and compute `attesting_indices` for them. It will drop any attestations that fail to verify, by the logic that attestations are most valuable in the few slots after they're observed, and are probably stale and useless by the time a node restarts. Exits and proposer slashings and similarly re-verified to obtain `SigVerifiedOp`s.
This PR contains a runtime killswitch `--paranoid-block-proposal` which opts out of all the optimisations in favour of closely verifying every included message. Although I'm quite sure that the optimisations are correct this flag could be useful in the event of an unforeseen emergency.
Finally, you might notice that the `RewardCache` appears quite useless in its current form because it is only updated on the hot-path immediately before proposal. My hope is that in future we can shift calls to `RewardCache::update` into the background, e.g. while performing the state advance. It is also forward-looking to `tree-states` compatibility, where iterating and indexing `state.{previous,current}_epoch_participation` is expensive and needs to be minimised.
32 lines
1.4 KiB
Rust
32 lines
1.4 KiB
Rust
use lazy_static::lazy_static;
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pub use lighthouse_metrics::*;
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lazy_static! {
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pub static ref BUILD_REWARD_CACHE_TIME: Result<Histogram> = try_create_histogram(
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"op_pool_build_reward_cache_time",
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"Time to build the reward cache before packing attestations"
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);
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pub static ref ATTESTATION_PREV_EPOCH_PACKING_TIME: Result<Histogram> = try_create_histogram(
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"op_pool_attestation_prev_epoch_packing_time",
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"Time to pack previous epoch attestations"
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);
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pub static ref ATTESTATION_CURR_EPOCH_PACKING_TIME: Result<Histogram> = try_create_histogram(
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"op_pool_attestation_curr_epoch_packing_time",
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"Time to pack current epoch attestations"
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);
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pub static ref NUM_PREV_EPOCH_ATTESTATIONS: Result<IntGauge> = try_create_int_gauge(
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"op_pool_prev_epoch_attestations",
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"Number of valid attestations considered for packing from the previous epoch"
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);
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pub static ref NUM_CURR_EPOCH_ATTESTATIONS: Result<IntGauge> = try_create_int_gauge(
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"op_pool_curr_epoch_attestations",
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"Number of valid attestations considered for packing from the current epoch"
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);
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pub static ref MAX_COVER_NON_ZERO_ITEMS: Result<IntGaugeVec> = try_create_int_gauge_vec(
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"op_pool_max_cover_non_zero_items",
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"Number of non-trivial items considered in a max coverage optimisation",
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&["label"]
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);
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}
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