## Proposed Changes
Implement the consensus changes necessary for the upcoming Altair hard fork.
## Additional Info
This is quite a heavy refactor, with pivotal types like the `BeaconState` and `BeaconBlock` changing from structs to enums. This ripples through the whole codebase with field accesses changing to methods, e.g. `state.slot` => `state.slot()`.
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
NA
## Proposed Changes
Add an optimization to perform `per_slot_processing` from the *leading-edge* of block processing to the *trailing-edge*. Ultimately, this allows us to import the block at slot `n` faster because we used the tail-end of slot `n - 1` to perform `per_slot_processing`.
Additionally, add a "block proposer cache" which allows us to cache the block proposer for some epoch. Since we're now doing trailing-edge `per_slot_processing`, we can prime this cache with the values for the next epoch before those blocks arrive (assuming those blocks don't have some weird forking).
There were several ancillary changes required to achieve this:
- Remove the `state_root` field of `BeaconSnapshot`, since there's no need to know it on a `pre_state` and in all other cases we can just read it from `block.state_root()`.
- This caused some "dust" changes of `snapshot.beacon_state_root` to `snapshot.beacon_state_root()`, where the `BeaconSnapshot::beacon_state_root()` func just reads the state root from the block.
- Rename `types::ShuffingId` to `AttestationShufflingId`. I originally did this because I added a `ProposerShufflingId` struct which turned out to be not so useful. I thought this new name was more descriptive so I kept it.
- Address https://github.com/ethereum/eth2.0-specs/pull/2196
- Add a debug log when we get a block with an unknown parent. There was previously no logging around this case.
- Add a function to `BeaconState` to compute all proposers for an epoch without re-computing the active indices for each slot.
## Additional Info
- ~~Blocked on #2173~~
- ~~Blocked on #2179~~ That PR was wrapped into this PR.
- There's potentially some places where we could avoid computing the proposer indices in `per_block_processing` but I haven't done this here. These would be an optimization beyond the issue at hand (improving block propagation times) and I think this PR is already doing enough. We can come back for that later.
## TODO
- [x] Tidy, improve comments.
- [x] ~~Try avoid computing proposer index in `per_block_processing`?~~
## Issue Addressed
NA
## Proposed Changes
- Panic or return error if we overflow `usize` in SSZ decoding/encoding derive macros.
- I claim that the panics can only be triggered by a faulty type definition in lighthouse, they cannot be triggered externally on a validly defined struct.
- Use `Ordering` instead of some `if` statements, as demanded by clippy.
- Remove some old clippy `allow` that seem to no longer be required.
- Add comments to interesting clippy statements that we're going to continue to ignore.
- Create #1713
## Additional Info
NA
- Resolves#1550
- Resolves#824
- Resolves#825
- Resolves#1131
- Resolves#1411
- Resolves#1256
- Resolve#1177
- Includes the `ShufflingId` struct initially defined in #1492. That PR is now closed and the changes are included here, with significant bug fixes.
- Implement the https://github.com/ethereum/eth2.0-APIs in a new `http_api` crate using `warp`. This replaces the `rest_api` crate.
- Add a new `common/eth2` crate which provides a wrapper around `reqwest`, providing the HTTP client that is used by the validator client and for testing. This replaces the `common/remote_beacon_node` crate.
- Create a `http_metrics` crate which is a dedicated server for Prometheus metrics (they are no longer served on the same port as the REST API). We now have flags for `--metrics`, `--metrics-address`, etc.
- Allow the `subnet_id` to be an optional parameter for `VerifiedUnaggregatedAttestation::verify`. This means it does not need to be provided unnecessarily by the validator client.
- Move `fn map_attestation_committee` in `mod beacon_chain::attestation_verification` to a new `fn with_committee_cache` on the `BeaconChain` so the same cache can be used for obtaining validator duties.
- Add some other helpers to `BeaconChain` to assist with common API duties (e.g., `block_root_at_slot`, `head_beacon_block_root`).
- Change the `NaiveAggregationPool` so it can index attestations by `hash_tree_root(attestation.data)`. This is a requirement of the API.
- Add functions to `BeaconChainHarness` to allow it to create slashings and exits.
- Allow for `eth1::Eth1NetworkId` to go to/from a `String`.
- Add functions to the `OperationPool` to allow getting all objects in the pool.
- Add function to `BeaconState` to check if a committee cache is initialized.
- Fix bug where `seconds_per_eth1_block` was not transferring over from `YamlConfig` to `ChainSpec`.
- Add the `deposit_contract_address` to `YamlConfig` and `ChainSpec`. We needed to be able to return it in an API response.
- Change some uses of serde `serialize_with` and `deserialize_with` to a single use of `with` (code quality).
- Impl `Display` and `FromStr` for several BLS fields.
- Check for clock discrepancy when VC polls BN for sync state (with +/- 1 slot tolerance). This is not intended to be comprehensive, it was just easy to do.
- See #1434 for a per-endpoint overview.
- Seeking clarity here: https://github.com/ethereum/eth2.0-APIs/issues/75
- [x] Add docs for prom port to close#1256
- [x] Follow up on this #1177
- [x] ~~Follow up with #1424~~ Will fix in future PR.
- [x] Follow up with #1411
- [x] ~~Follow up with #1260~~ Will fix in future PR.
- [x] Add quotes to all integers.
- [x] Remove `rest_types`
- [x] Address missing beacon block error. (#1629)
- [x] ~~Add tests for lighthouse/peers endpoints~~ Wontfix
- [x] ~~Follow up with validator status proposal~~ Tracked in #1434
- [x] Unify graffiti structs
- [x] ~~Start server when waiting for genesis?~~ Will fix in future PR.
- [x] TODO in http_api tests
- [x] Move lighthouse endpoints off /eth/v1
- [x] Update docs to link to standard
- ~~Blocked on #1586~~
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
- Resolves#1616
## Proposed Changes
If we look at the function which persists fork choice and the canonical head to disk:
1db8daae0c/beacon_node/beacon_chain/src/beacon_chain.rs (L234-L280)
There is a race-condition which might cause the canonical head and fork choice values to be out-of-sync.
I believe this is the cause of #1616. I managed to recreate the issue and produce a database that was unable to sync under the `master` branch but able to sync with this branch.
These new changes solve the issue by ignoring the persisted `canonical_head_block_root` value and instead getting fork choice to generate it. This ensures that the canonical head is in-sync with fork choice.
## Additional Info
This is hotfix method that leaves some crusty code hanging around. Once this PR is merged (to satisfy the v0.2.x users) we should later update and merge #1638 so we can have a clean fix for the v0.3.x versions.
## Issue Addressed
- Resolves#1616
## Proposed Changes
Fixes a bug where we are unable to read the finalized block from fork choice.
## Detail
I had made an assumption that the finalized block always has a parent root of `None`:
e5fc6bab48/consensus/fork_choice/src/fork_choice.rs (L749-L752)
This was a faulty assumption, we don't set parent *roots* to `None`. Instead we *sometimes* set parent *indices* to `None`, depending if this pruning condition is satisfied:
e5fc6bab48/consensus/proto_array/src/proto_array.rs (L229-L232)
The bug manifested itself like this:
1. We attempt to get the finalized block from fork choice
1. We try to check that the block is descendant of the finalized block (note: they're the same block).
1. We expect the parent root to be `None`, but it's actually the parent root of the finalized root.
1. We therefore end up checking if the parent of the finalized root is a descendant of itself. (note: it's an *ancestor* not a *descendant*).
1. We therefore declare that the finalized block is not a descendant of (or eq to) the finalized block. Bad.
## Additional Info
In reflection, I made a poor assumption in the quest to obtain a probably negligible performance gain. The performance gain wasn't worth the risk and we got burnt.
## Issue Addressed
- Resolves#1451
## Proposed Changes
- Restricts the `contains_block` and `contains_block` so they only indicate a block is present if it descends from the finalized root. This helps to ensure that fork choice never points to a block that has been pruned from the database.
- Resolves#1451
- Before importing a block, double-check that its parent is known and a descendant of the finalized root.
- Split a big, monolithic block verification test into smaller tests.
## Additional Notes
I suspect there would be a craftier way to do the `is_descendant_of_finalized` check, but we're a bit tight on time now and we can optimize later if it starts showing in benches.
## TODO
- [x] Tests
