## Issue Addressed
Closes#2526
## Proposed Changes
If the head block fails to decode on start up, do two things:
1. Revert all blocks between the head and the most recent hard fork (to `fork_slot - 1`).
2. Reset fork choice so that it contains the new head, and all blocks back to the new head's finalized checkpoint.
## Additional Info
I tweaked some of the beacon chain test harness stuff in order to make it generic enough to test with a non-zero slot clock on start-up. In the process I consolidated all the various `new_` methods into a single generic one which will hopefully serve all future uses 🤞
## Issue Addressed
Resolves#2524
## Proposed Changes
- Return all known forks in the `/config/fork_schedule`, previously returned only the head of the chain's fork.
- Deleted the `StateId::head` method because it was only previously used in this endpoint.
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Proposed Changes
* Consolidate Tokio versions: everything now uses the latest v1.10.0, no more `tokio-compat`.
* Many semver-compatible changes via `cargo update`. Notably this upgrades from the yanked v0.8.0 version of crossbeam-deque which is present in v1.5.0-rc.0
* Many semver incompatible upgrades via `cargo upgrades` and `cargo upgrade --workspace pkg_name`. Notable ommissions:
- Prometheus, to be handled separately: https://github.com/sigp/lighthouse/issues/2485
- `rand`, `rand_xorshift`: the libsecp256k1 package requires 0.7.x, so we'll stick with that for now
- `ethereum-types` is pinned at 0.11.0 because that's what `web3` is using and it seems nice to have just a single version
## Additional Info
We still have two versions of `libp2p-core` due to `discv5` depending on the v0.29.0 release rather than `master`. AFAIK it should be OK to release in this state (cc @AgeManning )
## Issue Addressed
- Resolves#2502
## Proposed Changes
Adds tree-hash caching (THC 🍁) for `state.inactivity_scores`, as per #2502.
Since the `inactivity_scores` field is introduced during Altair, the cache must be optional (i.e., not present pre-Altair). The mechanism for optional caches was already implemented via the `ParticipationTreeHashCache`, albeit not quite generically enough. To this end, I made the `ParticipationTreeHashCache` more generic and renamed it to `OptionalTreeHashCache`. This made the code a little more verbose around the previous/current epoch participation fields, but overall less verbose when the needs of `inactivity_scores` are considered.
All changes to `ParticipationTreeHashCache` should be *non-substantial*.
## Additional Info
NA
## Proposed Changes
* Implement the validator client and HTTP API changes necessary to support Altair
Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
N/A
## Proposed Changes
- Removing a bunch of unnecessary references
- Updated `Error::VariantError` to `Error::Variant`
- There were additional enum variant lints that I ignored, because I thought our variant names were fine
- removed `MonitoredValidator`'s `pubkey` field, because I couldn't find it used anywhere. It looks like we just use the string version of the pubkey (the `id` field) if there is no index
## Additional Info
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
- Resolves#2169
## Proposed Changes
Adds the `AttesterCache` to allow validators to produce attestations for older slots. Presently, some arbitrary restrictions can force validators to receive an error when attesting to a slot earlier than the present one. This can cause attestation misses when there is excessive load on the validator client or time sync issues between the VC and BN.
## Additional Info
NA
## Proposed Changes
Add the `sync_aggregate` from `BeaconBlock` to the bulk signature verifier for blocks. This necessitates a new signature set constructor for the sync aggregate, which is different from the others due to the use of [`eth2_fast_aggregate_verify`](https://github.com/ethereum/eth2.0-specs/blob/v1.1.0-alpha.7/specs/altair/bls.md#eth2_fast_aggregate_verify) for sync aggregates, per [`process_sync_aggregate`](https://github.com/ethereum/eth2.0-specs/blob/v1.1.0-alpha.7/specs/altair/beacon-chain.md#sync-aggregate-processing). I made the choice to return an optional signature set, with `None` representing the case where the signature is valid on account of being the point at infinity (requires no further checking).
To "dogfood" the changes and prevent duplication, the consensus logic now uses the signature set approach as well whenever it is required to verify signatures (which should only be in testing AFAIK). The EF tests pass with the code as it exists currently, but failed before I adapted the `eth2_fast_aggregate_verify` changes (which is good).
As a result of this change Altair block processing should be a little faster, and importantly, we will no longer accidentally verify signatures when replaying blocks, e.g. when replaying blocks from the database.
## Issue Addressed
NA
## Proposed Changes
This PR addresses two things:
1. Allows the `ValidatorMonitor` to work with Altair states.
1. Optimizes `altair::process_epoch` (see [code](https://github.com/paulhauner/lighthouse/blob/participation-cache/consensus/state_processing/src/per_epoch_processing/altair/participation_cache.rs) for description)
## Breaking Changes
The breaking changes in this PR revolve around one premise:
*After the Altair fork, it's not longer possible (given only a `BeaconState`) to identify if a validator had *any* attestation included during some epoch. The best we can do is see if that validator made the "timely" source/target/head flags.*
Whilst this seems annoying, it's not actually too bad. Finalization is based upon "timely target" attestations, so that's really the most important thing. Although there's *some* value in knowing if a validator had *any* attestation included, it's far more important to know about "timely target" participation, since this is what affects finality and justification.
For simplicity and consistency, I've also removed the ability to determine if *any* attestation was included from metrics and API endpoints. Now, all Altair and non-Altair states will simply report on the head/target attestations.
The following section details where we've removed fields and provides replacement values.
### Breaking Changes: Prometheus Metrics
Some participation metrics have been removed and replaced. Some were removed since they are no longer relevant to Altair (e.g., total attesting balance) and others replaced with gwei values instead of pre-computed values. This provides more flexibility at display-time (e.g., Grafana).
The following metrics were added as replacements:
- `beacon_participation_prev_epoch_head_attesting_gwei_total`
- `beacon_participation_prev_epoch_target_attesting_gwei_total`
- `beacon_participation_prev_epoch_source_attesting_gwei_total`
- `beacon_participation_prev_epoch_active_gwei_total`
The following metrics were removed:
- `beacon_participation_prev_epoch_attester`
- instead use `beacon_participation_prev_epoch_source_attesting_gwei_total / beacon_participation_prev_epoch_active_gwei_total`.
- `beacon_participation_prev_epoch_target_attester`
- instead use `beacon_participation_prev_epoch_target_attesting_gwei_total / beacon_participation_prev_epoch_active_gwei_total`.
- `beacon_participation_prev_epoch_head_attester`
- instead use `beacon_participation_prev_epoch_head_attesting_gwei_total / beacon_participation_prev_epoch_active_gwei_total`.
The `beacon_participation_prev_epoch_attester` endpoint has been removed. Users should instead use the pre-existing `beacon_participation_prev_epoch_target_attester`.
### Breaking Changes: HTTP API
The `/lighthouse/validator_inclusion/{epoch}/{validator_id}` endpoint loses the following fields:
- `current_epoch_attesting_gwei` (use `current_epoch_target_attesting_gwei` instead)
- `previous_epoch_attesting_gwei` (use `previous_epoch_target_attesting_gwei` instead)
The `/lighthouse/validator_inclusion/{epoch}/{validator_id}` endpoint lose the following fields:
- `is_current_epoch_attester` (use `is_current_epoch_target_attester` instead)
- `is_previous_epoch_attester` (use `is_previous_epoch_target_attester` instead)
- `is_active_in_current_epoch` becomes `is_active_unslashed_in_current_epoch`.
- `is_active_in_previous_epoch` becomes `is_active_unslashed_in_previous_epoch`.
## Additional Info
NA
## TODO
- [x] Deal with total balances
- [x] Update validator_inclusion API
- [ ] Ensure `beacon_participation_prev_epoch_target_attester` and `beacon_participation_prev_epoch_head_attester` work before Altair
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Proposed Changes
Update to the latest version of the Altair spec, which includes new tests and a tweak to the target sync aggregators.
## Additional Info
This change is _not_ required for the imminent Altair devnet, and is waiting on the merge of #2321 to unstable.
Co-authored-by: Paul Hauner <paul@paulhauner.com>
## Proposed Changes
Remove the remaining Altair `FIXME`s from consensus land.
1. Implement tree hash caching for the participation lists. This required some light type manipulation, including removing the `TreeHash` bound from `CachedTreeHash` which was purely descriptive.
2. Plumb the proposer index through Altair attestation processing, to avoid calculating it for _every_ attestation (potentially 128ms on large networks). This duplicates some work from #2431, but with the aim of getting it in sooner, particularly for the Altair devnets.
3. Removes two FIXMEs related to `superstruct` and cloning, which are unlikely to be particularly detrimental and will be tracked here instead: https://github.com/sigp/superstruct/issues/5
## Issue Addressed
#635
## Proposed Changes
- Keep attestations that reference a block we have not seen for 30secs before being re processed
- If we do import the block before that time elapses, it is reprocessed in that moment
- The first time it fails, do nothing wrt to gossipsub propagation or peer downscoring. If after being re processed it fails, downscore with a `LowToleranceError` and ignore the message.
## Issue Addressed
NA
## Proposed Changes
Adds a metric to see how many set bits are in the sync aggregate for each beacon block being imported.
## Additional Info
NA
## Proposed Changes
Modify the SHA256 implementation in `eth2_hashing` so that it switches between `ring` and `sha2` to take advantage of [x86_64 SHA extensions](https://en.wikipedia.org/wiki/Intel_SHA_extensions). The extensions are available on modern Intel and AMD CPUs, and seem to provide a considerable speed-up: on my Ryzen 5950X it dropped state tree hashing times by about 30% from 35ms to 25ms (on Prater).
## Additional Info
The extensions became available in the `sha2` crate [last year](https://www.reddit.com/r/rust/comments/hf2vcx/ann_rustcryptos_sha1_and_sha2_now_support/), and are not available in Ring, which uses a [pure Rust implementation of sha2](https://github.com/briansmith/ring/blob/main/src/digest/sha2.rs). Ring is faster on CPUs that lack the extensions so I've implemented a runtime switch to use `sha2` only when the extensions are available. The runtime switching seems to impose a miniscule penalty (see the benchmarks linked below).
## 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
`make lint` failing on rust 1.53.0.
## Proposed Changes
1.53.0 updates
## Additional Info
I haven't figure out why yet, we were now hitting the recursion limit in a few crates. So I had to add `#![recursion_limit = "256"]` in a few places
Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
NA
## Primary Change
When investigating memory usage, I noticed that retrieving a block from an early slot (e.g., slot 900) would cause a sharp increase in the memory footprint (from 400mb to 800mb+) which seemed to be ever-lasting.
After some investigation, I found that the reverse iteration from the head back to that slot was the likely culprit. To counter this, I've switched the `BeaconChain::block_root_at_slot` to use the forwards iterator, instead of the reverse one.
I also noticed that the networking stack is using `BeaconChain::root_at_slot` to check if a peer is relevant (`check_peer_relevance`). Perhaps the steep, seemingly-random-but-consistent increases in memory usage are caused by the use of this function.
Using the forwards iterator with the HTTP API alleviated the sharp increases in memory usage. It also made the response much faster (before it felt like to took 1-2s, now it feels instant).
## Additional Changes
In the process I also noticed that we have two functions for getting block roots:
- `BeaconChain::block_root_at_slot`: returns `None` for a skip slot.
- `BeaconChain::root_at_slot`: returns the previous root for a skip slot.
I unified these two functions into `block_root_at_slot` and added the `WhenSlotSkipped` enum. Now, the caller must be explicit about the skip-slot behaviour when requesting a root.
Additionally, I replaced `vec![]` with `Vec::with_capacity` in `store::chunked_vector::range_query`. I stumbled across this whilst debugging and made this modification to see what effect it would have (not much). It seems like a decent change to keep around, but I'm not concerned either way.
Also, `BeaconChain::get_ancestor_block_root` is unused, so I got rid of it 🗑️.
## Additional Info
I haven't also done the same for state roots here. Whilst it's possible and a good idea, it's more work since the fwds iterators are presently block-roots-specific.
Whilst there's a few places a reverse iteration of state roots could be triggered (e.g., attestation production, HTTP API), they're no where near as common as the `check_peer_relevance` call. As such, I think we should get this PR merged first, then come back for the state root iters. I made an issue here https://github.com/sigp/lighthouse/issues/2377.
## Issue Addressed
The latest version of Rust has new clippy rules & the codebase isn't up to date with them.
## Proposed Changes
Small formatting changes that clippy tells me are functionally equivalent
## Issue Addressed
Closes#2274
## Proposed Changes
* Modify the `YamlConfig` to collect unknown fields into an `extra_fields` map, instead of failing hard.
* Log a debug message if there are extra fields returned to the VC from one of its BNs.
This restores Lighthouse's compatibility with Teku beacon nodes (and therefore Infura)
## Issue Addressed
NA
## Proposed Changes
Whilst hacking on something I noticed that the default implementation of `FixedVector` can violate the length constraint!
E.g., `let v: FixedVector<u8; U4> = <_>::default()` would create a fixed vector with length 0, even though it promises to *always* have length 4! This causes SSZ deserialization to fail and probably other things too.
This isn't a security risk as it can't be triggered externally, however it's a foot gun for LH devs.
## Additional Info
NA
## Issue Addressed
Closes#2052
## Proposed Changes
- Refactor the attester/proposer duties endpoints in the BN
- Performance improvements
- Fixes some potential inconsistencies with the dependent root fields.
- Removes `http_api::beacon_proposer_cache` and just uses the one on the `BeaconChain` instead.
- Move the code for the proposer/attester duties endpoints into separate files, for readability.
- Refactor the `DutiesService` in the VC
- Required to reduce the delay on broadcasting new blocks.
- Gets rid of the `ValidatorDuty` shim struct that came about when we adopted the standard API.
- Separate block/attestation duty tasks so that they don't block each other when one is slow.
- In the VC, use `PublicKeyBytes` to represent validators instead of `PublicKey`. `PublicKey` is a legit crypto object whilst `PublicKeyBytes` is just a byte-array, it's much faster to clone/hash `PublicKeyBytes` and this change has had a significant impact on runtimes.
- Unfortunately this has created lots of dust changes.
- In the BN, store `PublicKeyBytes` in the `beacon_proposer_cache` and allow access to them. The HTTP API always sends `PublicKeyBytes` over the wire and the conversion from `PublicKey` -> `PublickeyBytes` is non-trivial, especially when queries have 100s/1000s of validators (like Pyrmont).
- Add the `state_processing::state_advance` mod which dedups a lot of the "apply `n` skip slots to the state" code.
- This also fixes a bug with some functions which were failing to include a state root as per [this comment](072695284f/consensus/state_processing/src/state_advance.rs (L69-L74)). I couldn't find any instance of this bug that resulted in anything more severe than keying a shuffling cache by the wrong block root.
- Swap the VC block service to use `mpsc` from `tokio` instead of `futures`. This is consistent with the rest of the code base.
~~This PR *reduces* the size of the codebase 🎉~~ It *used* to reduce the size of the code base before I added more comments.
## Observations on Prymont
- Proposer duties times down from peaks of 450ms to consistent <1ms.
- Current epoch attester duties times down from >1s peaks to a consistent 20-30ms.
- Block production down from +600ms to 100-200ms.
## Additional Info
- ~~Blocked on #2241~~
- ~~Blocked on #2234~~
## TODO
- [x] ~~Refactor this into some smaller PRs?~~ Leaving this as-is for now.
- [x] Address `per_slot_processing` roots.
- [x] Investigate slow next epoch times. Not getting added to cache on block processing?
- [x] Consider [this](072695284f/beacon_node/store/src/hot_cold_store.rs (L811-L812)) in the scenario of replacing the state roots
Co-authored-by: pawan <pawandhananjay@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
Resolves#1944
## Proposed Changes
Adds a "graffiti" key to the `validator_definitions.yml`. Setting the key will override anything passed through the validator `--graffiti` flag.
Returns an error if the value for the graffiti key is > 32 bytes instead of silently truncating.
## Issue Addressed
Closes#1621
## Proposed Changes
Use the `disallowed_method` lint to ban uses of `Iterator::{sum,product}` from `types` and `state_processing`.
## Additional Info
The lint is turned off in the tree hash caching code, as it is performance sensitive and overflowy arithmetic is already allowed there.
## 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
Rust 1.50 has landed 🎉
The shiny new `clippy` peers down upon us mere mortals with disgust. Brutish peasants wrapping our `usize`s in superfluous `Option`s... tsk tsk.
I've performed the goat sacrifice and corrected our evil ways in this PR. Tonight we shall pray that Github Actions bestows the almighty green tick upon us.
## Additional Info
NA
Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
resolves#2129resolves#2099
addresses some of #1712
unblocks #2076
unblocks #2153
## Proposed Changes
- Updates all the dependencies mentioned in #2129, except for web3. They haven't merged their tokio 1.0 update because they are waiting on some dependencies of their own. Since we only use web3 in tests, I think updating it in a separate issue is fine. If they are able to merge soon though, I can update in this PR.
- Updates `tokio_util` to 0.6.2 and `bytes` to 1.0.1.
- We haven't made a discv5 release since merging tokio 1.0 updates so I'm using a commit rather than release atm. **Edit:** I think we should merge an update of `tokio_util` to 0.6.2 into discv5 before this release because it has panic fixes in `DelayQueue` --> PR in discv5: https://github.com/sigp/discv5/pull/58
## Additional Info
tokio 1.0 changes that required some changes in lighthouse:
- `interval.next().await.is_some()` -> `interval.tick().await`
- `sleep` future is now `!Unpin` -> https://github.com/tokio-rs/tokio/issues/3028
- `try_recv` has been temporarily removed from `mpsc` -> https://github.com/tokio-rs/tokio/issues/3350
- stream features have moved to `tokio-stream` and `broadcast::Receiver::into_stream()` has been temporarily removed -> `https://github.com/tokio-rs/tokio/issues/2870
- I've copied over the `BroadcastStream` wrapper from this PR, but can update to use `tokio-stream` once it's merged https://github.com/tokio-rs/tokio/pull/3384
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
NA
## Proposed Changes
Reduces allocations by initializing the `pubkeys` vec to its final size. I doubt this will make a substantial difference, but it's nice to do it this way.
Seeing as `indexed_attestation.attesting_indices` has a [fixed length](e4b62139d7/consensus/types/src/indexed_attestation.rs (L22)), there's no real risk of a memory blow-up by pre-allocating the size of the `Vec`.
## Additional Info
NA
## Issue Addressed
- Resolves#2064
## Proposed Changes
Adds a `ValidatorMonitor` struct which provides additional logging and Grafana metrics for specific validators.
Use `lighthouse bn --validator-monitor` to automatically enable monitoring for any validator that hits the [subnet subscription](https://ethereum.github.io/eth2.0-APIs/#/Validator/prepareBeaconCommitteeSubnet) HTTP API endpoint.
Also, use `lighthouse bn --validator-monitor-pubkeys` to supply a list of validators which will always be monitored.
See the new docs included in this PR for more info.
## TODO
- [x] Track validator balance, `slashed` status, etc.
- [x] ~~Register slashings in current epoch, not offense epoch~~
- [ ] Publish Grafana dashboard, update TODO link in docs
- [x] ~~#2130 is merged into this branch, resolve that~~
## Issue Addressed
NA
## Proposed Changes
Copied from #2083, changes the config milliseconds_per_slot to seconds_per_slot to avoid errors when slot duration is not a multiple of a second. To avoid deserializing old serialized data (with milliseconds instead of seconds) the Serialize and Deserialize derive got removed from the Spec struct (isn't currently used anyway).
This PR replaces #2083 for the purpose of fixing a merge conflict without requiring the input of @blacktemplar.
## Additional Info
NA
Co-authored-by: blacktemplar <blacktemplar@a1.net>
## Issue Addressed
NA
## Proposed Changes
As discussed with @protolambda, add an additional loop inside proto_array to ensure weights are coherent.
## Additional Info
NA
## Issue Addressed
`Epoch::end_slot()` returns incorrect value when the epoch is the last epoch which can be represented by u64.
```rust
let slots_per_epoch = 32;
// The last epoch which can be represented by u64.
let epoch = Epoch::new(u64::max_value() / slots_per_epoch);
println!("{}", epoch.end_slot(slots_per_epoch));
// Slot(18446744073709551614)
// -> correctly, the result should be `Slot(18446744073709551615)`.
```
## Issue Addressed
`test_dht_persistence` failing
## Proposed Changes
Bind `NetworkService::start` to an underscore prefixed variable rather than `_`. `_` was causing it to be dropped immediately
This was failing 5/100 times before this update, but I haven't been able to get it to fail after updating it
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
`cargo audit` is failing because of a potential for an overflow in the version of `smallvec` we're using
## Proposed Changes
Update to the latest version of `smallvec`, which has the fix
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Proposed Changes
This quiets the slasher logs when ingesting slashings that are already known. Previously we would log an `ERRO` when a slashing was rediscovered locally but had already been submitted on-chain. This is to be expected from time to time, as different users' slashers will run at different times, and it's likely that slashings will make it on-chain before all users have detected them locally.
## Issue Addressed
NA
## Proposed Changes
Updates out of date dependencies.
## Additional Info
See also https://github.com/sigp/lighthouse/issues/1712 for a list of dependencies that are still out of date and the resasons.
This is an implementation of a slasher that lives inside the BN and can be enabled via `lighthouse bn --slasher`.
Features included in this PR:
- [x] Detection of attester slashing conditions (double votes, surrounds existing, surrounded by existing)
- [x] Integration into Lighthouse's attestation verification flow
- [x] Detection of proposer slashing conditions
- [x] Extraction of attestations from blocks as they are verified
- [x] Compression of chunks
- [x] Configurable history length
- [x] Pruning of old attestations and blocks
- [x] More tests
Future work:
* Focus on a slice of history separate from the most recent N epochs (e.g. epochs `current - K` to `current - M`)
* Run out-of-process
* Ingest attestations from the chain without a resync
Design notes are here https://hackmd.io/@sproul/HJSEklmPL
## Issue Addressed
Resolves#1333
## Proposed Changes
- Remove `deposit_signature_set()` function
- Prevent deposits from being in `SignatureSets`
- User `Signature.verify()` to verify deposit signatures rather than a signature set which uses `fast_aggregate_verify()`
## Additional Info
n/a
## Issue Addressed
NA
## Proposed Changes
Removes most of the temporary string initializations in network metrics and replaces them by directly using `&str`. This further improves on PR https://github.com/sigp/lighthouse/pull/1895.
For the subnet id handling the current approach uses a build script to create a static map. This has the disadvantage that the build script hardcodes the number of subnets. If we want to use more than 64 subnets we need to adjust this in the build script.
## Additional Info
We still have some string initializations for the enum `PeerKind`. To also replace that by `&str` I created a PR in the libp2p dependency: https://github.com/sigp/rust-libp2p/pull/91. Either we wait with merging until this dependency PR is merged (and all conflicts with the newest libp2p version are resolved) or we just merge as is and I will create another PR when the dependency is ready.
## Issue Addressed
NA
## Proposed Changes
Avoids lots of grow allocations when decoding a `VariableList` of fixed-length items. This is the function used for decoding the `state.validators` list.
## Additional Info
NA
