## Overview
This rather extensive PR achieves two primary goals:
1. Uses the finalized/justified checkpoints of fork choice (FC), rather than that of the head state.
2. Refactors fork choice, block production and block processing to `async` functions.
Additionally, it achieves:
- Concurrent forkchoice updates to the EL and cache pruning after a new head is selected.
- Concurrent "block packing" (attestations, etc) and execution payload retrieval during block production.
- Concurrent per-block-processing and execution payload verification during block processing.
- The `Arc`-ification of `SignedBeaconBlock` during block processing (it's never mutated, so why not?):
- I had to do this to deal with sending blocks into spawned tasks.
- Previously we were cloning the beacon block at least 2 times during each block processing, these clones are either removed or turned into cheaper `Arc` clones.
- We were also `Box`-ing and un-`Box`-ing beacon blocks as they moved throughout the networking crate. This is not a big deal, but it's nice to avoid shifting things between the stack and heap.
- Avoids cloning *all the blocks* in *every chain segment* during sync.
- It also has the potential to clean up our code where we need to pass an *owned* block around so we can send it back in the case of an error (I didn't do much of this, my PR is already big enough 😅)
- The `BeaconChain::HeadSafetyStatus` struct was removed. It was an old relic from prior merge specs.
For motivation for this change, see https://github.com/sigp/lighthouse/pull/3244#issuecomment-1160963273
## Changes to `canonical_head` and `fork_choice`
Previously, the `BeaconChain` had two separate fields:
```
canonical_head: RwLock<Snapshot>,
fork_choice: RwLock<BeaconForkChoice>
```
Now, we have grouped these values under a single struct:
```
canonical_head: CanonicalHead {
cached_head: RwLock<Arc<Snapshot>>,
fork_choice: RwLock<BeaconForkChoice>
}
```
Apart from ergonomics, the only *actual* change here is wrapping the canonical head snapshot in an `Arc`. This means that we no longer need to hold the `cached_head` (`canonical_head`, in old terms) lock when we want to pull some values from it. This was done to avoid deadlock risks by preventing functions from acquiring (and holding) the `cached_head` and `fork_choice` locks simultaneously.
## Breaking Changes
### The `state` (root) field in the `finalized_checkpoint` SSE event
Consider the scenario where epoch `n` is just finalized, but `start_slot(n)` is skipped. There are two state roots we might in the `finalized_checkpoint` SSE event:
1. The state root of the finalized block, which is `get_block(finalized_checkpoint.root).state_root`.
4. The state root at slot of `start_slot(n)`, which would be the state from (1), but "skipped forward" through any skip slots.
Previously, Lighthouse would choose (2). However, we can see that when [Teku generates that event](de2b2801c8/data/beaconrestapi/src/main/java/tech/pegasys/teku/beaconrestapi/handlers/v1/events/EventSubscriptionManager.java (L171-L182)) it uses [`getStateRootFromBlockRoot`](de2b2801c8/data/provider/src/main/java/tech/pegasys/teku/api/ChainDataProvider.java (L336-L341)) which uses (1).
I have switched Lighthouse from (2) to (1). I think it's a somewhat arbitrary choice between the two, where (1) is easier to compute and is consistent with Teku.
## Notes for Reviewers
I've renamed `BeaconChain::fork_choice` to `BeaconChain::recompute_head`. Doing this helped ensure I broke all previous uses of fork choice and I also find it more descriptive. It describes an action and can't be confused with trying to get a reference to the `ForkChoice` struct.
I've changed the ordering of SSE events when a block is received. It used to be `[block, finalized, head]` and now it's `[block, head, finalized]`. It was easier this way and I don't think we were making any promises about SSE event ordering so it's not "breaking".
I've made it so fork choice will run when it's first constructed. I did this because I wanted to have a cached version of the last call to `get_head`. Ensuring `get_head` has been run *at least once* means that the cached values doesn't need to wrapped in an `Option`. This was fairly simple, it just involved passing a `slot` to the constructor so it knows *when* it's being run. When loading a fork choice from the store and a slot clock isn't handy I've just used the `slot` that was saved in the `fork_choice_store`. That seems like it would be a faithful representation of the slot when we saved it.
I added the `genesis_time: u64` to the `BeaconChain`. It's small, constant and nice to have around.
Since we're using FC for the fin/just checkpoints, we no longer get the `0x00..00` roots at genesis. You can see I had to remove a work-around in `ef-tests` here: b56be3bc2. I can't find any reason why this would be an issue, if anything I think it'll be better since the genesis-alias has caught us out a few times (0x00..00 isn't actually a real root). Edit: I did find a case where the `network` expected the 0x00..00 alias and patched it here: 3f26ac3e2.
You'll notice a lot of changes in tests. Generally, tests should be functionally equivalent. Here are the things creating the most diff-noise in tests:
- Changing tests to be `tokio::async` tests.
- Adding `.await` to fork choice, block processing and block production functions.
- Refactor of the `canonical_head` "API" provided by the `BeaconChain`. E.g., `chain.canonical_head.cached_head()` instead of `chain.canonical_head.read()`.
- Wrapping `SignedBeaconBlock` in an `Arc`.
- In the `beacon_chain/tests/block_verification`, we can't use the `lazy_static` `CHAIN_SEGMENT` variable anymore since it's generated with an async function. We just generate it in each test, not so efficient but hopefully insignificant.
I had to disable `rayon` concurrent tests in the `fork_choice` tests. This is because the use of `rayon` and `block_on` was causing a panic.
Co-authored-by: Mac L <mjladson@pm.me>
## Issue Addressed
Deprecates the step parameter in the blocks by range request
## Proposed Changes
- Modifies the BlocksByRangeRequest type to remove the step parameter and everywhere we took it into account before
- Adds a new type to still handle coding and decoding of requests that use the parameter
## Additional Info
I went with a deprecation over the type itself so that requests received outside `lighthouse_network` don't even need to deal with this parameter. After the deprecation period just removing the Old blocks by range request should be straightforward
## Issue Addressed
N/A
## Proposed Changes
https://github.com/sigp/lighthouse/pull/3133 changed the rpc type limits to be fork aware i.e. if our current fork based on wall clock slot is Altair, then we apply only altair rpc type limits. This is a bug because phase0 blocks can still be sent over rpc and phase 0 block minimum size is smaller than altair block minimum size. So a phase0 block with `size < SIGNED_BEACON_BLOCK_ALTAIR_MIN` will return an `InvalidData` error as it doesn't pass the rpc types bound check.
This error can be seen when we try syncing pre-altair blocks with size smaller than `SIGNED_BEACON_BLOCK_ALTAIR_MIN`.
This PR fixes the issue by also accounting for forks earlier than current_fork in the rpc limits calculation in the `rpc_block_limits_by_fork` function. I decided to hardcode the limits in the function because that seemed simpler than calculating previous forks based on current fork and doing a min across forks. Adding a new fork variant is simple and can the limits can be easily checked in a review.
Adds unit tests and modifies the syncing simulator to check the syncing from across fork boundaries.
The syncing simulator's block 1 would always be of phase 0 minimum size (404 bytes) which is smaller than altair min block size (since block 1 contains no attestations).
## Issue Addressed
N/A
## Proposed Changes
Fix the upper bound for blocks by root responses to be equal to the max merge block size instead of altair.
Further make the rpc response limits fork aware.
Fix max packet sizes
Fix max_payload_size function
Add merge block test
Fix max size calculation; fix up test
Clear comments
Add a payload_size_function
Use safe arith for payload calculation
Return an error if block too big in block production
Separate test to check if block is over limit
Added Execution Payload from Rayonism Fork
Updated new Containers to match Merge Spec
Updated BeaconBlockBody for Merge Spec
Completed updating BeaconState and BeaconBlockBody
Modified ExecutionPayload<T> to use Transaction<T>
Mostly Finished Changes for beacon-chain.md
Added some things for fork-choice.md
Update to match new fork-choice.md/fork.md changes
ran cargo fmt
Added Missing Pieces in eth2_libp2p for Merge
fix ef test
Various Changes to Conform Closer to Merge Spec
## Description
The `eth2_libp2p` crate was originally named and designed to incorporate a simple libp2p integration into lighthouse. Since its origins the crates purpose has expanded dramatically. It now houses a lot more sophistication that is specific to lighthouse and no longer just a libp2p integration.
As of this writing it currently houses the following high-level lighthouse-specific logic:
- Lighthouse's implementation of the eth2 RPC protocol and specific encodings/decodings
- Integration and handling of ENRs with respect to libp2p and eth2
- Lighthouse's discovery logic, its integration with discv5 and logic about searching and handling peers.
- Lighthouse's peer manager - This is a large module handling various aspects of Lighthouse's network, such as peer scoring, handling pings and metadata, connection maintenance and recording, etc.
- Lighthouse's peer database - This is a collection of information stored for each individual peer which is specific to lighthouse. We store connection state, sync state, last seen ips and scores etc. The data stored for each peer is designed for various elements of the lighthouse code base such as syncing and the http api.
- Gossipsub scoring - This stores a collection of gossipsub 1.1 scoring mechanisms that are continuously analyssed and updated based on the ethereum 2 networks and how Lighthouse performs on these networks.
- Lighthouse specific types for managing gossipsub topics, sync status and ENR fields
- Lighthouse's network HTTP API metrics - A collection of metrics for lighthouse network monitoring
- Lighthouse's custom configuration of all networking protocols, RPC, gossipsub, discovery, identify and libp2p.
Therefore it makes sense to rename the crate to be more akin to its current purposes, simply that it manages the majority of Lighthouse's network stack. This PR renames this crate to `lighthouse_network`
Co-authored-by: Paul Hauner <paul@paulhauner.com>
