be4e261e74
## 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>
221 lines
7.1 KiB
Rust
221 lines
7.1 KiB
Rust
#![cfg(not(debug_assertions))]
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use beacon_chain::test_utils::{AttestationStrategy, BeaconChainHarness, BlockStrategy};
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use beacon_chain::{StateSkipConfig, WhenSlotSkipped};
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use lazy_static::lazy_static;
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use std::sync::Arc;
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use tree_hash::TreeHash;
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use types::{AggregateSignature, EthSpec, Keypair, MainnetEthSpec, RelativeEpoch, Slot};
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pub const VALIDATOR_COUNT: usize = 16;
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lazy_static! {
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/// A cached set of keys.
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static ref KEYPAIRS: Vec<Keypair> = types::test_utils::generate_deterministic_keypairs(VALIDATOR_COUNT);
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}
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/// This test builds a chain that is just long enough to finalize an epoch then it produces an
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/// attestation at each slot from genesis through to three epochs past the head.
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///
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/// It checks the produced attestation against some locally computed values.
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#[tokio::test]
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async fn produces_attestations() {
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let num_blocks_produced = MainnetEthSpec::slots_per_epoch() * 4;
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let additional_slots_tested = MainnetEthSpec::slots_per_epoch() * 3;
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let harness = BeaconChainHarness::builder(MainnetEthSpec)
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.default_spec()
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.keypairs(KEYPAIRS[..].to_vec())
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.fresh_ephemeral_store()
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.mock_execution_layer()
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.build();
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let chain = &harness.chain;
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// Test all valid committee indices for all slots in the chain.
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// for slot in 0..=current_slot.as_u64() + MainnetEthSpec::slots_per_epoch() * 3 {
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for slot in 0..=num_blocks_produced + additional_slots_tested {
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if slot > 0 && slot <= num_blocks_produced {
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harness.advance_slot();
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harness
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.extend_chain(
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1,
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BlockStrategy::OnCanonicalHead,
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AttestationStrategy::AllValidators,
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)
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.await;
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}
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let slot = Slot::from(slot);
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let mut state = chain
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.state_at_slot(slot, StateSkipConfig::WithStateRoots)
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.expect("should get state");
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let block_slot = if slot <= num_blocks_produced {
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slot
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} else {
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Slot::from(num_blocks_produced)
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};
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let blinded_block = chain
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.block_at_slot(block_slot, WhenSlotSkipped::Prev)
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.expect("should get block")
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.expect("block should not be skipped");
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let block_root = blinded_block.message().tree_hash_root();
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let block = chain
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.store
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.make_full_block(&block_root, blinded_block)
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.unwrap();
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let epoch_boundary_slot = state
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.current_epoch()
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.start_slot(MainnetEthSpec::slots_per_epoch());
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let target_root = if state.slot() == epoch_boundary_slot {
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block_root
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} else {
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*state
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.get_block_root(epoch_boundary_slot)
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.expect("should get target block root")
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};
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state
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.build_committee_cache(RelativeEpoch::Current, &harness.chain.spec)
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.unwrap();
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let committee_cache = state
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.committee_cache(RelativeEpoch::Current)
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.expect("should get committee_cache");
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let committee_count = committee_cache.committees_per_slot();
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for index in 0..committee_count {
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let committee_len = committee_cache
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.get_beacon_committee(slot, index)
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.expect("should get committee for slot")
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.committee
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.len();
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let attestation = chain
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.produce_unaggregated_attestation(slot, index)
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.expect("should produce attestation");
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let data = &attestation.data;
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assert_eq!(
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attestation.aggregation_bits.len(),
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committee_len,
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"bad committee len"
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);
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assert!(
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attestation.aggregation_bits.is_zero(),
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"some committee bits are set"
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);
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assert_eq!(
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attestation.signature,
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AggregateSignature::empty(),
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"bad signature"
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);
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assert_eq!(data.index, index, "bad index");
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assert_eq!(data.slot, slot, "bad slot");
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assert_eq!(data.beacon_block_root, block_root, "bad block root");
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assert_eq!(
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data.source,
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state.current_justified_checkpoint(),
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"bad source"
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);
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assert_eq!(
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data.source,
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state.current_justified_checkpoint(),
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"bad source"
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);
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assert_eq!(data.target.epoch, state.current_epoch(), "bad target epoch");
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assert_eq!(data.target.root, target_root, "bad target root");
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let early_attestation = {
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let proto_block = chain
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.canonical_head
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.fork_choice_read_lock()
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.get_block(&block_root)
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.unwrap();
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chain
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.early_attester_cache
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.add_head_block(
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block_root,
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Arc::new(block.clone()),
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proto_block,
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&state,
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&chain.spec,
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)
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.unwrap();
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chain
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.early_attester_cache
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.try_attest(slot, index, &chain.spec)
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.unwrap()
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.unwrap()
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};
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assert_eq!(
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attestation, early_attestation,
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"early attester cache inconsistent"
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);
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}
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}
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}
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/// Ensures that the early attester cache wont create an attestation to a block in a later slot than
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/// the one requested.
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#[tokio::test]
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async fn early_attester_cache_old_request() {
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let harness = BeaconChainHarness::builder(MainnetEthSpec)
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.default_spec()
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.keypairs(KEYPAIRS[..].to_vec())
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.fresh_ephemeral_store()
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.mock_execution_layer()
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.build();
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harness.advance_slot();
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harness
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.extend_chain(
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2,
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BlockStrategy::OnCanonicalHead,
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AttestationStrategy::AllValidators,
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)
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.await;
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let head = harness.chain.head_snapshot();
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assert_eq!(head.beacon_block.slot(), 2);
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let head_proto_block = harness
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.chain
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.canonical_head
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.fork_choice_read_lock()
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.get_block(&head.beacon_block_root)
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.unwrap();
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harness
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.chain
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.early_attester_cache
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.add_head_block(
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head.beacon_block_root,
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head.beacon_block.clone(),
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head_proto_block,
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&head.beacon_state,
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&harness.chain.spec,
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)
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.unwrap();
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let attest_slot = head.beacon_block.slot() - 1;
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let attestation = harness
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.chain
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.produce_unaggregated_attestation(attest_slot, 0)
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.unwrap();
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assert_eq!(attestation.data.slot, attest_slot);
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let attested_block = harness
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.chain
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.get_blinded_block(&attestation.data.beacon_block_root)
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.unwrap()
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.unwrap();
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assert_eq!(attested_block.slot(), attest_slot);
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}
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