lighthouse/beacon_node/beacon_chain/tests/attestation_production.rs
Paul Hauner be4e261e74 Use async code when interacting with EL (#3244)
## 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>
2022-07-03 05:36:50 +00:00

221 lines
7.1 KiB
Rust

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