Files
lighthouse/consensus/state_processing/src/per_epoch_processing/tests.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

170 lines
5.8 KiB
Rust

#![cfg(test)]
use crate::per_epoch_processing::process_epoch;
use beacon_chain::test_utils::BeaconChainHarness;
use beacon_chain::types::{EthSpec, MinimalEthSpec};
use bls::Hash256;
use env_logger::{Builder, Env};
use types::Slot;
#[tokio::test]
async fn runs_without_error() {
Builder::from_env(Env::default().default_filter_or("error")).init();
let harness = BeaconChainHarness::builder(MinimalEthSpec)
.default_spec()
.deterministic_keypairs(8)
.fresh_ephemeral_store()
.build();
harness.advance_slot();
let spec = MinimalEthSpec::default_spec();
let target_slot =
(MinimalEthSpec::genesis_epoch() + 4).end_slot(MinimalEthSpec::slots_per_epoch());
let state = harness.get_current_state();
harness
.add_attested_blocks_at_slots(
state,
Hash256::zero(),
(1..target_slot.as_u64())
.map(Slot::new)
.collect::<Vec<_>>()
.as_slice(),
(0..8).collect::<Vec<_>>().as_slice(),
)
.await;
let mut new_head_state = harness.get_current_state();
process_epoch(&mut new_head_state, &spec).unwrap();
}
#[cfg(not(debug_assertions))]
mod release_tests {
use super::*;
use crate::{
per_slot_processing::per_slot_processing, EpochProcessingError, SlotProcessingError,
};
use beacon_chain::test_utils::{AttestationStrategy, BlockStrategy};
use types::{Epoch, ForkName, InconsistentFork, MainnetEthSpec};
#[tokio::test]
async fn altair_state_on_base_fork() {
let mut spec = MainnetEthSpec::default_spec();
let slots_per_epoch = MainnetEthSpec::slots_per_epoch();
// The Altair fork happens at epoch 1.
spec.altair_fork_epoch = Some(Epoch::new(1));
let altair_state = {
let harness = BeaconChainHarness::builder(MainnetEthSpec)
.spec(spec.clone())
.deterministic_keypairs(8)
.fresh_ephemeral_store()
.build();
harness.advance_slot();
harness
.extend_chain(
// Build out enough blocks so we get an Altair block at the very end of an epoch.
(slots_per_epoch * 2 - 1) as usize,
BlockStrategy::OnCanonicalHead,
AttestationStrategy::AllValidators,
)
.await;
harness.get_current_state()
};
// Pre-conditions for a valid test.
assert_eq!(altair_state.fork_name(&spec).unwrap(), ForkName::Altair);
assert_eq!(
altair_state.slot(),
altair_state.current_epoch().end_slot(slots_per_epoch)
);
// Check the state is valid before starting this test.
process_epoch(&mut altair_state.clone(), &spec)
.expect("state passes intial epoch processing");
per_slot_processing(&mut altair_state.clone(), None, &spec)
.expect("state passes intial slot processing");
// Modify the spec so altair never happens.
spec.altair_fork_epoch = None;
let expected_err = InconsistentFork {
fork_at_slot: ForkName::Base,
object_fork: ForkName::Altair,
};
assert_eq!(altair_state.fork_name(&spec), Err(expected_err));
assert_eq!(
process_epoch(&mut altair_state.clone(), &spec),
Err(EpochProcessingError::InconsistentStateFork(expected_err))
);
assert_eq!(
per_slot_processing(&mut altair_state.clone(), None, &spec),
Err(SlotProcessingError::InconsistentStateFork(expected_err))
);
}
#[tokio::test]
async fn base_state_on_altair_fork() {
let mut spec = MainnetEthSpec::default_spec();
let slots_per_epoch = MainnetEthSpec::slots_per_epoch();
// The Altair fork never happens.
spec.altair_fork_epoch = None;
let base_state = {
let harness = BeaconChainHarness::builder(MainnetEthSpec)
.spec(spec.clone())
.deterministic_keypairs(8)
.fresh_ephemeral_store()
.build();
harness.advance_slot();
harness
.extend_chain(
// Build out enough blocks so we get a block at the very end of an epoch.
(slots_per_epoch * 2 - 1) as usize,
BlockStrategy::OnCanonicalHead,
AttestationStrategy::AllValidators,
)
.await;
harness.get_current_state()
};
// Pre-conditions for a valid test.
assert_eq!(base_state.fork_name(&spec).unwrap(), ForkName::Base);
assert_eq!(
base_state.slot(),
base_state.current_epoch().end_slot(slots_per_epoch)
);
// Check the state is valid before starting this test.
process_epoch(&mut base_state.clone(), &spec)
.expect("state passes intial epoch processing");
per_slot_processing(&mut base_state.clone(), None, &spec)
.expect("state passes intial slot processing");
// Modify the spec so Altair happens at the first epoch.
spec.altair_fork_epoch = Some(Epoch::new(1));
let expected_err = InconsistentFork {
fork_at_slot: ForkName::Altair,
object_fork: ForkName::Base,
};
assert_eq!(base_state.fork_name(&spec), Err(expected_err));
assert_eq!(
process_epoch(&mut base_state.clone(), &spec),
Err(EpochProcessingError::InconsistentStateFork(expected_err))
);
assert_eq!(
per_slot_processing(&mut base_state.clone(), None, &spec),
Err(SlotProcessingError::InconsistentStateFork(expected_err))
);
}
}