lighthouse/beacon_node/store/src/metadata.rs

120 lines
3.4 KiB
Rust
Raw Normal View History

use crate::{DBColumn, Error, StoreItem};
use serde_derive::{Deserialize, Serialize};
use ssz::{Decode, Encode};
use ssz_derive::{Decode, Encode};
use types::{Checkpoint, Hash256, Slot};
Refactor op pool for speed and correctness (#3312) ## Proposed Changes This PR has two aims: to speed up attestation packing in the op pool, and to fix bugs in the verification of attester slashings, proposer slashings and voluntary exits. The changes are bundled into a single database schema upgrade (v12). Attestation packing is sped up by removing several inefficiencies: - No more recalculation of `attesting_indices` during packing. - No (unnecessary) examination of the `ParticipationFlags`: a bitfield suffices. See `RewardCache`. - No re-checking of attestation validity during packing: the `AttestationMap` provides attestations which are "correct by construction" (I have checked this using Hydra). - No SSZ re-serialization for the clunky `AttestationId` type (it can be removed in a future release). So far the speed-up seems to be roughly 2-10x, from 500ms down to 50-100ms. Verification of attester slashings, proposer slashings and voluntary exits is fixed by: - Tracking the `ForkVersion`s that were used to verify each message inside the `SigVerifiedOp`. This allows us to quickly re-verify that they match the head state's opinion of what the `ForkVersion` should be at the epoch(s) relevant to the message. - Storing the `SigVerifiedOp` on disk rather than the raw operation. This allows us to continue track the fork versions after a reboot. This is mostly contained in this commit 52bb1840ae5c4356a8fc3a51e5df23ed65ed2c7f. ## Additional Info The schema upgrade uses the justified state to re-verify attestations and compute `attesting_indices` for them. It will drop any attestations that fail to verify, by the logic that attestations are most valuable in the few slots after they're observed, and are probably stale and useless by the time a node restarts. Exits and proposer slashings and similarly re-verified to obtain `SigVerifiedOp`s. This PR contains a runtime killswitch `--paranoid-block-proposal` which opts out of all the optimisations in favour of closely verifying every included message. Although I'm quite sure that the optimisations are correct this flag could be useful in the event of an unforeseen emergency. Finally, you might notice that the `RewardCache` appears quite useless in its current form because it is only updated on the hot-path immediately before proposal. My hope is that in future we can shift calls to `RewardCache::update` into the background, e.g. while performing the state advance. It is also forward-looking to `tree-states` compatibility, where iterating and indexing `state.{previous,current}_epoch_participation` is expensive and needs to be minimised.
2022-08-29 09:10:26 +00:00
pub const CURRENT_SCHEMA_VERSION: SchemaVersion = SchemaVersion(12);
// All the keys that get stored under the `BeaconMeta` column.
//
// We use `repeat_byte` because it's a const fn.
pub const SCHEMA_VERSION_KEY: Hash256 = Hash256::repeat_byte(0);
pub const CONFIG_KEY: Hash256 = Hash256::repeat_byte(1);
pub const SPLIT_KEY: Hash256 = Hash256::repeat_byte(2);
pub const PRUNING_CHECKPOINT_KEY: Hash256 = Hash256::repeat_byte(3);
pub const COMPACTION_TIMESTAMP_KEY: Hash256 = Hash256::repeat_byte(4);
pub const ANCHOR_INFO_KEY: Hash256 = Hash256::repeat_byte(5);
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub struct SchemaVersion(pub u64);
Implement database temp states to reduce memory usage (#1798) ## Issue Addressed Closes #800 Closes #1713 ## Proposed Changes Implement the temporary state storage algorithm described in #800. Specifically: * Add `DBColumn::BeaconStateTemporary`, for storing 0-length temporary marker values. * Store intermediate states immediately as they are created, marked temporary. Delete the temporary flag if the block is processed successfully. * Add a garbage collection process to delete leftover temporary states on start-up. * Bump the database schema version to 2 so that a DB with temporary states can't accidentally be used with older versions of the software. The auto-migration is a no-op, but puts in place some infra that we can use for future migrations (e.g. #1784) ## Additional Info There are two known race conditions, one potentially causing permanent faults (hopefully rare), and the other insignificant. ### Race 1: Permanent state marked temporary EDIT: this has been fixed by the addition of a lock around the relevant critical section There are 2 threads that are trying to store 2 different blocks that share some intermediate states (e.g. they both skip some slots from the current head). Consider this sequence of events: 1. Thread 1 checks if state `s` already exists, and seeing that it doesn't, prepares an atomic commit of `(s, s_temporary_flag)`. 2. Thread 2 does the same, but also gets as far as committing the state txn, finishing the processing of its block, and _deleting_ the temporary flag. 3. Thread 1 is (finally) scheduled again, and marks `s` as temporary with its transaction. 4. a) The process is killed, or thread 1's block fails verification and the temp flag is not deleted. This is a permanent failure! Any attempt to load state `s` will fail... hope it isn't on the main chain! Alternatively (4b) happens... b) Thread 1 finishes, and re-deletes the temporary flag. In this case the failure is transient, state `s` will disappear temporarily, but will come back once thread 1 finishes running. I _hope_ that steps 1-3 only happen very rarely, and 4a even more rarely. It's hard to know This once again begs the question of why we're using LevelDB (#483), when it clearly doesn't care about atomicity! A ham-fisted fix would be to wrap the hot and cold DBs in locks, which would bring us closer to how other DBs handle read-write transactions. E.g. [LMDB only allows one R/W transaction at a time](https://docs.rs/lmdb/0.8.0/lmdb/struct.Environment.html#method.begin_rw_txn). ### Race 2: Temporary state returned from `get_state` I don't think this race really matters, but in `load_hot_state`, if another thread stores a state between when we call `load_state_temporary_flag` and when we call `load_hot_state_summary`, then we could end up returning that state even though it's only a temporary state. I can't think of any case where this would be relevant, and I suspect if it did come up, it would be safe/recoverable (having data is safer than _not_ having data). This could be fixed by using a LevelDB read snapshot, but that would require substantial changes to how we read all our values, so I don't think it's worth it right now.
2020-10-23 01:27:51 +00:00
impl SchemaVersion {
pub fn as_u64(self) -> u64 {
self.0
}
}
impl StoreItem for SchemaVersion {
fn db_column() -> DBColumn {
DBColumn::BeaconMeta
}
fn as_store_bytes(&self) -> Vec<u8> {
self.0.as_ssz_bytes()
}
fn from_store_bytes(bytes: &[u8]) -> Result<Self, Error> {
Ok(SchemaVersion(u64::from_ssz_bytes(bytes)?))
}
}
/// The checkpoint used for pruning the database.
///
/// Updated whenever pruning is successful.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct PruningCheckpoint {
pub checkpoint: Checkpoint,
}
impl StoreItem for PruningCheckpoint {
fn db_column() -> DBColumn {
DBColumn::BeaconMeta
}
fn as_store_bytes(&self) -> Vec<u8> {
self.checkpoint.as_ssz_bytes()
}
fn from_store_bytes(bytes: &[u8]) -> Result<Self, Error> {
Ok(PruningCheckpoint {
checkpoint: Checkpoint::from_ssz_bytes(bytes)?,
})
}
}
/// The last time the database was compacted.
pub struct CompactionTimestamp(pub u64);
impl StoreItem for CompactionTimestamp {
fn db_column() -> DBColumn {
DBColumn::BeaconMeta
}
fn as_store_bytes(&self) -> Vec<u8> {
self.0.as_ssz_bytes()
}
fn from_store_bytes(bytes: &[u8]) -> Result<Self, Error> {
Ok(CompactionTimestamp(u64::from_ssz_bytes(bytes)?))
}
}
/// Database parameters relevant to weak subjectivity sync.
#[derive(Debug, PartialEq, Eq, Clone, Encode, Decode, Serialize, Deserialize)]
pub struct AnchorInfo {
/// The slot at which the anchor state is present and which we cannot revert.
pub anchor_slot: Slot,
/// The slot from which historical blocks are available (>=).
pub oldest_block_slot: Slot,
/// The block root of the next block that needs to be added to fill in the history.
///
/// Zero if we know all blocks back to genesis.
pub oldest_block_parent: Hash256,
/// The slot from which historical states are available (>=).
pub state_upper_limit: Slot,
/// The slot before which historical states are available (<=).
pub state_lower_limit: Slot,
}
impl AnchorInfo {
/// Returns true if the block backfill has completed.
pub fn block_backfill_complete(&self) -> bool {
self.oldest_block_slot == 0
}
}
impl StoreItem for AnchorInfo {
fn db_column() -> DBColumn {
DBColumn::BeaconMeta
}
fn as_store_bytes(&self) -> Vec<u8> {
self.as_ssz_bytes()
}
fn from_store_bytes(bytes: &[u8]) -> Result<Self, Error> {
Ok(Self::from_ssz_bytes(bytes)?)
}
}