Add cache for parallel HTTP requests (sigp#4879)

Author: michaelsproul

Cargo.lock

@@ -37,6 +37,7 @@ members = [
     "common/malloc_utils",
     "common/oneshot_broadcast",
     "common/pretty_reqwest_error",
+    "common/promise_cache",
     "common/sensitive_url",
     "common/slot_clock",
     "common/system_health",

Cargo.toml

@@ -43,9 +43,9 @@ lighthouse_metrics = { workspace = true }
 logging = { workspace = true }
 lru = { workspace = true }
 merkle_proof = { workspace = true }
-oneshot_broadcast = { path = "../../common/oneshot_broadcast/" }
 operation_pool = { workspace = true }
 parking_lot = { workspace = true }
+promise_cache = { path = "../../common/promise_cache" }
 proto_array = { workspace = true }
 rand = { workspace = true }
 rayon = { workspace = true }

beacon_node/beacon_chain/Cargo.toml

@@ -53,6 +53,7 @@ use crate::observed_blob_sidecars::ObservedBlobSidecars;
 use crate::observed_block_producers::ObservedBlockProducers;
 use crate::observed_operations::{ObservationOutcome, ObservedOperations};
 use crate::observed_slashable::ObservedSlashable;
+use crate::parallel_state_cache::ParallelStateCache;
 use crate::persisted_beacon_chain::{PersistedBeaconChain, DUMMY_CANONICAL_HEAD_BLOCK_ROOT};
 use crate::persisted_fork_choice::PersistedForkChoice;
 use crate::pre_finalization_cache::PreFinalizationBlockCache;
@@ -460,6 +461,10 @@ pub struct BeaconChain<T: BeaconChainTypes> {
     pub block_times_cache: Arc<RwLock<BlockTimesCache>>,
     /// A cache used to track pre-finalization block roots for quick rejection.
     pub pre_finalization_block_cache: PreFinalizationBlockCache,
+    /// A cache used to de-duplicate HTTP state requests.
+    ///
+    /// The cache is keyed by `state_root`.
+    pub parallel_state_cache: Arc<RwLock<ParallelStateCache<T::EthSpec>>>,
     /// Sender given to tasks, so that if they encounter a state in which execution cannot
     /// continue they can request that everything shuts down.
     pub shutdown_sender: Sender<ShutdownReason>,
@@ -3868,7 +3873,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 self.shuffling_cache
                     .try_write_for(ATTESTATION_CACHE_LOCK_TIMEOUT)
                     .ok_or(Error::AttestationCacheLockTimeout)?
-                    .insert_committee_cache(shuffling_id, committee_cache);
+                    .insert_value(shuffling_id, committee_cache);
             }
         }
         Ok(())
@@ -6041,7 +6046,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             // access.
             drop(shuffling_cache);
 
-            let committee_cache = cache_item.wait()?;
+            let committee_cache = cache_item.wait().map_err(Error::ShufflingCacheError)?;
             map_fn(&committee_cache, shuffling_id.shuffling_decision_block)
         } else {
             // Create an entry in the cache that "promises" this value will eventually be computed.
@@ -6050,7 +6055,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             //
             // Creating the promise whilst we hold the `shuffling_cache` lock will prevent the same
             // promise from being created twice.
-            let sender = shuffling_cache.create_promise(shuffling_id.clone())?;
+            let sender = shuffling_cache
+                .create_promise(shuffling_id.clone())
+                .map_err(Error::ShufflingCacheError)?;
 
             // Drop the shuffling cache to avoid holding the lock for any longer than
             // required.
@@ -6144,7 +6151,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             self.shuffling_cache
                 .try_write_for(ATTESTATION_CACHE_LOCK_TIMEOUT)
                 .ok_or(Error::AttestationCacheLockTimeout)?
-                .insert_committee_cache(shuffling_id, &committee_cache);
+                .insert_value(shuffling_id, &committee_cache);
 
             metrics::stop_timer(committee_building_timer);
 
@@ -6446,6 +6453,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         self.data_availability_checker.data_availability_boundary()
     }
 
+    pub fn logger(&self) -> &Logger {
+        &self.log
+    }
+
     /// Gets the `LightClientBootstrap` object for a requested block root.
     ///
     /// Returns `None` when the state or block is not found in the database.

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -23,6 +23,7 @@ use futures::channel::mpsc::Sender;
 use kzg::{Kzg, TrustedSetup};
 use operation_pool::{OperationPool, PersistedOperationPool};
 use parking_lot::{Mutex, RwLock};
+use promise_cache::PromiseCache;
 use proto_array::{DisallowedReOrgOffsets, ReOrgThreshold};
 use slasher::Slasher;
 use slog::{crit, debug, error, info, o, Logger};
@@ -851,6 +852,7 @@ where
         let genesis_time = head_snapshot.beacon_state.genesis_time();
         let canonical_head = CanonicalHead::new(fork_choice, Arc::new(head_snapshot));
         let shuffling_cache_size = self.chain_config.shuffling_cache_size;
+        let parallel_state_cache_size = self.chain_config.parallel_state_cache_size;
 
         // Calculate the weak subjectivity point in which to backfill blocks to.
         let genesis_backfill_slot = if self.chain_config.genesis_backfill {
@@ -933,6 +935,11 @@ where
             beacon_proposer_cache,
             block_times_cache: <_>::default(),
             pre_finalization_block_cache: <_>::default(),
+            parallel_state_cache: Arc::new(RwLock::new(PromiseCache::new(
+                parallel_state_cache_size,
+                Default::default(),
+                log.clone(),
+            ))),
             validator_pubkey_cache,
             attester_cache: <_>::default(),
             early_attester_cache: <_>::default(),

beacon_node/beacon_chain/src/builder.rs

@@ -820,9 +820,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             Ok(head_shuffling_ids) => {
                 self.shuffling_cache
                     .try_write_for(ATTESTATION_CACHE_LOCK_TIMEOUT)
-                    .map(|mut shuffling_cache| {
-                        shuffling_cache.update_head_shuffling_ids(head_shuffling_ids)
-                    })
+                    .map(|mut shuffling_cache| shuffling_cache.update_protector(head_shuffling_ids))
                     .unwrap_or_else(|| {
                         error!(
                             self.log,

beacon_node/beacon_chain/src/canonical_head.rs

@@ -15,6 +15,9 @@ pub const DEFAULT_PREPARE_PAYLOAD_LOOKAHEAD_FACTOR: u32 = 3;
 /// Fraction of a slot lookahead for fork choice in the state advance timer (500ms on mainnet).
 pub const FORK_CHOICE_LOOKAHEAD_FACTOR: u32 = 24;
 
+/// Cache only a small number of states in the parallel cache by default.
+pub const DEFAULT_PARALLEL_STATE_CACHE_SIZE: usize = 2;
+
 #[derive(Debug, PartialEq, Eq, Clone, Deserialize, Serialize)]
 pub struct ChainConfig {
     /// Maximum number of slots to skip when importing an attestation.
@@ -83,6 +86,8 @@ pub struct ChainConfig {
     pub progressive_balances_mode: ProgressiveBalancesMode,
     /// Number of epochs between each migration of data from the hot database to the freezer.
     pub epochs_per_migration: u64,
+    /// Size of the promise cache for de-duplicating parallel state requests.
+    pub parallel_state_cache_size: usize,
 }
 
 impl Default for ChainConfig {
@@ -114,6 +119,7 @@ impl Default for ChainConfig {
             always_prepare_payload: false,
             progressive_balances_mode: ProgressiveBalancesMode::Fast,
             epochs_per_migration: crate::migrate::DEFAULT_EPOCHS_PER_MIGRATION,
+            parallel_state_cache_size: DEFAULT_PARALLEL_STATE_CACHE_SIZE,
         }
     }
 }

beacon_node/beacon_chain/src/chain_config.rs

@@ -211,8 +211,7 @@ pub enum BeaconChainError {
     },
     AttestationHeadNotInForkChoice(Hash256),
     MissingPersistedForkChoice,
-    CommitteePromiseFailed(oneshot_broadcast::Error),
-    MaxCommitteePromises(usize),
+    ShufflingCacheError(promise_cache::PromiseCacheError),
     BlsToExecutionPriorToCapella,
     BlsToExecutionConflictsWithPool,
     InconsistentFork(InconsistentFork),

beacon_node/beacon_chain/src/errors.rs

@@ -42,6 +42,7 @@ pub mod observed_block_producers;
 pub mod observed_operations;
 mod observed_slashable;
 pub mod otb_verification_service;
+mod parallel_state_cache;
 mod persisted_beacon_chain;
 mod persisted_fork_choice;
 mod pre_finalization_cache;

beacon_node/beacon_chain/src/lib.rs

@@ -0,0 +1,22 @@
+use promise_cache::{PromiseCache, Protect};
+use types::{BeaconState, Hash256};
+
+#[derive(Debug, Default)]
+pub struct ParallelStateProtector;
+
+impl Protect<Hash256> for ParallelStateProtector {
+    type SortKey = usize;
+
+    /// Evict in arbitrary (hashmap) order by using the same key for every value.
+    fn sort_key(&self, _: &Hash256) -> Self::SortKey {
+        0
+    }
+
+    /// We don't care too much about preventing evictions of particular states here. All the states
+    /// in this cache should be different from the head state.
+    fn protect_from_eviction(&self, _: &Hash256) -> bool {
+        false
+    }
+}
+
+pub type ParallelStateCache<E> = PromiseCache<Hash256, BeaconState<E>, ParallelStateProtector>;