[Merged by Bors] - Customisable shuffling cache size

beacon_node/beacon_chain/src/builder.rs

@@ -765,6 +765,7 @@ where
         let genesis_time = head_snapshot.beacon_state.genesis_time();
         let head_for_snapshot_cache = head_snapshot.clone();
         let canonical_head = CanonicalHead::new(fork_choice, Arc::new(head_snapshot));
+        let shuffling_cache_size = self.chain_config.shuffling_cache_size;
 
         let beacon_chain = BeaconChain {
             spec: self.spec,
@@ -818,7 +819,7 @@ where
                 DEFAULT_SNAPSHOT_CACHE_SIZE,
                 head_for_snapshot_cache,
             )),
-            shuffling_cache: TimeoutRwLock::new(ShufflingCache::new()),
+            shuffling_cache: TimeoutRwLock::new(ShufflingCache::new(shuffling_cache_size)),
             eth1_finalization_cache: TimeoutRwLock::new(Eth1FinalizationCache::new(log.clone())),
             beacon_proposer_cache: <_>::default(),
             block_times_cache: <_>::default(),

beacon_node/beacon_chain/src/chain_config.rs

@@ -67,6 +67,8 @@ pub struct ChainConfig {
     pub prepare_payload_lookahead: Duration,
     /// Use EL-free optimistic sync for the finalized part of the chain.
     pub optimistic_finalized_sync: bool,
+    /// The size of the shuffling cache,
+    pub shuffling_cache_size: usize,
     /// Whether to send payload attributes every slot, regardless of connected proposers.
     ///
     /// This is useful for block builders and testing.
@@ -97,6 +99,7 @@ impl Default for ChainConfig {
             prepare_payload_lookahead: Duration::from_secs(4),
             // This value isn't actually read except in tests.
             optimistic_finalized_sync: true,
+            shuffling_cache_size: crate::shuffling_cache::DEFAULT_CACHE_SIZE,
             always_prepare_payload: false,
         }
     }

beacon_node/beacon_chain/src/lib.rs

@@ -40,7 +40,7 @@ mod persisted_fork_choice;
 mod pre_finalization_cache;
 pub mod proposer_prep_service;
 pub mod schema_change;
-mod shuffling_cache;
+pub mod shuffling_cache;
 mod snapshot_cache;
 pub mod state_advance_timer;
 pub mod sync_committee_rewards;

beacon_node/beacon_chain/src/shuffling_cache.rs

@@ -9,7 +9,7 @@ use types::{beacon_state::CommitteeCache, AttestationShufflingId, Epoch, Hash256
 /// Each entry should be `8 + 800,000 = 800,008` bytes in size with 100k validators. (8-byte hash +
 /// 100k indices). Therefore, this cache should be approx `16 * 800,008 = 12.8 MB`. (Note: this
 /// ignores a few extra bytes in the caches that should be insignificant compared to the indices).
-const CACHE_SIZE: usize = 16;
+pub const DEFAULT_CACHE_SIZE: usize = 16;
 
 /// The maximum number of concurrent committee cache "promises" that can be issued. In effect, this
 /// limits the number of concurrent states that can be loaded into memory for the committee cache.
@@ -54,9 +54,9 @@ pub struct ShufflingCache {
 }
 
 impl ShufflingCache {
-    pub fn new() -> Self {
+    pub fn new(cache_size: usize) -> Self {
         Self {
-            cache: LruCache::new(CACHE_SIZE),
+            cache: LruCache::new(cache_size),
         }
     }
 
@@ -172,7 +172,7 @@ impl ToArcCommitteeCache for Arc<CommitteeCache> {
 
 impl Default for ShufflingCache {
     fn default() -> Self {
-        Self::new()
+        Self::new(DEFAULT_CACHE_SIZE)
     }
 }
 
@@ -249,7 +249,7 @@ mod test {
     fn resolved_promise() {
         let (committee_a, _) = committee_caches();
         let id_a = shuffling_id(1);
-        let mut cache = ShufflingCache::new();
+        let mut cache = ShufflingCache::default();
 
         // Create a promise.
         let sender = cache.create_promise(id_a.clone()).unwrap();
@@ -276,7 +276,7 @@ mod test {
     #[test]
     fn unresolved_promise() {
         let id_a = shuffling_id(1);
-        let mut cache = ShufflingCache::new();
+        let mut cache = ShufflingCache::default();
 
         // Create a promise.
         let sender = cache.create_promise(id_a.clone()).unwrap();
@@ -301,7 +301,7 @@ mod test {
     fn two_promises() {
         let (committee_a, committee_b) = committee_caches();
         let (id_a, id_b) = (shuffling_id(1), shuffling_id(2));
-        let mut cache = ShufflingCache::new();
+        let mut cache = ShufflingCache::default();
 
         // Create promise A.
         let sender_a = cache.create_promise(id_a.clone()).unwrap();
@@ -355,7 +355,7 @@ mod test {
 
     #[test]
     fn too_many_promises() {
-        let mut cache = ShufflingCache::new();
+        let mut cache = ShufflingCache::default();
 
         for i in 0..MAX_CONCURRENT_PROMISES {
             cache.create_promise(shuffling_id(i as u64)).unwrap();

beacon_node/http_api/src/lib.rs

@@ -54,8 +54,8 @@ use system_health::observe_system_health_bn;
 use tokio::sync::mpsc::{Sender, UnboundedSender};
 use tokio_stream::{wrappers::BroadcastStream, StreamExt};
 use types::{
-    Attestation, AttestationData, AttesterSlashing, BeaconStateError, BlindedPayload,
-    CommitteeCache, ConfigAndPreset, Epoch, EthSpec, ForkName, FullPayload,
+    Attestation, AttestationData, AttestationShufflingId, AttesterSlashing, BeaconStateError,
+    BlindedPayload, CommitteeCache, ConfigAndPreset, Epoch, EthSpec, ForkName, FullPayload,
     ProposerPreparationData, ProposerSlashing, RelativeEpoch, SignedAggregateAndProof,
     SignedBeaconBlock, SignedBlindedBeaconBlock, SignedBlsToExecutionChange,
     SignedContributionAndProof, SignedValidatorRegistrationData, SignedVoluntaryExit, Slot,
@@ -784,39 +784,112 @@ pub fn serve<T: BeaconChainTypes>(
                                 let current_epoch = state.current_epoch();
                                 let epoch = query.epoch.unwrap_or(current_epoch);
 
-                                let committee_cache =
-                                    match RelativeEpoch::from_epoch(current_epoch, epoch) {
-                                        Ok(relative_epoch)
-                                            if state
-                                                .committee_cache_is_initialized(relative_epoch) =>
-                                        {
-                                            state.committee_cache(relative_epoch).map(Cow::Borrowed)
-                                        }
-                                        _ => CommitteeCache::initialized(state, epoch, &chain.spec)
+                                // Attempt to obtain the committee_cache from the beacon chain
+                                let decision_slot = (epoch.saturating_sub(2u64))
+                                    .end_slot(T::EthSpec::slots_per_epoch());
+                                // Find the decision block and skip to another method on any kind
+                                // of failure
+                                let shuffling_id = if let Ok(Some(shuffling_decision_block)) =
+                                    chain.block_root_at_slot(decision_slot, WhenSlotSkipped::Prev)
+                                {
+                                    Some(AttestationShufflingId {
+                                        shuffling_epoch: epoch,
+                                        shuffling_decision_block,
+                                    })
+                                } else {
+                                    None
+                                };
+
+                                // Attempt to read from the chain cache if there exists a
+                                // shuffling_id
+                                let maybe_cached_shuffling = if let Some(shuffling_id) =
+                                    shuffling_id.as_ref()
+                                {
+                                    chain
+                                        .shuffling_cache
+                                        .try_write_for(std::time::Duration::from_secs(1))
+                                        .and_then(|mut cache_write| cache_write.get(shuffling_id))
+                                        .and_then(|cache_item| cache_item.wait().ok())
+                                } else {
+                                    None
+                                };
+
+                                let committee_cache = if let Some(ref shuffling) =
+                                    maybe_cached_shuffling
+                                {
+                                    Cow::Borrowed(&**shuffling)
+                                } else {
+                                    let possibly_built_cache =
+                                        match RelativeEpoch::from_epoch(current_epoch, epoch) {
+                                            Ok(relative_epoch)
+                                                if state.committee_cache_is_initialized(
+                                                    relative_epoch,
+                                                ) =>
+                                            {
+                                                state
+                                                    .committee_cache(relative_epoch)
+                                                    .map(Cow::Borrowed)
+                                            }
+                                            _ => CommitteeCache::initialized(
+                                                state,
+                                                epoch,
+                                                &chain.spec,
+                                            )
                                             .map(Cow::Owned),
-                                    }
-                                    .map_err(|e| match e {
-                                        BeaconStateError::EpochOutOfBounds => {
-                                            let max_sprp =
-                                                T::EthSpec::slots_per_historical_root() as u64;
-                                            let first_subsequent_restore_point_slot = ((epoch
-                                                .start_slot(T::EthSpec::slots_per_epoch())
-                                                / max_sprp)
-                                                + 1)
-                                                * max_sprp;
-                                            if epoch < current_epoch {
-                                                warp_utils::reject::custom_bad_request(format!(
-                                                    "epoch out of bounds, try state at slot {}",
-                                                    first_subsequent_restore_point_slot,
-                                                ))
-                                            } else {
-                                                warp_utils::reject::custom_bad_request(
-                                                    "epoch out of bounds, too far in future".into(),
-                                                )
+                                        }
+                                        .map_err(|e| {
+                                            match e {
+                                                BeaconStateError::EpochOutOfBounds => {
+                                                    let max_sprp =
+                                                        T::EthSpec::slots_per_historical_root()
+                                                            as u64;
+                                                    let first_subsequent_restore_point_slot =
+                                                        ((epoch.start_slot(
+                                                            T::EthSpec::slots_per_epoch(),
+                                                        ) / max_sprp)
+                                                            + 1)
+                                                            * max_sprp;
+                                                    if epoch < current_epoch {
+                                                        warp_utils::reject::custom_bad_request(
+                                                            format!(
+                                                                "epoch out of bounds, \
+                                                                 try state at slot {}",
+                                                                first_subsequent_restore_point_slot,
+                                                            ),
+                                                        )
+                                                    } else {
+                                                        warp_utils::reject::custom_bad_request(
+                                                            "epoch out of bounds, \
+                                                             too far in future"
+                                                                .into(),
+                                                        )
+                                                    }
+                                                }
+                                                _ => {
+                                                    warp_utils::reject::beacon_chain_error(e.into())
+                                                }
+                                            }
+                                        })?;
+
+                                    // Attempt to write to the beacon cache (only if the cache
+                                    // size is not the default value).
+                                    if chain.config.shuffling_cache_size
+                                        != beacon_chain::shuffling_cache::DEFAULT_CACHE_SIZE
+                                    {
+                                        if let Some(shuffling_id) = shuffling_id {
+                                            if let Some(mut cache_write) = chain
+                                                .shuffling_cache
+                                                .try_write_for(std::time::Duration::from_secs(1))
+                                            {
+                                                cache_write.insert_committee_cache(
+                                                    shuffling_id,
+                                                    &*possibly_built_cache,
+                                                );
                                             }
                                         }
-                                        _ => warp_utils::reject::beacon_chain_error(e.into()),
-                                    })?;
+                                    }
+                                    possibly_built_cache
+                                };
 
                                 // Use either the supplied slot or all slots in the epoch.
                                 let slots =

beacon_node/src/cli.rs

@@ -370,6 +370,14 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                     address of this server (e.g., http://localhost:5054).")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("shuffling-cache-size")
+            .long("shuffling-cache-size")
+            .help("Some HTTP API requests can be optimised by caching the shufflings at each epoch. \
+            This flag allows the user to set the shuffling cache size in epochs. \
+            Shufflings are dependent on validator count and setting this value to a large number can consume a large amount of memory.")
+            .takes_value(true)
+        )
 
         /*
          * Monitoring metrics

beacon_node/src/config.rs

@@ -148,6 +148,10 @@ pub fn get_config<E: EthSpec>(
         client_config.http_api.allow_sync_stalled = true;
     }
 
+    if let Some(cache_size) = clap_utils::parse_optional(cli_args, "shuffling-cache-size")? {
+        client_config.chain.shuffling_cache_size = cache_size;
+    }
+
     /*
      * Prometheus metrics HTTP server
      */

lighthouse/tests/beacon_node.rs

@@ -118,6 +118,26 @@ fn disable_lock_timeouts_flag() {
         .with_config(|config| assert!(!config.chain.enable_lock_timeouts));
 }
 
+#[test]
+fn shuffling_cache_default() {
+    CommandLineTest::new()
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert_eq!(
+                config.chain.shuffling_cache_size,
+                beacon_node::beacon_chain::shuffling_cache::DEFAULT_CACHE_SIZE
+            )
+        });
+}
+
+#[test]
+fn shuffling_cache_set() {
+    CommandLineTest::new()
+        .flag("shuffling-cache-size", Some("500"))
+        .run_with_zero_port()
+        .with_config(|config| assert_eq!(config.chain.shuffling_cache_size, 500));
+}
+
 #[test]
 fn fork_choice_before_proposal_timeout_default() {
     CommandLineTest::new()