Avoid changing slasher schema for Electra

slasher/src/database.rs

@@ -13,13 +13,15 @@ use parking_lot::Mutex;
 use serde::de::DeserializeOwned;
 use slog::{info, Logger};
 use ssz::{Decode, Encode};
+use ssz_derive::{Decode, Encode};
 use std::borrow::{Borrow, Cow};
 use std::marker::PhantomData;
 use std::sync::Arc;
 use tree_hash::TreeHash;
 use types::{
-    Epoch, EthSpec, Hash256, IndexedAttestation, IndexedAttestationOnDisk,
-    IndexedAttestationRefOnDisk, ProposerSlashing, SignedBeaconBlockHeader, Slot,
+    AggregateSignature, AttestationData, ChainSpec, Epoch, EthSpec, ForkName, Hash256,
+    IndexedAttestation, IndexedAttestationBase, IndexedAttestationElectra, ProposerSlashing,
+    SignedBeaconBlockHeader, Slot, VariableList,
 };
 
 /// Current database schema version, to check compatibility of on-disk DB with software.
@@ -70,6 +72,7 @@ pub struct SlasherDB<E: EthSpec> {
     /// LRU cache mapping indexed attestation IDs to their attestation data roots.
     attestation_root_cache: Mutex<LruCache<IndexedAttestationId, Hash256>>,
     pub(crate) config: Arc<Config>,
+    pub(crate) spec: Arc<ChainSpec>,
     _phantom: PhantomData<E>,
 }
 
@@ -236,6 +239,43 @@ impl AsRef<[u8]> for IndexedAttestationId {
     }
 }
 
+/// Indexed attestation that abstracts over Phase0 and Electra variants by using a plain `Vec` for
+/// the attesting indices.
+///
+/// This allows us to avoid rewriting the entire indexed attestation database at Electra, which
+/// saves a lot of execution time. The bytes that it encodes to are the same as the bytes that a
+/// regular IndexedAttestation encodes to, because SSZ doesn't care about the length-bound.
+#[derive(Debug, PartialEq, Decode, Encode)]
+pub struct IndexedAttestationOnDisk {
+    attesting_indices: Vec<u64>,
+    data: AttestationData,
+    signature: AggregateSignature,
+}
+
+impl IndexedAttestationOnDisk {
+    fn into_indexed_attestation<E: EthSpec>(
+        self,
+        spec: &ChainSpec,
+    ) -> Result<IndexedAttestation<E>, Error> {
+        let fork_at_target_epoch = spec.fork_name_at_epoch(self.data.target.epoch);
+        if fork_at_target_epoch >= ForkName::Electra {
+            let attesting_indices = VariableList::new(self.attesting_indices)?;
+            Ok(IndexedAttestation::Electra(IndexedAttestationElectra {
+                attesting_indices,
+                data: self.data,
+                signature: self.signature,
+            }))
+        } else {
+            let attesting_indices = VariableList::new(self.attesting_indices)?;
+            Ok(IndexedAttestation::Base(IndexedAttestationBase {
+                attesting_indices,
+                data: self.data,
+                signature: self.signature,
+            }))
+        }
+    }
+}
+
 /// Bincode deserialization specialised to `Cow<[u8]>`.
 fn bincode_deserialize<T: DeserializeOwned>(bytes: Cow<[u8]>) -> Result<T, Error> {
     Ok(bincode::deserialize(bytes.borrow())?)
@@ -246,7 +286,7 @@ fn ssz_decode<T: Decode>(bytes: Cow<[u8]>) -> Result<T, Error> {
 }
 
 impl<E: EthSpec> SlasherDB<E> {
-    pub fn open(config: Arc<Config>, log: Logger) -> Result<Self, Error> {
+    pub fn open(config: Arc<Config>, spec: Arc<ChainSpec>, log: Logger) -> Result<Self, Error> {
         info!(log, "Opening slasher database"; "backend" => %config.backend);
 
         std::fs::create_dir_all(&config.database_path)?;
@@ -269,6 +309,7 @@ impl<E: EthSpec> SlasherDB<E> {
             databases,
             attestation_root_cache,
             config,
+            spec,
             _phantom: PhantomData,
         };
 
@@ -458,9 +499,8 @@ impl<E: EthSpec> SlasherDB<E> {
         };
 
         let attestation_key = IndexedAttestationId::new(indexed_att_id);
-        let indexed_attestation_on_disk: IndexedAttestationRefOnDisk<E> =
-            indexed_attestation.into();
-        let data = indexed_attestation_on_disk.as_ssz_bytes();
+        // IndexedAttestationOnDisk and IndexedAttestation have compatible encodings.
+        let data = indexed_attestation.as_ssz_bytes();
 
         cursor.put(attestation_key.as_ref(), &data)?;
         drop(cursor);
@@ -484,8 +524,8 @@ impl<E: EthSpec> SlasherDB<E> {
             .ok_or(Error::MissingIndexedAttestation {
                 id: indexed_attestation_id.as_u64(),
             })?;
-        let indexed_attestation: IndexedAttestationOnDisk<E> = ssz_decode(bytes)?;
-        Ok(indexed_attestation.into())
+        let indexed_attestation_on_disk: IndexedAttestationOnDisk = ssz_decode(bytes)?;
+        indexed_attestation_on_disk.into_indexed_attestation(&self.spec)
     }
 
     fn get_attestation_data_root(
@@ -775,3 +815,84 @@ impl<E: EthSpec> SlasherDB<E> {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use types::{Checkpoint, MainnetEthSpec};
+
+    type E = MainnetEthSpec;
+
+    fn indexed_attestation_on_disk_roundtrip_test(
+        spec: &ChainSpec,
+        make_attestation: fn(
+            Vec<u64>,
+            AttestationData,
+            AggregateSignature,
+        ) -> IndexedAttestation<E>,
+    ) {
+        let attestation_data = AttestationData {
+            slot: Slot::new(1000),
+            index: 0,
+            beacon_block_root: Hash256::repeat_byte(0xaa),
+            source: Checkpoint {
+                epoch: Epoch::new(0),
+                root: Hash256::repeat_byte(0xbb),
+            },
+            target: Checkpoint {
+                epoch: Epoch::new(31),
+                root: Hash256::repeat_byte(0xcc),
+            },
+        };
+
+        let attesting_indices = vec![1, 14, 160, 812737];
+        let signature = AggregateSignature::infinity();
+
+        let fork_attestation = make_attestation(
+            attesting_indices.clone(),
+            attestation_data.clone(),
+            signature.clone(),
+        );
+
+        let on_disk = IndexedAttestationOnDisk {
+            attesting_indices,
+            data: attestation_data,
+            signature,
+        };
+        let encoded = on_disk.as_ssz_bytes();
+        assert_eq!(encoded, fork_attestation.as_ssz_bytes());
+
+        let decoded_on_disk = IndexedAttestationOnDisk::from_ssz_bytes(&encoded).unwrap();
+        assert_eq!(decoded_on_disk, on_disk);
+
+        let decoded = on_disk.into_indexed_attestation(&spec).unwrap();
+        assert_eq!(decoded, fork_attestation);
+    }
+
+    /// Check that `IndexedAttestationOnDisk` and `IndexedAttestation` have compatible encodings.
+    #[test]
+    fn indexed_attestation_on_disk_roundtrip_base() {
+        let spec = ForkName::Base.make_genesis_spec(E::default_spec());
+        let make_attestation = |attesting_indices, data, signature| {
+            IndexedAttestation::<E>::Base(IndexedAttestationBase {
+                attesting_indices: VariableList::new(attesting_indices).unwrap(),
+                data,
+                signature,
+            })
+        };
+        indexed_attestation_on_disk_roundtrip_test(&spec, make_attestation)
+    }
+
+    #[test]
+    fn indexed_attestation_on_disk_roundtrip_electra() {
+        let spec = ForkName::Electra.make_genesis_spec(E::default_spec());
+        let make_attestation = |attesting_indices, data, signature| {
+            IndexedAttestation::<E>::Electra(IndexedAttestationElectra {
+                attesting_indices: VariableList::new(attesting_indices).unwrap(),
+                data,
+                signature,
+            })
+        };
+        indexed_attestation_on_disk_roundtrip_test(&spec, make_attestation)
+    }
+}