Store beacon state committee cache in DB

beacon_node/store/src/impls/beacon_state.rs

@@ -0,0 +1,64 @@
+use crate::*;
+use ssz::{Decode, DecodeError, Encode};
+use ssz_derive::{Decode, Encode};
+use std::convert::TryInto;
+use types::beacon_state::{CACHED_EPOCHS, CommitteeCache};
+
+/// A container for storing `BeaconState` components.
+#[derive(Encode, Decode)]
+struct StorageContainer {
+    state_bytes: Vec<u8>,
+    committee_caches_bytes: Vec<Vec<u8>>,
+}
+
+impl StorageContainer {
+    /// Create a new instance for storing a `BeaconState`.
+    pub fn new<T: EthSpec>(state: &BeaconState<T>) -> Self {
+        let mut committee_caches_bytes = vec![];
+
+        for cache in state.committee_caches[..].iter() {
+            committee_caches_bytes.push(cache.as_ssz_bytes());
+        }
+
+        Self {
+            state_bytes: state.as_ssz_bytes(),
+            committee_caches_bytes,
+        }
+    }
+}
+
+impl<T: EthSpec> TryInto<BeaconState<T>> for StorageContainer {
+    type Error = Error;
+
+    fn try_into(self) -> Result<BeaconState<T>, Error> {
+        let mut state: BeaconState<T> = BeaconState::from_ssz_bytes(&self.state_bytes)?;
+
+        for i in 0..CACHED_EPOCHS {
+            let bytes = &self.committee_caches_bytes.get(i).ok_or_else(|| {
+                Error::SszDecodeError(DecodeError::BytesInvalid(
+                    "Insufficient committees for BeaconState".to_string(),
+                ))
+            })?;
+
+            state.committee_caches[i] = CommitteeCache::from_ssz_bytes(bytes)?;
+        }
+
+        Ok(state)
+    }
+}
+
+impl<T: EthSpec> StoreItem for BeaconState<T> {
+    fn db_column() -> DBColumn {
+        DBColumn::BeaconState
+    }
+
+    fn as_store_bytes(&self) -> Vec<u8> {
+        let container = StorageContainer::new(self);
+        container.as_ssz_bytes()
+    }
+
+    fn from_store_bytes(bytes: &mut [u8]) -> Result<Self, Error> {
+        let container = StorageContainer::from_ssz_bytes(bytes)?;
+        container.try_into()
+    }
+}