Implement basic BeaconChain persistence.

beacon_node/beacon_chain/Cargo.toml

@@ -21,6 +21,7 @@ serde_derive = "1.0"
 serde_json = "1.0"
 slot_clock = { path = "../../eth2/utils/slot_clock" }
 ssz = { path = "../../eth2/utils/ssz" }
+ssz_derive = { path = "../../eth2/utils/ssz_derive" }
 state_processing = { path = "../../eth2/state_processing" }
 tree_hash = { path = "../../eth2/utils/tree_hash" }
 types = { path = "../../eth2/types" }

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -1,5 +1,6 @@
 use crate::checkpoint::CheckPoint;
 use crate::errors::{BeaconChainError as Error, BlockProductionError};
+use crate::persisted_beacon_chain::{PersistedBeaconChain, BEACON_CHAIN_DB_KEY};
 use fork_choice::{ForkChoice, ForkChoiceError};
 use log::{debug, trace};
 use operation_pool::DepositInsertStatus;
@@ -140,6 +141,51 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         })
     }
 
+    /// Attempt to load an existing instance from the given `store`.
+    pub fn from_store(store: Arc<T::Store>) -> Result<Option<BeaconChain<T>>, Error> {
+        let key = Hash256::from_slice(&BEACON_CHAIN_DB_KEY.as_bytes());
+        let p: PersistedBeaconChain<T> = match store.get(&key) {
+            Err(e) => return Err(e.into()),
+            Ok(None) => return Ok(None),
+            Ok(Some(p)) => p,
+        };
+
+        let spec = T::EthSpec::spec();
+
+        let slot_clock = T::SlotClock::new(
+            spec.genesis_slot,
+            p.state.genesis_time,
+            spec.seconds_per_slot,
+        );
+
+        let fork_choice = T::ForkChoice::new(store.clone());
+
+        Ok(Some(BeaconChain {
+            store,
+            slot_clock,
+            op_pool: OperationPool::default(),
+            canonical_head: RwLock::new(p.canonical_head),
+            finalized_head: RwLock::new(p.finalized_head),
+            state: RwLock::new(p.state),
+            spec,
+            fork_choice: RwLock::new(fork_choice),
+        }))
+    }
+
+    /// Attempt to save this instance to `self.store`.
+    pub fn persist(&self) -> Result<(), Error> {
+        let p: PersistedBeaconChain<T> = PersistedBeaconChain {
+            canonical_head: self.canonical_head.read().clone(),
+            finalized_head: self.finalized_head.read().clone(),
+            state: self.state.read().clone(),
+        };
+
+        let key = Hash256::from_slice(&BEACON_CHAIN_DB_KEY.as_bytes());
+        self.store.put(&key, &p)?;
+
+        Ok(())
+    }
+
     /// Returns the beacon block body for each beacon block root in `roots`.
     ///
     /// Fails if any root in `roots` does not have a corresponding block.

beacon_node/beacon_chain/src/checkpoint.rs

@@ -1,9 +1,10 @@
 use serde_derive::Serialize;
+use ssz_derive::{Decode, Encode};
 use types::{BeaconBlock, BeaconState, EthSpec, Hash256};
 
 /// Represents some block and it's associated state. Generally, this will be used for tracking the
 /// head, justified head and finalized head.
-#[derive(Clone, Serialize, PartialEq, Debug)]
+#[derive(Clone, Serialize, PartialEq, Debug, Encode, Decode)]
 pub struct CheckPoint<E: EthSpec> {
     pub beacon_block: BeaconBlock,
     pub beacon_block_root: Hash256,

beacon_node/beacon_chain/src/lib.rs

@@ -1,6 +1,7 @@
 mod beacon_chain;
 mod checkpoint;
 mod errors;
+mod persisted_beacon_chain;
 
 pub use self::beacon_chain::{
     BeaconChain, BeaconChainTypes, BlockProcessingOutcome, InvalidBlock, ValidBlock,

beacon_node/beacon_chain/src/persisted_beacon_chain.rs

@@ -0,0 +1,30 @@
+use crate::{BeaconChainTypes, CheckPoint};
+use ssz::{Decode, Encode};
+use ssz_derive::{Decode, Encode};
+use store::{DBColumn, Error as StoreError, StoreItem};
+use types::BeaconState;
+
+/// 32-byte key for accessing the `PersistedBeaconChain`.
+pub const BEACON_CHAIN_DB_KEY: &str = "PERSISTEDBEACONCHAINPERSISTEDBEA";
+
+#[derive(Encode, Decode)]
+pub struct PersistedBeaconChain<T: BeaconChainTypes> {
+    pub canonical_head: CheckPoint<T::EthSpec>,
+    pub finalized_head: CheckPoint<T::EthSpec>,
+    // TODO: operations pool.
+    pub state: BeaconState<T::EthSpec>,
+}
+
+impl<T: BeaconChainTypes> StoreItem for PersistedBeaconChain<T> {
+    fn db_column() -> DBColumn {
+        DBColumn::BeaconChain
+    }
+
+    fn as_store_bytes(&self) -> Vec<u8> {
+        self.as_ssz_bytes()
+    }
+
+    fn from_store_bytes(bytes: &mut [u8]) -> Result<Self, StoreError> {
+        Self::from_ssz_bytes(bytes).map_err(Into::into)
+    }
+}

beacon_node/client/src/beacon_chain_types.rs

@@ -1,4 +1,3 @@
-use crate::ClientConfig;
 use beacon_chain::{
     fork_choice::BitwiseLMDGhost,
     slot_clock::SystemTimeSlotClock,
@@ -15,7 +14,7 @@ use types::{
 
 /// Provides a new, initialized `BeaconChain`
 pub trait InitialiseBeaconChain<T: BeaconChainTypes> {
-    fn initialise_beacon_chain(config: &ClientConfig) -> BeaconChain<T>;
+    fn initialise_beacon_chain(store: Arc<T::Store>) -> BeaconChain<T>;
 }
 
 /// A testnet-suitable BeaconChainType, using `MemoryStore`.
@@ -29,16 +28,9 @@ impl BeaconChainTypes for TestnetMemoryBeaconChainTypes {
     type EthSpec = FewValidatorsEthSpec;
 }
 
-impl<T> InitialiseBeaconChain<T> for TestnetMemoryBeaconChainTypes
-where
-    T: BeaconChainTypes<
-        Store = MemoryStore,
-        SlotClock = SystemTimeSlotClock,
-        ForkChoice = BitwiseLMDGhost<MemoryStore, FewValidatorsEthSpec>,
-    >,
-{
-    fn initialise_beacon_chain(_config: &ClientConfig) -> BeaconChain<T> {
-        initialize_chain::<_, _, FewValidatorsEthSpec>(MemoryStore::open())
+impl<T: BeaconChainTypes> InitialiseBeaconChain<T> for TestnetMemoryBeaconChainTypes {
+    fn initialise_beacon_chain(store: Arc<T::Store>) -> BeaconChain<T> {
+        maybe_load_from_store_for_testnet::<_, T::Store, T::EthSpec>(store)
     }
 }
 
@@ -53,55 +45,49 @@ impl BeaconChainTypes for TestnetDiskBeaconChainTypes {
     type EthSpec = FewValidatorsEthSpec;
 }
 
-impl<T> InitialiseBeaconChain<T> for TestnetDiskBeaconChainTypes
-where
-    T: BeaconChainTypes<
-        Store = DiskStore,
-        SlotClock = SystemTimeSlotClock,
-        ForkChoice = BitwiseLMDGhost<DiskStore, FewValidatorsEthSpec>,
-    >,
-{
-    fn initialise_beacon_chain(config: &ClientConfig) -> BeaconChain<T> {
-        let store = DiskStore::open(&config.db_name).expect("Unable to open DB.");
-
-        initialize_chain::<_, _, FewValidatorsEthSpec>(store)
+impl<T: BeaconChainTypes> InitialiseBeaconChain<T> for TestnetDiskBeaconChainTypes {
+    fn initialise_beacon_chain(store: Arc<T::Store>) -> BeaconChain<T> {
+        maybe_load_from_store_for_testnet::<_, T::Store, T::EthSpec>(store)
     }
 }
 
-/// Produces a `BeaconChain` given some pre-initialized `Store`.
-fn initialize_chain<T, U: Store, V: EthSpec>(store: U) -> BeaconChain<T>
+/// Loads a `BeaconChain` from `store`, if it exists. Otherwise, create a new chain from genesis.
+fn maybe_load_from_store_for_testnet<T, U: Store, V: EthSpec>(store: Arc<U>) -> BeaconChain<T>
 where
     T: BeaconChainTypes<Store = U>,
     T::ForkChoice: ForkChoice<U>,
 {
-    let spec = T::EthSpec::spec();
+    if let Ok(Some(beacon_chain)) = BeaconChain::from_store(store.clone()) {
+        beacon_chain
+    } else {
+        let spec = T::EthSpec::spec();
 
-    let store = Arc::new(store);
+        let state_builder =
+            TestingBeaconStateBuilder::from_default_keypairs_file_if_exists(8, &spec);
+        let (genesis_state, _keypairs) = state_builder.build();
 
-    let state_builder = TestingBeaconStateBuilder::from_default_keypairs_file_if_exists(8, &spec);
-    let (genesis_state, _keypairs) = state_builder.build();
+        let mut genesis_block = BeaconBlock::empty(&spec);
+        genesis_block.state_root = Hash256::from_slice(&genesis_state.tree_hash_root());
 
-    let mut genesis_block = BeaconBlock::empty(&spec);
-    genesis_block.state_root = Hash256::from_slice(&genesis_state.tree_hash_root());
+        // Slot clock
+        let slot_clock = T::SlotClock::new(
+            spec.genesis_slot,
+            genesis_state.genesis_time,
+            spec.seconds_per_slot,
+        );
+        // Choose the fork choice
+        let fork_choice = T::ForkChoice::new(store.clone());
 
-    // Slot clock
-    let slot_clock = T::SlotClock::new(
-        spec.genesis_slot,
-        genesis_state.genesis_time,
-        spec.seconds_per_slot,
-    );
-    // Choose the fork choice
-    let fork_choice = T::ForkChoice::new(store.clone());
-
-    // Genesis chain
-    //TODO: Handle error correctly
-    BeaconChain::from_genesis(
-        store,
-        slot_clock,
-        genesis_state,
-        genesis_block,
-        spec.clone(),
-        fork_choice,
-    )
-    .expect("Terminate if beacon chain generation fails")
+        // Genesis chain
+        //TODO: Handle error correctly
+        BeaconChain::from_genesis(
+            store,
+            slot_clock,
+            genesis_state,
+            genesis_block,
+            spec.clone(),
+            fork_choice,
+        )
+        .expect("Terminate if beacon chain generation fails")
+    }
 }

beacon_node/client/src/error.rs

@@ -1,10 +1,6 @@
-// generates error types
 use network;
 
-use error_chain::{
-    error_chain, error_chain_processing, impl_error_chain_kind, impl_error_chain_processed,
-    impl_extract_backtrace,
-};
+use error_chain::error_chain;
 
 error_chain! {
    links  {

beacon_node/client/src/lib.rs

@@ -50,11 +50,14 @@ where
     /// Generate an instance of the client. Spawn and link all internal sub-processes.
     pub fn new(
         config: ClientConfig,
+        store: T::Store,
         log: slog::Logger,
         executor: &TaskExecutor,
     ) -> error::Result<Self> {
-        // generate a beacon chain
-        let beacon_chain = Arc::new(T::initialise_beacon_chain(&config));
+        let store = Arc::new(store);
+
+        // Load a `BeaconChain` from the store, or create a new one if it does not exist.
+        let beacon_chain = Arc::new(T::initialise_beacon_chain(store));
 
         if beacon_chain.read_slot_clock().is_none() {
             panic!("Cannot start client before genesis!")

beacon_node/eth2-libp2p/src/error.rs

@@ -1,8 +1,5 @@
 // generates error types
 
-use error_chain::{
-    error_chain, error_chain_processing, impl_error_chain_kind, impl_error_chain_processed,
-    impl_extract_backtrace,
-};
+use error_chain::error_chain;
 
 error_chain! {}

beacon_node/network/src/beacon_chain.rs

@@ -5,9 +5,7 @@ use beacon_chain::{
     AttestationValidationError, CheckPoint,
 };
 use eth2_libp2p::rpc::HelloMessage;
-use types::{
-    Attestation, BeaconBlock, BeaconBlockBody, BeaconBlockHeader, Epoch, EthSpec, Hash256, Slot,
-};
+use types::{Attestation, BeaconBlock, BeaconBlockBody, BeaconBlockHeader, Epoch, Hash256, Slot};
 
 pub use beacon_chain::{BeaconChainError, BeaconChainTypes, BlockProcessingOutcome, InvalidBlock};
 

beacon_node/network/src/error.rs

@@ -1,10 +1,7 @@
 // generates error types
 use eth2_libp2p;
 
-use error_chain::{
-    error_chain, error_chain_processing, impl_error_chain_kind, impl_error_chain_processed,
-    impl_extract_backtrace,
-};
+use error_chain::error_chain;
 
 error_chain! {
    links  {

beacon_node/rpc/src/beacon_chain.rs

@@ -5,7 +5,7 @@ use beacon_chain::{
     AttestationValidationError, BlockProductionError,
 };
 pub use beacon_chain::{BeaconChainError, BeaconChainTypes, BlockProcessingOutcome};
-use types::{Attestation, AttestationData, BeaconBlock, EthSpec};
+use types::{Attestation, AttestationData, BeaconBlock};
 
 /// The RPC's API to the beacon chain.
 pub trait BeaconChain<T: BeaconChainTypes>: Send + Sync {

beacon_node/src/run.rs

@@ -6,6 +6,7 @@ use futures::sync::oneshot;
 use futures::Future;
 use slog::info;
 use std::cell::RefCell;
+use store::{DiskStore, MemoryStore};
 use tokio::runtime::Builder;
 use tokio::runtime::Runtime;
 use tokio::runtime::TaskExecutor;
@@ -32,8 +33,11 @@ pub fn run_beacon_node(config: ClientConfig, log: &slog::Logger) -> error::Resul
                 "BeaconNode starting";
                 "type" => "TestnetDiskBeaconChainTypes"
             );
+
+            let store = DiskStore::open(&config.db_name).expect("Unable to open DB.");
+
             let client: Client<TestnetDiskBeaconChainTypes> =
-                Client::new(config, log.clone(), &executor)?;
+                Client::new(config, store, log.clone(), &executor)?;
 
             run(client, executor, runtime, log)
         }
@@ -43,8 +47,11 @@ pub fn run_beacon_node(config: ClientConfig, log: &slog::Logger) -> error::Resul
                 "BeaconNode starting";
                 "type" => "TestnetMemoryBeaconChainTypes"
             );
+
+            let store = MemoryStore::open();
+
             let client: Client<TestnetMemoryBeaconChainTypes> =
-                Client::new(config, log.clone(), &executor)?;
+                Client::new(config, store, log.clone(), &executor)?;
 
             run(client, executor, runtime, log)
         }