Refactor block prod. to produce for forks

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -23,6 +23,12 @@ use store::{Error as DBError, Store};
 use tree_hash::TreeHash;
 use types::*;
 
+// Text included in blocks.
+// Must be 32-bytes or panic.
+//
+//                          |-------must be this long------|
+pub const GRAFFITI: &str = "sigp/lighthouse-0.0.0-prerelease";
+
 #[derive(Debug, PartialEq)]
 pub enum BlockProcessingOutcome {
     /// Block was valid and imported into the block graph.
@@ -657,16 +663,41 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         &self,
         randao_reveal: Signature,
     ) -> Result<(BeaconBlock, BeaconState<T::EthSpec>), BlockProductionError> {
-        debug!("Producing block at slot {}...", self.state.read().slot);
+        let state = self.state.read().clone();
+        let slot = self
+            .read_slot_clock()
+            .ok_or_else(|| BlockProductionError::UnableToReadSlot)?;
+
+        self.produce_block_on_state(state, slot, randao_reveal)
+    }
+
+    /// Produce a block for some `slot` upon the given `state`.
+    ///
+    /// Typically the `self.produce_block()` function should be used, instead of calling this
+    /// function directly. This function is useful for purposefully creating forks or blocks at
+    /// non-current slots.
+    ///
+    /// The given state will be advanced to the given `produce_at_slot`, then a block will be
+    /// produced at that slot height.
+    pub fn produce_block_on_state(
+        &self,
+        mut state: BeaconState<T::EthSpec>,
+        produce_at_slot: Slot,
+        randao_reveal: Signature,
+    ) -> Result<(BeaconBlock, BeaconState<T::EthSpec>), BlockProductionError> {
         self.metrics.block_production_requests.inc();
         let timer = self.metrics.block_production_times.start_timer();
 
-        let mut state = self.state.read().clone();
+        // If required, transition the new state to the present slot.
+        for _ in state.slot.as_u64()..produce_at_slot.as_u64() {
+            // Ensure the next epoch state caches are built in case of an epoch transition.
+            state.build_committee_cache(RelativeEpoch::Next, &self.spec)?;
+
+            per_slot_processing(&mut state, &self.spec)?;
+        }
 
         state.build_committee_cache(RelativeEpoch::Current, &self.spec)?;
 
-        trace!("Finding attestations for new block...");
-
         let previous_block_root = if state.slot > 0 {
             *state
                 .get_block_root(state.slot - 1)
@@ -675,8 +706,11 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             state.latest_block_header.canonical_root()
         };
 
+        let mut graffiti: [u8; 32] = [0; 32];
+        graffiti.copy_from_slice(GRAFFITI.as_bytes());
+
         let (proposer_slashings, attester_slashings) =
-            self.op_pool.get_slashings(&*self.state.read(), &self.spec);
+            self.op_pool.get_slashings(&state, &self.spec);
 
         let mut block = BeaconBlock {
             slot: state.slot,
@@ -691,8 +725,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     deposit_root: Hash256::zero(),
                     block_hash: Hash256::zero(),
                 },
-                // TODO: badass Lighthouse graffiti
-                graffiti: [0; 32],
+                graffiti,
                 proposer_slashings,
                 attester_slashings,
                 attestations: self

beacon_node/beacon_chain/src/errors.rs

@@ -40,9 +40,12 @@ impl From<MetricsError> for BeaconChainError {
 #[derive(Debug, PartialEq)]
 pub enum BlockProductionError {
     UnableToGetBlockRootFromState,
+    UnableToReadSlot,
+    SlotProcessingError(SlotProcessingError),
     BlockProcessingError(BlockProcessingError),
     BeaconStateError(BeaconStateError),
 }
 
 easy_from_to!(BlockProcessingError, BlockProductionError);
 easy_from_to!(BeaconStateError, BlockProductionError);
+easy_from_to!(SlotProcessingError, BlockProductionError);

beacon_node/beacon_chain/src/test_utils.rs

@@ -5,13 +5,20 @@ use slot_clock::TestingSlotClock;
 use std::marker::PhantomData;
 use std::sync::Arc;
 use store::MemoryStore;
+use store::Store;
 use tree_hash::{SignedRoot, TreeHash};
 use types::{
     test_utils::TestingBeaconStateBuilder, AggregateSignature, Attestation,
-    AttestationDataAndCustodyBit, BeaconBlock, Bitfield, ChainSpec, Domain, EthSpec, Hash256,
-    Keypair, SecretKey, Signature,
+    AttestationDataAndCustodyBit, BeaconBlock, BeaconState, Bitfield, ChainSpec, Domain, EthSpec,
+    Hash256, Keypair, RelativeEpoch, SecretKey, Signature, Slot,
 };
 
+#[derive(Clone, Copy)]
+pub enum BuildStrategy {
+    OnCanonicalHead,
+    ForkCanonicalChainAt(Slot),
+}
+
 pub struct CommonTypes<L, E>
 where
     L: LmdGhost<MemoryStore, E>,
@@ -82,11 +89,11 @@ where
         }
     }
 
-    pub fn extend_canonical_chain(&self) {
+    pub fn extend_chain(&self, build_strategy: BuildStrategy) {
         self.chain.slot_clock.advance_slot();
         self.chain.catchup_state().expect("should catchup state");
 
-        let block = self.build_block();
+        let block = self.build_block(build_strategy);
         let outcome = self
             .chain
             .process_block(block)
@@ -96,18 +103,47 @@ where
         self.add_attestations_to_op_pool();
     }
 
-    fn build_block(&self) -> BeaconBlock {
-        let slot = self.chain.read_slot_clock().unwrap();
-
-        let sk = {
-            let proposer = self
+    fn get_state(&self, build_strategy: BuildStrategy) -> BeaconState<E> {
+        match build_strategy {
+            BuildStrategy::OnCanonicalHead => self.chain.current_state().clone(),
+            BuildStrategy::ForkCanonicalChainAt(fork_slot) => {
+                let state_root = self
                     .chain
-                .block_proposer(slot)
-                .expect("should get block propoer");
-            &self.keypairs[proposer].sk
+                    .rev_iter_state_roots(self.chain.head().beacon_state.slot - 1)
+                    .find(|(_hash, slot)| *slot == fork_slot)
+                    .map(|(hash, _slot)| hash)
+                    .expect("could not find state root for fork");
+
+                self.chain
+                    .store
+                    .get(&state_root)
+                    .expect("should read db")
+                    .expect("should find state root")
+            }
+        }
+    }
+
+    fn build_block(&self, build_strategy: BuildStrategy) -> BeaconBlock {
+        let mut state = self.get_state(build_strategy);
+        state.build_all_caches(&self.spec).unwrap();
+
+        let slot = match build_strategy {
+            BuildStrategy::OnCanonicalHead => self.chain.read_slot_clock().unwrap(),
+            BuildStrategy::ForkCanonicalChainAt(slot) => slot,
         };
 
-        let fork = &self.chain.head().beacon_state.fork;
+        let proposer_index = match build_strategy {
+            BuildStrategy::OnCanonicalHead => self
+                .chain
+                .block_proposer(slot)
+                .expect("should get block proposer from chain"),
+            _ => state
+                .get_beacon_proposer_index(slot, RelativeEpoch::Current, &self.spec)
+                .expect("should get block proposer from state"),
+        };
+
+        let sk = &self.keypairs[proposer_index].sk;
+        let fork = &state.fork.clone();
 
         let randao_reveal = {
             let epoch = slot.epoch(E::slots_per_epoch());
@@ -118,8 +154,8 @@ where
 
         let (mut block, _state) = self
             .chain
-            .produce_block(randao_reveal)
-            .expect("should producer block");
+            .produce_block_on_state(state, slot, randao_reveal)
+            .expect("should produce block");
 
         block.signature = {
             let message = block.signed_root();
@@ -195,7 +231,7 @@ where
 }
 
 #[cfg(test)]
-#[cfg(not(debug_assertions))]
+// #[cfg(not(debug_assertions))]
 mod test {
     use super::*;
     use lmd_ghost::ThreadSafeReducedTree;
@@ -213,7 +249,7 @@ mod test {
         > = BeaconChainHarness::new(VALIDATOR_COUNT);
 
         for _ in 0..num_blocks_produced {
-            harness.extend_canonical_chain();
+            harness.extend_chain(BuildStrategy::OnCanonicalHead);
         }
 
         let state = &harness.chain.head().beacon_state;

beacon_node/network/src/sync/simple_sync.rs

@@ -182,7 +182,7 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
             && (!self
                 .chain
                 .rev_iter_block_roots(local.best_slot)
-                .any(|root| root == remote.latest_finalized_root))
+                .any(|(root, _slot)| root == remote.latest_finalized_root))
             && (local.latest_finalized_root != spec.zero_hash)
             && (remote.latest_finalized_root != spec.zero_hash)
         {
@@ -266,11 +266,12 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
             "start_slot" => req.start_slot,
         );
 
-        let mut roots: Vec<Hash256> = self
+        let mut roots: Vec<BlockRootSlot> = self
             .chain
             .rev_iter_block_roots(req.start_slot + req.count)
             .skip(1)
             .take(req.count as usize)
+            .map(|(block_root, slot)| BlockRootSlot { slot, block_root })
             .collect();
 
         if roots.len() as u64 != req.count {
@@ -285,16 +286,6 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
         }
 
         roots.reverse();
-
-        let mut roots: Vec<BlockRootSlot> = roots
-            .iter()
-            .enumerate()
-            .map(|(i, block_root)| BlockRootSlot {
-                slot: req.start_slot + Slot::from(i),
-                block_root: *block_root,
-            })
-            .collect();
-
         roots.dedup_by_key(|brs| brs.block_root);
 
         network.send_rpc_response(
@@ -392,6 +383,7 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
             .chain
             .rev_iter_block_roots(req.start_slot + (count - 1))
             .take(count as usize)
+            .map(|(root, _slot)| root)
             .collect();
 
         roots.reverse();