Add initial works on extending the chain

beacon_chain/chain/src/block_context.rs

@@ -1,33 +1,24 @@
-extern crate ssz_helpers;
-extern crate validation;
-
 use db::{
     ClientDB,
 };
 use db::stores::{
     BeaconBlockAtSlotError,
 };
-use self::validation::block_validation::{
+use validation::block_validation::{
     BeaconBlockValidationContext,
-    SszBeaconBlockValidationError,
 };
 use super::{
     BeaconChain,
-    BeaconChainError,
 };
-use self::ssz_helpers::ssz_beacon_block::{
+use ssz_helpers::ssz_beacon_block::{
     SszBeaconBlock,
-    SszBeaconBlockError,
 };
 use std::sync::Arc;
 use types::{
-    BeaconBlock,
     Hash256,
 };
 
-pub use self::validation::block_validation::BeaconBlockStatus;
-
-pub enum BeaconChainBlockError {
+pub enum BlockValidationContextError {
     UnknownCrystallizedState,
     UnknownActiveState,
     UnknownAttesterProposerMaps,
@@ -35,37 +26,20 @@ pub enum BeaconChainBlockError {
     UnknownJustifiedBlock,
     BlockAlreadyKnown,
     BlockSlotLookupError(BeaconBlockAtSlotError),
-    BadSsz(SszBeaconBlockError),
-    BlockValidationError(SszBeaconBlockValidationError),
-    DBError(String),
 }
 
-impl From<BeaconBlockAtSlotError> for BeaconChainBlockError {
-    fn from(e: BeaconBlockAtSlotError) -> BeaconChainBlockError {
-        BeaconChainBlockError::BlockSlotLookupError(e)
+impl From<BeaconBlockAtSlotError> for BlockValidationContextError {
+    fn from(e: BeaconBlockAtSlotError) -> BlockValidationContextError {
+        BlockValidationContextError::BlockSlotLookupError(e)
     }
 }
 
-impl From<SszBeaconBlockValidationError> for BeaconChainBlockError {
-    fn from(e: SszBeaconBlockValidationError) -> BeaconChainBlockError {
-        BeaconChainBlockError::BlockValidationError(e)
-    }
-}
-
-pub type BlockStatusTriple = (BeaconBlockStatus, Hash256, BeaconBlock);
-
 impl<T> BeaconChain<T>
     where T: ClientDB + Sized
 {
-    fn block_preprocessing(&self, ssz: &[u8], present_slot: u64)
-        -> Result<BlockStatusTriple, BeaconChainBlockError>
+    pub(crate) fn block_validation_context(&self, block: &SszBeaconBlock, present_slot: u64)
+        -> Result<BeaconBlockValidationContext<T>, BlockValidationContextError>
     {
-        /*
-         * Generate a SszBlock to read directly from the serialized SSZ.
-         */
-        let block = SszBeaconBlock::from_slice(ssz)?;
-        let block_hash = Hash256::from(&block.block_hash()[..]);
-
         /*
          * Load the crystallized state for this block from our caches.
          *
@@ -73,7 +47,7 @@ impl<T> BeaconChain<T>
          */
         let cry_state_root = Hash256::from(block.cry_state_root());
         let cry_state = self.crystallized_states.get(&cry_state_root)
-            .ok_or(BeaconChainBlockError::UnknownCrystallizedState)?;
+            .ok_or(BlockValidationContextError::UnknownCrystallizedState)?;
 
         /*
          * Load the active state for this block from our caches.
@@ -82,7 +56,7 @@ impl<T> BeaconChain<T>
          */
         let act_state_root = Hash256::from(block.act_state_root());
         let act_state = self.active_states.get(&act_state_root)
-            .ok_or(BeaconChainBlockError::UnknownActiveState)?;
+            .ok_or(BlockValidationContextError::UnknownActiveState)?;
 
         /*
          * Learn the last justified slot from the crystallized state and load
@@ -90,21 +64,18 @@ impl<T> BeaconChain<T>
          */
         let last_justified_slot = cry_state.last_justified_slot;
         let parent_block_hash = block.parent_hash()
-            .ok_or(BeaconChainBlockError::NoParentHash)?;
+            .ok_or(BlockValidationContextError::NoParentHash)?;
         let (last_justified_block_hash, _) = self.store.block.block_at_slot(
             &parent_block_hash, last_justified_slot)?
-            .ok_or(BeaconChainBlockError::UnknownJustifiedBlock)?;
+            .ok_or(BlockValidationContextError::UnknownJustifiedBlock)?;
 
         /*
          * Load the attester and proposer maps for the crystallized state.
          */
         let (attester_map, proposer_map) = self.attester_proposer_maps.get(&cry_state_root)
-            .ok_or(BeaconChainBlockError::UnknownAttesterProposerMaps)?;
+            .ok_or(BlockValidationContextError::UnknownAttesterProposerMaps)?;
 
-        /*
-         * Build a block validation context to test the block against.
-         */
-        let validation_context = BeaconBlockValidationContext {
+        Ok(BeaconBlockValidationContext {
             present_slot,
             cycle_length: self.config.cycle_length,
             last_justified_slot: cry_state.last_justified_slot,
@@ -116,17 +87,6 @@ impl<T> BeaconChain<T>
             block_store: self.store.block.clone(),
             validator_store: self.store.validator.clone(),
             pow_store: self.store.pow_chain.clone(),
-        };
-        let (block_status, deserialized_block) = validation_context.validate_ssz_block(&block_hash, &block)?;
-        match deserialized_block {
-            Some(b) => Ok((block_status, block_hash, b)),
-            None => Err(BeaconChainBlockError::BlockAlreadyKnown)
-        }
-    }
-}
-
-impl From<SszBeaconBlockError> for BeaconChainBlockError {
-    fn from(e: SszBeaconBlockError) -> BeaconChainBlockError {
-        BeaconChainBlockError::BadSsz(e)
+        })
     }
 }

beacon_chain/chain/src/block_processing.rs

@@ -0,0 +1,109 @@
+use super::{
+    BeaconChain,
+    ClientDB,
+};
+use super::block_context::{
+    BlockValidationContextError,
+};
+use ssz_helpers::ssz_beacon_block::{
+    SszBeaconBlock,
+    SszBeaconBlockError,
+};
+use types::{
+    Hash256,
+};
+use validation::block_validation::{
+    BeaconBlockStatus,
+    SszBeaconBlockValidationError,
+};
+
+pub enum BlockProcessingOutcome {
+    BlockAlreadyKnown,
+    NewCanonicalBlock,
+    NewForkBlock,
+}
+
+pub enum BlockProcessingError {
+    ContextGenerationError(BlockValidationContextError),
+    DeserializationFailed(SszBeaconBlockError),
+    ValidationFailed(SszBeaconBlockValidationError),
+}
+
+impl<T> BeaconChain<T>
+    where T: ClientDB + Sized
+{
+    pub fn process_block(&mut self, ssz: &[u8], present_slot: u64)
+        -> Result<(BlockProcessingOutcome, Hash256), BlockProcessingError>
+    {
+        /*
+         * Generate a SszBlock to read directly from the serialized SSZ.
+         */
+        let ssz_block = SszBeaconBlock::from_slice(ssz)?;
+        let block_hash = Hash256::from(&ssz_block.block_hash()[..]);
+        let parent_hash = ssz_block.parent_hash()
+            .ok_or(BlockProcessingError::ValidationFailed(
+                    SszBeaconBlockValidationError::UnknownParentHash))?;
+
+        /*
+         * Generate the context in which to validate this block.
+         */
+        let validation_context = self.block_validation_context(&ssz_block, present_slot)?;
+
+        /*
+         * Validate the block against the context, checking signatures, parent_hashes, etc.
+         */
+        let (block_status, block) = validation_context.validate_ssz_block(&block_hash, &block)?;
+
+        match block_status {
+            /*
+             *
+             */
+            BeaconBlockStatus::KnownBlock => {
+                Ok((BlockProcessingOutcome::BlockAlreadyKnown, block_hash))
+            }
+            BeaconBlockStatus::NewBlock => {
+                let head_hash_index = {
+                    match self.head_block_hashes.iter().position(|x| *x == Hash256::from(parent_hash)) {
+                        Some(i) => i,
+                        None => {
+                            self.head_block_hashes.push(block_hash);
+                            self.head_block_hashes.len() - 1
+                        }
+                    }
+                };
+
+                if head_hash_index == self.canonical_head_block_hash {
+                    Ok((BlockProcessingOutcome::NewCanonicalBlock, block_hash))
+                } else {
+                    Ok((BlockProcessingOutcome::NewForkBlock, block_hash))
+                }
+            }
+        }
+    }
+
+    pub fn extend_chain(
+        &self,
+        block: &Block,
+        block_hash: &Hash256,
+        head_hash_index: usize)
+        -> Result<>
+}
+
+
+impl From<BlockValidationContextError> for BlockProcessingError {
+    fn from(e: BlockValidationContextError) -> Self {
+        BlockProcessingError::ContextGenerationError(e)
+    }
+}
+
+impl From<SszBeaconBlockError> for BlockProcessingError {
+    fn from(e: SszBeaconBlockError) -> Self {
+        BlockProcessingError::DeserializationFailed(e)
+    }
+}
+
+impl From<SszBeaconBlockValidationError> for BlockProcessingError {
+    fn from(e: SszBeaconBlockValidationError) -> Self {
+        BlockProcessingError::ValidationFailed(e)
+    }
+}

beacon_chain/chain/src/lib.rs

@@ -1,10 +1,13 @@
 extern crate db;
 extern crate types;
+extern crate ssz_helpers;
+extern crate validation;
 extern crate validator_induction;
 extern crate validator_shuffling;
 
 mod stores;
-mod block_preprocessing;
+mod block_context;
+mod block_processing;
 mod maps;
 mod genesis;
 
@@ -43,10 +46,10 @@ impl From<AttesterAndProposerMapError> for BeaconChainError {
 pub struct BeaconChain<T: ClientDB + Sized> {
     /// The last slot which has been finalized, this is common to all forks.
     pub last_finalized_slot: u64,
-    /// The hash of the head of the canonical chain.
-    pub canonical_latest_block_hash: Hash256,
-    /// A vec of hashes of heads of fork (non-canonical) chains.
-    pub fork_latest_block_hashes: Vec<Hash256>,
+    /// A vec of all block heads (tips of chains).
+    pub head_block_hashes: Vec<Hash256>,
+    /// The index of the canonical block in `head_block_hashes`.
+    pub canonical_head_block_hash: usize,
     /// A map where the value is an active state the the key is its hash.
     pub active_states: HashMap<Hash256, ActiveState>,
     /// A map where the value is crystallized state the the key is its hash.
@@ -72,7 +75,8 @@ impl<T> BeaconChain<T>
         let (active_state, crystallized_state) = genesis_states(&config)?;
 
         let canonical_latest_block_hash = Hash256::zero();
-        let fork_latest_block_hashes = vec![];
+        let head_block_hashes = vec![canonical_latest_block_hash];
+        let canonical_head_block_hash = 0;
         let mut active_states = HashMap::new();
         let mut crystallized_states = HashMap::new();
         let mut attester_proposer_maps = HashMap::new();
@@ -88,8 +92,8 @@ impl<T> BeaconChain<T>
 
         Ok(Self{
             last_finalized_slot: 0,
-            canonical_latest_block_hash,
-            fork_latest_block_hashes,
+            head_block_hashes,
+            canonical_head_block_hash,
             active_states,
             crystallized_states,
             attester_proposer_maps,
@@ -97,6 +101,10 @@ impl<T> BeaconChain<T>
             config,
         })
     }
+
+    pub fn canonical_block_hash(self) -> Hash256 {
+        self.head_block_hashes[self.canonical_head_block_hash]
+    }
 }
 
 
@@ -128,7 +136,7 @@ mod tests {
         let (act, cry) = genesis_states(&config).unwrap();
 
         assert_eq!(chain.last_finalized_slot, 0);
-        assert_eq!(chain.canonical_latest_block_hash, Hash256::zero());
+        assert_eq!(chain.canonical_block_hash(), Hash256::zero());
 
         let stored_act = chain.active_states.get(&Hash256::zero()).unwrap();
         assert_eq!(act, *stored_act);

lighthouse/db/src/stores/beacon_block_store.rs

@@ -51,13 +51,6 @@ impl<T: ClientDB> BeaconBlockStore<T> {
         self.db.exists(DB_COLUMN, hash)
     }
 
-    pub fn block_exists_in_canonical_chain(&self, hash: &[u8])
-        -> Result<bool, DBError>
-    {
-        // TODO: implement logic for canonical chain
-        self.db.exists(DB_COLUMN, hash)
-    }
-
     /// Retrieve the block at a slot given a "head_hash" and a slot.
     ///
     /// A "head_hash" must be a block hash with a slot number greater than or equal to the desired