Remove reliance on a blockchain read lock from block/commit

coordinator/src/main.rs

@@ -175,8 +175,8 @@ pub async fn heartbeat_tributaries<D: Db, P: P2p>(
     for ActiveTributary { spec: _, tributary } in tributaries.read().await.values() {
       let tributary = tributary.read().await;
       let tip = tributary.tip().await;
-      let block_time = SystemTime::UNIX_EPOCH +
-        Duration::from_secs(tributary.time_of_block(&tip).await.unwrap_or(0));
+      let block_time =
+        SystemTime::UNIX_EPOCH + Duration::from_secs(tributary.time_of_block(&tip).unwrap_or(0));
 
       // Only trigger syncing if the block is more than a minute behind
       if SystemTime::now() > (block_time + Duration::from_secs(60)) {

coordinator/src/tests/tributary/chain.rs

@@ -124,14 +124,14 @@ pub async fn wait_for_tx_inclusion(
       continue;
     }
 
-    let mut queue = vec![tributary.block(&tip).await.unwrap()];
+    let mut queue = vec![tributary.block(&tip).unwrap()];
     let mut block = None;
     while {
       let parent = queue.last().unwrap().parent();
       if parent == tributary.genesis() {
         false
       } else {
-        block = Some(tributary.block(&parent).await.unwrap());
+        block = Some(tributary.block(&parent).unwrap());
         block.as_ref().unwrap().hash() != last_checked
       }
     } {

coordinator/src/tests/tributary/tx.rs

@@ -46,7 +46,7 @@ async fn tx_test() {
 
   // All tributaries should have acknowledged this transaction in a block
   for (_, tributary) in tributaries {
-    let block = tributary.block(&included_in).await.unwrap();
+    let block = tributary.block(&included_in).unwrap();
     assert_eq!(block.transactions, vec![tx.clone()]);
   }
 }

coordinator/src/tributary/scanner.rs

@@ -307,7 +307,7 @@ pub async fn handle_new_blocks<D: Db, Pro: Processor, P: P2p>(
 
   let mut blocks = VecDeque::new();
   // This is a new block, as per the prior if check
-  blocks.push_back(tributary.block(&latest).await.unwrap());
+  blocks.push_back(tributary.block(&latest).unwrap());
 
   let mut block = None;
   while {
@@ -317,7 +317,7 @@ pub async fn handle_new_blocks<D: Db, Pro: Processor, P: P2p>(
       false
     } else {
       // Get this block
-      block = Some(tributary.block(&parent).await.unwrap());
+      block = Some(tributary.block(&parent).unwrap());
       // If it's the last block we've scanned, it's the end. Else, push it
       block.as_ref().unwrap().hash() != last_block
     }

coordinator/tributary/src/blockchain.rs

@@ -29,12 +29,12 @@ impl<D: Db, T: Transaction> Blockchain<D, T> {
   fn block_number_key(&self) -> Vec<u8> {
     D::key(b"tributary_blockchain", b"block_number", self.genesis)
   }
-  fn block_key(&self, hash: &[u8; 32]) -> Vec<u8> {
+  fn block_key(hash: &[u8; 32]) -> Vec<u8> {
     // Since block hashes incorporate their parent, and the first parent is the genesis, this is
     // fine not incorporating the hash unless there's a hash collision
     D::key(b"tributary_blockchain", b"block", hash)
   }
-  fn commit_key(&self, hash: &[u8; 32]) -> Vec<u8> {
+  fn commit_key(hash: &[u8; 32]) -> Vec<u8> {
     D::key(b"tributary_blockchain", b"commit", hash)
   }
   fn next_nonce_key(&self, signer: &<Ristretto as Ciphersuite>::G) -> Vec<u8> {
@@ -92,17 +92,17 @@ impl<D: Db, T: Transaction> Blockchain<D, T> {
     self.block_number
   }
 
-  pub(crate) fn block(&self, block: &[u8; 32]) -> Option<Block<T>> {
-    self
-      .db
-      .as_ref()
-      .unwrap()
-      .get(self.block_key(block))
+  pub(crate) fn block_from_db(db: &D, block: &[u8; 32]) -> Option<Block<T>> {
+    db.get(Self::block_key(block))
       .map(|bytes| Block::<T>::read::<&[u8]>(&mut bytes.as_ref()).unwrap())
   }
 
+  pub(crate) fn commit_from_db(db: &D, block: &[u8; 32]) -> Option<Vec<u8>> {
+    db.get(Self::commit_key(block))
+  }
+
   pub(crate) fn commit(&self, block: &[u8; 32]) -> Option<Vec<u8>> {
-    self.db.as_ref().unwrap().get(self.commit_key(block))
+    Self::commit_from_db(self.db.as_ref().unwrap(), block)
   }
 
   pub(crate) fn add_transaction(&mut self, internal: bool, tx: T) -> bool {
@@ -155,8 +155,8 @@ impl<D: Db, T: Transaction> Blockchain<D, T> {
     self.block_number += 1;
     txn.put(self.block_number_key(), self.block_number.to_le_bytes());
 
-    txn.put(self.block_key(&self.tip), block.serialize());
-    txn.put(self.commit_key(&self.tip), commit);
+    txn.put(Self::block_key(&self.tip), block.serialize());
+    txn.put(Self::commit_key(&self.tip), commit);
 
     for tx in &block.transactions {
       match tx.kind() {

coordinator/tributary/src/lib.rs

@@ -83,6 +83,8 @@ impl<P: P2p> P2p for Arc<P> {
 
 #[derive(Clone)]
 pub struct Tributary<D: Db, T: Transaction, P: P2p> {
+  db: D,
+
   genesis: [u8; 32],
   network: TendermintNetwork<D, T, P>,
 
@@ -104,7 +106,7 @@ impl<D: Db, T: Transaction, P: P2p> Tributary<D, T, P> {
     let signer = Arc::new(Signer::new(genesis, key));
     let validators = Arc::new(Validators::new(genesis, validators)?);
 
-    let mut blockchain = Blockchain::new(db, genesis, &validators_vec);
+    let mut blockchain = Blockchain::new(db.clone(), genesis, &validators_vec);
     let block_number = BlockNumber(blockchain.block_number().into());
 
     let start_time = if let Some(commit) = blockchain.commit(&blockchain.tip()) {
@@ -121,7 +123,7 @@ impl<D: Db, T: Transaction, P: P2p> Tributary<D, T, P> {
       TendermintMachine::new(network.clone(), block_number, start_time, proposal).await;
     tokio::task::spawn(machine.run());
 
-    Some(Self { genesis, network, synced_block, messages: Arc::new(RwLock::new(messages)) })
+    Some(Self { db, genesis, network, synced_block, messages: Arc::new(RwLock::new(messages)) })
   }
 
   pub fn block_time() -> u32 {
@@ -132,29 +134,26 @@ impl<D: Db, T: Transaction, P: P2p> Tributary<D, T, P> {
     self.genesis
   }
 
-  // TODO: block, time_of_block, and commit shouldn't require acquiring the read lock
-  // These values can be safely read directly from the database since they're static
   pub async fn block_number(&self) -> u32 {
     self.network.blockchain.read().await.block_number()
   }
   pub async fn tip(&self) -> [u8; 32] {
     self.network.blockchain.read().await.tip()
   }
-  pub async fn block(&self, hash: &[u8; 32]) -> Option<Block<T>> {
-    self.network.blockchain.read().await.block(hash)
+
+  // Since these values are static, they can be safely read from the database without lock
+  // acquisition
+  pub fn block(&self, hash: &[u8; 32]) -> Option<Block<T>> {
+    Blockchain::<D, T>::block_from_db(&self.db, hash)
   }
-  pub async fn time_of_block(&self, hash: &[u8; 32]) -> Option<u64> {
+  pub fn commit(&self, hash: &[u8; 32]) -> Option<Vec<u8>> {
+    Blockchain::<D, T>::commit_from_db(&self.db, hash)
+  }
+  pub fn time_of_block(&self, hash: &[u8; 32]) -> Option<u64> {
     self
-      .network
-      .blockchain
-      .read()
-      .await
       .commit(hash)
       .map(|commit| Commit::<Validators>::decode(&mut commit.as_ref()).unwrap().end_time)
   }
-  pub async fn commit(&self, hash: &[u8; 32]) -> Option<Vec<u8>> {
-    self.network.blockchain.read().await.commit(hash)
-  }
 
   pub async fn provide_transaction(&self, tx: T) -> Result<(), ProvidedError> {
     self.network.blockchain.write().await.provide_transaction(tx)