Merge pull request ProvableHQ#1967 from niklaslong/cache-committee

Cache the current committee in ledger

ledger/src/advance.rs

@@ -75,11 +75,17 @@ impl<N: Network, C: ConsensusStorage<N>> Ledger<N, C> {
         // Drop the write lock on the current block.
         drop(current_block);
 
+        // Update the cached committee from storage.
+        if let Ok(current_committee) = self.vm.finalize_store().committee_store().current_committee() {
+            *self.current_committee.write() = Some(current_committee);
+        }
+
         // If the block is the start of a new epoch, or the epoch challenge has not been set, update the current epoch challenge.
         if block.height() % N::NUM_BLOCKS_PER_EPOCH == 0 || self.current_epoch_challenge.read().is_none() {
             // Update the current epoch challenge.
             self.current_epoch_challenge.write().clone_from(&self.get_epoch_challenge(block.height()).ok());
         }
+
         Ok(())
     }
 }

ledger/src/lib.rs

@@ -109,6 +109,8 @@ pub struct Ledger<N: Network, C: ConsensusStorage<N>> {
     coinbase_puzzle: CoinbasePuzzle<N>,
     /// The current epoch challenge.
     current_epoch_challenge: Arc<RwLock<Option<EpochChallenge<N>>>>,
+    /// The current committee.
+    current_committee: Arc<RwLock<Option<Committee<N>>>>,
     /// The current block.
     current_block: Arc<RwLock<Block<N>>>,
 }
@@ -161,12 +163,16 @@ impl<N: Network, C: ConsensusStorage<N>> Ledger<N, C> {
         let vm = VM::from(store)?;
         lap!(timer, "Initialize a new VM");
 
+        // Retrieve the current committee.
+        let current_committee = vm.finalize_store().committee_store().current_committee().ok();
+
         // Initialize the ledger.
         let mut ledger = Self {
             vm,
             genesis_block: genesis_block.clone(),
             coinbase_puzzle: CoinbasePuzzle::<N>::load()?,
             current_epoch_challenge: Default::default(),
+            current_committee: Arc::new(RwLock::new(current_committee)),
             current_block: Arc::new(RwLock::new(genesis_block.clone())),
         };
 
@@ -187,11 +193,12 @@ impl<N: Network, C: ConsensusStorage<N>> Ledger<N, C> {
 
         // Set the current block.
         ledger.current_block = Arc::new(RwLock::new(block));
+        // Set the current committee (and ensures the latest committee exists).
+        ledger.current_committee = Arc::new(RwLock::new(Some(ledger.latest_committee()?)));
         // Set the current epoch challenge.
         ledger.current_epoch_challenge = Arc::new(RwLock::new(Some(ledger.get_epoch_challenge(latest_height)?)));
-        lap!(timer, "Initialize ledger");
 
-        finish!(timer);
+        finish!(timer, "Initialize ledger");
         Ok(ledger)
     }
 
@@ -207,7 +214,10 @@ impl<N: Network, C: ConsensusStorage<N>> Ledger<N, C> {
 
     /// Returns the latest committee.
     pub fn latest_committee(&self) -> Result<Committee<N>> {
-        self.vm.finalize_store().committee_store().current_committee()
+        match self.current_committee.read().as_ref() {
+            Some(committee) => Ok(committee.clone()),
+            None => self.vm.finalize_store().committee_store().current_committee(),
+        }
     }
 
     /// Returns the latest state root.