Process attestations when the state from their target block state is …

…available in cache. (#7142)

Co-authored-by: Paul Harris <paul.harris@consensys.net>

ethereum/dataproviders/src/main/java/tech/pegasys/teku/dataproviders/generators/CachingTaskQueue.java

@@ -218,6 +218,10 @@ public void removeIf(final Predicate<K> removalCondition) {
     cache.keySet().removeIf(removalCondition);
   }
 
+  public void clear() {
+    cache.clear();
+  }
+
   public interface CacheableTask<K, V> {
     /**
      * The key that uniquely identifies this task. Two tasks with equal keys should also have

ethereum/statetransition/src/main/java/tech/pegasys/teku/statetransition/validation/AttestationStateSelector.java

@@ -88,6 +88,15 @@ public SafeFuture<Optional<BeaconState>> getStateToValidate(
       return completedFuture(Optional.empty());
     }
 
+    // Check if the attestations head block state is already available in cache and usable
+    if (targetBlockSlot.get().isGreaterThanOrEqualTo(earliestSlot)) {
+      final Optional<BeaconState> maybeState =
+          recentChainData.getStore().getBlockStateIfAvailable(targetBlockRoot);
+      if (maybeState.isPresent()) {
+        return SafeFuture.completedFuture(maybeState);
+      }
+    }
+
     if (isJustificationTooOld(targetBlockRoot, targetBlockSlot.get())) {
       // we already justified a more recent slot on all compatible heads
       LOG.debug(

ethereum/statetransition/src/test/java/tech/pegasys/teku/statetransition/validation/AttestationStateSelectorTest.java

@@ -164,6 +164,38 @@ void shouldIgnoreAttestationsWithTargetWhichIsAlreadyJustified() {
     assertThat(selectedState).isEmpty();
   }
 
+  @Test
+  void shouldNotRegenerateStateForAttestationsWithTargetWhichIsAlreadyJustified() {
+    // Advance the chain far enough that the finalized checkpoint isn't usable
+    chainUpdater.updateBestBlock(
+        chainUpdater.advanceChainUntil(spec.computeStartSlotAtEpoch(UInt64.valueOf(3))));
+
+    final ChainBuilder forkBuilder = chainBuilder.fork();
+
+    final SignedBlockAndState forkBlock =
+        forkBuilder.generateBlockAtSlot(spec.computeStartSlotAtEpoch(UInt64.valueOf(3)).plus(1));
+
+    chainUpdater.saveBlock(forkBlock);
+
+    // advance chain head to epoch 5 and justify epoch 4
+    chainUpdater.advanceChainUntil(spec.computeStartSlotAtEpoch(UInt64.valueOf(5)));
+    chainUpdater.justifyEpoch(4);
+
+    // Attestation slot of the fork block is before an already justified checkpoint
+    final UInt64 attestationSlot = forkBlock.getSlot();
+    final Bytes32 blockRoot = forkBlock.getRoot();
+
+    final SafeFuture<Optional<BeaconState>> resultWithCache =
+        selectStateFor(attestationSlot, blockRoot);
+    assertThatSafeFuture(resultWithCache).isCompletedWithOptionalContaining(forkBlock.getState());
+
+    recentChainData.getStore().clearCaches();
+
+    final SafeFuture<Optional<BeaconState>> resultWithNoCache =
+        selectStateFor(attestationSlot, blockRoot);
+    assertThatSafeFuture(resultWithNoCache).isCompletedWithEmptyOptional();
+  }
+
   private SafeFuture<Optional<BeaconState>> selectStateFor(
       final UInt64 attestationSlot, final Bytes32 blockRoot) {
     final AttestationData attestationData = attestationFor(attestationSlot, blockRoot);

storage/src/main/java/tech/pegasys/teku/storage/store/Store.java

@@ -298,6 +298,13 @@ public ForkChoiceStrategy getForkChoiceStrategy() {
     return forkChoiceStrategy;
   }
 
+  @Override
+  public void clearCaches() {
+    states.clear();
+    checkpointStates.clear();
+    blocks.clear();
+  }
+
   @Override
   public StoreTransaction startTransaction(final StorageUpdateChannel storageUpdateChannel) {
     return startTransaction(storageUpdateChannel, StoreUpdateHandler.NOOP);

storage/src/main/java/tech/pegasys/teku/storage/store/UpdatableStore.java

@@ -37,6 +37,9 @@ StoreTransaction startTransaction(
   @Override
   ForkChoiceStrategy getForkChoiceStrategy();
 
+  /** Clears in-memory caches. This is not something you'll want to do in production codee... */
+  void clearCaches();
+
   interface StoreTransaction extends MutableStore {
     SafeFuture<Void> commit();