Cache empty slots

CHANGELOG.md

@@ -6,6 +6,8 @@
 - Default configurations for the deprecated Ropsten, Kiln, Shandong, and Astor networks have been removed from the CLI network list. These networks can currently be accessed but will require a user-provided genesis configuration. [#4869](https://github.com/hyperledger/besu/pull/4869)
 
 ### Additions and Improvements
+
+- Improve SLOAD and SSTORE performance by caching empty slots [#4874](https://github.com/hyperledger/besu/pull/4874)
 - RPC methods that lookup block by hash will now return an error response if no block found [#4582](https://github.com/hyperledger/besu/pull/4582)
 
 ### Bug Fixes

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/bonsai/BonsaiWorldStateUpdater.java

@@ -52,6 +52,7 @@ public class BonsaiWorldStateUpdater extends AbstractWorldUpdater<BonsaiWorldVie
   private final Consumer<Hash> storagePreloader;
   private final Map<Address, BonsaiValue<Bytes>> codeToUpdate = new ConcurrentHashMap<>();
   private final Set<Address> storageToClear = Collections.synchronizedSet(new HashSet<>());
+  private final Set<Bytes> emptySlot = Collections.synchronizedSet(new HashSet<>());
 
   // storage sub mapped by _hashed_ key.  This is because in self_destruct calls we need to
   // enumerate the old storage and delete it.  Those are trie stored by hashed key by spec and the
@@ -87,6 +88,7 @@ void cloneFromUpdater(final BonsaiWorldStateUpdater source) {
     storageToUpdate.putAll(source.storageToUpdate);
     updatedAccounts.putAll(source.updatedAccounts);
     deletedAccounts.addAll(source.deletedAccounts);
+    emptySlot.addAll(source.emptySlot);
   }
 
   @Override
@@ -349,18 +351,26 @@ public Optional<UInt256> getStorageValueBySlotHash(final Address address, final
         return Optional.ofNullable(value.getUpdated());
       }
     }
-    final Optional<UInt256> valueUInt =
-        wrappedWorldView().getStorageValueBySlotHash(address, slotHash);
-    valueUInt.ifPresent(
-        v ->
-            storageToUpdate
-                .computeIfAbsent(
-                    address,
-                    key ->
-                        new StorageConsumingMap<>(
-                            address, new ConcurrentHashMap<>(), storagePreloader))
-                .put(slotHash, new BonsaiValue<>(v, v)));
-    return valueUInt;
+    final Bytes slot = Bytes.concatenate(Hash.hash(address), slotHash);
+    if (emptySlot.contains(slot)) {
+      return Optional.empty();
+    } else {
+      final Optional<UInt256> valueUInt =
+          wrappedWorldView().getStorageValueBySlotHash(address, slotHash);
+      valueUInt.ifPresentOrElse(
+          v ->
+              storageToUpdate
+                  .computeIfAbsent(
+                      address,
+                      key ->
+                          new StorageConsumingMap<>(
+                              address, new ConcurrentHashMap<>(), storagePreloader))
+                  .put(slotHash, new BonsaiValue<>(v, v)),
+          () -> {
+            emptySlot.add(Bytes.concatenate(Hash.hash(address), slotHash));
+          });
+      return valueUInt;
+    }
   }
 
   @Override
@@ -705,6 +715,7 @@ public void reset() {
     storageToUpdate.clear();
     codeToUpdate.clear();
     accountsToUpdate.clear();
+    emptySlot.clear();
     super.reset();
   }