refactor SimpleWorld to use Optional for storing accounts and extra n…

…ull checks (hyperledger#7532)

Signed-off-by: Luis Pinto <luis.pinto@consensys.net>

evm/src/main/java/org/hyperledger/besu/evm/fluent/SimpleAccount.java

@@ -214,21 +214,4 @@ public boolean commit() {
  return false;
  }
  }
-
- /**
- * Push changes into the parent account, if one exists
- *
- * @return true if a parent account was updated, false if not (this indicates the account should
- * be inserted into the parent contact).
- */
- public boolean updateParent() {
- if (parent instanceof SimpleAccount simpleAccount) {
- simpleAccount.balance = balance;
- simpleAccount.nonce = nonce;
- simpleAccount.storage.putAll(storage);
- return true;
- } else {
- return false;
- }
- }
 }

evm/src/main/java/org/hyperledger/besu/evm/fluent/SimpleWorld.java

@@ -29,10 +29,10 @@
 public class SimpleWorld implements WorldUpdater {
 
  /** The Parent. */
- SimpleWorld parent;
+ private final SimpleWorld parent;
 
  /** The Accounts. */
- Map<Address, SimpleAccount> accounts = new HashMap<>();
+ private Map<Address, Optional<SimpleAccount>> accounts = new HashMap<>();
 
  /** Instantiates a new Simple world. */
  public SimpleWorld() {
@@ -55,13 +55,15 @@ public WorldUpdater updater() {
 
  @Override
  public Account get(final Address address) {
+ Optional<SimpleAccount> account = Optional.empty();
  if (accounts.containsKey(address)) {
- return accounts.get(address);
+ account = accounts.get(address);
  } else if (parent != null) {
- return parent.get(address);
- } else {
- return null;
+ if (parent.get(address) instanceof SimpleAccount accountFromParent) {
+  account = Optional.of(accountFromParent);
+ }
  }
+ return account.orElse(null);
  }
 
  @Override
@@ -70,45 +72,46 @@ public MutableAccount createAccount(final Address address, final long nonce, fin
  throw new IllegalStateException("Cannot create an account when one already exists");
  }
  SimpleAccount account = new SimpleAccount(address, nonce, balance);
- accounts.put(address, account);
+ accounts.put(address, Optional.of(account));
  return account;
  }
 
  @Override
  public MutableAccount getAccount(final Address address) {
- SimpleAccount account = accounts.get(address);
+ Optional<SimpleAccount> account = accounts.get(address);
  if (account != null) {
- return account;
+ return account.orElse(null);
  }
  Account parentAccount = parent == null ? null : parent.getAccount(address);
  if (parentAccount != null) {
  account =
- new SimpleAccount(
- parentAccount,
- parentAccount.getAddress(),
- parentAccount.getNonce(),
- parentAccount.getBalance(),
- parentAccount.getCode());
+ Optional.of(
+ new SimpleAccount(
+ parentAccount,
+ parentAccount.getAddress(),
+ parentAccount.getNonce(),
+ parentAccount.getBalance(),
+ parentAccount.getCode()));
  accounts.put(address, account);
- return account;
+ return account.get();
  }
  return null;
  }
 
  @Override
  public void deleteAccount(final Address address) {
- accounts.put(address, null);
+ accounts.put(address, Optional.empty());
  }
 
  @Override
  public Collection<? extends Account> getTouchedAccounts() {
- return accounts.values();
+ return accounts.values().stream().filter(Optional::isPresent).map(Optional::get).toList();
  }
 
  @Override
  public Collection<Address> getDeletedAccountAddresses() {
  return accounts.entrySet().stream()
- .filter(e -> e.getValue() == null)
+ .filter(e -> e.getValue().isEmpty())
  .map(Map.Entry::getKey)
  .toList();
  }
@@ -122,8 +125,10 @@ public void revert() {
  public void commit() {
  accounts.forEach(
  (address, account) -> {
- if (!account.updateParent()) {
- parent.accounts.put(address, account);
+ if (account.isEmpty() || !account.get().commit()) {
+ if (parent != null) {
+ parent.accounts.put(address, account);
+ }
  }
  });
  }