Transaction pool, selection, and validation

Use transaction pool services to inspect pending transactions, control transaction pool availability, influence transaction selection, or add validation rules.

Observe pending transactions

TransactionPoolService exposes methods to:

• Disable or enable the transaction pool.
• Check whether the transaction pool is enabled.
• Retrieve pending transactions.

For event-based observation, BesuEvents exposes transaction added and transaction dropped listeners.

For example, inspect pending transaction count:

@Override
public void start() {
  serviceManager
      .getService(TransactionPoolService.class)
      .ifPresent(
          transactionPool -> {
            boolean enabled = transactionPool.isTransactionPoolEnabled();
            int pendingCount = transactionPool.getPendingTransactions().size();
          });
}

For event-based observation, register transaction listeners:

@Override
public void start() {
  serviceManager
      .getService(BesuEvents.class)
      .ifPresent(
          events -> {
            long addedListenerId = events.addTransactionAddedListener(transaction -> {});
            long droppedListenerId =
                events.addTransactionDroppedListener((transaction, reason) -> {});
          });
}

Influence selection

TransactionSelectionService exposes methods to create a plugin transaction selector, select pending transactions, and register a plugin transaction selector factory.

Use this service when the plugin needs to participate in transaction selection.

For example, register a selector factory:

@Override
public void register(final ServiceManager context) {
  this.serviceManager = context;
  serviceManager
      .getService(TransactionSelectionService.class)
      .ifPresent(
          selection ->
              selection.registerPluginTransactionSelectorFactory(transactionSelectorFactory));
}

The plugin supplies the PluginTransactionSelectorFactory implementation.

Validate transactions

TransactionPoolValidatorService exposes methods to create a plugin transaction pool validator and register a plugin transaction validator factory.

TransactionValidatorService exposes a method to register a transaction validation rule.

Use these services when a plugin needs custom validation behavior.

For example, register a transaction validation rule:

@Override
public void register(final ServiceManager context) {
  this.serviceManager = context;
  serviceManager
      .getService(TransactionValidatorService.class)
      .ifPresent(
          validator ->
              validator.registerTransactionValidatorRule(
                  transaction -> Optional.empty()));
}

Return an empty Optional when the transaction is valid, or an Optional containing a reason when the plugin rejects the transaction.

For transaction pool validation, register a validator factory:

@Override
public void register(final ServiceManager context) {
  this.serviceManager = context;
  serviceManager
      .getService(TransactionPoolValidatorService.class)
      .ifPresent(
          validator ->
              validator.registerPluginTransactionValidatorFactory(
                  transactionPoolValidatorFactory));
}

The plugin supplies the PluginTransactionPoolValidatorFactory implementation.