Allow TransactionOutbox#scheduler ThreadFactory customization

transactionoutbox-core/src/main/java/com/gruelbox/transactionoutbox/TransactionOutbox.java

@@ -3,6 +3,7 @@
 import java.time.Clock;
 import java.time.Duration;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ThreadFactory;
 import java.util.function.Supplier;
 import lombok.ToString;
 import org.slf4j.MDC;
@@ -152,6 +153,7 @@ abstract class TransactionOutboxBuilder {
     protected Boolean serializeMdc;
     protected Duration retentionThreshold;
     protected Boolean initializeImmediately;
+    protected ThreadFactory schedulerThreadFactory;
 
     protected TransactionOutboxBuilder() {}
 
@@ -298,6 +300,15 @@ public TransactionOutboxBuilder initializeImmediately(boolean initializeImmediat
       return this;
     }
 
+    /**
+     * @param schedulerThreadFactory The {@link ThreadFactory} that will be used to build the scheduler executor.
+     * @return Builder.
+     */
+    public TransactionOutboxBuilder schedulerThreadFactory(ThreadFactory schedulerThreadFactory) {
+      this.schedulerThreadFactory = schedulerThreadFactory;
+      return this;
+    }
+
     /**
      * Creates and initialises the {@link TransactionOutbox}.
      *

transactionoutbox-core/src/main/java/com/gruelbox/transactionoutbox/TransactionOutboxImpl.java

@@ -51,7 +51,7 @@ final class TransactionOutboxImpl implements TransactionOutbox, Validatable {
   private final Duration retentionThreshold;
   private final AtomicBoolean initialized = new AtomicBoolean();
   private final ProxyFactory proxyFactory = new ProxyFactory();
-  private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
+  private final ScheduledExecutorService scheduler;
 
   @Override
   public void validate(Validator validator) {
@@ -435,7 +435,8 @@ public TransactionOutboxImpl build() {
               Utils.firstNonNull(listener, () -> TransactionOutboxListener.EMPTY),
               serializeMdc == null || serializeMdc,
               validator,
-              retentionThreshold == null ? Duration.ofDays(7) : retentionThreshold);
+              retentionThreshold == null ? Duration.ofDays(7) : retentionThreshold,
+              schedulerThreadFactory == null? Executors.newSingleThreadScheduledExecutor() : Executors.newSingleThreadScheduledExecutor(schedulerThreadFactory));
       validator.validate(impl);
       if (initializeImmediately == null || initializeImmediately) {
         impl.initialize();