Extend transaction attributes with labels

TransactionAttribute now exposes a labels attribute that associates a
descriptive array of labels with a transaction.

Labels may be of a pure descriptive nature or may get evaluated by
transaction managers to associate technology-specific behavior
with the actual transaction.

spring-tx/src/main/java/org/springframework/transaction/annotation/SpringTransactionAnnotationParser.java

@@ -19,6 +19,7 @@ package org.springframework.transaction.annotation;
 import java.io.Serializable;
 import java.lang.reflect.AnnotatedElement;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import org.springframework.core.annotation.AnnotatedElementUtils;
@@ -34,6 +35,7 @@ import org.springframework.transaction.interceptor.TransactionAttribute;
  * Strategy implementation for parsing Spring's {@link Transactional} annotation.
  *
  * @author Juergen Hoeller
+ * @author Mark Paluch
  * @since 2.5
  */
 @SuppressWarnings("serial")
@@ -71,6 +73,7 @@ public class SpringTransactionAnnotationParser implements TransactionAnnotationP
 		rbta.setTimeout(attributes.getNumber("timeout").intValue());
 		rbta.setReadOnly(attributes.getBoolean("readOnly"));
 		rbta.setQualifier(attributes.getString("value"));
+		rbta.setLabels(Arrays.asList(attributes.getStringArray("label")));
 
 		List<RollbackRuleAttribute> rollbackRules = new ArrayList<>();
 		for (Class<?> rbRule : attributes.getClassArray("rollbackFor")) {

spring-tx/src/main/java/org/springframework/transaction/annotation/Transactional.java

@@ -51,6 +51,7 @@ import org.springframework.transaction.TransactionDefinition;
  * @author Colin Sampaleanu
  * @author Juergen Hoeller
  * @author Sam Brannen
+ * @author Mark Paluch
  * @since 1.2
  * @see org.springframework.transaction.interceptor.TransactionAttribute
  * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute
@@ -187,4 +188,17 @@ public @interface Transactional {
 	 */
 	String[] noRollbackForClassName() default {};
 
+	/**
+	 * Defines zero (0) or more transaction labels. Labels may be used to
+	 * describe a transaction and they can be evaluated by individual transaction
+	 * manager. Labels may serve a solely descriptive purpose or map to
+	 * pre-defined transaction manager-specific options.
+	 * <p>See the description of the actual transaction manager implementation
+	 * how it evaluates transaction labels.
+	 *
+	 * @since 5.3
+	 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute#getLabels()
+	 */
+	String[] label() default {};
+
 }

spring-tx/src/main/java/org/springframework/transaction/interceptor/DefaultTransactionAttribute.java

@@ -16,6 +16,9 @@
 
 package org.springframework.transaction.interceptor;
 
+import java.util.Collection;
+import java.util.Collections;
+
 import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.DefaultTransactionDefinition;
 import org.springframework.util.StringUtils;
@@ -26,6 +29,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Rod Johnson
  * @author Juergen Hoeller
+ * @author Mark Paluch
  * @since 16.03.2003
  */
 @SuppressWarnings("serial")
@@ -37,6 +41,8 @@ public class DefaultTransactionAttribute extends DefaultTransactionDefinition im
 	@Nullable
 	private String descriptor;
 
+	private Collection<String> labels = Collections.emptyList();
+
 
 	/**
 	 * Create a new DefaultTransactionAttribute, with default settings.
@@ -97,6 +103,21 @@ public class DefaultTransactionAttribute extends DefaultTransactionDefinition im
 		return this.qualifier;
 	}
 
+	/**
+	 * Associate one or more labels with this transaction attribute.
+	 * <p>This may be used for applying specific transactional behavior
+	 * or follow a purely descriptive nature.
+	 * @since 5.3
+	 */
+	public void setLabels(Collection<String> labels) {
+		this.labels = labels;
+	}
+
+	@Override
+	public Collection<String> getLabels() {
+		return this.labels;
+	}
+
 	/**
 	 * Set a descriptor for this transaction attribute,
 	 * e.g. indicating where the attribute is applying.
@@ -145,6 +166,9 @@ public class DefaultTransactionAttribute extends DefaultTransactionDefinition im
 		if (StringUtils.hasText(this.qualifier)) {
 			result.append("; '").append(this.qualifier).append("'");
 		}
+		if (!this.labels.isEmpty()) {
+			result.append("; ").append(this.labels);
+		}
 		return result;
 	}
 

spring-tx/src/main/java/org/springframework/transaction/interceptor/DelegatingTransactionAttribute.java

@@ -17,6 +17,7 @@
 package org.springframework.transaction.interceptor;
 
 import java.io.Serializable;
+import java.util.Collection;
 
 import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.DelegatingTransactionDefinition;
@@ -28,6 +29,7 @@ import org.springframework.transaction.support.DelegatingTransactionDefinition;
  * to the target instance.
  *
  * @author Juergen Hoeller
+ * @author Mark Paluch
  * @since 1.2
  */
 @SuppressWarnings("serial")
@@ -53,6 +55,11 @@ public abstract class DelegatingTransactionAttribute extends DelegatingTransacti
 		return this.targetAttribute.getQualifier();
 	}
 
+	@Override
+	public Collection<String> getLabels() {
+		return this.targetAttribute.getLabels();
+	}
+
 	@Override
 	public boolean rollbackOn(Throwable ex) {
 		return this.targetAttribute.rollbackOn(ex);

spring-tx/src/main/java/org/springframework/transaction/interceptor/TransactionAttribute.java

@@ -16,6 +16,8 @@
 
 package org.springframework.transaction.interceptor;
 
+import java.util.Collection;
+
 import org.springframework.lang.Nullable;
 import org.springframework.transaction.TransactionDefinition;
 
@@ -26,6 +28,7 @@ import org.springframework.transaction.TransactionDefinition;
  *
  * @author Rod Johnson
  * @author Juergen Hoeller
+ * @author Mark Paluch
  * @since 16.03.2003
  * @see DefaultTransactionAttribute
  * @see RuleBasedTransactionAttribute
@@ -41,6 +44,14 @@ public interface TransactionAttribute extends TransactionDefinition {
 	@Nullable
 	String getQualifier();
 
+	/**
+	 * Return labels associated with this transaction attribute.
+	 * <p>This may be used for applying specific transactional behavior
+	 * or follow a purely descriptive nature.
+	 * @since 5.3
+	 */
+	Collection<String> getLabels();
+
 	/**
 	 * Should we roll back on the given exception?
 	 * @param ex the exception to evaluate