Document that TX rollback rules may result in unintentional matches

Closes gh-28125

Author: sbrannen

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,17 +37,57 @@
  * <a href="https://docs.spring.io/spring-framework/docs/current/reference/html/data-access.html#transaction">Transaction Management</a>
  * section of the reference manual.
  *
- * <p>This annotation type is generally directly comparable to Spring's
+ * <p>This annotation is generally directly comparable to Spring's
  * {@link org.springframework.transaction.interceptor.RuleBasedTransactionAttribute}
  * class, and in fact {@link AnnotationTransactionAttributeSource} will directly
- * convert the data to the latter class, so that Spring's transaction support code
- * does not have to know about annotations. If no custom rollback rules apply,
- * the transaction will roll back on {@link RuntimeException} and {@link Error}
- * but not on checked exceptions.
+ * convert this annotation's attributes to properties in {@code RuleBasedTransactionAttribute},
+ * so that Spring's transaction support code does not have to know about annotations.
  *
- * <p>For specific information about the semantics of this annotation's attributes,
- * consult the {@link org.springframework.transaction.TransactionDefinition} and
- * {@link org.springframework.transaction.interceptor.TransactionAttribute} javadocs.
+ * <h3>Attribute Semantics</h3>
+ *
+ * <p>If no custom rollback rules are configured in this annotation, the transaction
+ * will roll back on {@link RuntimeException} and {@link Error} but not on checked
+ * exceptions.
+ *
+ * <p>Rollback rules determine if a transaction should be rolled back when a given
+ * exception is thrown, and the rules are based on patterns. A pattern can be a
+ * fully qualified class name or a substring of a fully qualified class name for
+ * an exception type (which must be a subclass of {@code Throwable}), with no
+ * wildcard support at present. For example, a value of
+ * {@code "javax.servlet.ServletException"} or {@code "ServletException"} will
+ * match {@code javax.servlet.ServletException} and its subclasses.
+ *
+ * <p>Rollback rules may be configured via {@link #rollbackFor}/{@link #noRollbackFor}
+ * and {@link #rollbackForClassName}/{@link #noRollbackForClassName}, which allow
+ * patterns to be specified as {@link Class} references or {@linkplain String
+ * strings}, respectively. When an exception type is specified as a class reference
+ * its fully qualified name will be used as the pattern. Consequently,
+ * {@code @Transactional(rollbackFor = example.CustomException.class)} is equivalent
+ * to {@code @Transactional(rollbackForClassName = "example.CustomException")}.
+ *
+ * <p><strong>WARNING:</strong> You must carefully consider how specific the pattern
+ * is and whether to include package information (which isn't mandatory). For example,
+ * {@code "Exception"} will match nearly anything and will probably hide other
+ * rules. {@code "java.lang.Exception"} would be correct if {@code "Exception"}
+ * were meant to define a rule for all checked exceptions. With more unique
+ * exception names such as {@code "BaseBusinessException"} there is likely no
+ * need to use the fully qualified class name for the exception pattern. Furthermore,
+ * rollback rules may result in unintentional matches for similarly named exceptions
+ * and nested classes. This is due to the fact that a thrown exception is considered
+ * to be a match for a given rollback rule if the name of thrown exception contains
+ * the exception pattern configured for the rollback rule. For example, given a
+ * rule configured to match on {@code com.example.CustomException}, that rule
+ * would match against an exception named
+ * {@code com.example.CustomExceptionV2} (an exception in the same package as
+ * {@code CustomException} but with an additional suffix) or an exception named
+ * {@code com.example.CustomException$AnotherException}
+ * (an exception declared as a nested class in {@code CustomException}).
+ *
+ * <p>For specific information about the semantics of other attributes in this
+ * annotation, consult the {@link org.springframework.transaction.TransactionDefinition}
+ * and {@link org.springframework.transaction.interceptor.TransactionAttribute} javadocs.
+ *
+ * <h3>Transaction Management</h3>
  *
  * <p>This annotation commonly works with thread-bound transactions managed by a
  * {@link org.springframework.transaction.PlatformTransactionManager}, exposing a
@@ -167,37 +207,33 @@
 	boolean readOnly() default false;
 
 	/**
-	 * Defines zero (0) or more exception {@link Class classes}, which must be
+	 * Defines zero (0) or more exception {@linkplain Class classes}, which must be
 	 * subclasses of {@link Throwable}, indicating which exception types must cause
 	 * a transaction rollback.
-	 * <p>By default, a transaction will be rolling back on {@link RuntimeException}
+	 * <p>By default, a transaction will be rolled back on {@link RuntimeException}
 	 * and {@link Error} but not on checked exceptions (business exceptions). See
 	 * {@link org.springframework.transaction.interceptor.DefaultTransactionAttribute#rollbackOn(Throwable)}
 	 * for a detailed explanation.
 	 * <p>This is the preferred way to construct a rollback rule (in contrast to
-	 * {@link #rollbackForClassName}), matching the exception class and its subclasses.
-	 * <p>Similar to {@link org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(Class clazz)}.
+	 * {@link #rollbackForClassName}), matching the exception type, its subclasses,
+	 * and its nested classes. See the {@linkplain Transactional class-level javadocs}
+	 * for further details on rollback rule semantics and warnings regarding possible
+	 * unintentional matches.
 	 * @see #rollbackForClassName
+	 * @see org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(Class)
 	 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute#rollbackOn(Throwable)
 	 */
 	Class<? extends Throwable>[] rollbackFor() default {};
 
 	/**
-	 * Defines zero (0) or more exception names (for exceptions which must be a
+	 * Defines zero (0) or more exception name patterns (for exceptions which must be a
 	 * subclass of {@link Throwable}), indicating which exception types must cause
 	 * a transaction rollback.
-	 * <p>This can be a substring of a fully qualified class name, with no wildcard
-	 * support at present. For example, a value of {@code "ServletException"} would
-	 * match {@code javax.servlet.ServletException} and its subclasses.
-	 * <p><b>NB:</b> Consider carefully how specific the pattern is and whether
-	 * to include package information (which isn't mandatory). For example,
-	 * {@code "Exception"} will match nearly anything and will probably hide other
-	 * rules. {@code "java.lang.Exception"} would be correct if {@code "Exception"}
-	 * were meant to define a rule for all checked exceptions. With more unusual
-	 * {@link Exception} names such as {@code "BaseBusinessException"} there is no
-	 * need to use a FQN.
-	 * <p>Similar to {@link org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(String exceptionName)}.
+	 * <p>See the {@linkplain Transactional class-level javadocs} for further details
+	 * on rollback rule semantics, patterns, and warnings regarding possible
+	 * unintentional matches.
 	 * @see #rollbackFor
+	 * @see org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(String)
 	 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute#rollbackOn(Throwable)
 	 */
 	String[] rollbackForClassName() default {};
@@ -206,23 +242,26 @@
 	 * Defines zero (0) or more exception {@link Class Classes}, which must be
 	 * subclasses of {@link Throwable}, indicating which exception types must
 	 * <b>not</b> cause a transaction rollback.
-	 * <p>This is the preferred way to construct a rollback rule (in contrast
-	 * to {@link #noRollbackForClassName}), matching the exception class and
-	 * its subclasses.
-	 * <p>Similar to {@link org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(Class clazz)}.
+	 * <p>This is the preferred way to construct a rollback rule (in contrast to
+	 * {@link #noRollbackForClassName}), matching the exception type, its subclasses,
+	 * and its nested classes. See the {@linkplain Transactional class-level javadocs}
+	 * for further details on rollback rule semantics and warnings regarding possible
+	 * unintentional matches.
 	 * @see #noRollbackForClassName
+	 * @see org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(Class)
 	 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute#rollbackOn(Throwable)
 	 */
 	Class<? extends Throwable>[] noRollbackFor() default {};
 
 	/**
-	 * Defines zero (0) or more exception names (for exceptions which must be a
+	 * Defines zero (0) or more exception name patterns (for exceptions which must be a
 	 * subclass of {@link Throwable}) indicating which exception types must <b>not</b>
 	 * cause a transaction rollback.
-	 * <p>See the description of {@link #rollbackForClassName} for further
-	 * information on how the specified names are treated.
-	 * <p>Similar to {@link org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(String exceptionName)}.
+	 * <p>See the {@linkplain Transactional class-level javadocs} for further details
+	 * on rollback rule semantics, patterns, and warnings regarding possible
+	 * unintentional matches.
 	 * @see #noRollbackFor
+	 * @see org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(String)
 	 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute#rollbackOn(Throwable)
 	 */
 	String[] noRollbackForClassName() default {};

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,29 +21,36 @@
  * to the {@code RollbackRuleAttribute} superclass.
  *
  * @author Rod Johnson
+ * @author Sam Brannen
  * @since 09.04.2003
  */
 @SuppressWarnings("serial")
 public class NoRollbackRuleAttribute extends RollbackRuleAttribute {
 
 	/**
 	 * Create a new instance of the {@code NoRollbackRuleAttribute} class
-	 * for the supplied {@link Throwable} class.
-	 * @param clazz the {@code Throwable} class
+	 * for the given {@code exceptionType}.
+	 * @param exceptionType exception type; must be {@link Throwable} or a subclass
+	 * of {@code Throwable}
+	 * @throws IllegalArgumentException if the supplied {@code exceptionType} is
+	 * not a {@code Throwable} type or is {@code null}
 	 * @see RollbackRuleAttribute#RollbackRuleAttribute(Class)
 	 */
-	public NoRollbackRuleAttribute(Class<?> clazz) {
-		super(clazz);
+	public NoRollbackRuleAttribute(Class<?> exceptionType) {
+		super(exceptionType);
 	}
 
 	/**
 	 * Create a new instance of the {@code NoRollbackRuleAttribute} class
-	 * for the supplied {@code exceptionName}.
-	 * @param exceptionName the exception name pattern
+	 * for the supplied {@code exceptionPattern}.
+	 * @param exceptionPattern the exception name pattern; can also be a fully
+	 * package-qualified class name
+	 * @throws IllegalArgumentException if the supplied {@code exceptionPattern}
+	 * is {@code null} or empty
 	 * @see RollbackRuleAttribute#RollbackRuleAttribute(String)
 	 */
-	public NoRollbackRuleAttribute(String exceptionName) {
-		super(exceptionName);
+	public NoRollbackRuleAttribute(String exceptionPattern) {
+		super(exceptionPattern);
 	}
 
 	@Override

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

@@ -27,6 +27,22 @@
  * <p>Multiple such rules can be applied to determine whether a transaction
  * should commit or rollback after an exception has been thrown.
  *
+ * <p>Each rule is based on an exception pattern which can be a fully qualified
+ * class name or a substring of a fully qualified class name for an exception
+ * type (which must be a subclass of {@code Throwable}), with no wildcard support
+ * at present. For example, a value of {@code "javax.servlet.ServletException"}
+ * or {@code "ServletException"} would match {@code javax.servlet.ServletException}
+ * and its subclasses.
+ *
+ * <p>An exception pattern can be specified as a {@link Class} reference or a
+ * {@link String} in {@link #RollbackRuleAttribute(Class)} and
+ * {@link #RollbackRuleAttribute(String)}, respectively. When an exception type
+ * is specified as a class reference its fully qualified name will be used as the
+ * pattern. See the javadocs for
+ * {@link org.springframework.transaction.annotation.Transactional @Transactional}
+ * for further details on rollback rule semantics, patterns, and warnings regarding
+ * possible unintentional matches.
+ *
  * @author Rod Johnson
  * @author Sam Brannen
  * @since 09.04.2003
@@ -56,6 +72,10 @@ public class RollbackRuleAttribute implements Serializable{
 	 * for the given {@code exceptionType}.
 	 * <p>This is the preferred way to construct a rollback rule that matches
 	 * the supplied exception type, its subclasses, and its nested classes.
+	 * <p>See the javadocs for
+	 * {@link org.springframework.transaction.annotation.Transactional @Transactional}
+	 * for further details on rollback rule semantics, patterns, and warnings regarding
+	 * possible unintentional matches.
 	 * @param exceptionType exception type; must be {@link Throwable} or a subclass
 	 * of {@code Throwable}
 	 * @throws IllegalArgumentException if the supplied {@code exceptionType} is
@@ -73,16 +93,10 @@ public RollbackRuleAttribute(Class<?> exceptionType) {
 	/**
 	 * Create a new instance of the {@code RollbackRuleAttribute} class
 	 * for the given {@code exceptionPattern}.
-	 * <p>This can be a substring, with no wildcard support at present. A value
-	 * of "ServletException" would match
-	 * {@code javax.servlet.ServletException} and subclasses, for example.
-	 * <p><b>NB:</b> Consider carefully how specific the pattern is, and
-	 * whether to include package information (which is not mandatory). For
-	 * example, "Exception" will match nearly anything, and will probably hide
-	 * other rules. "java.lang.Exception" would be correct if "Exception" was
-	 * meant to define a rule for all checked exceptions. With more unique
-	 * exception names such as "BaseBusinessException" there's no need to use a
-	 * fully package-qualified name.
+	 * <p>See the javadocs for
+	 * {@link org.springframework.transaction.annotation.Transactional @Transactional}
+	 * for further details on rollback rule semantics, patterns, and warnings regarding
+	 * possible unintentional matches.
 	 * @param exceptionPattern the exception name pattern; can also be a fully
 	 * package-qualified class name
 	 * @throws IllegalArgumentException if the supplied {@code exceptionPattern}
@@ -106,7 +120,7 @@ public String getExceptionName() {
 	 * Return the depth of the superclass matching, with the following semantics.
 	 * <ul>
 	 * <li>{@code -1} means this rule does not match the supplied {@code exception}.</li>
-	 * <li>{@code 0} means this rule matches the supplied {@code exception} exactly.</li>
+	 * <li>{@code 0} means this rule matches the supplied {@code exception} directly.</li>
 	 * <li>Any other positive value means this rule matches the supplied {@code exception}
 	 * within the superclass hierarchy, where the value is the number of levels in the
 	 * class hierarchy between the supplied {@code exception} and the exception against
@@ -115,22 +129,25 @@ public String getExceptionName() {
 	 * <p>When comparing roll back rules that match against a given exception, a rule
 	 * with a lower matching depth wins. For example, a direct match ({@code depth == 0})
 	 * wins over a match in the superclass hierarchy ({@code depth > 0}).
+	 * <p>A match against a nested exception type or similarly named exception type
+	 * will return a depth signifying a match at the corresponding level in the
+	 * class hierarchy as if there had been a direct match.
 	 */
 	public int getDepth(Throwable exception) {
 		return getDepth(exception.getClass(), 0);
 	}
 
 
-	private int getDepth(Class<?> exceptionClass, int depth) {
-		if (exceptionClass.getName().contains(this.exceptionPattern)) {
+	private int getDepth(Class<?> exceptionType, int depth) {
+		if (exceptionType.getName().contains(this.exceptionPattern)) {
 			// Found it!
 			return depth;
 		}
 		// If we've gone as far as we can go and haven't found it...
-		if (exceptionClass == Throwable.class) {
+		if (exceptionType == Throwable.class) {
 			return -1;
 		}
-		return getDepth(exceptionClass.getSuperclass(), depth + 1);
+		return getDepth(exceptionType.getSuperclass(), depth + 1);
 	}