avoid Synchronization List preparations upfront if possible (SPR-6999)

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@3128 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.transaction/src/main/java/org/springframework/transaction/jta/WebSphereUowTransactionManager.java

@@ -352,7 +352,9 @@ public class WebSphereUowTransactionManager extends JtaTransactionManager
 				if (status.isNewSynchronization()) {
 					List<TransactionSynchronization> synchronizations = TransactionSynchronizationManager.getSynchronizations();
 					TransactionSynchronizationManager.clear();
-					uowManager.registerInterposedSynchronization(new JtaAfterCompletionSynchronization(synchronizations));
+					if (!synchronizations.isEmpty()) {
+						uowManager.registerInterposedSynchronization(new JtaAfterCompletionSynchronization(synchronizations));
+					}
 				}
 			}
 		}

org.springframework.transaction/src/main/java/org/springframework/transaction/support/AbstractPlatformTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2010 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.
@@ -970,7 +970,7 @@ public abstract class AbstractPlatformTransactionManager implements PlatformTran
 				// invoke the afterCompletion callbacks immediately
 				invokeAfterCompletion(synchronizations, completionStatus);
 			}
-			else {
+			else if (!synchronizations.isEmpty()) {
 				// Existing transaction that we participate in, controlled outside
 				// of the scope of this Spring transaction manager -> try to register
 				// an afterCompletion callback with the existing (JTA) transaction.

org.springframework.transaction/src/main/java/org/springframework/transaction/support/TransactionSynchronizationManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2010 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.
@@ -287,16 +287,21 @@ public abstract class TransactionSynchronizationManager {
 	 * @see TransactionSynchronization
 	 */
 	public static List<TransactionSynchronization> getSynchronizations() throws IllegalStateException {
-		if (!isSynchronizationActive()) {
+		List<TransactionSynchronization> synchs = synchronizations.get();
+		if (synchs == null) {
 			throw new IllegalStateException("Transaction synchronization is not active");
 		}
-		List<TransactionSynchronization> synchs = synchronizations.get();
-		// Sort lazily here, not in registerSynchronization.
-		OrderComparator.sort(synchs);
 		// Return unmodifiable snapshot, to avoid ConcurrentModificationExceptions
 		// while iterating and invoking synchronization callbacks that in turn
 		// might register further synchronizations.
-		return Collections.unmodifiableList(new ArrayList<TransactionSynchronization>(synchs));
+		if (synchs.isEmpty()) {
+			return Collections.emptyList();
+		}
+		else {
+			// Sort lazily here, not in registerSynchronization.
+			OrderComparator.sort(synchs);
+			return Collections.unmodifiableList(new ArrayList<TransactionSynchronization>(synchs));
+		}
 	}
 
 	/**
@@ -359,9 +364,6 @@ public abstract class TransactionSynchronizationManager {
 	 * flush mode of a Hibernate Session to "FlushMode.NEVER" upfront.
 	 * @see org.springframework.transaction.TransactionDefinition#isReadOnly()
 	 * @see TransactionSynchronization#beforeCommit(boolean)
-	 * @see org.hibernate.Session#flush
-	 * @see org.hibernate.Session#setFlushMode
-	 * @see org.hibernate.FlushMode#NEVER
 	 */
 	public static boolean isCurrentTransactionReadOnly() {
 		return (currentTransactionReadOnly.get() != null);