Synchronize clear on TransactionAwareCacheDecorator

Previously, a cache decorated with TransactionAwareCacheDecorator would
clear the cache immediately, even when a transaction is running. This
commit updates the decorator to synchronize to the afterCommit phase for
the clear operation as well.

Issue: SPR-12653

spring-context-support/src/main/java/org/springframework/cache/transaction/TransactionAwareCacheDecorator.java

@@ -22,17 +22,18 @@ import org.springframework.transaction.support.TransactionSynchronizationManager
 import org.springframework.util.Assert;
 
 /**
- * Cache decorator which synchronizes its {@link #put} and {@link #evict} operations with
- * Spring-managed transactions (through Spring's {@link TransactionSynchronizationManager},
- * performing the actual cache put/evict operation only in the after-commit phase of a
- * successful transaction. If no transaction is active, {@link #put} and {@link #evict}
- * operations will be performed immediately, as usual.
+ * Cache decorator which synchronizes its {@link #put}, {@link #evict} and {@link #clear}
+ * operations with Spring-managed transactions (through Spring's {@link TransactionSynchronizationManager},
+ * performing the actual cache put/evict/clear operation only in the after-commit phase of a
+ * successful transaction. If no transaction is active, {@link #put}, {@link #evict} and
+ * {@link #clear} operations will be performed immediately, as usual.
  *
  * <p>Use of more aggressive operations such as {@link #putIfAbsent} cannot be deferred
  * to the after-commit phase of a running transaction. Use these with care.
  *
  * @author Juergen Hoeller
  * @author Stephane Nicoll
+ * @author Stas Volsky
  * @since 3.2
  * @see TransactionAwareCacheManagerProxy
  */
@@ -108,7 +109,17 @@ public class TransactionAwareCacheDecorator implements Cache {
 
 	@Override
 	public void clear() {
-		this.targetCache.clear();
+		if (TransactionSynchronizationManager.isSynchronizationActive()) {
+			TransactionSynchronizationManager.registerSynchronization(new TransactionSynchronizationAdapter() {
+				@Override
+				public void afterCommit() {
+					targetCache.clear();
+				}
+			});
+		}
+		else {
+			this.targetCache.clear();
+		}
 	}
 
 }

spring-context-support/src/test/java/org/springframework/cache/transaction/TransactionAwareCacheDecoratorTests.java

@@ -128,4 +128,31 @@ public class TransactionAwareCacheDecoratorTests {
 		assertNull(target.get(key));
 	}
 
+	@Test
+	public void clearNonTransactional() {
+		Cache target = new ConcurrentMapCache("testCache");
+		Cache cache = new TransactionAwareCacheDecorator(target);
+		Object key = new Object();
+		cache.put(key, "123");
+
+		cache.clear();
+		assertNull(target.get(key));
+	}
+
+	@Test
+	public void clearTransactional() {
+		Cache target = new ConcurrentMapCache("testCache");
+		Cache cache = new TransactionAwareCacheDecorator(target);
+		Object key = new Object();
+		cache.put(key, "123");
+
+
+		TransactionStatus status = txManager.getTransaction(new DefaultTransactionAttribute(
+				TransactionDefinition.PROPAGATION_REQUIRED));
+		cache.clear();
+		assertEquals("123", target.get(key, String.class));
+		txManager.commit(status);
+
+		assertNull(target.get(key));
+	}
 }