From 1890e04df18c152e61da62b5442008f8064ab127 Mon Sep 17 00:00:00 2001
From: Mark Paluch <mpaluch@pivotal.io>
Date: Tue, 23 Jul 2019 15:50:55 +0200
Subject: [PATCH] Introduce interface cache for EntityManager and Query types
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We now reuse interfaces for EntityManager and Query classes that
are proxied through ExtendedEntityManagerCreator and SharedEntityManagerCreator.

These caches prevent excessive object allocations through
ClassUtils.getAllInterfacesForClass(…) and
ClassUtils.getAllInterfacesForClassAsSet(…).
---
 .../orm/jpa/ExtendedEntityManagerCreator.java | 26 +++++++++++++++----
 .../orm/jpa/SharedEntityManagerCreator.java   |  7 ++++-
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/ExtendedEntityManagerCreator.java b/spring-orm/src/main/java/org/springframework/orm/jpa/ExtendedEntityManagerCreator.java
index 5e7a5259b1..714d691e91 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/ExtendedEntityManagerCreator.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/ExtendedEntityManagerCreator.java
@@ -43,6 +43,7 @@ import org.springframework.transaction.support.TransactionSynchronizationManager
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
  * Delegate for creating a variety of {@link javax.persistence.EntityManager}
@@ -65,6 +66,7 @@ import org.springframework.util.CollectionUtils;
  *
  * @author Juergen Hoeller
  * @author Rod Johnson
+ * @author Mark Paluch
  * @since 2.0
  * @see javax.persistence.EntityManagerFactory#createEntityManager()
  * @see javax.persistence.PersistenceContextType#EXTENDED
@@ -73,6 +75,8 @@ import org.springframework.util.CollectionUtils;
  */
 public abstract class ExtendedEntityManagerCreator {
 
+	private static final Map<Class<?>, Class[]> CACHED_ENTITY_MANAGER_INTERFACES = new ConcurrentReferenceHashMap<>();
+
 	/**
 	 * Create an application-managed extended EntityManager proxy.
 	 * @param rawEntityManager the raw EntityManager to decorate
@@ -222,17 +226,29 @@ public abstract class ExtendedEntityManagerCreator {
 			boolean containerManaged, boolean synchronizedWithTransaction) {
 
 		Assert.notNull(rawEm, "EntityManager must not be null");
-		Set<Class<?>> ifcs = new LinkedHashSet<>();
+		Class[] interfaces;
+
 		if (emIfc != null) {
-			ifcs.add(emIfc);
+			interfaces = CACHED_ENTITY_MANAGER_INTERFACES.computeIfAbsent(emIfc, key -> {
+				Set<Class<?>> ifcs = new LinkedHashSet<>();
+				ifcs.add(key);
+				ifcs.add(EntityManagerProxy.class);
+				return ClassUtils.toClassArray(ifcs);
+			});
 		}
 		else {
-			ifcs.addAll(ClassUtils.getAllInterfacesForClassAsSet(rawEm.getClass(), cl));
+			interfaces = CACHED_ENTITY_MANAGER_INTERFACES.computeIfAbsent(rawEm.getClass(), key -> {
+				Set<Class<?>> ifcs = new LinkedHashSet<>();
+				ifcs.addAll(ClassUtils
+						.getAllInterfacesForClassAsSet(key, cl));
+				ifcs.add(EntityManagerProxy.class);
+				return ClassUtils.toClassArray(ifcs);
+			});
 		}
-		ifcs.add(EntityManagerProxy.class);
+
 		return (EntityManager) Proxy.newProxyInstance(
 				(cl != null ? cl : ExtendedEntityManagerCreator.class.getClassLoader()),
-				ClassUtils.toClassArray(ifcs),
+				interfaces,
 				new ExtendedEntityManagerInvocationHandler(
 						rawEm, exceptionTranslator, jta, containerManaged, synchronizedWithTransaction));
 	}
diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/SharedEntityManagerCreator.java b/spring-orm/src/main/java/org/springframework/orm/jpa/SharedEntityManagerCreator.java
index 70b6b06da9..162733e3dc 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/SharedEntityManagerCreator.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/SharedEntityManagerCreator.java
@@ -41,6 +41,7 @@ import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
  * Delegate for creating a shareable JPA {@link javax.persistence.EntityManager}
@@ -59,6 +60,7 @@ import org.springframework.util.CollectionUtils;
  * @author Juergen Hoeller
  * @author Rod Johnson
  * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 2.0
  * @see javax.persistence.PersistenceContext
  * @see javax.persistence.PersistenceContextType#TRANSACTION
@@ -73,6 +75,8 @@ public abstract class SharedEntityManagerCreator {
 
 	private static final Set<String> queryTerminatingMethods = new HashSet<>(8);
 
+	private static final Map<Class<?>, Class[]> CACHED_QUERY_INTERFACES = new ConcurrentReferenceHashMap<>();
+
 	static {
 		transactionRequiringMethods.add("joinTransaction");
 		transactionRequiringMethods.add("flush");
@@ -310,7 +314,8 @@ public abstract class SharedEntityManagerCreator {
 				if (result instanceof Query) {
 					Query query = (Query) result;
 					if (isNewEm) {
-						Class<?>[] ifcs = ClassUtils.getAllInterfacesForClass(query.getClass(), this.proxyClassLoader);
+						Class<?>[] ifcs = CACHED_QUERY_INTERFACES.computeIfAbsent(query.getClass(), key ->
+								ClassUtils.getAllInterfacesForClass(key, this.proxyClassLoader));
 						result = Proxy.newProxyInstance(this.proxyClassLoader, ifcs,
 								new DeferredQueryInvocationHandler(query, target));
 						isNewEm = false;