Prevent thread from being blocked by JDK-8 ConcurrentHashMap#computeI…

…fAbsent()

This is a workaround for JDK-8161372

mybatis#1929
https://groups.google.com/g/mybatis-user/c/iBTN98c0dP4/m/H6IJS-LzAQAJ

We should drop this workaround once we drop Java 8 support or the fix is backported.

src/main/java/org/apache/ibatis/binding/MapperProxy.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2020 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -28,6 +28,7 @@
 
 import org.apache.ibatis.reflection.ExceptionUtil;
 import org.apache.ibatis.session.SqlSession;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * @author Clinton Begin
@@ -91,15 +92,7 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
 
   private MapperMethodInvoker cachedInvoker(Method method) throws Throwable {
     try {
-      // A workaround for https://bugs.openjdk.java.net/browse/JDK-8161372
-      // It should be removed once the fix is backported to Java 8 or
-      // MyBatis drops Java 8 support. See gh-1929
-      MapperMethodInvoker invoker = methodCache.get(method);
-      if (invoker != null) {
-        return invoker;
-      }
-
-      return methodCache.computeIfAbsent(method, m -> {
+      return MapUtil.computeIfAbsent(methodCache, method, m -> {
         if (m.isDefault()) {
           try {
             if (privateLookupInMethod == null) {

src/main/java/org/apache/ibatis/cache/TransactionalCacheManager.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2019 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -19,6 +19,7 @@
 import java.util.Map;
 
 import org.apache.ibatis.cache.decorators.TransactionalCache;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * @author Clinton Begin
@@ -52,7 +53,7 @@ public void rollback() {
   }
 
   private TransactionalCache getTransactionalCache(Cache cache) {
-    return transactionalCaches.computeIfAbsent(cache, TransactionalCache::new);
+    return MapUtil.computeIfAbsent(transactionalCaches, cache, TransactionalCache::new);
   }
 
 }

src/main/java/org/apache/ibatis/executor/keygen/Jdbc3KeyGenerator.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2020 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -42,6 +42,7 @@
 import org.apache.ibatis.type.JdbcType;
 import org.apache.ibatis.type.TypeHandler;
 import org.apache.ibatis.type.TypeHandlerRegistry;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * @author Clinton Begin
@@ -156,7 +157,7 @@ private void assignKeysToParamMap(Configuration configuration, ResultSet rs, Res
     for (int i = 0; i < keyProperties.length; i++) {
       Entry<String, KeyAssigner> entry = getAssignerForParamMap(configuration, rsmd, i + 1, paramMap, keyProperties[i],
           keyProperties, true);
-      Entry<Iterator<?>, List<KeyAssigner>> iteratorPair = assignerMap.computeIfAbsent(entry.getKey(),
+      Entry<Iterator<?>, List<KeyAssigner>> iteratorPair = MapUtil.computeIfAbsent(assignerMap, entry.getKey(),
           k -> entry(collectionize(paramMap.get(k)).iterator(), new ArrayList<>()));
       iteratorPair.getValue().add(entry.getValue());
     }

src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2020 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -61,6 +61,7 @@
 import org.apache.ibatis.type.JdbcType;
 import org.apache.ibatis.type.TypeHandler;
 import org.apache.ibatis.type.TypeHandlerRegistry;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * @author Clinton Begin
@@ -589,7 +590,7 @@ private void addPendingChildRelation(ResultSet rs, MetaObject metaResultObject,
     PendingRelation deferLoad = new PendingRelation();
     deferLoad.metaObject = metaResultObject;
     deferLoad.propertyMapping = parentMapping;
-    List<PendingRelation> relations = pendingRelations.computeIfAbsent(cacheKey, k -> new ArrayList<>());
+    List<PendingRelation> relations = MapUtil.computeIfAbsent(pendingRelations, cacheKey, k -> new ArrayList<>());
     // issue #255
     relations.add(deferLoad);
     ResultMapping previous = nextResultMaps.get(parentMapping.getResultSet());

src/main/java/org/apache/ibatis/plugin/Plugin.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2020 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -24,6 +24,7 @@
 import java.util.Set;
 
 import org.apache.ibatis.reflection.ExceptionUtil;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * @author Clinton Begin
@@ -75,7 +76,7 @@ private static Map<Class<?>, Set<Method>> getSignatureMap(Interceptor intercepto
     Signature[] sigs = interceptsAnnotation.value();
     Map<Class<?>, Set<Method>> signatureMap = new HashMap<>();
     for (Signature sig : sigs) {
-      Set<Method> methods = signatureMap.computeIfAbsent(sig.type(), k -> new HashSet<>());
+      Set<Method> methods = MapUtil.computeIfAbsent(signatureMap, sig.type(), k -> new HashSet<>());
       try {
         Method method = sig.type().getMethod(sig.method(), sig.args());
         methods.add(method);

src/main/java/org/apache/ibatis/reflection/DefaultReflectorFactory.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2019 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -18,6 +18,8 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
+import org.apache.ibatis.util.MapUtil;
+
 public class DefaultReflectorFactory implements ReflectorFactory {
   private boolean classCacheEnabled = true;
   private final ConcurrentMap<Class<?>, Reflector> reflectorMap = new ConcurrentHashMap<>();
@@ -39,7 +41,7 @@ public void setClassCacheEnabled(boolean classCacheEnabled) {
   public Reflector findForClass(Class<?> type) {
     if (classCacheEnabled) {
       // synchronized (type) removed see issue #461
-      return reflectorMap.computeIfAbsent(type, Reflector::new);
+      return MapUtil.computeIfAbsent(reflectorMap, type, Reflector::new);
     } else {
       return new Reflector(type);
     }

src/main/java/org/apache/ibatis/reflection/Reflector.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2020 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -40,6 +40,7 @@
 import org.apache.ibatis.reflection.invoker.MethodInvoker;
 import org.apache.ibatis.reflection.invoker.SetFieldInvoker;
 import org.apache.ibatis.reflection.property.PropertyNamer;
+import org.apache.ibatis.util.MapUtil;
 
 /**
  * This class represents a cached set of class definition information that
@@ -143,7 +144,7 @@ private void addSetMethods(Class<?> clazz) {
 
   private void addMethodConflict(Map<String, List<Method>> conflictingMethods, String name, Method method) {
     if (isValidPropertyName(name)) {
-      List<Method> list = conflictingMethods.computeIfAbsent(name, k -> new ArrayList<>());
+      List<Method> list = MapUtil.computeIfAbsent(conflictingMethods, name, k -> new ArrayList<>());
       list.add(method);
     }
   }

src/main/java/org/apache/ibatis/scripting/LanguageDriverRegistry.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2009-2019 the original author or authors.
+ *    Copyright 2009-2021 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.
@@ -18,6 +18,8 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import org.apache.ibatis.util.MapUtil;
+
 /**
  * @author Frank D. Martinez [mnesarco]
  */
@@ -31,7 +33,7 @@ public void register(Class<? extends LanguageDriver> cls) {
     if (cls == null) {
       throw new IllegalArgumentException("null is not a valid Language Driver");
     }
-    LANGUAGE_DRIVER_MAP.computeIfAbsent(cls, k -> {
+    MapUtil.computeIfAbsent(LANGUAGE_DRIVER_MAP, cls, k -> {
       try {
         return k.getDeclaredConstructor().newInstance();
       } catch (Exception ex) {

src/main/java/org/apache/ibatis/util/MapUtil.java

@@ -0,0 +1,40 @@
+/**
+ *    Copyright 2009-2021 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.
+ *    You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+package org.apache.ibatis.util;
+
+import java.util.Map;
+import java.util.function.Function;
+
+public class MapUtil {
+  /**
+   * A temporary workaround for Java 8 specific performance issue JDK-8161372 .<br>
+   * This class should be removed once we drop Java 8 support.
+   *
+   * @see <a href="https://bugs.openjdk.java.net/browse/JDK-8161372">https://bugs.openjdk.java.net/browse/JDK-8161372</a>
+   */
+  public static <K, V> V computeIfAbsent(Map<K, V> map, K key, Function<K, V> mappingFunction) {
+    V value = map.get(key);
+    if (value != null) {
+      return value;
+    }
+    return map.computeIfAbsent(key, mappingFunction::apply);
+  }
+
+  private MapUtil() {
+    super();
+  }
+}