From 49e3de4a06394e6c1343bfda72324165438b03a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Mart=C3=ADn=20Sotuyo=20Dodero?= <jmsotuyo@monits.com>
Date: Mon, 14 Nov 2016 00:08:56 -0300
Subject: [PATCH] Allow concurrency in AttributeAxisIterator

---
 .../pmd/lang/ast/xpath/AttributeAxisIterator.java     | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/xpath/AttributeAxisIterator.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/xpath/AttributeAxisIterator.java
index beb15161f9..bec48ccb2c 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/xpath/AttributeAxisIterator.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/xpath/AttributeAxisIterator.java
@@ -5,11 +5,10 @@ package net.sourceforge.pmd.lang.ast.xpath;
 
 import java.lang.reflect.Method;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
-import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import net.sourceforge.pmd.lang.ast.Node;
 
@@ -49,8 +48,8 @@ public class AttributeAxisIterator implements Iterator<Attribute> {
     private int position;
     private Node node;
 
-    private static Map<Class<?>, MethodWrapper[]> methodCache =
-            Collections.synchronizedMap(new HashMap<Class<?>, MethodWrapper[]>());
+    private static ConcurrentMap<Class<?>, MethodWrapper[]> methodCache =
+            new ConcurrentHashMap<Class<?>, MethodWrapper[]>();
 
     public AttributeAxisIterator(Node contextNode) {
         this.node = contextNode;
@@ -62,7 +61,7 @@ public class AttributeAxisIterator implements Iterator<Attribute> {
                     postFilter.add(new MethodWrapper(element));
                 }
             }
-            methodCache.put(contextNode.getClass(), postFilter.toArray(new MethodWrapper[postFilter.size()]));
+            methodCache.putIfAbsent(contextNode.getClass(), postFilter.toArray(new MethodWrapper[postFilter.size()]));
         }
         this.methodWrappers = methodCache.get(contextNode.getClass());