BATCH-1709: Fix concurrency issue in BeanWrapperFieldSetMapper

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/mapping/BeanWrapperFieldSetMapper.java

@@ -22,6 +22,8 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import org.springframework.batch.item.file.transform.FieldSet;
 import org.springframework.batch.support.DefaultPropertyEditorRegistrar;
@@ -94,7 +96,7 @@ public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar
 
 	private BeanFactory beanFactory;
 
-	private static Map<DistanceHolder, Map<String, String>> propertiesMatched = new HashMap<DistanceHolder, Map<String, String>>();
+	private ConcurrentMap<DistanceHolder, ConcurrentMap<String, String>> propertiesMatched = new ConcurrentHashMap<DistanceHolder, ConcurrentMap<String, String>>();
 
 	private int distanceLimit = 5;
 
@@ -249,11 +251,10 @@ public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar
 
 		// Map from field names to property names
 		DistanceHolder distanceKey = new DistanceHolder(cls, distanceLimit);
-		Map<String, String> matches = propertiesMatched.get(distanceKey);
+		if (!propertiesMatched.containsKey(distanceKey)) {
-		if (matches == null) {
+			propertiesMatched.putIfAbsent(distanceKey, new ConcurrentHashMap<String, String>());
-			matches = new HashMap<String, String>();
-			propertiesMatched.put(distanceKey, matches);
 		}
+		Map<String, String> matches = new HashMap<String, String>(propertiesMatched.get(distanceKey));
 
 		Set<String> keys = new HashSet(properties.keySet());
 		for (String key : keys) {
@@ -281,6 +282,9 @@ public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar
 			}
 		}
 
+		if (!propertiesMatched.containsKey(distanceKey)) {
+			propertiesMatched.putIfAbsent(distanceKey, new ConcurrentHashMap<String, String>(matches));
+		}
 		return properties;
 	}
 
@@ -379,12 +383,13 @@ public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar
 
 	private static class DistanceHolder {
 		private final Class<?> cls;
+
 		private final int distance;
 
 		public DistanceHolder(Class<?> cls, int distance) {
 			this.cls = cls;
 			this.distance = distance;
-			
+
 		}
 
 		@Override
@@ -417,5 +422,4 @@ public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar
 		}
 	}
 
-
 }

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/mapping/BeanWrapperFieldSetMapperConcurrentTests.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2006-2007 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.springframework.batch.item.file.mapping;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.springframework.batch.item.file.transform.DelimitedLineTokenizer;
+
+public class BeanWrapperFieldSetMapperConcurrentTests {
+
+	@Test
+	public void testConcurrentUsage() throws Exception {
+		final BeanWrapperFieldSetMapper<GreenBean> mapper = new BeanWrapperFieldSetMapper<GreenBean>();
+		mapper.setStrict(true);
+		mapper.setTargetType(GreenBean.class);
+		// mapper.setDistanceLimit(0);
+		final DelimitedLineTokenizer lineTokenizer = new DelimitedLineTokenizer();
+		String[] names = { "blue", "green" };
+		lineTokenizer.setNames(names);
+
+		ExecutorService executorService = Executors.newFixedThreadPool(5);
+		Collection<Future<Boolean>> results = new ArrayList<Future<Boolean>>();
+		for (int i = 0; i < 10; i++) {
+			Future<Boolean> result = executorService.submit(new Callable<Boolean>() {
+				public Boolean call() throws Exception {
+					for (int i = 0; i < 10; i++) {
+						GreenBean bean = mapper.mapFieldSet(lineTokenizer.tokenize("blue,green"));
+						Assert.assertEquals("green", bean.getGreen());
+					}
+					return true;
+				}
+			});
+			results.add(result);
+		}
+		for (Future<Boolean> future : results) {
+			assertTrue(future.get());
+		}
+	}
+
+	public static class GreenBean {
+		private String green;
+
+		private String blue;
+
+		public String getBlue() {
+			return blue;
+		}
+
+		public void setBlue(String blue) {
+			this.blue = blue;
+		}
+
+		public String getGreen() {
+			return green;
+		}
+
+		public void setGreen(String green) {
+			this.green = green;
+		}
+
+	}
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/mapping/BeanWrapperFieldSetMapperTests.java

@@ -49,7 +49,7 @@ import org.springframework.validation.BindException;
 import org.springframework.validation.DataBinder;
 
 public class BeanWrapperFieldSetMapperTests {
-
+	
 	@Test
 	public void testNameAndTypeSpecified() throws Exception {
 		BeanWrapperFieldSetMapper<TestObject> mapper = new BeanWrapperFieldSetMapper<TestObject>();