Make dynamicPropertyHandlerMap in ValueUtils thread-safe

Author: Dima1224

src/main/java/org/apache/commons/jxpath/util/ValueUtils.java

@@ -26,10 +26,10 @@
 import java.util.ArrayList;
 import java.util.Collection;
 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 org.apache.commons.jxpath.Container;
 import org.apache.commons.jxpath.DynamicPropertyHandler;
@@ -40,7 +40,7 @@
  */
 public class ValueUtils {
 
-    private static Map<Class, DynamicPropertyHandler> dynamicPropertyHandlerMap = new HashMap<>();
+    private static Map<Class, DynamicPropertyHandler> dynamicPropertyHandlerMap = new ConcurrentHashMap<>();
     private static final int UNKNOWN_LENGTH_MAX_COUNT = 16000;
 
     /**

src/test/java/org/apache/commons/jxpath/util/ValueUtilsTest.java

@@ -20,11 +20,18 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
 
+import org.apache.commons.jxpath.DynamicPropertyHandler;
 import org.junit.jupiter.api.Test;
 
 class ValueUtilsTest {
@@ -87,4 +94,47 @@ void testGetValueFromSetNegativeIndex() {
     void testGetValueFromSetTooSmall() {
         assertNull(ValueUtils.getValue(Collections.EMPTY_SET, 2));
     }
+
+    @Test
+    void testGetDynamicPropertyHandlerConcurrently() throws InterruptedException {
+        // This test is to ensure that the dynamic property handler can be accessed concurrently
+        // without throwing any exceptions. It does not assert any specific behavior, but rather
+        // ensures that no exceptions are thrown during concurrent access.
+        int nThreads = 200; // Number of threads to simulate concurrent access
+        List<Future<?>> futures = new ArrayList<>();
+        ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
+        for (int i = 0; i < nThreads; i++) {
+           futures.add(threadPool.submit(() -> ValueUtils.getDynamicPropertyHandler(DummyHandler.class)));
+        }
+
+        threadPool.shutdown();
+        threadPool.awaitTermination(1, TimeUnit.SECONDS);
+
+        for (Future<?> future : futures) {
+            try {
+                future.get(); // This will throw an exception if any thread encountered an issue
+            } catch (Exception e) {
+                // If an exception is thrown, the test fails
+                throw new AssertionError("Exception thrown during concurrent access", e);
+            }
+        }
+    }
+
+    public static class DummyHandler implements DynamicPropertyHandler {
+
+        @Override
+        public Object getProperty(Object object, String propertyName) {
+            return null;
+        }
+
+        @Override
+        public String[] getPropertyNames(Object object) {
+            return new String[0];
+        }
+
+        @Override
+        public void setProperty(Object object, String propertyName, Object value) {
+
+        }
+    }
 }