[LOG4J2-2604/2649] Change MethodHandle to Constructor to adapt graalvm (

apache#291)

* change MethodHandle to Constructor

* format space.

* add comment about why change to Constructor

log4j-core/src/main/java/org/apache/logging/log4j/core/impl/ContextDataFactory.java

@@ -16,9 +16,7 @@
  */
 package org.apache.logging.log4j.core.impl;
 
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
+import java.lang.reflect.Constructor;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -48,11 +46,17 @@
  * @since 2.7
  */
 public class ContextDataFactory {
-    private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
     private static final String CLASS_NAME = PropertiesUtil.getProperties().getStringProperty("log4j2.ContextData");
     private static final Class<? extends StringMap> CACHED_CLASS = createCachedClass(CLASS_NAME);
-    private static final MethodHandle DEFAULT_CONSTRUCTOR = createDefaultConstructor(CACHED_CLASS);
-    private static final MethodHandle INITIAL_CAPACITY_CONSTRUCTOR = createInitialCapacityConstructor(CACHED_CLASS);
+
+    /**
+     * In LOG4J2-2649 (https://issues.apache.org/jira/browse/LOG4J2-2649),
+     * the reporter said some reason about using graalvm to static compile.
+     * In graalvm doc (https://github.com/oracle/graal/blob/master/substratevm/LIMITATIONS.md),
+     * graalvm is not support MethodHandle now, so the Constructor need not to return MethodHandle.
+     */
+    private static final Constructor<?> DEFAULT_CONSTRUCTOR = createDefaultConstructor(CACHED_CLASS);
+    private static final Constructor<?> INITIAL_CAPACITY_CONSTRUCTOR = createInitialCapacityConstructor(CACHED_CLASS);
 
     private static final StringMap EMPTY_STRING_MAP = createContextData(0);
 
@@ -71,24 +75,24 @@ private static Class<? extends StringMap> createCachedClass(final String classNa
         }
     }
 
-    private static MethodHandle createDefaultConstructor(final Class<? extends StringMap> cachedClass) {
+    private static Constructor<?> createDefaultConstructor(final Class<? extends StringMap> cachedClass){
         if (cachedClass == null) {
             return null;
         }
         try {
-            return LOOKUP.findConstructor(cachedClass, MethodType.methodType(void.class));
-        } catch (final NoSuchMethodException | IllegalAccessException ignored) {
+            return cachedClass.getConstructor();
+        } catch (final NoSuchMethodException | IllegalAccessError ignored) {
             return null;
         }
     }
 
-    private static MethodHandle createInitialCapacityConstructor(final Class<? extends StringMap> cachedClass) {
+    private static Constructor<?> createInitialCapacityConstructor(final Class<? extends StringMap> cachedClass){
         if (cachedClass == null) {
             return null;
         }
         try {
-            return LOOKUP.findConstructor(cachedClass, MethodType.methodType(void.class, int.class));
-        } catch (final NoSuchMethodException | IllegalAccessException ignored) {
+            return cachedClass.getConstructor(int.class);
+        } catch (final NoSuchMethodException | IllegalAccessError ignored) {
             return null;
         }
     }
@@ -98,7 +102,7 @@ public static StringMap createContextData() {
             return new SortedArrayStringMap();
         }
         try {
-            return (IndexedStringMap) DEFAULT_CONSTRUCTOR.invoke();
+            return (IndexedStringMap) DEFAULT_CONSTRUCTOR.newInstance();
         } catch (final Throwable ignored) {
             return new SortedArrayStringMap();
         }
@@ -109,7 +113,7 @@ public static StringMap createContextData(final int initialCapacity) {
             return new SortedArrayStringMap(initialCapacity);
         }
         try {
-            return (IndexedStringMap) INITIAL_CAPACITY_CONSTRUCTOR.invoke(initialCapacity);
+            return (IndexedStringMap) INITIAL_CAPACITY_CONSTRUCTOR.newInstance(initialCapacity);
         } catch (final Throwable ignored) {
             return new SortedArrayStringMap(initialCapacity);
         }