Use Lazy in some places from 3.0

Author: jvz

log4j-api/src/main/java/org/apache/logging/log4j/message/ThreadDumpMessage.java

@@ -27,6 +27,7 @@
 import aQute.bnd.annotation.Resolution;
 import aQute.bnd.annotation.spi.ServiceConsumer;
 import org.apache.logging.log4j.message.ThreadDumpMessage.ThreadInfoFactory;
+import org.apache.logging.log4j.util.Lazy;
 import org.apache.logging.log4j.util.ServiceLoaderUtil;
 import org.apache.logging.log4j.util.StringBuilderFormattable;
 import org.apache.logging.log4j.util.Strings;
@@ -40,7 +41,7 @@
 @ServiceConsumer(value = ThreadInfoFactory.class, resolution = Resolution.OPTIONAL, cardinality = Cardinality.SINGLE)
 public class ThreadDumpMessage implements Message, StringBuilderFormattable {
     private static final long serialVersionUID = -1103400781608841088L;
-    private static ThreadInfoFactory FACTORY;
+    private static final Lazy<ThreadInfoFactory> FACTORY = Lazy.lazy(ThreadDumpMessage::initFactory);
 
     private volatile Map<ThreadInformation, StackTraceElement[]> threads;
     private final String title;
@@ -52,21 +53,14 @@ public class ThreadDumpMessage implements Message, StringBuilderFormattable {
      */
     public ThreadDumpMessage(final String title) {
         this.title = title == null ? Strings.EMPTY : title;
-        threads = getFactory().createThreadInfo();
+        threads = FACTORY.get().createThreadInfo();
     }
 
     private ThreadDumpMessage(final String formattedMsg, final String title) {
         this.formattedMessage = formattedMsg;
         this.title = title == null ? Strings.EMPTY : title;
     }
 
-    private static ThreadInfoFactory getFactory() {
-        if (FACTORY == null) {
-            FACTORY = initFactory();
-        }
-        return FACTORY;
-    }
-
     private static ThreadInfoFactory initFactory() {
         return ServiceLoaderUtil.loadServices(ThreadInfoFactory.class, MethodHandles.lookup(), false)
                 .findFirst()

log4j-api/src/main/java/org/apache/logging/log4j/util/PropertiesUtil.java

@@ -57,7 +57,8 @@ public final class PropertiesUtil {
 
     private static final String LOG4J_PROPERTIES_FILE_NAME = "log4j2.component.properties";
     private static final String LOG4J_SYSTEM_PROPERTIES_FILE_NAME = "log4j2.system.properties";
-    private static final PropertiesUtil LOG4J_PROPERTIES = new PropertiesUtil(LOG4J_PROPERTIES_FILE_NAME, false);
+    private static final Lazy<PropertiesUtil> COMPONENT_PROPERTIES =
+            Lazy.lazy(() -> new PropertiesUtil(LOG4J_PROPERTIES_FILE_NAME, false));
 
     private final Environment environment;
 
@@ -123,7 +124,7 @@ static Properties loadClose(final InputStream in, final Object source) {
      * @return the main Log4j PropertiesUtil instance.
      */
     public static PropertiesUtil getProperties() {
-        return LOG4J_PROPERTIES;
+        return COMPONENT_PROPERTIES.get();
     }
 
     /**

log4j-core/src/main/java/org/apache/logging/log4j/core/selector/BasicContextSelector.java

@@ -17,20 +17,20 @@
 package org.apache.logging.log4j.core.selector;
 
 import java.net.URI;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.impl.ContextAnchor;
+import org.apache.logging.log4j.util.Lazy;
 
 /**
  * Returns either this Thread's context or the default LoggerContext.
  */
 public class BasicContextSelector implements ContextSelector {
 
-    private static final LoggerContext CONTEXT = new LoggerContext("Default");
+    private final Lazy<LoggerContext> defaultLoggerContext = Lazy.lazy(() -> new LoggerContext("Default"));
 
     @Override
     public void shutdown(final String fqcn, final ClassLoader loader, final boolean currentContext, final boolean allContexts) {
@@ -49,7 +49,7 @@ public boolean hasContext(final String fqcn, final ClassLoader loader, final boo
     @Override
     public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
         final LoggerContext ctx = ContextAnchor.THREAD_CONTEXT.get();
-        return ctx != null ? ctx : CONTEXT;
+        return ctx != null ? ctx : defaultLoggerContext.get();
     }
 
 
@@ -58,11 +58,11 @@ public LoggerContext getContext(final String fqcn, final ClassLoader loader, fin
                                     final URI configLocation) {
 
         final LoggerContext ctx = ContextAnchor.THREAD_CONTEXT.get();
-        return ctx != null ? ctx : CONTEXT;
+        return ctx != null ? ctx : defaultLoggerContext.get();
     }
 
     public LoggerContext locateContext(final String name, final String configLocation) {
-        return CONTEXT;
+        return defaultLoggerContext.get();
     }
 
     @Override
@@ -77,9 +77,7 @@ public boolean isClassLoaderDependent() {
 
     @Override
     public List<LoggerContext> getLoggerContexts() {
-        final List<LoggerContext> list = new ArrayList<>();
-        list.add(CONTEXT);
-        return Collections.unmodifiableList(list);
+        return Collections.singletonList(defaultLoggerContext.get());
     }
 
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector.java

@@ -32,6 +32,7 @@
 import org.apache.logging.log4j.core.impl.ContextAnchor;
 import org.apache.logging.log4j.spi.LoggerContextShutdownAware;
 import org.apache.logging.log4j.status.StatusLogger;
+import org.apache.logging.log4j.util.Lazy;
 import org.apache.logging.log4j.util.StackLocatorUtil;
 
 /**
@@ -47,13 +48,14 @@
  */
 public class ClassLoaderContextSelector implements ContextSelector, LoggerContextShutdownAware {
 
-    private static final AtomicReference<LoggerContext> DEFAULT_CONTEXT = new AtomicReference<>();
-
     protected static final StatusLogger LOGGER = StatusLogger.getLogger();
 
     protected static final ConcurrentMap<String, AtomicReference<WeakReference<LoggerContext>>> CONTEXT_MAP =
             new ConcurrentHashMap<>();
 
+    private final Lazy<LoggerContext> defaultLoggerContext =
+            Lazy.lazy(() -> createContext(defaultContextName(), null));
+
     @Override
     public void shutdown(final String fqcn, final ClassLoader loader, final boolean currentContext,
                          final boolean allContexts) {
@@ -259,12 +261,7 @@ protected String toContextMapKey(final ClassLoader loader) {
     }
 
     protected LoggerContext getDefault() {
-        final LoggerContext ctx = DEFAULT_CONTEXT.get();
-        if (ctx != null) {
-            return ctx;
-        }
-        DEFAULT_CONTEXT.compareAndSet(null, createContext(defaultContextName(), null));
-        return DEFAULT_CONTEXT.get();
+        return defaultLoggerContext.get();
     }
 
     protected String defaultContextName() {