LOG4J2-2893 - Allow reconfiguration when Log4j 1 configuration files are updated.

log4j-1.2-api/src/main/java/org/apache/log4j/config/PropertiesConfiguration.java

@@ -26,11 +26,13 @@ import org.apache.log4j.helpers.OptionConverter;
 import org.apache.log4j.spi.ErrorHandler;
 import org.apache.log4j.spi.Filter;
 import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.config.ConfigurationSource;
 import org.apache.logging.log4j.core.config.LoggerConfig;
 import org.apache.logging.log4j.core.config.status.StatusConfiguration;
 import org.apache.logging.log4j.util.LoaderUtil;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
@@ -90,6 +92,23 @@ public class PropertiesConfiguration  extends Log4j1Configuration {
         doConfigure(props);
     }
 
+    @Override
+    public Configuration reconfigure() {
+        try {
+            final ConfigurationSource source = getConfigurationSource().resetInputStream();
+            if (source == null) {
+                return null;
+            }
+            final PropertiesConfigurationFactory factory = new PropertiesConfigurationFactory();
+            final PropertiesConfiguration config =
+                    (PropertiesConfiguration) factory.getConfiguration(getLoggerContext(), source);
+            return config == null || config.getState() != State.INITIALIZING ? null : config;
+        } catch (final IOException ex) {
+            LOGGER.error("Cannot locate file {}: {}", getConfigurationSource(), ex);
+        }
+        return null;
+    }
+
     /**
      * Read configuration from a file. <b>The existing configuration is
      * not cleared nor reset.</b> If you require a different behavior,

log4j-1.2-api/src/main/java/org/apache/log4j/xml/XmlConfiguration.java

@@ -22,6 +22,8 @@ import org.apache.log4j.Level;
 import org.apache.log4j.bridge.AppenderAdapter;
 import org.apache.log4j.bridge.AppenderWrapper;
 import org.apache.log4j.config.Log4j1Configuration;
+import org.apache.log4j.config.PropertiesConfiguration;
+import org.apache.log4j.config.PropertiesConfigurationFactory;
 import org.apache.log4j.config.PropertySetter;
 import org.apache.log4j.helpers.OptionConverter;
 import org.apache.log4j.rewrite.RewritePolicy;
@@ -29,6 +31,7 @@ import org.apache.log4j.spi.AppenderAttachable;
 import org.apache.log4j.spi.ErrorHandler;
 import org.apache.log4j.spi.Filter;
 import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.config.ConfigurationSource;
 import org.apache.logging.log4j.core.config.LoggerConfig;
 import org.apache.logging.log4j.core.config.status.StatusConfiguration;
@@ -171,6 +174,23 @@ public class XmlConfiguration extends Log4j1Configuration {
         }
     }
 
+    @Override
+    public Configuration reconfigure() {
+        try {
+            final ConfigurationSource source = getConfigurationSource().resetInputStream();
+            if (source == null) {
+                return null;
+            }
+            final XmlConfigurationFactory factory = new XmlConfigurationFactory();
+            final XmlConfiguration config =
+                    (XmlConfiguration) factory.getConfiguration(getLoggerContext(), source);
+            return config == null || config.getState() != State.INITIALIZING ? null : config;
+        } catch (final IOException ex) {
+            LOGGER.error("Cannot locate file {}: {}", getConfigurationSource(), ex);
+        }
+        return null;
+    }
+
     /**
      * Delegates unrecognized content to created instance if it supports UnrecognizedElementParser.
      *

log4j-1.2-api/src/test/java/org/apache/log4j/config/PropertiesReconfigurationTest.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.log4j.config;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.Configuration;
+import org.apache.logging.log4j.core.config.ConfigurationListener;
+import org.apache.logging.log4j.core.config.ConfigurationSource;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.logging.log4j.core.config.Reconfigurable;
+import org.apache.logging.log4j.spi.LoggerContextFactory;
+import org.junit.Test;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+/**
+ * Test reconfiguring with an XML configuration.
+ */
+public class PropertiesReconfigurationTest {
+
+    private static final String CONFIG = "target/test-classes/log4j1-file.properties";
+    private static final long FIVE_MINUTES = 5 * 60 * 1000;
+
+    private CountDownLatch toggle = new CountDownLatch(1);
+
+    @Test
+    public void testReconfiguration() throws Exception {
+        System.setProperty(Log4j1Configuration.MONITOR_INTERVAL, "1");
+        File file = new File(CONFIG);
+        assertNotNull("No Config file", file);
+        long configMillis = file.lastModified();
+        assertTrue("Unable to modified file time", file.setLastModified(configMillis - FIVE_MINUTES));
+        LoggerContext context = configure(file);
+        Logger logger = LogManager.getLogger("test");
+        logger.info("Hello");
+        Configuration original = context.getConfiguration();
+        TestListener listener = new TestListener();
+        original.addListener(listener);
+        file.setLastModified(System.currentTimeMillis());
+        try {
+            if (!toggle.await(3, TimeUnit.SECONDS)) {
+                fail("Reconfiguration timed out");
+            }
+            // Allow reconfiguration to complete.
+            Thread.sleep(500);
+        } catch (InterruptedException ie) {
+            fail("Reconfiguration interupted");
+        }
+        Configuration updated = context.getConfiguration();
+        assertTrue("Configurations are the same", original != updated);
+    }
+
+    private class TestListener implements ConfigurationListener {
+
+        public synchronized void onChange(final Reconfigurable reconfigurable) {
+            toggle.countDown();
+        }
+
+    }
+
+    private LoggerContext configure(File configFile) throws Exception {
+        InputStream is = new FileInputStream(configFile);
+        ConfigurationSource source = new ConfigurationSource(is, configFile);
+        LoggerContextFactory factory = org.apache.logging.log4j.LogManager.getFactory();
+        LoggerContext context = (LoggerContext) org.apache.logging.log4j.LogManager.getContext(false);
+        Configuration configuration = new PropertiesConfigurationFactory().getConfiguration(context, source);
+        assertNotNull("No configuration created", configuration);
+        Configurator.reconfigure(configuration);
+        return context;
+    }
+}

log4j-1.2-api/src/test/java/org/apache/log4j/config/XmlReconfigurationTest.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.log4j.config;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.log4j.xml.XmlConfigurationFactory;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.Configuration;
+import org.apache.logging.log4j.core.config.ConfigurationListener;
+import org.apache.logging.log4j.core.config.ConfigurationSource;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.logging.log4j.core.config.Reconfigurable;
+import org.apache.logging.log4j.spi.LoggerContextFactory;
+import org.junit.Test;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+/**
+ * Test reconfiguring with an XML configuration.
+ */
+public class XmlReconfigurationTest {
+
+    private static final String CONFIG = "target/test-classes/log4j1-file.xml";
+    private static final long FIVE_MINUTES = 5 * 60 * 1000;
+
+    private CountDownLatch toggle = new CountDownLatch(1);
+
+    @Test
+    public void testReconfiguration() throws Exception {
+        System.setProperty(Log4j1Configuration.MONITOR_INTERVAL, "1");
+        File file = new File(CONFIG);
+        assertNotNull("No Config file", file);
+        long configMillis = file.lastModified();
+        assertTrue("Unable to modified file time", file.setLastModified(configMillis - FIVE_MINUTES));
+        LoggerContext context = configure(file);
+        Logger logger = LogManager.getLogger("test");
+        logger.info("Hello");
+        Configuration original = context.getConfiguration();
+        TestListener listener = new TestListener();
+        original.addListener(listener);
+        file.setLastModified(System.currentTimeMillis());
+        try {
+            if (!toggle.await(3, TimeUnit.SECONDS)) {
+                fail("Reconfiguration timed out");
+            }
+            // Allow reconfiguration to complete.
+            Thread.sleep(500);
+        } catch (InterruptedException ie) {
+            fail("Reconfiguration interupted");
+        }
+        Configuration updated = context.getConfiguration();
+        assertTrue("Configurations are the same", original != updated);
+    }
+
+    private class TestListener implements ConfigurationListener {
+
+        public synchronized void onChange(final Reconfigurable reconfigurable) {
+            toggle.countDown();
+        }
+
+    }
+
+    private LoggerContext configure(File configFile) throws Exception {
+        InputStream is = new FileInputStream(configFile);
+        ConfigurationSource source = new ConfigurationSource(is, configFile);
+        LoggerContextFactory factory = org.apache.logging.log4j.LogManager.getFactory();
+        LoggerContext context = (LoggerContext) org.apache.logging.log4j.LogManager.getContext(false);
+        Configuration configuration = new XmlConfigurationFactory().getConfiguration(context, source);
+        assertNotNull("No configuration created", configuration);
+        Configurator.reconfigure(configuration);
+        return context;
+    }
+}

src/changes/changes.xml

@@ -94,6 +94,9 @@
         Support stack trace truncation in JsonTemplateLayout.
       </action>
       <!-- UPDATES -->
+      <action issue="LOG4J2-2893" dev="rgoers" type="update">
+        Allow reconfiguration when Log4j 1 configuration files are updated.
+      </action>
       <action dev="rgoers" type="update">
         Update Spring dependencies to 5.3.2, Spring Boot to 2.3.6, and Spring Cloud to Hoxton.SR9
       </action>