ongoing work to enable AsyncAppender support in Joran

logback-access/src/main/java/ch/qos/logback/access/joran/JoranConfigurator.java

@@ -62,9 +62,6 @@ public void addInstanceRules(RuleStore rs) {
 
         rs.addRule(new ElementSelector("configuration"), new ConfigurationAction());
         rs.addRule(new ElementSelector("configuration/appender-ref"), new AppenderRefAction());
-
-        //rs.addRule(new ElementSelector("configuration/appender/sift/*"), new NOPAction());
-
         rs.addRule(new ElementSelector("configuration/include"), new IncludeModelAction());
     }
 
@@ -122,6 +119,7 @@ private void injectModelFilters(DefaultProcessor defaultProcessor) {
 		fistPhaseDefintionFilter.denyAll();
 		defaultProcessor.setPhaseOneFilter(fistPhaseDefintionFilter);
 
+		// Note: AppenderModel is in the second phase
 
 		defaultProcessor.setPhaseTwoFilter(new AllowAllModelFilter());
 

logback-classic/src/test/input/joran/appenderRefByProperty.xml

@@ -4,7 +4,6 @@
 <configuration debug="false">
 
   <appender name="A" class="ch.qos.logback.core.read.ListAppender"/>
-  <appender name="B" class="ch.qos.logback.core.read.ListAppender"/>
 
   <logger name="ch.qos.logback.classic.joran" level="INFO">
     <appender-ref ref="${logback.appenderRef}"/>

logback-classic/src/test/input/joran/asyncAppender.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE configuration>
+
+<configuration debug="false">
+
+
+    <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
+      <queueSize>256</queueSize>
+      <includeCallerData>false</includeCallerData>
+      <appender-ref ref="LIST" />
+    </appender>
+
+    <appender name="LIST" class="ch.qos.logback.core.read.ListAppender"/>
+
+
+    <root level="debug">
+        <appender-ref ref="ASYNC" />
+    </root>
+
+
+</configuration>

logback-classic/src/test/input/joran/unreferencedAppender1.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE configuration>
+
+<configuration debug="false">
+
+  <appender name="A" class="ch.qos.logback.core.read.ListAppender"/>
+  <appender name="B" class="ch.qos.logback.core.read.ListAppender"/>
+
+
+  <root level="ERROR">
+    <appender-ref ref="A"/>
+  </root>
+
+</configuration>

logback-classic/src/test/java/ch/qos/logback/classic/joran/JoranConfiguratorTest.java

@@ -27,6 +27,7 @@
 import org.junit.Test;
 import org.slf4j.MDC;
 
+import ch.qos.logback.classic.AsyncAppender;
 import ch.qos.logback.classic.ClassicTestConstants;
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.Logger;
@@ -132,15 +133,18 @@ public void appenderRefSettingBySystemProperty() throws JoranException {
 		final String propertyName = "logback.appenderRef";
 		System.setProperty(propertyName, "A");
 		configure(ClassicTestConstants.JORAN_INPUT_PREFIX + "appenderRefByProperty.xml");
+		StatusPrinter.print(loggerContext);
 		final Logger logger = loggerContext.getLogger("ch.qos.logback.classic.joran");
 		final ListAppender<ILoggingEvent> listAppender = (ListAppender<ILoggingEvent>) logger.getAppender("A");
 		assertEquals(0, listAppender.list.size());
 		final String msg = "hello world";
 		logger.info(msg);
+
 		assertEquals(1, listAppender.list.size());
 		System.clearProperty(propertyName);
 	}
 
+
 	@Test
 	public void statusListener() throws JoranException {
 		configure(ClassicTestConstants.JORAN_INPUT_PREFIX + "statusListener.xml");
@@ -479,4 +483,31 @@ public void appenderRefBeforeAppenderTest() throws JoranException {
 		assertEquals(msg, le.getMessage());
 		checker.assertIsErrorFree();
 	}
+
+	@Test
+	public void unreferencedAppendersShouldBeSkipped() throws JoranException {
+		configure(ClassicTestConstants.JORAN_INPUT_PREFIX + "unreferencedAppender1.xml");
+
+		final ListAppender<ILoggingEvent> listAppenderA = (ListAppender<ILoggingEvent>) root.getAppender("A");
+		assertNotNull(listAppenderA);
+		StatusPrinter.print(loggerContext);
+		StatusChecker checker = new StatusChecker(loggerContext);	
+		checker.assertContainsMatch(Status.WARN, "Appender named \\[B\\] not referenced. Skipping further processing.");
+	}
+
+
+	@Test
+	public void asynAppender() throws JoranException {
+		configure(ClassicTestConstants.JORAN_INPUT_PREFIX + "asyncAppender.xml");
+
+		final AsyncAppender asyncAppender = (AsyncAppender) root.getAppender("ASYNC");
+		assertNotNull(asyncAppender);
+		StatusPrinter.print(loggerContext);
+
+		assertTrue(asyncAppender.isStarted());
+		StatusPrinter.print(loggerContext);
+
+		StatusChecker checker = new StatusChecker(loggerContext);	
+		//checker.assertContainsMatch(Status.WARN, "Appender named \\[B\\] not referenced. Skipping further processing.");
+	}
 }

logback-core/src/main/java/ch/qos/logback/core/model/processor/AppenderModelHandler.java

@@ -37,7 +37,7 @@ public void handle(InterpretationContext interpContext, Model model) throws Mode
 		this.appenderAttachable = appenderRefBag.get(appenderName);
 
 		if(this.appenderAttachable == null) {
-			addWarn("Processing appender named ["+appenderName+"] not referenced. Skipping.");
+			addWarn("Appender named ["+appenderName+"] not referenced. Skipping further processing.");
 			skipped = true;
 			return;
 		}

logback-site/src/site/pages/news.html

@@ -47,7 +47,10 @@ <h3>11th of October, 2019, Release of version 1.3.0-alpha5</h3>
     <p>Joran, logback's configuration system, has been rewritten to
     use an internal representation model which can be processed
     separately. As a side-effect, logback configuration scripts are
-    now order-free. Given the breadth of the changes, support for
+    now largely order-free. For example, appenders can now be defined
+    after they are first referenced in a logger. Moreover,
+    unreferenced appenders are no longer instantiated. Given the
+    breadth of the changes in Joran codebase, support for
     <code>SiftingAppender</code> and Groovy configuration have been
     dropped temporarily.
     </p>