Lazy daemon (#1419)

No amount of work changes (all this happened before, but in default ctor). But make it happen lazily.

The pro is that now we have access to all user options, like settings as well (and settings is discriminating).

mvnd 2.x is NOT affected by this, only 1.x.

Fixes #1174

daemon/src/main/java/org/apache/maven/cli/DaemonMavenCli.java

@@ -156,8 +156,6 @@ public class DaemonMavenCli implements DaemonCli {
     private static final String UNABLE_TO_FIND_ROOT_PROJECT_MESSAGE = "Unable to find the root directory. Create a "
             + DOT_MVN + " directory in the project root directory to identify it.";
 
-    private static final String EXTENSIONS_FILENAME = DOT_MVN + "/extensions.xml";
-
     private static final String MVN_MAVEN_CONFIG = DOT_MVN + "/maven.config";
 
     public static final String STYLE_COLOR_PROPERTY = "style.color";
@@ -174,23 +172,16 @@ public class DaemonMavenCli implements DaemonCli {
 
     private final ClassWorld classWorld;
 
-    private final DefaultPlexusContainer container;
-
-    private final EventSpyDispatcher eventSpyDispatcher;
-
-    private final ModelProcessor modelProcessor;
-
-    private final Maven maven;
-
-    private final MavenExecutionRequestPopulator executionRequestPopulator;
-
-    private final ToolchainsBuilder toolchainsBuilder;
-
-    private final DefaultSecDispatcher dispatcher;
-
-    private final Map<String, ConfigurationProcessor> configurationProcessors;
-
-    private final LoggingExecutionListener executionListener;
+    // lazily created
+    private DefaultPlexusContainer container;
+    private EventSpyDispatcher eventSpyDispatcher;
+    private ModelProcessor modelProcessor;
+    private Maven maven;
+    private MavenExecutionRequestPopulator executionRequestPopulator;
+    private ToolchainsBuilder toolchainsBuilder;
+    private DefaultSecDispatcher dispatcher;
+    private Map<String, ConfigurationProcessor> configurationProcessors;
+    private LoggingExecutionListener executionListener;
 
     /** Non-volatile, assuming that it is accessed only from the main thread */
     private BuildEventListener buildEventListener = BuildEventListener.dummy();
@@ -201,17 +192,6 @@ public class DaemonMavenCli implements DaemonCli {
         plexusLoggerManager = new Slf4jLoggerManager();
 
         this.classWorld = ((ClassRealm) Thread.currentThread().getContextClassLoader()).getWorld();
-
-        container = container();
-
-        eventSpyDispatcher = container.lookup(EventSpyDispatcher.class);
-        maven = container.lookup(Maven.class);
-        executionRequestPopulator = container.lookup(MavenExecutionRequestPopulator.class);
-        modelProcessor = createModelProcessor(container);
-        configurationProcessors = container.lookupMap(ConfigurationProcessor.class);
-        toolchainsBuilder = container.lookup(ToolchainsBuilder.class);
-        dispatcher = (DefaultSecDispatcher) container.lookup(SecDispatcher.class, "maven");
-        executionListener = container.lookup(LoggingExecutionListener.class);
     }
 
     public int main(
@@ -237,7 +217,9 @@ public class DaemonMavenCli implements DaemonCli {
         Properties props = (Properties) System.getProperties().clone();
         ClassLoader tccl = Thread.currentThread().getContextClassLoader();
         try {
-            Thread.currentThread().setContextClassLoader(container.getContainerRealm());
+            if (container != null) {
+                Thread.currentThread().setContextClassLoader(container.getContainerRealm());
+            }
             initialize(cliRequest);
             environment(cliRequest.workingDirectory, clientEnv);
             cli(cliRequest);
@@ -245,7 +227,7 @@ public class DaemonMavenCli implements DaemonCli {
             logging(cliRequest);
             informativeCommands(cliRequest);
             version(cliRequest);
-            container(cliRequest);
+            container(cliRequest); // we have here all
             configure(cliRequest, eventSpyDispatcher, configurationProcessors);
             toolchains(cliRequest);
             populateRequest(cliRequest);
@@ -257,7 +239,9 @@ public class DaemonMavenCli implements DaemonCli {
             // pure user error, suppress stack trace
             return 1;
         } finally {
-            eventSpyDispatcher.close();
+            if (eventSpyDispatcher != null) {
+                eventSpyDispatcher.close();
+            }
             System.setProperties(props);
             Thread.currentThread().setContextClassLoader(tccl);
         }
@@ -628,17 +612,30 @@ public class DaemonMavenCli implements DaemonCli {
         return interpolator;
     }
 
-    void container(CliRequest cliRequest) {
+    void container(CliRequest cliRequest) throws Exception {
+        if (this.container == null) {
+            this.container = doCreateContainer(cliRequest);
+
+            this.eventSpyDispatcher = container.lookup(EventSpyDispatcher.class);
+            this.maven = container.lookup(Maven.class);
+            this.executionRequestPopulator = container.lookup(MavenExecutionRequestPopulator.class);
+            this.modelProcessor = createModelProcessor(container);
+            this.configurationProcessors = container.lookupMap(ConfigurationProcessor.class);
+            this.toolchainsBuilder = container.lookup(ToolchainsBuilder.class);
+            this.dispatcher = (DefaultSecDispatcher) container.lookup(SecDispatcher.class, "maven");
+            this.executionListener = container.lookup(LoggingExecutionListener.class);
+        }
+
         Map<String, Object> data = new HashMap<>();
         data.put("plexus", container);
         data.put("workingDirectory", cliRequest.workingDirectory);
         data.put("systemProperties", cliRequest.systemProperties);
         data.put("userProperties", cliRequest.userProperties);
         data.put("versionProperties", CLIReportingUtils.getBuildProperties());
-        eventSpyDispatcher.init(() -> data);
+        this.eventSpyDispatcher.init(() -> data);
     }
 
-    DefaultPlexusContainer container() throws Exception {
+    DefaultPlexusContainer doCreateContainer(CliRequest cliRequest) throws Exception {
         ClassRealm coreRealm = classWorld.getClassRealm("plexus.core");
         if (coreRealm == null) {
             coreRealm = classWorld.getRealms().iterator().next();
@@ -665,7 +662,7 @@ public class DaemonMavenCli implements DaemonCli {
                 })
                 .collect(Collectors.toList());
         List<CoreExtensionEntry> extensionsEntries =
-                loadCoreExtensions(extensions, coreRealm, coreEntry.getExportedArtifacts());
+                loadCoreExtensions(cliRequest, extensions, coreRealm, coreEntry.getExportedArtifacts());
         ClassRealm containerRealm = setupContainerRealm(classWorld, coreRealm, extClassPath, extensionsEntries);
 
         ContainerConfiguration cc = new DefaultContainerConfiguration()
@@ -717,7 +714,11 @@ public class DaemonMavenCli implements DaemonCli {
     }
 
     private List<CoreExtensionEntry> loadCoreExtensions(
-            List<CoreExtension> extensions, ClassRealm containerRealm, Set<String> providedArtifacts) throws Exception {
+            CliRequest cliRequest,
+            List<CoreExtension> extensions,
+            ClassRealm containerRealm,
+            Set<String> providedArtifacts)
+            throws Exception {
         if (extensions.isEmpty()) {
             return Collections.emptyList();
         }
@@ -737,8 +738,6 @@ public class DaemonMavenCli implements DaemonCli {
         });
         MavenExecutionRequestPopulator executionRequestPopulator = null;
         try {
-            CliRequest cliRequest = new CliRequest(new String[0], classWorld);
-            cliRequest.commandLine = new CommandLine.Builder().build();
             container.setLookupRealm(null);
             container.setLoggerManager(plexusLoggerManager);
             container.getLoggerManager().setThresholds(cliRequest.request.getLoggingLevel());