Eliminating need for agent

retrolambda-maven-plugin/src/main/java/net/orfjackal/retrolambda/maven/ProcessClassesMojo.java

@@ -6,14 +6,18 @@
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableMap;
+import java.io.*;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.*;
+import org.apache.maven.artifact.Artifact;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.*;
 import org.apache.maven.plugins.annotations.*;
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.toolchain.*;
 
-import java.io.*;
-import java.util.*;
 
 import static org.twdata.maven.mojoexecutor.MojoExecutor.*;
 
@@ -63,6 +67,16 @@ abstract class ProcessClassesMojo extends AbstractMojo {
      */
     @Parameter(defaultValue = "1.7", property = "retrolambdaTarget", required = true)
     public String target;
+
+    /**
+     * Should we start new process or perform the retrolambdafication in the 
+     * same VM as Maven runs in (which has to be 1.8 then)? If the VM is
+     * forked, it uses -javaagent argument to intercept class definitions.
+     * When we run in the same process, we hook into the class generation
+     * by internal "lambda dumping" API.
+     */
+    @Parameter(defaultValue = "false")
+    public boolean fork;
 
     protected abstract File getInputDir();
 
@@ -79,7 +93,11 @@ public void execute() throws MojoExecutionException {
         retrieveRetrolambdaJar(version);
 
         getLog().info("Processing classes with Retrolambda");
-        processClasses();
+        if (fork) {
+            processClassesWithAgent();
+        } else {
+            processClasses();
+        }
     }
 
     String getJavaCommand() {
@@ -130,7 +148,7 @@ private void retrieveRetrolambdaJar(String version) throws MojoExecutionExceptio
                 executionEnvironment(project, session, pluginManager));
     }
 
-    private void processClasses() throws MojoExecutionException {
+    private void processClassesWithAgent() throws MojoExecutionException {
         String retrolambdaJar = getRetrolambdaJarPath();
         executeMojo(
                 plugin(groupId("org.apache.maven.plugins"),
@@ -155,6 +173,33 @@ private void processClasses() throws MojoExecutionException {
                                 element("arg", attribute("value", retrolambdaJar))))),
                 executionEnvironment(project, session, pluginManager));
     }
+
+    private void processClasses() throws MojoExecutionException {
+        String retrolambdaJar = getRetrolambdaJarPath();
+        File jar = new File(retrolambdaJar);
+
+        try {
+            StringBuilder sb = new StringBuilder();
+            sb.append(getInputDir());
+            for (Artifact a : project.getArtifacts()) {
+                if (a.getFile() != null) {
+                    sb.append(File.pathSeparator);
+                    sb.append(a.getFile());
+                }
+            }
+
+            URLClassLoader url = new URLClassLoader(new URL[] { jar.toURI().toURL() });
+            Class<?> mainClass = Class.forName("net.orfjackal.retrolambda.Main", true, url);
+            System.setProperty("retrolambda.bytecodeVersion", "" + targetBytecodeVersions.get(target));
+            System.setProperty("retrolambda.inputDir", getInputDir().getAbsolutePath());
+            System.setProperty("retrolambda.outputDir", getOutputDir().getAbsolutePath());
+            System.setProperty("retrolambda.classpath", sb.toString());
+            Method main = mainClass.getMethod("main", String[].class);
+            main.invoke(null, (Object) new String[0]);
+        } catch (Exception ex) {
+            throw new MojoExecutionException("Cannot initialize classloader for " + retrolambdaJar, ex);
+        }
+    }
 
     private String getRetrolambdaJarPath() {
         return getRetrolambdaJarDir() + "/" + getRetrolambdaJarName();

retrolambda/src/main/java/net/orfjackal/retrolambda/Config.java

@@ -43,7 +43,7 @@ public Config(Properties p) {
     }
 
     public boolean isFullyConfigured() {
-        return hasAllRequiredProperties() && PreMain.isAgentLoaded();
+        return hasAllRequiredProperties();
     }
 
     private boolean hasAllRequiredProperties() {