Remove compilation of LibN.java

build.gradle

@@ -43,11 +43,6 @@ dependencies {
 
 // FIXME: add test resources.
 sourceSets {
-  corecomm {
-    resources {
-      srcDirs = ['java/org/contikios/cooja/corecomm']
-    }
-  }
   data {
     resources {
       srcDirs = ['tools/coffee-manager']
@@ -57,10 +52,9 @@ sourceSets {
   main {
     java {
       srcDirs = ['java', 'tools/coffee-manager']
-      exclude 'org/contikios/cooja/corecomm/CoreCommTemplate.java'
     }
     resources {
-      srcDirs = [corecomm.resources, data.resources, 'config']
+      srcDirs = [data.resources, 'config']
     }
   }
 }
@@ -124,10 +118,7 @@ tasks.register('fullJar', Jar) {
 run {
   // Bad Cooja location detected with gradle run, explicitly pass -cooja.
   doFirst {
-    args += ['--cooja', "$projectDir",
-             '--javac', javaToolchains.compilerFor {
-                         languageVersion = JavaLanguageVersion.of(javaVersion)
-                       }.get().executablePath]
+    args += ['--cooja', "$projectDir"]
   }
   // Connect stdin to make the MSPSim CLI work, except when running in CI.
   if (System.getenv('CI') == null) {

java/org/contikios/cooja/Cooja.java

@@ -1687,7 +1687,7 @@ public static void loadQuickHelp(final Object obj) {
    */
   public record Config(LogbackColors logColors, boolean vis, String externalToolsConfig,
                        String nashornArgs, String logDir,
-                       String contikiPath, String coojaPath, String javac) {}
+                       String contikiPath, String coojaPath) {}
 
   public record LogbackColors(String error, String warn, String info, String fallback) {}
   private record PathIdentifier(String id, String path) {}

java/org/contikios/cooja/Main.java

@@ -96,12 +96,6 @@ class Main {
   @Option(names = "--cooja", paramLabel = "DIR", description = "the Cooja directory")
   String coojaPath;
 
-  /**
-   * Option for specifying javac path.
-   */
-  @Option(names = "--javac", paramLabel = "FILE", description = "the javac binary")
-  String javac;
-
   /**
    * Option for specifying external user config file.
    */
@@ -301,23 +295,13 @@ public static void main(String[] args) {
       System.exit(1);
     }
 
-    if (options.mspSimPlatform == null && options.javac == null) {
-      System.err.println("Missing required option: '--javac=FILE'");
-      System.exit(1);
-    }
-
-    if (options.mspSimPlatform == null && !Files.exists(Path.of(options.javac))) {
-      System.err.println("Java compiler '" + options.javac + "' does not exist");
-      System.exit(1);
-    }
-
     if (options.mspSimPlatform == null) { // Start Cooja.
       // Use colors that are good on a dark background and readable on a white background.
       var colors = new LogbackColors(ANSIConstants.BOLD + "91", "96",
               ANSIConstants.GREEN_FG, ANSIConstants.DEFAULT_FG);
       var cfg = new Config(colors, options.gui, options.externalUserConfig,
                 options.nashornArgs,
-                options.logDir, options.contikiPath, options.coojaPath, options.javac);
+                options.logDir, options.contikiPath, options.coojaPath);
       Cooja.go(cfg, simConfigs);
     } else { // Start MSPSim.
       var config = new ArgumentManager(options.simulationFiles.toArray(new String[0]));

java/org/contikios/cooja/MoteType.java

@@ -157,6 +157,12 @@ default long getExecutableAddressOf(File file, int lineNr) {
     return -1;
   }
 
+  /** Called when the mote type is added to the simulation. */
+  default void added() { }
+
+  /** Called when the mote type is removed from the simulation. */
+  default void removed() { }
+
   class MoteTypeCreationException extends Exception {
     private MessageList compilationOutput;
 

java/org/contikios/cooja/Simulation.java

@@ -883,6 +883,7 @@ public MoteType[] getMoteTypes() {
   public void addMoteType(MoteType newMoteType) {
     Cooja.usedMoteTypeIDs.add(newMoteType.getIdentifier());
     moteTypes.add(newMoteType);
+    newMoteType.added();
     moteTypeTriggers.trigger(AddRemove.ADD, newMoteType);
   }
 
@@ -897,14 +898,10 @@ public void removeMoteType(MoteType type) {
         removeMote(m);
       }
     }
-
-    // FIXME: call type.removed(), so ContikiMoteType can call arena.close()
-    //        to unload the shared library.
-    //        For more details, see "Obtaining a symbol lookup" at:
-    // https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/lang/foreign/SymbolLookup.html
     if (moteTypes.remove(type)) {
       moteTypeTriggers.trigger(AddRemove.REMOVE, type);
     }
+    type.removed();
   }
 
   /**

java/org/contikios/cooja/contikimote/ContikiMoteType.java

@@ -31,30 +31,23 @@
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
-import java.io.InputStreamReader;
+import java.lang.foreign.Arena;
 import java.lang.foreign.MemorySegment;
 import java.lang.foreign.SegmentScope;
-import java.net.URL;
-import java.net.URLClassLoader;
-import java.nio.file.Files;
-import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.Scanner;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import org.contikios.cooja.AbstractionLevelDescription;
 import org.contikios.cooja.ClassDescription;
 import org.contikios.cooja.Cooja;
-import org.contikios.cooja.CoreComm;
 import org.contikios.cooja.Mote;
 import org.contikios.cooja.MoteInterface;
 import org.contikios.cooja.ProjectConfig;
@@ -113,10 +106,9 @@
 // Do not bother end-user with warnings about internal Cooja details.
 @SuppressWarnings("preview")
 public class ContikiMoteType extends BaseContikiMoteType {
-
   private static final Logger logger = LoggerFactory.getLogger(ContikiMoteType.class);
-  private static int fileCounter = 1;
-
+  // Shared Arena since MoteTypes are allocated/removed in different threads.
+  private final Arena arena = Arena.openShared();
   /**
    * Communication stacks in Contiki.
    */
@@ -247,20 +239,9 @@ public boolean loadMoteFirmware(boolean vis) throws MoteTypeCreationException {
     if (myCoreComm != null) {
       throw new MoteTypeCreationException("Core communicator already used: " + myCoreComm.getClass().getName());
     }
-    Path tmpDir;
-    try {
-      tmpDir = Files.createTempDirectory("cooja");
-    } catch (IOException e) {
-      logger.warn("Failed to create temp directory:" + e);
-      return false;
-    }
-    tmpDir.toFile().deleteOnExit();
-
-    // Create, compile, and load the Java wrapper that loads the C library.
-
     // Allocate core communicator class
     final var firmwareFile = getContikiFirmwareFile();
-    myCoreComm = createCoreComm(tmpDir, firmwareFile);
+    myCoreComm = new CoreComm(arena.scope(), firmwareFile);
 
     /* Parse addresses using map file
      * or output of command specified in external tools settings (e.g. nm -a )
@@ -788,112 +769,8 @@ public boolean setConfigXML(Simulation simulation,
     return configureAndInit(Cooja.getTopParentContainer(), simulation, Cooja.isVisualized());
   }
 
-  /**
-   * Generates new source file by reading default source template and replacing
-   * the class name field.
-   *
-   * @param tempDir Directory for temporary files
-   * @param className Java class name (without extension)
-   * @throws MoteTypeCreationException If error occurs
-   */
-  private static void generateLibSourceFile(Path tempDir, String className) throws MoteTypeCreationException {
-    // Create the temporary directory and ensure it is deleted on exit.
-    File dir = tempDir.toFile();
-    StringBuilder path = new StringBuilder(tempDir.toString());
-    // Gradually do mkdir() since mkdirs() makes deleteOnExit() leave the
-    // directory when Cooja quits.
-    for (String p : new String[]{"/org", "/contikios", "/cooja", "/corecomm"}) {
-      path.append(p);
-      dir = new File(path.toString());
-      if (!dir.mkdir()) {
-        throw new MoteTypeCreationException("Could not create temporary directory: " + dir);
-      }
-      dir.deleteOnExit();
-    }
-    Path dst = Path.of(dir + "/" + className + ".java");
-    dst.toFile().deleteOnExit();
-
-    // Instantiate the CoreComm template into the temporary directory.
-    try (var input = ContikiMoteType.class.getResourceAsStream('/' + "CoreCommTemplate.java");
-         var reader = new BufferedReader(new InputStreamReader(Objects.requireNonNull(input), UTF_8));
-         var writer = Files.newBufferedWriter(dst, UTF_8)) {
-      String line;
-      while ((line = reader.readLine()) != null) {
-        writer.write(line.replace("CoreCommTemplate", className) + "\n");
-      }
-    } catch (Exception e) {
-      throw new MoteTypeCreationException("Could not generate corecomm source file: " + className + ".java", e);
-    }
-  }
-
-  /**
-   * Compiles Java class.
-   *
-   * @param tempDir   Directory for temporary files
-   * @param className Java class name (without extension)
-   * @throws MoteTypeCreationException If Java class compilation error occurs
-   */
-  private static void compileSourceFile(Path tempDir, String className) throws MoteTypeCreationException {
-    String[] cmd = {Cooja.configuration.javac(),
-            "-cp", System.getProperty("java.class.path"), "--release", String.valueOf(Runtime.version().feature()),
-            "--enable-preview",
-            tempDir + "/org/contikios/cooja/corecomm/" + className + ".java" };
-    ProcessBuilder pb = new ProcessBuilder(cmd);
-    Process p;
-    try {
-      p = pb.start();
-    } catch (IOException e) {
-      throw new MoteTypeCreationException("Could not start Java compiler: " + cmd[0], e);
-    }
-
-    // Try to create a message list with support for GUI - will give not UI if headless.
-    var compilationOutput = MessageContainer.createMessageList(true);
-    var stdout = compilationOutput.getInputStream(MessageList.NORMAL);
-    var stderr = compilationOutput.getInputStream(MessageList.ERROR);
-    try (var outputStream = p.inputReader(UTF_8);
-         var errorStream = p.errorReader(UTF_8)) {
-      int b;
-      while ((b = outputStream.read()) >= 0) {
-        stdout.write(b);
-      }
-      while ((b = errorStream.read()) >= 0) {
-        stderr.write(b);
-      }
-      if (p.waitFor() == 0) {
-        File classFile = new File(tempDir + "/org/contikios/cooja/corecomm/" + className + ".class");
-        classFile.deleteOnExit();
-        return;
-      }
-    } catch (IOException | InterruptedException e) {
-      throw new MoteTypeCreationException("Could not compile corecomm source file: " + className + ".java", e, compilationOutput);
-    }
-    throw new MoteTypeCreationException("Could not compile corecomm source file: " + className + ".java", compilationOutput);
-  }
-
-  /**
-   * Create and return an instance of the core communicator identified by
-   * className. This core communicator will load the native library libFile.
-   *
-   * @param tempDir Directory for temporary files
-   * @param libFile Native library file
-   * @return Core Communicator
-   */
-  private static CoreComm createCoreComm(Path tempDir, File libFile) throws MoteTypeCreationException {
-    // Loading a class might leave residue in the JVM so use a new name for the next call.
-    final var className = "Lib" + fileCounter++;
-    generateLibSourceFile(tempDir, className);
-    compileSourceFile(tempDir, className);
-    Class<? extends CoreComm> newCoreCommClass;
-    try (var loader = URLClassLoader.newInstance(new URL[]{tempDir.toUri().toURL()})) {
-      newCoreCommClass = loader.loadClass("org.contikios.cooja.corecomm." + className).asSubclass(CoreComm.class);
-    } catch (IOException | NullPointerException | ClassNotFoundException e1) {
-      throw new MoteTypeCreationException("Could not load corecomm class file: " + className + ".class", e1);
-    }
-
-    try {
-      return newCoreCommClass.getConstructor(File.class).newInstance(libFile);
-    } catch (Exception e) {
-      throw new MoteTypeCreationException("Error when creating corecomm instance: " + className, e);
-    }
+  @Override
+  public void removed() {
+    arena.close();
   }
 }

java/org/contikios/cooja/CoreComm.java → java/org/contikios/cooja/contikimote/CoreComm.java

@@ -26,50 +26,60 @@
  *
  */
 
-package org.contikios.cooja;
+package org.contikios.cooja.contikimote;
 
+import java.io.File;
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.Linker;
+import java.lang.foreign.SegmentScope;
+import java.lang.foreign.SymbolLookup;
+import java.lang.invoke.MethodHandle;
 
 /**
- * The purpose of CoreComm is to communicate with a compiled Contiki system
- * using Java Native Interface (JNI). Each implemented class (named
- * Lib[number]), loads a shared library which belongs to one mote type. The
- * reason for this somewhat strange design is that once loaded, a native library
- * cannot be unloaded in Java (in the current versions available). Therefore, if
- * we wish to load several libraries, the names and associated native functions
- * must have unique names. And those names are defined via the calling class in
- * JNI. For example, the corresponding function for a native tick method in
- * class Lib1 will be named Java_org_contikios_cooja_corecomm_Lib1_tick. When creating
- * a new mote type, the main Contiki source file is built with function
- * names compatible with the next available corecomm class. This also implies
- * that even if a mote type is deleted, a new one cannot be created using the
- * same corecomm class without restarting the JVM and thus the entire
- * simulation.
- * <p>
- * Each implemented CoreComm class needs read-access to the following core
- * variables:
- * <ul>
- * <li>referenceVar
- * </ul>
- * and the following native functions:
- * <ul>
- * <li>tick()
- * <li>init()
- * <li>getReferenceAbsAddr()
- * <li>getMemory(int start, int length, byte[] mem)
- * <li>setMemory(int start, int length, byte[] mem)
- * </ul>
- *
- * @author Fredrik Osterlind
+ * CoreComm loads a library file and keeps track of the method handles
+ * to the tick and getReferenceAddress methods.
  */
-public interface CoreComm {
+// Do not bother end-user with warnings about internal Cooja details.
+@SuppressWarnings("preview")
+class CoreComm {
+  private final SymbolLookup symbols;
+  private final MethodHandle coojaTick;
+  /**
+   * Loads library libFile with a scope.
+   *
+   * @param scope Scope to load the library file in
+   * @param libFile Library file
+   */
+  CoreComm(SegmentScope scope, File libFile) {
+    symbols = SymbolLookup.libraryLookup(libFile.getAbsolutePath(), scope);
+    var linker = Linker.nativeLinker();
+    coojaTick = linker.downcallHandle(symbols.find("cooja_tick").get(),
+            FunctionDescriptor.ofVoid());
+    // Call cooja_init() in Contiki-NG.
+    var coojaInit = linker.downcallHandle(symbols.find("cooja_init").get(),
+            FunctionDescriptor.ofVoid());
+    try {
+      coojaInit.invokeExact();
+    } catch (Throwable e) {
+      throw new RuntimeException("Calling cooja_init failed: " + e.getMessage(), e);
+    }
+  }
 
   /**
    * Ticks a mote once.
    */
-  void tick();
+  void tick() {
+    try {
+      coojaTick.invokeExact();
+    } catch (Throwable e) {
+      throw new RuntimeException("Calling cooja_tick failed: " + e.getMessage(), e);
+    }
+  }
 
   /**
    * Returns the absolute memory address of the reference variable.
    */
-  long getReferenceAddress();
+  long getReferenceAddress() {
+    return symbols.find("referenceVar").get().address();
+  }
 }