<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>jezek2</groupId>
  <artifactId>jstackalloc</artifactId>
  <packaging>jar</packaging>
  <version>20080716</version>
  <name>jstackalloc</name>
  <url>http://www.java-gaming.org/topics/jstackalloc-stack-allocation-of-quot-value-quot-objects-in-java/18843/view.html</url>
  <dependencies>
    <dependency>
      <groupId>org.apache.ant</groupId>
      <artifactId>ant</artifactId>
      <version>1.7.1</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>asm</groupId>
      <artifactId>asm-all</artifactId>
      <version>3.1</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.0.2</version>
        <configuration>
          <source>1.6</source>
          <target>1.6</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

[...]
    <dependency>
      <groupId>jezek2</groupId>
      <artifactId>jstackalloc</artifactId>
      <version>20080716</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
[...]
      <plugin>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.3</version>
        <executions>
          <execution>
            <phase>process-classes</phase>
            <configuration>
              <tasks>
                <property name="compile_classpath" refid="maven.compile.classpath"/>
                <taskdef name="instrument-stack"
                    classname="cz.advel.stack.instrument.InstrumentationTask"
                    classpath="${compile_classpath}"/>
                <instrument-stack dest="${project.build.outputDirectory}" packageName="com.bulletphysics" isolated="true" singlethread="true">
                    <fileset dir="${project.build.outputDirectory}" includes="**/*.class"/>
                </instrument-stack>
              </tasks>
            </configuration>
            <goals>
              <goal>run</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
[...]

--- /home/magnus/tmp/InstrumentationTask.java   2008-07-16 19:43:34.000000000 +0200
+++ /home/magnus/dev/dev/madmind/master.git/jstackalloc-20080716/src/cz/advel/stack/instrument/InstrumentationTask.java   2009-08-29 11:51:33.000000000 +0200
 -105,13 +105,14 @@
    @Override
    public void execute() throws BuildException {
       try {
          List<File> files = new ArrayList<File>();
          for (FileSet fs : fileSets) {
-            String[] fileNames = fs.getDirectoryScanner().getIncludedFiles();
+            String[] fileNames = fs.getDirectoryScanner(
+                  getProject()).getIncludedFiles();
             for (String fname : fileNames) {
-               File file = new File(fs.getDir(), fname);
+               File file = new File(fs.getDir(getProject()), fname);
                if (file.getName().endsWith(".class")) {
                   files.add(file);
                }
             }
          }

[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] org.apache.tools.ant.types.FileSet.getDirectoryScanner()Lorg/apache/tools/ant/DirectoryScanner;
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NoSuchMethodError: org.apache.tools.ant.types.FileSet.getDirectoryScanner()Lorg/apache/tools/ant/DirectoryScanner;
   at cz.advel.stack.instrument.InstrumentationTask.execute(InstrumentationTask.java:110)
   at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
   at org.apache.tools.ant.Task.perform(Task.java:364)
   at org.apache.tools.ant.Target.execute(Target.java:341)
   at org.apache.maven.plugin.antrun.AbstractAntMojo.executeTasks(AbstractAntMojo.java:108)
   at org.apache.maven.plugin.antrun.AntRunMojo.execute(AntRunMojo.java:83)
   at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:451)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:558)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:499)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:478)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:330)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:291)
   at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
   at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
   at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
   at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
   at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
   at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
   at org.codehaus.classworlds.Launcher.main(Launcher.java:375)

   // Below, childPart might be an upper arm,
   // and parentPart would then be the torso.
   // Or the child part could be the left shin leg;
   // the parent part would then be the left thigh.)

   // The constraint that just limits movement.
   if (constraintType == HINGE_CONSTRAINT_TYPE) {
      childPart.joint = new HingeConstraint(
            parentPart.physics(), childPart.physics(),
            new Transform(parentFrame), new Transform(childFrame));
   }
   else if (constraintType == CONETWIST_CONSTRAINT_TYPE) {
      childPart.joint = new ConeTwistConstraint(
            parentPart.physics(), childPart.physics(),
            new Transform(parentFrame), new Transform(childFrame));
   }
   ...
 
   // The muscle actuation constraint.
   childPart.motor = new Generic6DofConstraint(
         parentPart.physics(), childPart.physics(),
         new Transform(parentFrame), new Transform(childFrame), true);
 
   // To apply muscle actuation, the motor child frame is rotated
   // (relative the parent frame); the motor limits remain 0, always.
   childPart.motor.setLimit(3 + 0, 0, 0);
   childPart.motor.setLimit(3 + 1, 0, 0);
   childPart.motor.setLimit(3 + 2, 0, 0);


// And in some function, to rotate the child body part
// relative the parent body part:

   childPart.motor.setFrameBaseB(newRotation);
   // Function is not present in JBullet, but see below:


public class Generic6DofConstraint extends TypedConstraint {
   ...
   public void setFrameBaseB(Quat4f basis) {
      frameInB.basis.set(basis);
   }
   ...
}

public class Vector3f extends Tuple3f implements Serializable {

    public static final Vector3f PLUS_X = new Vector3f(1, 0, 0).sealForever();
    public static final Vector3f PLUS_Y = new Vector3f(0, 1, 0).sealForever();
    ...

public class KeyFrame<L extends Enum<L> & BodyPart> {

    // ...

   /**
    * Also seals the Quat4f instances. */
   private final EnumMap<L, Quat4f> limbRotations;

   /**
    * Sets the rotation of {@code limb} to a normalized clone of {@code rotation}.
    */
   public void setRotation(L limb, Quat4f rotation) {
      limbRotations.put(limb, new Quat4f(rotation).normalize().seal(limbRotations));
   }

   /**
    * Returns the rotation of {@code limb}, for read access only.
    */
   public Quat4f getRotation(L limb) {
      return limbRotations.get(limb);
   }

   /**
    * Interpolates this {@code KeyFrame} and {@code target},
    * and places the result into this instance.
    * @param amount how close to {@code target} the resulting key frame should be. In [0, 1].
    */
   public void interpolate(KeyFrame<L> target, float amount) {

      for (Entry<L, Quat4f> entry : limbRotations.entrySet()) {
         L limb = entry.getKey();
         Quat4f quatThis = entry.getValue();
         Quat4f quatTarget = target.limbRotations.get(limb);
         quatThis.unseal(limbRotations);
         quatThis.interpolate(quatTarget, amount);
         quatThis.seal(limbRotations);
      }
   }

package madmath;

public abstract class Sealable {
    /**
     * Read-only forever tag.
     */
    private static final Object IMMUTABLE = new Object();
    /**
     * Read-only lock.
     */
    private transient Object key = null;

    public Sealable seal(Object key) {
        if (this.key != null && this.key != key)
            throw new IllegalArgumentException(getClass().getSimpleName() +
                    " instance already sealed with other key");
        if (key == null)
            throw new NullPointerException("key is null");
        this.key = key;
        return this;
    }

    public Sealable sealForever() {
        return seal(IMMUTABLE); // cannot remove this seal
    }

    public Sealable unseal(Object key) {
        if (this.key != null && this.key != key)
            throw new IllegalArgumentException("Wrong key");
        this.key = null;
        return this;
    }

    void _checkWritable() {
        if (key != null)
            throw new IllegalStateException(getClass().getSimpleName() + " instance is " +
                    (key == IMMUTABLE ? "immutable" : "read only"));
    }

}

public abstract class Tuple3f extends Sealable implements Serializable {
    public final void set(float x, float y, float z) {
   _checkWritable();
   this.x = x;
   this.y = y;
   this.z = z;
    }

public class MemTest {

   static class SmallVec3f {
      float x, y, z;
   }

   static class SmallQuat4f {
      float x, y, z, w;
   }

   static class SmallMat3f {
      float m00, m01, m02,
            m10, m11, m12,
            m20, m21, m22;
   }

   static class SmallMat4f {
      float m00, m01, m02, m03,
            m10, m11, m12, m13,
            m20, m21, m22, m23,
            m30, m31, m32, m33;
   }

   public static void main(String args[]) {

      int num = 10000;
      ArrayList<Object> objs = new ArrayList<Object>();

      for (int i = 0; i < num; ++i) {
         objs.add(new SmallVec3f());
         objs.add(new SmallQuat4f());
         objs.add(new SmallMat3f());
         objs.add(new SmallMat4f());

         // These 4 below have an additional field ``Object key''.
         objs.add(new Vector3f());
         objs.add(new Quat4f());
         objs.add(new Matrix3f());
         objs.add(new Matrix4f());
      }

      while (true) {
         // check profiler results
      }
   }
}