RecursiveThreadGroupLock: New recursive lock interface and impl, allowing 'spawn off' process to become the lock owner.

To avoid complicated synchronization via synchronized, wait and notify between one thread
and a 'spawn' off thread which temporarly requires the hold lock,
RecursiveThreadGroupLock allows to add and remove other threads to become owners of the lock
as if they were the original holder.

This simplifies some rare locking use cases, eg. in JOGL's GLProfile initialization sequence
where a SharedResourceRunner thread is taking over initialization of shared resources.

5 files changed, 686 insertions, 2 deletions

diff --git a/make/scripts/runtest.sh b/make/scripts/runtest.sh
index ec4701d..34f3bc6 100755
--- a/make/scripts/runtest.sh
+++ b/make/scripts/runtest.sh
@@ -55,6 +55,7 @@ function onetest() {
 #onetest com.jogamp.common.util.TestVersionInfo 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.TestIteratorIndexCORE 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.locks.TestRecursiveLock01 2>&1 | tee -a $LOG
+onetest com.jogamp.common.util.locks.TestRecursiveThreadGroupLock01 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.TestArrayHashSet01 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.IntIntHashMapTest 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.IntObjectHashMapTest 2>&1 | tee -a $LOG
@@ -64,7 +65,7 @@ function onetest() {
 #onetest com.jogamp.common.nio.TestPointerBufferEndian 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.nio.TestStructAccessorEndian 2>&1 | tee -a $LOG
 #onetest com.jogamp.gluegen.test.junit.generation.Test1p1JavaEmitter 2>&1 | tee -a $LOG
-onetest com.jogamp.gluegen.test.junit.generation.Test1p2ProcAddressEmitter 2>&1 | tee -a $LOG
+#onetest com.jogamp.gluegen.test.junit.generation.Test1p2ProcAddressEmitter 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.TestPlatform01 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.TestRunnableTask01 2>&1 | tee -a $LOG
 #onetest com.jogamp.common.util.TestIOUtil01 2>&1 | tee -a $LOG
diff --git a/src/java/com/jogamp/common/util/locks/LockFactory.java b/src/java/com/jogamp/common/util/locks/LockFactory.java
index c374c2d..bb2d5f4 100644
--- a/src/java/com/jogamp/common/util/locks/LockFactory.java
+++ b/src/java/com/jogamp/common/util/locks/LockFactory.java
@@ -30,11 +30,12 @@ package com.jogamp.common.util.locks;
 import jogamp.common.util.locks.RecursiveLockImpl01CompleteFair;
 import jogamp.common.util.locks.RecursiveLockImpl01Unfairish;
 import jogamp.common.util.locks.RecursiveLockImplJava5;
+import jogamp.common.util.locks.RecursiveThreadGroupLockImpl01Unfairish;
 
 public class LockFactory {
 
     public enum ImplType {
-        Int01(0), Java5(1); 
+        Int01(0), Java5(1), Int02ThreadGroup(2); 
         
         public final int id;
 
@@ -48,12 +49,19 @@ public class LockFactory {
         return new RecursiveLockImpl01Unfairish();
     }
     
+    /** default is ImplType.Int02ThreadGroup, unfair'ish (fastest w/ least deviation) */
+    public static RecursiveThreadGroupLock createRecursiveThreadGroupLock() {
+        return new RecursiveThreadGroupLockImpl01Unfairish();
+    }
+    
     public static RecursiveLock createRecursiveLock(ImplType t, boolean fair) {
         switch(t) {
             case Int01:
                 return fair ? new RecursiveLockImpl01CompleteFair() : new RecursiveLockImpl01Unfairish();
             case Java5:
                 return new RecursiveLockImplJava5(fair);
+            case Int02ThreadGroup:
+                return new RecursiveThreadGroupLockImpl01Unfairish();
         }
         throw new InternalError("XXX");
     }
diff --git a/src/java/com/jogamp/common/util/locks/RecursiveThreadGroupLock.java b/src/java/com/jogamp/common/util/locks/RecursiveThreadGroupLock.java
new file mode 100644
index 0000000..5e11f29
--- /dev/null
+++ b/src/java/com/jogamp/common/util/locks/RecursiveThreadGroupLock.java
@@ -0,0 +1,137 @@
+/**
+ * Copyright 2011 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+package com.jogamp.common.util.locks;
+
+/**
+ * Reentrance capable locking toolkit, supporting multiple threads as owner.
+ * <p>
+ * See use case description at {@link #addOwner(Thread)}.
+ * </p>
+ */
+public interface RecursiveThreadGroupLock extends RecursiveLock {
+    /** 
+     * Returns true if the current thread is the original lock owner, ie. 
+     * successfully claimed this lock the first time, ie. {@link #getHoldCount()} == 1.
+     */
+    boolean isOriginalOwner();
+    
+    /** 
+     * Returns true if the passed thread is the original lock owner, ie. 
+     * successfully claimed this lock the first time, ie. {@link #getHoldCount()} == 1.
+     */
+    boolean isOriginalOwner(Thread thread);
+    
+    /** 
+     * Add a thread to the list of additional lock owners, which enables them to recursively claim this lock.
+     * <p>
+     * The caller must hold this lock and be the original lock owner, see {@link #isOriginalOwner()}.
+     * </p>
+     * <p>
+     * If the original owner releases this lock via {@link #unlock()} 
+     * all additional lock owners are released as well.
+     * This ensures consistency of spawn off additional lock owner threads and it's release.
+     * </p> 
+     * Use case:
+     * <pre>
+     * Thread2 thread2 = new Thread2();
+     * 
+     * Thread1 {
+     * 
+     *   // Claim this lock and become the original lock owner.
+     *   lock.lock();
+     *   
+     *   try {
+     *   
+     *     // Allow Thread2 to claim the lock, ie. make thread2 an additional lock owner
+     *     addOwner(thread2);
+     *     
+     *     // Start thread2
+     *     thread2.start();
+     *     
+     *     // Wait until thread2 has finished requiring this lock, but keep thread2 running
+     *     while(!thread2.waitForResult()) sleep(); 
+     *     
+     *     // Optional: Only if sure that this thread doesn't hold the lock anymore,
+     *     // otherwise just release the lock via unlock(). 
+     *     removeOwner(thread2);
+     *     
+     *   } finally {
+     *   
+     *     // Release this lock and remove all additional lock owners.
+     *     // Implicit wait until thread2 gets off the lock.
+     *     lock.unlock();
+     *     
+     *   }
+     *   
+     * }.start();
+     * </pre>
+     *  
+     * @param t the thread to be added to the list of additional owning threads 
+     * @throws RuntimeException if the current thread does not hold the lock.
+     * @throws IllegalArgumentException if the passed thread is the lock owner or already added.
+     * 
+     * @see #removeOwner(Thread)
+     * @see #unlock()
+     * @see #lock()
+     */
+    void addOwner(Thread t) throws RuntimeException, IllegalArgumentException;
+
+    /**
+     * Remove a thread from the list of additional lock owner threads.
+     * <p>
+     * The caller must hold this lock and be the original lock owner, see {@link #isOriginalOwner()}.
+     * </p>
+     * <p>
+     * Only use this method if sure that the thread doesn't hold the lock anymore.
+     * </p>
+     * 
+     * @param t the thread to be removed from the list of additional owning threads 
+     * @throws RuntimeException if the current thread does not hold the lock.
+     * @throws IllegalArgumentException if the passed thread is not added by {@link #addOwner(Thread)}
+     */
+    void removeOwner(Thread t) throws RuntimeException, IllegalArgumentException;
+    
+    /**
+     * <p>
+     * Wait's until all additional owners released this lock before releasing it.
+     * </p>
+     * 
+     * {@inheritDoc}
+     */
+    void unlock() throws RuntimeException;
+    
+    /**
+     * <p>
+     * Wait's until all additional owners released this lock before releasing it.
+     * </p>
+     * 
+     * {@inheritDoc}
+     */
+    void unlock(Runnable taskAfterUnlockBeforeNotify);    
+    
+}
diff --git a/src/java/jogamp/common/util/locks/RecursiveThreadGroupLockImpl01Unfairish.java b/src/java/jogamp/common/util/locks/RecursiveThreadGroupLockImpl01Unfairish.java
new file mode 100644
index 0000000..561ac61
--- /dev/null
+++ b/src/java/jogamp/common/util/locks/RecursiveThreadGroupLockImpl01Unfairish.java
@@ -0,0 +1,211 @@
+/**
+ * Copyright 2010 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+package jogamp.common.util.locks;
+
+import java.util.Arrays;
+
+import com.jogamp.common.util.locks.RecursiveThreadGroupLock;
+
+public class RecursiveThreadGroupLockImpl01Unfairish 
+    extends RecursiveLockImpl01Unfairish 
+    implements RecursiveThreadGroupLock 
+{
+    /* package */ @SuppressWarnings("serial")
+    static class ThreadGroupSync extends SingleThreadSync {        
+        /* package */ ThreadGroupSync() {
+            super();
+            threadNum = 0;
+            threads = null;
+            holdCountAdditionOwner = 0;
+        }
+        public final void incrHoldCount(Thread t) { 
+            super.incrHoldCount(t); 
+            if(!isOriginalOwner(t)) { 
+                holdCountAdditionOwner++; 
+            } 
+        }
+        public final void decrHoldCount(Thread t) { 
+            super.decrHoldCount(t); 
+            if(!isOriginalOwner(t)) { 
+                holdCountAdditionOwner--; 
+            } 
+        }
+        public final int getAdditionalOwnerHoldCount() {
+            return holdCountAdditionOwner;
+        }
+        
+        public final boolean isOriginalOwner(Thread t) {
+            return super.isOwner(t);
+        }
+        public final boolean isOwner(Thread t) {
+            if(getExclusiveOwnerThread()==t) {
+                return true;
+            }
+            for(int i=threadNum-1; 0<=i; i--) {
+                if(threads[i]==t) {
+                    return true;
+                }
+            }
+            return false;
+        }
+        
+        public final int getAddOwnerCount() {
+            return threadNum;
+        }
+        public final void addOwner(Thread t) throws IllegalArgumentException {            
+            if(null == threads) {
+                if(threadNum>0) {
+                    throw new InternalError("XXX");
+                }
+                threads = new Thread[4];
+            }
+            for(int i=threadNum-1; 0<=i; i--) {
+                if(threads[i]==t) {
+                    throw new IllegalArgumentException("Thread already added: "+t);
+                }
+            }
+            if (threadNum == threads.length) {
+                threads = Arrays.copyOf(threads, threadNum * 2);
+            }
+            threads[threadNum] = t;
+            threadNum++;
+        }
+        
+        public final void removeAllOwners() {
+            for(int i=threadNum-1; 0<=i; i--) {
+                threads[i]=null;
+            }
+            threadNum=0;            
+        }
+        
+        public final void removeOwner(Thread t) throws IllegalArgumentException {       
+            for (int i = 0 ; i < threadNum ; i++) {
+                if (threads[i] == t) {
+                    threadNum--;
+                    System.arraycopy(threads, i + 1, threads, i, threadNum - i);
+                    threads[threadNum] = null; // cleanup 'dead' [or duplicate] reference for GC
+                    return;
+                }
+            }
+            throw new IllegalArgumentException("Not an owner: "+t);
+        }
+        
+        String addOwnerToString() {
+            StringBuffer sb = new StringBuffer();
+            for(int i=0; i<threadNum; i++) {
+                if(i>0) {
+                    sb.append(", ");
+                }
+                sb.append(threads[i].getName());
+            }
+            return sb.toString();            
+        }
+        
+        // lock count by addition owner threads
+        private int holdCountAdditionOwner;        
+        private Thread[] threads;
+        private int threadNum;
+    }
+    
+    public RecursiveThreadGroupLockImpl01Unfairish() {
+        super(new ThreadGroupSync());
+    }
+    
+    public final boolean isOriginalOwner() {
+        return isOriginalOwner(Thread.currentThread());
+    }
+
+    public final boolean isOriginalOwner(Thread thread) {
+        synchronized(sync) {
+            return ((ThreadGroupSync)sync).isOriginalOwner(thread) ;
+        }
+    }
+
+    public final void addOwner(Thread t) throws RuntimeException, IllegalArgumentException {
+        validateLocked();
+        final Thread cur = Thread.currentThread();
+        final ThreadGroupSync tgSync = (ThreadGroupSync)sync;
+        if(!tgSync.isOriginalOwner(cur)) {
+            throw new IllegalArgumentException("Current thread is not the original owner: orig-owner: "+tgSync.getOwner()+", current "+cur);
+        }
+        if(tgSync.isOriginalOwner(t)) {
+            throw new IllegalArgumentException("Passed thread is original owner: "+t);
+        }
+        tgSync.addOwner(t);
+    }
+    
+    public final void unlock(Runnable taskAfterUnlockBeforeNotify) {
+        synchronized(sync) {
+            final Thread cur = Thread.currentThread();
+            final ThreadGroupSync tgSync = (ThreadGroupSync)sync;
+            
+            if( tgSync.getAddOwnerCount()>0 ) {
+                if(DEBUG) {
+                    System.err.println("++ unlock(0): currentThread "+cur.getName()+", lock: "+this.toString());
+                }
+                if( tgSync.isOriginalOwner(cur) ) {
+                    // original locking owner thread
+                    if( tgSync.getHoldCount() - tgSync.getAdditionalOwnerHoldCount() == 1 ) {
+                        // release orig. lock
+                        while ( tgSync.getAdditionalOwnerHoldCount() > 0 ) {
+                            try {
+                                sync.wait();
+                            } catch (InterruptedException e) {
+                                // regular wake up!
+                            }
+                        }
+                        tgSync.removeAllOwners();
+                    }
+                } else if( tgSync.getAdditionalOwnerHoldCount() == 1 ) {
+                    // last additional owner thread wakes up original owner
+                    final Thread originalOwner = tgSync.getOwner();
+                    if(originalOwner.getState() == Thread.State.WAITING) {
+                        originalOwner.interrupt();
+                    }                
+                }
+            }
+            if(DEBUG) {
+                System.err.println("++ unlock(X): currentThread "+cur.getName()+", lock: "+this.toString());
+            }
+            super.unlock(taskAfterUnlockBeforeNotify);       
+        }
+    }
+    
+    public final void removeOwner(Thread t) throws RuntimeException, IllegalArgumentException {
+        validateLocked();
+        ((ThreadGroupSync)sync).removeOwner(t);
+    }
+    
+    public String toString() {
+        final ThreadGroupSync tgSync = (ThreadGroupSync)sync;
+        final int hc = sync.getHoldCount();
+        final int addHC = tgSync.getAdditionalOwnerHoldCount();
+        return syncName()+"[count "+hc+" [ add. "+addHC+", orig "+(hc-addHC)+
+                           "], qsz "+sync.getQSz()+", owner "+threadName(sync.getOwner())+", add.owner "+tgSync.addOwnerToString()+"]";
+    }
+}
diff --git a/src/junit/com/jogamp/common/util/locks/TestRecursiveThreadGroupLock01.java b/src/junit/com/jogamp/common/util/locks/TestRecursiveThreadGroupLock01.java
new file mode 100644
index 0000000..2eecce1
--- /dev/null
+++ b/src/junit/com/jogamp/common/util/locks/TestRecursiveThreadGroupLock01.java
@@ -0,0 +1,327 @@
+/**
+ * Copyright 2010 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ * 
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ * 
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+ 
+package com.jogamp.common.util.locks;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.jogamp.common.os.Platform;
+import com.jogamp.junit.util.JunitTracer;
+
+public class TestRecursiveThreadGroupLock01 extends JunitTracer {
+
+    public enum YieldMode {
+        NONE(0), YIELD(1), SLEEP(2); 
+        
+        public final int id;
+
+        YieldMode(int id){
+            this.id = id;
+        }
+    }    
+    
+    static void yield(YieldMode mode) {
+        switch(mode) {
+            case YIELD:
+                Thread.yield();
+                break;
+            case SLEEP:
+                try {
+                    Thread.sleep(10);
+                } catch (InterruptedException ie) {
+                    ie.printStackTrace();
+                }
+                break;
+            default:
+                break;
+        }
+
+    }
+
+    static class LockedObject {
+        static final boolean DEBUG = false;
+        
+        private RecursiveThreadGroupLock locker; // post
+        private volatile int slaveCounter;
+
+        public LockedObject() {
+            locker = LockFactory.createRecursiveThreadGroupLock();
+            slaveCounter = 0;
+        }
+
+        public final void masterAction(String tab, String name, Thread[] slaves, int loops, int mark, final YieldMode yieldMode) {
+            locker.lock();
+            if(DEBUG) {
+                System.err.println(tab+"<"+name+" c "+slaveCounter);
+            }
+            Assert.assertTrue(mark>loops);
+            Assert.assertTrue(loops*loops>mark);
+            try {
+                if(slaveCounter<mark) {
+                    for(int i=0; i<slaves.length; i++) {
+                        locker.addOwner(slaves[i]);
+                        slaves[i].start();
+                    }
+                    while(slaveCounter<mark) {
+                        yield(yieldMode);
+                    }
+                }
+            } finally {
+                if(DEBUG) {
+                    System.err.println(tab+" "+name+" c "+slaveCounter+">");
+                }
+                // Implicit waits until all slaves got off the lock
+                locker.unlock();
+            }
+        }
+
+        public final void slaveAction(String tab, String name, int loops, int mark, YieldMode yieldMode) {
+            if(slaveCounter>=mark) {
+                if(DEBUG) {
+                    System.err.println(tab+"["+name+" c "+slaveCounter+" - NOP]");
+                }
+                return;                
+            }
+            locker.lock();
+            if(DEBUG) {
+                System.err.println(tab+"["+name+" c "+slaveCounter);
+            }
+            Assert.assertTrue(mark>loops);
+            Assert.assertTrue(loops*loops>mark);
+            try {
+                while(loops>0 && slaveCounter<mark) {
+                    slaveCounter++;
+                    loops--;
+                }
+                /**
+                while(slaveCounter<mark) {
+                    slaveCounter++;
+                } */
+                yield(yieldMode);
+            } finally {
+                if(DEBUG) {
+                    System.err.println(tab+" "+name+" c "+slaveCounter+"]");
+                }
+                locker.unlock();
+            }
+        }
+
+        public final boolean isLocked() {
+            return locker.isLocked();
+        }
+        
+    }
+
+    interface LockedObjectRunner extends Runnable {
+        void stop();
+        boolean isStarted();
+        boolean isStopped();
+        void waitUntilStopped();
+    }
+
+    class LockedObjectRunner1 implements LockedObjectRunner {
+        volatile boolean shouldStop;
+        volatile boolean stopped;
+        volatile boolean started;
+        String tab, name;
+        LockedObject lo;
+        Thread[] slaves;
+        int loops;
+        int mark;
+        YieldMode yieldMode;
+
+        /** master constructor */
+        public LockedObjectRunner1(String tab, String name, LockedObject lo, Thread[] slaves, int loops, int mark, YieldMode yieldMode) {
+            this.tab = tab;
+            this.name = name;
+            this.lo = lo;
+            this.slaves = slaves;
+            this.loops = loops;
+            this.mark = mark;
+            this.shouldStop = false;
+            this.stopped = false;
+            this.yieldMode = yieldMode;
+            Assert.assertTrue(mark>loops);
+            Assert.assertTrue(loops*loops>mark);
+        }
+
+        /** slave constructor */
+        public LockedObjectRunner1(String tab, String name, LockedObject lo, int loops, int mark, YieldMode yieldMode) {
+            this.tab = tab;
+            this.name = name;
+            this.lo = lo;
+            this.slaves = null; // slave
+            this.loops = loops;
+            this.mark = mark;
+            this.shouldStop = false;
+            this.stopped = false;
+            this.yieldMode = yieldMode;
+            Assert.assertTrue(mark>loops);
+            Assert.assertTrue(loops*loops>mark);
+        }
+        
+        public final void stop() {
+            shouldStop = true;
+        }
+
+        public final boolean isStarted() {
+            return started;
+        }
+        public final boolean isStopped() {
+            return stopped;
+        }
+        
+        public void waitUntilStopped() {
+            synchronized(this) {
+                while(!stopped) {
+                    try {
+                        this.wait();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+            }
+            
+        }
+
+        public void run() {
+            synchronized(this) {
+                started = true;
+                for(int i=0; !shouldStop && i<loops; i++) {
+                    if(null != slaves) {
+                        lo.masterAction(tab, name, slaves, loops, mark, yieldMode);
+                    } else {
+                        lo.slaveAction(tab, name, loops, mark, yieldMode);
+                    }
+                }
+                stopped = true;
+                this.notifyAll();
+            }
+        }
+    }
+
+    protected long testLockedObjectImpl(LockFactory.ImplType implType, boolean fair, 
+                                        int slaveThreadNum, int concurrentThreadNum, 
+                                        int loops, int mark, YieldMode yieldMode) throws InterruptedException {
+        final long t0 = System.currentTimeMillis();
+        LockedObject lo = new LockedObject();
+        LockedObjectRunner[] concurrentRunners = new LockedObjectRunner[concurrentThreadNum];
+        LockedObjectRunner[] slaveRunners = new LockedObjectRunner[slaveThreadNum];
+        Thread[] concurrentThreads = new Thread[concurrentThreadNum];
+        Thread[] slaveThreads = new Thread[slaveThreadNum];
+        Thread[] noCoOwnerThreads = new Thread[0];
+        int i;
+
+        for(i=0; i<slaveThreadNum; i++) {
+            slaveRunners[i] = new LockedObjectRunner1("    ", "s"+i, lo, loops, mark, yieldMode);
+            String name = "ActionThread-Slaves-"+i+"_of_"+slaveThreadNum;
+            slaveThreads[i] = new Thread( slaveRunners[i], name );
+        }
+        for(i=0; i<concurrentThreadNum; i++) {
+            String name;
+            if(i==0) {
+                concurrentRunners[i] = new LockedObjectRunner1("", "M0", lo, slaveThreads, loops, mark, yieldMode);
+                name = "ActionThread-Master-"+i+"_of_"+concurrentThreadNum;            
+            } else {
+                concurrentRunners[i] = new LockedObjectRunner1("  ", "O"+i, lo, noCoOwnerThreads, loops, mark, yieldMode);
+                name = "ActionThread-Others-"+i+"_of_"+concurrentThreadNum;
+            }
+            concurrentThreads[i] = new Thread( concurrentRunners[i], name );
+            concurrentThreads[i].start();
+            if(i==0) {
+                // master thread w/ slaves shall start first
+                while(!concurrentRunners[i].isStarted()) {
+                    Thread.sleep(100);
+                }
+            }
+        }
+
+        for( i=0; i<slaveThreadNum; i++ ) {
+            slaveRunners[i].waitUntilStopped();
+        }
+        for( i=0; i<concurrentThreadNum; i++ ) {
+            concurrentRunners[i].waitUntilStopped();
+        }
+        Assert.assertEquals(0, lo.locker.getHoldCount());
+        Assert.assertEquals(false, lo.locker.isLocked());
+        
+        final long dt = System.currentTimeMillis()-t0;
+        
+        System.err.println();
+        final String fair_S = fair ? "fair  " : "unfair" ;
+        System.err.printf("---- TestRecursiveLock01.testLockedObjectThreading: i %5s, %s, threads %2d, loops-outter %6d, loops-inner %6d, yield %5s - dt %6d ms", 
+                implType, fair_S, concurrentThreadNum, loops, mark, yieldMode, dt);
+        System.err.println();
+        return dt;
+    }
+    
+    @Test
+    public void testTwoThreadsInGroup() throws InterruptedException {
+        LockFactory.ImplType t = LockFactory.ImplType.Int02ThreadGroup; 
+        boolean fair=true;
+        int coOwnerThreadNum=2;
+        int threadNum=5; 
+        int loops=1000; 
+        int mark=10000; 
+        YieldMode yieldMode=YieldMode.YIELD;
+        
+        if( Platform.getCPUFamily() == Platform.CPUFamily.ARM ) {
+            loops=5; mark=10;
+        }
+        
+        testLockedObjectImpl(t, fair, coOwnerThreadNum, threadNum, loops, mark, yieldMode);
+    }
+
+    public static void main(String args[]) throws IOException, InterruptedException {
+        String tstname = TestRecursiveThreadGroupLock01.class.getName();
+        org.junit.runner.JUnitCore.main(tstname);
+        
+        /**
+        BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
+        System.err.println("Press enter to continue");
+        System.err.println(stdin.readLine()); 
+        TestRecursiveLock01 t = new TestRecursiveLock01();
+        t.testLockedObjectThreading5x1000x10000N_Int01_Unfair();
+        
+        t.testLockedObjectThreading5x1000x10000N_Int01_Fair();
+        t.testLockedObjectThreading5x1000x10000N_Java5_Fair();
+        t.testLockedObjectThreading5x1000x10000N_Int01_Unfair();
+        t.testLockedObjectThreading5x1000x10000N_Java5_Unfair();
+        */
+    }
+
+}