Lock ChangeSet (fin): Cleanup, fix and enhance RecursiveLock implementation

- RecursiveLock _is_ interface.

- Use LockFactory to create a RecursiveLock.

- Impl: RecursiveLockImpl01Unfairish
  - just using notify w/o any queue: fast
  - still enqueuing new lock-applicants if queue full (nice)
  - lock's sync extends AbstractOwnableSynchronizer and uses it (monitor)

- Impl: RecursiveLockImpl01CompleteFair
  - using queue and interrupt for correctness (slow)
  - lock's sync extends AbstractOwnableSynchronizer and uses it (monitor)

- Impl: RecursiveLockImplJava5 for using Java5's concurrency impl.
  - to verify correctness, performance and deviation of locking time

TestRecursiveLock01 new performance measurements incl. simple avrg and deviation
shows best combined performance-deviation w/ our RecursiveLockImpl01Unfairish
os Linux and MacOSX.
RecursiveLockImpl01Unfairish is the default in LockFactory.

Adding 'private' LockDebugUtil, allowing validating all holdings locks
of one thread as stack traces (Throwable).
Besides the AbstractOwnableSynchronizer utilization, this helps debugging deadlocks
and starvation very well.

1 files changed, 140 insertions, 122 deletions

diff --git a/src/java/jogamp/common/util/locks/RecursiveLockImpl01Unfairish.java b/src/java/jogamp/common/util/locks/RecursiveLockImpl01Unfairish.java
index ad29f78..23e2c90 100644
--- a/src/java/jogamp/common/util/locks/RecursiveLockImpl01Unfairish.java
+++ b/src/java/jogamp/common/util/locks/RecursiveLockImpl01Unfairish.java
@@ -26,35 +26,54 @@
  * or implied, of JogAmp Community.
  */
 
-package com.jogamp.common.util.locks;
+package jogamp.common.util.locks;
 
-import jogamp.common.Debug;
-import java.security.AccessController;
+import java.util.List;
+import java.util.concurrent.locks.AbstractOwnableSynchronizer;
 
-import java.util.LinkedList;
+import com.jogamp.common.util.locks.RecursiveLock;
 
 /**
- * Reentrance locking toolkit, impl a complete fair FIFO scheduler
+ * Reentrance locking toolkit, impl a non-complete fair FIFO scheduler.
+ * <p>
+ * Fair scheduling is not guaranteed due to the usage of {@link Object#notify()},
+ * however new lock-applicants will wait if queue is not empty for {@link #lock()} 
+ * and {@link #tryLock(long) tryLock}(timeout>0).</p>
+ * 
+ * <p>
+ * Sync object extends {@link AbstractOwnableSynchronizer}, hence monitoring is possible.</p>
  */
-public class RecursiveLock implements LockExt {
+public class RecursiveLockImpl01Unfairish implements RecursiveLock {
 
-    static class SyncData {
-        // owner of the lock
-        Thread owner = null; 
-        // lock recursion
-        int recursionCount = 0; 
+    @SuppressWarnings("serial")
+    private static class Sync extends AbstractOwnableSynchronizer {
+        private Sync() {
+            super();
+        }
+        private final Thread getOwner() {
+            return getExclusiveOwnerThread();
+        }
+        private final void setOwner(Thread t) {
+            setExclusiveOwnerThread(t);
+        }
+        private final void setLockedStack(Throwable s) {
+            List<Throwable> ls = LockDebugUtil.getRecursiveLockTrace();
+            if(s==null) {
+                ls.remove(lockedStack);
+            } else {
+                ls.add(s);
+            }            
+            lockedStack = s;
+        }
+        // lock count by same thread
+        private int holdCount = 0;
         // stack trace of the lock, only used if DEBUG
-        Throwable lockedStack = null;
-        // waiting thread queue
-        LinkedList threadQueue = new LinkedList(); 
-        // flag signaling unlock has woken up a waiting thread
-        boolean signaled = false; 
+        private Throwable lockedStack = null;
+        private int qsz = 0;
     }
-    private final SyncData sdata = new SyncData(); // synchronized (flow/mem)  mutable access
-
-    private static final boolean TRACE_LOCK = Debug.isPropertyDefined("jogamp.debug.Lock.TraceLock", true, AccessController.getContext());
-
-    public RecursiveLock() {
+    private Sync sync = new Sync();
+        
+    public RecursiveLockImpl01Unfairish() {
     }
 
     /**
@@ -63,131 +82,127 @@ public class RecursiveLock implements LockExt {
      * @see com.jogamp.common.util.locks.Lock#DEBUG
      */
     public final Throwable getLockedStack() {
-        synchronized(sdata) {
-            return sdata.lockedStack;
+        synchronized(sync) {
+            return sync.lockedStack;
         }
     }
 
     public final Thread getOwner() {
-        synchronized(sdata) {
-            return sdata.owner;
+        synchronized(sync) {
+            return sync.getOwner();
         }
     }
 
     public final boolean isOwner() {
-        return isOwner(Thread.currentThread());
+        synchronized(sync) {
+            return isOwner(Thread.currentThread());
+        }
     }
 
     public final boolean isOwner(Thread thread) {
-        synchronized(sdata) {
-            return sdata.owner == thread ;
+        synchronized(sync) {
+            return sync.getOwner() == thread ;
         }
     }
 
     public final boolean isLocked() {
-        synchronized(sdata) {
-            return null != sdata.owner;
+        synchronized(sync) {
+            return null != sync.getOwner();
         }
     }
 
     public final boolean isLockedByOtherThread() {
-        synchronized(sdata) {
-            return null != sdata.owner && Thread.currentThread() != sdata.owner ;
+        synchronized(sync) {
+            return null != sync.getOwner() && Thread.currentThread() != sync.getOwner() ;
         }
     }
 
-    public final int getRecursionCount() {
-        synchronized(sdata) {
-            return sdata.recursionCount;
+    public final int getHoldCount() {
+        synchronized(sync) {
+            return sync.holdCount;
         }
     }
 
     public final void validateLocked() {
-        synchronized(sdata) {
-            if ( null == sdata.owner ) {
-                throw new RuntimeException(Thread.currentThread()+": Not locked");
-            }
-            if ( Thread.currentThread() != sdata.owner ) {
-                if(null!=sdata.lockedStack) {
-                    sdata.lockedStack.printStackTrace();
+        synchronized(sync) {
+            if ( Thread.currentThread() != sync.getOwner() ) {
+                if ( null == sync.getOwner() ) {
+                    throw new RuntimeException(threadName(Thread.currentThread())+": Not locked: "+toString());
                 }
-                throw new RuntimeException(Thread.currentThread()+": Not owner, owner is "+sdata.owner);
+                if(null!=sync.lockedStack) {
+                    sync.lockedStack.printStackTrace();
+                }
+                throw new RuntimeException(Thread.currentThread()+": Not owner: "+toString());
             }
         }
     }
 
     public final void lock() {
-        synchronized(sdata) {
-            if(!tryLock(TIMEOUT)) {
-                if(null!=sdata.lockedStack) {
-                    sdata.lockedStack.printStackTrace();
+        synchronized(sync) {
+            try {
+                if(!tryLock(TIMEOUT)) {
+                    if(null!=sync.lockedStack) {
+                        sync.lockedStack.printStackTrace();
+                    }
+                    throw new RuntimeException("Waited "+TIMEOUT+"ms for: "+toString()+" - "+threadName(Thread.currentThread()));
                 }
-                throw new RuntimeException("Waited "+TIMEOUT+"ms for: "+sdata.owner+" - "+Thread.currentThread()+", with recursionCount "+sdata.recursionCount+", lock: "+this+", qsz "+sdata.threadQueue.size());
+            } catch (InterruptedException e) {
+                throw new RuntimeException("Interrupted", e);
             }
         }
     }
 
-    public boolean tryLock(long maxwait) {
-        synchronized(sdata) {
-            Thread cur = Thread.currentThread();
+    public final boolean tryLock(long timeout) throws InterruptedException {
+        synchronized(sync) {
+            final Thread cur = Thread.currentThread();
             if(TRACE_LOCK) {
-                String msg = "LOCK 0 ["+this+"], recursions "+sdata.recursionCount+", cur "+cur+", owner "+sdata.owner;
-                System.err.println(msg);
-                //Throwable tt = new Throwable(msg);
-                //tt.printStackTrace();
+                System.err.println("+++ LOCK 0 "+toString()+", cur "+threadName(cur));
             }
-            if (sdata.owner == cur) {
-                ++sdata.recursionCount;
+            if (sync.getOwner() == cur) {
+                ++sync.holdCount;
                 if(TRACE_LOCK) {
-                    System.err.println("+++ LOCK 2 ["+this+"], recursions "+sdata.recursionCount+", "+cur);
+                    System.err.println("+++ LOCK XR "+toString()+", cur "+threadName(cur));
                 }
                 return true;
             }
-
-            if ( sdata.owner != null || 
-                 0 < maxwait && ( sdata.signaled || sdata.threadQueue.size() > 0 ) ) {
-
-                if ( 0 >= maxwait ) {
-                    // implies 'sdata.owner != null': locked by other thread
-                    // no waiting requested, bail out right away
+    
+            if ( sync.getOwner() != null || ( 0<timeout && 0<sync.qsz ) ) {
+    
+                if ( 0 >= timeout ) {
+                    // locked by other thread and no waiting requested
                     return false;
                 }
-
-                boolean timedOut = false;
+    
+                ++sync.qsz;
                 do {
-                    sdata.threadQueue.addFirst(cur); // should only happen once 
-                    try {
-                        sdata.wait(maxwait);
-                        timedOut = sdata.threadQueue.remove(cur); // TIMEOUT if not already removed by unlock
-                    } catch (InterruptedException e) {
-                        if(!sdata.signaled) {
-                            // theoretically we could stay in the loop,
-                            // in case the interrupt wasn't issued by unlock, 
-                            // hence the re-enqueue
-                            sdata.threadQueue.remove(cur);
-                            if(TRACE_LOCK) {
-                                System.err.println("XXX LOCK - ["+this+"], recursions "+sdata.recursionCount+", "+cur);
-                            }
-                        }
+                    final long t0 = System.currentTimeMillis();
+                    sync.wait(timeout);
+                    timeout -= System.currentTimeMillis() - t0;
+                } while (null != sync.getOwner() && 0 < timeout) ;
+                --sync.qsz;
+    
+                if( 0 >= timeout ) {
+                    // timed out
+                    if(TRACE_LOCK || DEBUG) {
+                        System.err.println("+++ LOCK XX "+toString()+", cur "+threadName(cur)+", left "+timeout+" ms");
                     }
-                } while (null != sdata.owner && !timedOut) ;
-
-                sdata.signaled = false;
-
-                if(timedOut || null != sdata.owner) {
                     return false;
                 }
-
+    
+                ++sync.holdCount;
+                if(TRACE_LOCK) {
+                    System.err.println("+++ LOCK X1 "+toString()+", cur "+threadName(cur)+", left "+timeout+" ms");
+                }
+            } else {
+                ++sync.holdCount;
                 if(TRACE_LOCK) {
-                    System.err.println("+++ LOCK 3 ["+this+"], recursions "+sdata.recursionCount+", qsz "+sdata.threadQueue.size()+", "+cur);
+                    System.err.println("+++ LOCK X0 "+toString()+", cur "+threadName(cur));
                 }
-            } else if(TRACE_LOCK) {
-                System.err.println("+++ LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", qsz "+sdata.threadQueue.size()+", "+cur);
             }
-
-            sdata.owner = cur;
+    
+            sync.setOwner(cur);
             if(DEBUG) {
-                sdata.lockedStack = new Throwable("Previously locked by "+sdata.owner+", lock: "+this);
+                sync.setLockedStack(new Throwable("Previously locked by "+toString()));
             }
             return true;
         }
@@ -195,51 +210,54 @@ public class RecursiveLock implements LockExt {
     
 
     public final void unlock() {
-        unlock(null);
+        synchronized(sync) {
+            unlock(null);
+        }
     }
 
     public final void unlock(Runnable taskAfterUnlockBeforeNotify) {
-        synchronized(sdata) {
+        synchronized(sync) {
             validateLocked();
-
-            if (sdata.recursionCount > 0) {
-                --sdata.recursionCount;
+            final Thread cur = Thread.currentThread();
+            
+            --sync.holdCount;
+            
+            if (sync.holdCount > 0) {
                 if(TRACE_LOCK) {
-                    System.err.println("--- LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
+                    System.err.println("--- LOCK XR "+toString()+", cur "+threadName(cur));
                 }
                 return;
             }
-            sdata.owner = null;
-            sdata.lockedStack = null;
+            
+            sync.setOwner(null);
+            if(DEBUG) {
+                sync.setLockedStack(null);
+            }
             if(null!=taskAfterUnlockBeforeNotify) {
                 taskAfterUnlockBeforeNotify.run();
             }
-
-            int qsz = sdata.threadQueue.size();
-            if(qsz > 0) {
-                Thread parkedThread = (Thread) sdata.threadQueue.removeLast();
-                if(TRACE_LOCK) {
-                    System.err.println("--- LOCK X ["+this+"], recursions "+sdata.recursionCount+
-                                       ", "+Thread.currentThread()+", irq "+(qsz-1)+": "+parkedThread);
-                }
-                sdata.signaled = true;
-                if(qsz==1) {
-                    // fast path, just one waiting thread
-                    sdata.notify();
-                } else {
-                    // signal the oldest one ..
-                    parkedThread.interrupt(); // Propagate SecurityException if it happens
-                }
-            } else if(TRACE_LOCK) {
-                System.err.println("--- LOCK X ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
+    
+            if(TRACE_LOCK) {
+                System.err.println("--- LOCK X0 "+toString()+", cur "+threadName(cur)+", signal any");
             }
+            sync.notify();
         }
     }
     
-    public int getWaitingThreadQueueSize() {
-        synchronized(sdata) {
-            return sdata.threadQueue.size();
+    public final int getQueueLength() {
+        synchronized(sync) {
+            return sync.qsz;
         }
     }
+    
+    public String toString() {
+        return syncName()+"[count "+sync.holdCount+
+                           ", qsz "+sync.qsz+", owner "+threadName(sync.getOwner())+"]";
+    }
+    
+    private final String syncName() {
+        return "<"+Integer.toHexString(this.hashCode())+", "+Integer.toHexString(sync.hashCode())+">";
+    }
+    private final String threadName(Thread t) { return null!=t ? "<"+t.getName()+">" : "<NULL>" ; }
 }