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.

1 files changed, 211 insertions, 0 deletions

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()+"]";
+    }
+}