Fix: NativeWindow RecursiveToolkitLock, GLWindow lockSurface/unlockSurface

Fix: NativeWindow RecursiveToolkitLock
    - Use notify(), instead of notifyAll(), so only one thread is being awakened
      for the single resource. Otherwise starvation and timeout happen, since
      the oldest thread might not get waken up (earlier than other threads) within timeout.

    - Inner class for all synchronized (flow/mem) fields for easier fine grained sync/lock.

Fix: GLWindow lockSurface/unlockSurface
    - Enter locked surface block only if surface lock could be acquired

1 files changed, 101 insertions, 67 deletions

diff --git a/src/nativewindow/classes/com/jogamp/nativewindow/impl/RecursiveToolkitLock.java b/src/nativewindow/classes/com/jogamp/nativewindow/impl/RecursiveToolkitLock.java
index a894c61..bfa3d32 100644
--- a/src/nativewindow/classes/com/jogamp/nativewindow/impl/RecursiveToolkitLock.java
+++ b/src/nativewindow/classes/com/jogamp/nativewindow/impl/RecursiveToolkitLock.java
@@ -34,110 +34,144 @@ import javax.media.nativewindow.*;
 // Reentrance locking toolkit
 // 
 public class RecursiveToolkitLock {
-    private Thread owner = null;
-    private int recursionCount = 0;
-    private Exception lockedStack = null;
-    private static final long timeout = 5000;  // maximum wait 5s
-    // private static final long timeout = 300000;  // maximum wait 300s
+    static class SyncData {
+        Thread owner = null;
+        int recursionCount = 0;
+        Exception lockedStack = null;
+    }
+    private SyncData sdata = new SyncData(); // synchronized (flow/mem)  mutable access
+
+    private long timeout;
+    private static final long defaultTimeout = 5000;  // default maximum wait 5s
+    // private static final long defaultTimeout = 10000;  // default maximum wait 10s
+    // private static final long defaultTimeout = 300000;  // default maximum wait 300s / 5min
     private static final boolean TRACE_LOCK = Debug.debug("TraceLock");
 
-    public Exception getLockedStack() {
-        return lockedStack;
+    public RecursiveToolkitLock() {
+        this.timeout = defaultTimeout;
     }
 
-    public Thread getOwner() {
-        return owner;
+    public RecursiveToolkitLock(long timeout) {
+        this.timeout = timeout;
     }
 
-    public boolean isOwner() {
-        return isOwner(Thread.currentThread());
+    public final Exception getLockedStack() {
+        synchronized(sdata) {
+            return sdata.lockedStack;
+        }
     }
 
-    public synchronized boolean isOwner(Thread thread) {
-        return owner == thread ;
+    public final Thread getOwner() {
+        synchronized(sdata) {
+            return sdata.owner;
+        }
     }
 
-    public synchronized boolean isLocked() {
-        return null != owner;
+    public final boolean isOwner() {
+        return isOwner(Thread.currentThread());
     }
 
-    public synchronized boolean isLockedByOtherThread() {
-        return null != owner && Thread.currentThread() != owner ;
+    public final boolean isOwner(Thread thread) {
+        synchronized(sdata) {
+            return sdata.owner == thread ;
+        }
     }
 
-    public synchronized int getRecursionCount() {
-        return recursionCount;
+    public final boolean isLocked() {
+        synchronized(sdata) {
+            return null != sdata.owner;
+        }
     }
 
-    public synchronized void validateLocked() {
-        if ( !isLocked() ) {
-            throw new RuntimeException(Thread.currentThread()+": Not locked");
+    public final boolean isLockedByOtherThread() {
+        synchronized(sdata) {
+            return null != sdata.owner && Thread.currentThread() != sdata.owner ;
         }
-        if ( !isOwner() ) {
-            getLockedStack().printStackTrace();
-            throw new RuntimeException(Thread.currentThread()+": Not owner, owner is "+owner);
+    }
+
+    public final int getRecursionCount() {
+        synchronized(sdata) {
+            return sdata.recursionCount;
         }
     }
 
-    /** Recursive and blocking lockSurface() implementation */
-    public synchronized void lock() {
-        Thread cur = Thread.currentThread();
-        if(TRACE_LOCK) {
-            System.out.println("... LOCK 0 ["+this+"], recursions "+recursionCount+", "+cur);
+    public final void validateLocked() {
+        synchronized(sdata) {
+            if ( null == sdata.owner ) {
+                throw new RuntimeException(Thread.currentThread()+": Not locked");
+            }
+            if ( Thread.currentThread() != sdata.owner ) {
+                getLockedStack().printStackTrace();
+                throw new RuntimeException(Thread.currentThread()+": Not owner, owner is "+sdata.owner);
+            }
         }
-        if (owner == cur) {
-            ++recursionCount;
+    }
+
+    /** Recursive and blocking lockSurface() implementation */
+    public final void lock() {
+        synchronized(sdata) {
+            Thread cur = Thread.currentThread();
             if(TRACE_LOCK) {
-                System.out.println("+++ LOCK 1 ["+this+"], recursions "+recursionCount+", "+cur);
+                System.out.println("... LOCK 0 ["+this+"], recursions "+sdata.recursionCount+", "+cur);
+            }
+            if (sdata.owner == cur) {
+                ++sdata.recursionCount;
+                if(TRACE_LOCK) {
+                    System.out.println("+++ LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", "+cur);
+                }
+                return;
             }
-            return;
-        }
 
-        long ts = System.currentTimeMillis();
-        while (owner != null && (System.currentTimeMillis()-ts) < timeout) {
-            try {
-                wait(timeout);
-            } catch (InterruptedException e) {
-                throw new RuntimeException(e);
+            long ts = System.currentTimeMillis();
+            while (sdata.owner != null && (System.currentTimeMillis()-ts) < timeout) {
+                try {
+                    sdata.wait(timeout);
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
             }
+            if(sdata.owner != null) {
+                sdata.lockedStack.printStackTrace();
+                throw new RuntimeException("Waited "+timeout+"ms for: "+sdata.owner+" - "+cur+", with recursionCount "+sdata.recursionCount+", lock: "+this);
+            }
+            if(TRACE_LOCK) {
+                System.out.println("+++ LOCK X ["+this+"], recursions "+sdata.recursionCount+", "+cur);
+            }
+            sdata.owner = cur;
+            sdata.lockedStack = new Exception("Previously locked by "+sdata.owner+", lock: "+this);
         }
-        if(owner != null) {
-            lockedStack.printStackTrace();
-            throw new RuntimeException("Waited "+timeout+"ms for: "+owner+" - "+cur+", with recursionCount "+recursionCount+", lock: "+this);
-        }
-        if(TRACE_LOCK) {
-            System.out.println("+++ LOCK X ["+this+"], recursions "+recursionCount+", "+cur);
-        }
-        owner = cur;
-        lockedStack = new Exception("Previously locked by "+owner+", lock: "+this);
     }
     
 
     /** Recursive and unblocking unlockSurface() implementation */
-    public synchronized void unlock() {
+    public final void unlock() {
         unlock(null);
     }
 
     /** Recursive and unblocking unlockSurface() implementation */
-    public synchronized void unlock(Runnable taskAfterUnlockBeforeNotify) {
-        validateLocked();
-
-        if (recursionCount > 0) {
-            --recursionCount;
+    public final void unlock(Runnable taskAfterUnlockBeforeNotify) {
+        synchronized(sdata) {
+            validateLocked();
+
+            if (sdata.recursionCount > 0) {
+                --sdata.recursionCount;
+                if(TRACE_LOCK) {
+                    System.out.println("--- LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
+                }
+                return;
+            }
+            sdata.owner = null;
+            sdata.lockedStack = null;
+            if(null!=taskAfterUnlockBeforeNotify) {
+                taskAfterUnlockBeforeNotify.run();
+            }
             if(TRACE_LOCK) {
-                System.out.println("--- LOCK 1 ["+this+"], recursions "+recursionCount+", "+Thread.currentThread());
+                System.out.println("--- LOCK X ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
             }
-            return;
-        }
-        owner = null;
-        lockedStack = null;
-        if(null!=taskAfterUnlockBeforeNotify) {
-            taskAfterUnlockBeforeNotify.run();
-        }
-        if(TRACE_LOCK) {
-            System.out.println("--- LOCK X ["+this+"], recursions "+recursionCount+", "+Thread.currentThread());
+            // Assuming notify() implementation weaks up the longest waiting thread, to avoid starvation. 
+            // Otherwise we would need to have a Thread queue implemented, using sleep(timeout) and interrupt.
+            sdata.notify();
         }
-        notifyAll();
     }
 }