1 files changed, 157 insertions, 0 deletions
diff --git a/src/jogl/classes/jogamp/opengl/GLContextLock.java b/src/jogl/classes/jogamp/opengl/GLContextLock.java
new file mode 100644
index 000000000..ea78f5209
--- /dev/null
+++ b/src/jogl/classes/jogamp/opengl/GLContextLock.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
+ * Copyright (c) 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:
+ * 
+ * - Redistribution of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * 
+ * - Redistribution 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.
+ * 
+ * Neither the name of Sun Microsystems, Inc. or the names of
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ * 
+ * This software is provided "AS IS," without a warranty of any kind. ALL
+ * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
+ * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
+ * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
+ * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
+ * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
+ * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
+ * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
+ * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
+ * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
+ * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
+ * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+ * 
+ * You acknowledge that this software is not designed or intended for use
+ * in the design, construction, operation or maintenance of any nuclear
+ * facility.
+ * 
+ * Sun gratefully acknowledges that this software was originally authored
+ * and developed by Kenneth Bradley Russell and Christopher John Kline.
+ */
+
+package com.jogamp.opengl.impl;
+
+import javax.media.opengl.*;
+
+/** Implements the makeCurrent / release locking behavior of the
+    GLContext class. When "fail fast mode" is enabled, attempts to
+    lock the same GLContextLock on more than one thread cause
+    GLException to be raised. This lock is not recursive. Attempts to
+    lock it more than once on a given thread will cause GLException to
+    be raised. */
+
+public class GLContextLock {
+  protected static final boolean DEBUG = GLContextImpl.DEBUG;
+
+  static class SyncData {
+      boolean failFastMode = true;
+      Thread owner = null;
+      int waiters = 0;
+      Exception lockedStack = null; // only enabled if DEBUG
+  }
+  private SyncData sdata = new SyncData(); // synchronized (flow/mem)  mutable access
+
+  /** Locks this GLContextLock on the current thread. If fail fast
+      mode is enabled and the GLContextLock is already owned by
+      another thread, throws GLException. */
+  public final void lock() throws GLException {
+    synchronized(sdata) {
+      Thread current = Thread.currentThread();
+      if (sdata.owner == null) {
+        sdata.owner = current;
+        if(DEBUG) {
+            sdata.lockedStack = new Exception("Error: Previously made current (1) by "+sdata.owner+", lock: "+this);
+        }
+      } else if (sdata.owner != current) {
+        while (sdata.owner != null) {
+          if (sdata.failFastMode) {
+            if(null!=sdata.lockedStack) {
+                sdata.lockedStack.printStackTrace();
+            }
+            throw new GLException("Error: Attempt to make context current on thread " + current +
+                                  " which is already current on thread " + sdata.owner);
+          } else {
+            try {
+              ++sdata.waiters;
+              sdata.wait();
+            } catch (InterruptedException e) {
+              throw new GLException(e);
+            } finally {
+              --sdata.waiters;
+            }
+          }
+        }
+        sdata.owner = current;
+        if(DEBUG) {
+            sdata.lockedStack = new Exception("Previously made current (2) by "+sdata.owner+", lock: "+this);
+        }
+      } else {
+        throw new GLException("Attempt to make the same context current twice on thread " + current);
+      }
+    }
+  }
+
+  /** Unlocks this GLContextLock. */
+  public final void unlock() throws GLException {
+    synchronized (sdata) {
+      Thread current = Thread.currentThread();
+      if (sdata.owner == current) {
+        sdata.owner = null;
+        sdata.lockedStack = null;
+        // 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();
+      } else {
+        if (sdata.owner != null) {
+          throw new GLException("Attempt by thread " + current +
+                                " to release context owned by thread " + sdata.owner);
+        } else {
+          throw new GLException("Attempt by thread " + current +
+                                " to release unowned context");
+        }
+      }
+    }
+  }
+
+  /** Indicates whether this lock is held by the current thread. */
+  public final boolean isHeld() {
+    synchronized(sdata) {
+      return (Thread.currentThread() == sdata.owner);
+    }
+  }
+
+  public final void setFailFastMode(boolean onOrOff) {
+    synchronized(sdata) {
+        sdata.failFastMode = onOrOff;
+    }
+  }
+
+  public final boolean getFailFastMode() {
+    synchronized(sdata) {
+        return sdata.failFastMode;
+    }
+  }
+
+  public final boolean hasWaiters() {
+    synchronized(sdata) {
+        return (0 != sdata.waiters);
+    }
+  }
+
+  /** holding the owners stack trace when lock is acquired and DEBUG is true */
+  public final Exception getLockedStack() {
+    synchronized(sdata) {
+        return sdata.lockedStack;
+    }
+  }
+
+}