Bug 1054: GLContext: makeCurrent() needs a null-check of [mutable] drawable; Review null checks and synchronization/locking.

'drawable' field of GLContextImpl is mutable via setGLDrawable(..),
which requires high-level locking as documented.

The required high-level locking allows us to _not_ add special
synchronization to this field (and drawableRead).

A simple null-check in makeCurrent() shall be sufficient,
plus ensuring mentioned high-level locking is applied.

GLContextImpl 'drawable' and 'drawableRead' synchronization:
  - commit ad79bd072b600a3f2416cc6f0c61e2925000069d check of null drawable is sufficient
  - Add GLAutoDrawable upstream-lock locking to:
    - AWT GLCanvas setupPrint/releasePrint
    - AWT GLJPanel (was missing)

Misc:
  - validate shared-context native-surface locking, throw exception if not successful
  - pixelDataEvaluated does not need to be synchronized, since it's being called while context is current, locking
  - GLDrawableHelper.recreateGLDrawable(..): Remove redundant glFinish() call

1 files changed, 30 insertions, 2 deletions

diff --git a/src/jogl/classes/javax/media/opengl/GLContext.java b/src/jogl/classes/javax/media/opengl/GLContext.java
index e10579df1..9389ccabb 100644
--- a/src/jogl/classes/javax/media/opengl/GLContext.java
+++ b/src/jogl/classes/javax/media/opengl/GLContext.java
@@ -326,6 +326,9 @@ public abstract class GLContext {
    * If the read-drawable has not been changed manually via {@link #setGLReadDrawable(GLDrawable)},
    * it equals to the write-drawable (default).
    * </p>
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    * @see #setGLDrawable(GLDrawable, boolean)
    * @see #setGLReadDrawable(GLDrawable)
    */
@@ -364,6 +367,9 @@ public abstract class GLContext {
    * If the read-drawable has not been changed manually via {@link #setGLReadDrawable(GLDrawable)},
    * it equals to the write-drawable (default).
    * </p>
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    * @see #isGLReadDrawableAvailable()
    * @see #setGLReadDrawable(GLDrawable)
    * @see #getGLReadDrawable()
@@ -1262,6 +1268,9 @@ public abstract class GLContext {
   /**
    * Return the framebuffer name bound to this context,
    * see {@link GL#glBindFramebuffer(int, int)}.
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    */
   public abstract int getBoundFramebuffer(int target);
 
@@ -1272,6 +1281,9 @@ public abstract class GLContext {
    * in case an framebuffer object ({@link com.jogamp.opengl.FBObject}) based drawable
    * is being used.
    * </p>
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    */
   public abstract int getDefaultDrawFramebuffer();
 
@@ -1282,6 +1294,9 @@ public abstract class GLContext {
    * in case an framebuffer object ({@link com.jogamp.opengl.FBObject}) based drawable
    * is being used.
    * </p>
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    */
   public abstract int getDefaultReadFramebuffer();
 
@@ -1306,13 +1321,26 @@ public abstract class GLContext {
    * Note-3: See {@link com.jogamp.opengl.util.GLDrawableUtil#swapBuffersBeforeRead(GLCapabilitiesImmutable) swapBuffersBeforeRead}
    * for read-pixels and swap-buffers implications.
    * </p>
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
    */
   public abstract int getDefaultReadBuffer();
 
-  /** Get the default pixel data type, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}. */
+  /**
+   * Get the default pixel data type, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}.
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
+   */
   public abstract int getDefaultPixelDataType();
 
-  /** Get the default pixel data format, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}. */
+  /**
+   * Get the default pixel data format, as required by e.g. {@link GL#glReadPixels(int, int, int, int, int, int, java.nio.Buffer)}.
+   * <p>
+   * Method is only thread-safe while context is {@link #makeCurrent() made current}.
+   * </p>
+   */
   public abstract int getDefaultPixelDataFormat();
 
   /**