Bug 370219 - Selection service could use an ability to pause dependencyv20120131-1449I20120202-0615I20120131-2200

recording

1 files changed, 35 insertions, 0 deletions

diff --git a/bundles/org.eclipse.e4.core.contexts/src/org/eclipse/e4/core/contexts/RunAndTrack.java b/bundles/org.eclipse.e4.core.contexts/src/org/eclipse/e4/core/contexts/RunAndTrack.java
index 791ae1e53..3022a34ec 100644
--- a/bundles/org.eclipse.e4.core.contexts/src/org/eclipse/e4/core/contexts/RunAndTrack.java
+++ b/bundles/org.eclipse.e4.core.contexts/src/org/eclipse/e4/core/contexts/RunAndTrack.java
@@ -10,6 +10,10 @@
  ******************************************************************************/
 package org.eclipse.e4.core.contexts;
 
+import java.util.Stack;
+import org.eclipse.e4.core.internal.contexts.Computation;
+import org.eclipse.e4.core.internal.contexts.EclipseContext;
+
 /**
  * Extended version of a runnable that can be used with the
  * {@link IEclipseContext#runAndTrack(RunAndTrack)} version gets more detailed
@@ -17,6 +21,8 @@ package org.eclipse.e4.core.contexts;
  */
 abstract public class RunAndTrack {
 
+	private boolean isRecordingPaused = false;
+
 	/**
 	 * Creates a new instance of trackable computation
 	 */
@@ -35,4 +41,33 @@ abstract public class RunAndTrack {
 	 * @return <code>true</code> to continue to be called on updates; <code>false</code> otherwise
 	 */
 	abstract public boolean changed(IEclipseContext context);
+
+	/**
+	 * This method can be called to pause dependency recording while {@link #changed(IEclipseContext)}
+	 * does its processing. This can be especially useful if external code
+	 * has to be called. The method {@link #resumeRecoding()} must be called before RunAndTrack
+	 * returns control to its caller.  
+	 */
+	synchronized protected void pauseRecording() {
+		if (isRecordingPaused)
+			return;
+		Stack<Computation> current = EclipseContext.getCalculatedComputations();
+		current.push(null);
+		isRecordingPaused = true;
+	}
+
+	/**
+	 * Call this method to resume dependency recording previously paused by 
+	 * the {@link #pauseRecording()}.
+	 */
+	synchronized protected void resumeRecoding() {
+		if (!isRecordingPaused)
+			return;
+		Stack<Computation> current = EclipseContext.getCalculatedComputations();
+		Computation plug = current.pop();
+		if (plug != null)
+			throw new IllegalArgumentException("Internal error in nested computation processing"); //$NON-NLS-1$
+		isRecordingPaused = false;
+	}
+
 }