NEW - bug 232180: stop unnecessary saves of task list and related information upon startup

https://bugs.eclipse.org/bugs/show_bug.cgi?id=232180

10 files changed, 135 insertions, 113 deletions

diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/ITaskList.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/ITaskList.java
index 37e528116..e51216104 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/ITaskList.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/ITaskList.java
@@ -11,6 +11,7 @@ package org.eclipse.mylyn.internal.tasks.core;
 import java.util.Set;
 
 import org.eclipse.mylyn.tasks.core.ITask;
+import org.eclipse.mylyn.tasks.core.ITaskElement;
 import org.eclipse.mylyn.tasks.core.ITaskListChangeListener;
 
 /**
@@ -66,10 +67,9 @@ public interface ITaskList {
 
 	/**
 	 * @param task
-	 * @param content
-	 * 		true if the content for the task (e.g. repository task data) has changed
+	 * 		list element
 	 */
-	public abstract void notifyTaskChanged(ITask task, boolean content);
+	public abstract void notifyElementChanged(ITaskElement element);
 
 	public abstract void removeChangeListener(ITaskListChangeListener listener);
 
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/RepositoryExternalizationParticipant.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/RepositoryExternalizationParticipant.java
index ef1bf9b15..5d9a3519a 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/RepositoryExternalizationParticipant.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/RepositoryExternalizationParticipant.java
@@ -61,6 +61,7 @@ public class RepositoryExternalizationParticipant extends AbstractExternalizatio
 
 		switch (context.getKind()) {
 		case SAVE:
+			System.err.println(">>> save repositories");
 			if (!takeSnapshot(repositoriesFile)) {
 				StatusHandler.fail(new Status(IStatus.WARNING, ITasksCoreConstants.ID_PLUGIN,
 						"Task List snapshot failed"));
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskActivityManager.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskActivityManager.java
index b82264a47..42296f5ec 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskActivityManager.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskActivityManager.java
@@ -518,7 +518,7 @@ public class TaskActivityManager implements ITaskActivityManager {
 			removeScheduledTask(task);
 			addScheduledTask(task);
 		}
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 	}
 
 	public void setDueDate(ITask task, Date dueDate) {
@@ -529,7 +529,7 @@ public class TaskActivityManager implements ITaskActivityManager {
 			removeDueTask(task);
 			addDueTask(task);
 		}
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 	}
 
 	/**
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskList.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskList.java
index 5b40afe2b..0188c42da 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskList.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/TaskList.java
@@ -94,7 +94,7 @@ public class TaskList implements ISchedulingRule, ITaskList {
 		if (orphans != null) {
 			task.addParentContainer(orphans);
 			orphans.internalAddChild(task);
-			delta.add(new TaskContainerDelta(orphans, TaskContainerDelta.Kind.CHANGED));
+			delta.add(new TaskContainerDelta(task, orphans, TaskContainerDelta.Kind.ADDED));
 		}
 	}
 
@@ -158,8 +158,7 @@ public class TaskList implements ISchedulingRule, ITaskList {
 
 			(task).addParentContainer(container);
 			container.internalAddChild(task);
-			delta.add(new TaskContainerDelta(task, TaskContainerDelta.Kind.CHANGED));
-			delta.add(new TaskContainerDelta(container, TaskContainerDelta.Kind.CHANGED));
+			delta.add(new TaskContainerDelta(task, container, TaskContainerDelta.Kind.ADDED));
 		} finally {
 			unlock();
 		}
@@ -231,10 +230,15 @@ public class TaskList implements ISchedulingRule, ITaskList {
 		}
 	}
 
-	private void fireDelta(HashSet<TaskContainerDelta> deltaToFire) {
+	private void fireDelta(HashSet<TaskContainerDelta> deltasToFire) {
 		if (readComplete) {
 			for (ITaskListChangeListener listener : changeListeners) {
-				listener.containersChanged(deltaToFire);
+				try {
+					listener.containersChanged(Collections.unmodifiableSet(deltasToFire));
+				} catch (Throwable t) {
+					StatusHandler.log(new Status(IStatus.ERROR, ITasksCoreConstants.ID_PLUGIN,
+							"Notification failed for: " + listener, t));
+				}
 			}
 		}
 	}
@@ -443,45 +447,32 @@ public class TaskList implements ISchedulingRule, ITaskList {
 		return rule instanceof TaskList || rule instanceof ITaskElement;
 	}
 
-	public void notifyContainersUpdated(Set<? extends AbstractTaskContainer> containers) {
-		HashSet<TaskContainerDelta> containersUpdatedDelta = new HashSet<TaskContainerDelta>();
-		if (containers == null) {
-			containersUpdatedDelta.add(new TaskContainerDelta(null, TaskContainerDelta.Kind.ROOT));
+	public void notifyElementsChanged(Set<? extends ITaskElement> elements) {
+		HashSet<TaskContainerDelta> deltas = new HashSet<TaskContainerDelta>();
+		if (elements == null) {
+			deltas.add(new TaskContainerDelta(null, TaskContainerDelta.Kind.ROOT));
 		} else {
-			for (AbstractTaskContainer abstractTaskContainer : containers) {
-				containersUpdatedDelta.add(new TaskContainerDelta(abstractTaskContainer,
-						TaskContainerDelta.Kind.CHANGED));
+			for (ITaskElement element : elements) {
+				deltas.add(new TaskContainerDelta(element, TaskContainerDelta.Kind.CONTENT));
 			}
 		}
 
-		for (ITaskListChangeListener listener : changeListeners) {
-			try {
-				listener.containersChanged(Collections.unmodifiableSet(containersUpdatedDelta));
-			} catch (Throwable t) {
-				StatusHandler.log(new Status(IStatus.ERROR, ITasksCoreConstants.ID_PLUGIN, "Notification failed for: "
-						+ listener, t));
-			}
-		}
+		fireDelta(deltas);
 	}
 
-	public void notifyTaskChanged(ITask task, boolean content) {
+	public void notifySyncStateChanged(Set<? extends AbstractTaskContainer> containers) {
 		HashSet<TaskContainerDelta> taskChangeDeltas = new HashSet<TaskContainerDelta>();
-		TaskContainerDelta.Kind kind;
-		if (content) {
-			kind = TaskContainerDelta.Kind.CONTENT;
-		} else {
-			kind = TaskContainerDelta.Kind.CHANGED;
+		for (AbstractTaskContainer abstractTaskContainer : containers) {
+			TaskContainerDelta delta = new TaskContainerDelta(abstractTaskContainer, TaskContainerDelta.Kind.CONTENT);
+			delta.setTransient(true);
+			taskChangeDeltas.add(delta);
 		}
-		taskChangeDeltas.add(new TaskContainerDelta(task, kind));
 
-		for (ITaskListChangeListener listener : changeListeners) {
-			try {
-				listener.containersChanged(Collections.unmodifiableSet(taskChangeDeltas));
-			} catch (Throwable t) {
-				StatusHandler.log(new Status(IStatus.ERROR, ITasksCoreConstants.ID_PLUGIN, "Notification failed for: "
-						+ listener, t));
-			}
-		}
+		fireDelta(taskChangeDeltas);
+	}
+
+	public void notifyElementChanged(ITaskElement element) {
+		notifyElementsChanged(Collections.singleton(element));
 	}
 
 	public void refactorRepositoryUrl(String oldRepositoryUrl, String newRepositoryUrl) {
@@ -505,7 +496,7 @@ public class TaskList implements ISchedulingRule, ITaskList {
 			for (RepositoryQuery query : queries.values()) {
 				if (query.getRepositoryUrl().equals(oldRepositoryUrl)) {
 					query.setRepositoryUrl(newRepositoryUrl);
-					delta.add(new TaskContainerDelta(query, TaskContainerDelta.Kind.CHANGED));
+					delta.add(new TaskContainerDelta(query, TaskContainerDelta.Kind.CONTENT));
 				}
 			}
 
@@ -516,7 +507,7 @@ public class TaskList implements ISchedulingRule, ITaskList {
 					orphans.setRepositoryUrl(newRepositoryUrl);
 					repositoryOrphansMap.put(newRepositoryUrl, orphans);
 					//categories.put(orphans.getHandleIdentifier(), orphans);
-					delta.add(new TaskContainerDelta(orphans, TaskContainerDelta.Kind.CHANGED));
+					delta.add(new TaskContainerDelta(orphans, TaskContainerDelta.Kind.CONTENT));
 				}
 			}
 		} finally {
@@ -558,15 +549,14 @@ public class TaskList implements ISchedulingRule, ITaskList {
 		container.internalRemoveChild(task);
 		((AbstractTask) task).removeParentContainer(container);
 
-		delta.add(new TaskContainerDelta(task, TaskContainerDelta.Kind.CHANGED));
-		delta.add(new TaskContainerDelta(container, TaskContainerDelta.Kind.CHANGED));
+		delta.add(new TaskContainerDelta(task, container, TaskContainerDelta.Kind.REMOVED));
 	}
 
 	private void removeOrphan(AbstractTask task, Set<TaskContainerDelta> delta) {
 		AbstractTaskContainer orphans = getUnmatchedContainer(task.getRepositoryUrl());
 		if (orphans != null) {
 			if (orphans.internalRemoveChild(task)) {
-				delta.add(new TaskContainerDelta(orphans, TaskContainerDelta.Kind.CHANGED));
+				delta.add(new TaskContainerDelta(task, orphans, TaskContainerDelta.Kind.REMOVED));
 				task.removeParentContainer(orphans);
 			}
 		}
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataManager.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataManager.java
index 433105a59..0e76840d5 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataManager.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/data/TaskDataManager.java
@@ -147,7 +147,7 @@ public class TaskDataManager implements ITaskDataManager {
 				result[0] = state;
 			}
 		});
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 		return result[0];
 	}
 
@@ -163,7 +163,7 @@ public class TaskDataManager implements ITaskDataManager {
 				taskList.addTask(task);
 			}
 		});
-		taskList.notifyTaskChanged(task, true);
+		taskList.notifyElementChanged(task);
 	}
 
 	public void putUpdatedTaskData(final ITask itask, final TaskData taskData, boolean user) throws CoreException {
@@ -206,7 +206,7 @@ public class TaskDataManager implements ITaskDataManager {
 					task.setSynchronizing(false);
 				}
 			});
-			taskList.notifyTaskChanged(task, true);
+			taskList.notifyElementChanged(task);
 		}
 	}
 
@@ -249,14 +249,14 @@ public class TaskDataManager implements ITaskDataManager {
 				}
 			}
 		});
-		taskList.notifyTaskChanged(task, true);
+		taskList.notifyElementChanged(task);
 	}
 
 	@Deprecated
 	public void discardOutgoing(AbstractTask repositoryTask) {
 		taskDataStorageManager.discardEdits(repositoryTask.getRepositoryUrl(), repositoryTask.getTaskId());
 		repositoryTask.setSynchronizationState(SynchronizationState.SYNCHRONIZED);
-		taskList.notifyTaskChanged(repositoryTask, true);
+		taskList.notifyElementChanged(repositoryTask);
 	}
 
 	private File findFile(ITask task, String kind) {
@@ -362,7 +362,7 @@ public class TaskDataManager implements ITaskDataManager {
 				task.setSubmitting(false);
 			}
 		});
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 	}
 
 	/**
@@ -444,7 +444,7 @@ public class TaskDataManager implements ITaskDataManager {
 		repositoryTask.setSynchronizationState(SynchronizationState.OUTGOING);
 		taskDataStorageManager.saveEdits(repositoryTask.getRepositoryUrl(), repositoryTask.getTaskId(),
 				Collections.unmodifiableSet(modifiedAttributes));
-		taskList.notifyTaskChanged(repositoryTask, false);
+		taskList.notifyElementChanged(repositoryTask);
 	}
 
 	public void setDataPath(String dataPath) {
@@ -495,7 +495,7 @@ public class TaskDataManager implements ITaskDataManager {
 			StatusHandler.log(new Status(IStatus.ERROR, ITasksCoreConstants.ID_PLUGIN,
 					"Unexpected error while marking task read", e));
 		}
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 	}
 
 	@Deprecated
@@ -508,13 +508,13 @@ public class TaskDataManager implements ITaskDataManager {
 				taskDataStorageManager.setOldTaskData(taskData);
 			}
 			task.setSynchronizationState(SynchronizationState.SYNCHRONIZED);
-			taskList.notifyTaskChanged(task, false);
+			taskList.notifyElementChanged(task);
 		} else if (read && task.getSynchronizationState().equals(SynchronizationState.CONFLICT)) {
 			if (taskData != null && taskData.getLastModified() != null) {
 				task.setLastReadTimeStamp(taskData.getLastModified());
 			}
 			task.setSynchronizationState(SynchronizationState.OUTGOING);
-			taskList.notifyTaskChanged(task, false);
+			taskList.notifyElementChanged(task);
 		} else if (read && task.getSynchronizationState().equals(SynchronizationState.SYNCHRONIZED)) {
 			if (taskData != null && taskData.getLastModified() != null) {
 				task.setLastReadTimeStamp(taskData.getLastModified());
@@ -536,7 +536,7 @@ public class TaskDataManager implements ITaskDataManager {
 
 		} else if (!read && task.getSynchronizationState().equals(SynchronizationState.SYNCHRONIZED)) {
 			task.setSynchronizationState(SynchronizationState.INCOMING);
-			taskList.notifyTaskChanged(task, false);
+			taskList.notifyElementChanged(task);
 		}
 
 		// for connectors that don't support task data set read date to now (bug#204741)
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/externalization/TaskListExternalizationParticipant.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/externalization/TaskListExternalizationParticipant.java
index 6ac133e71..fbe3349c0 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/externalization/TaskListExternalizationParticipant.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/externalization/TaskListExternalizationParticipant.java
@@ -140,10 +140,15 @@ public class TaskListExternalizationParticipant extends AbstractExternalizationP
 	}
 
 	public void containersChanged(Set<TaskContainerDelta> containers) {
-		synchronized (TaskListExternalizationParticipant.this) {
-			dirty = true;
+		for (TaskContainerDelta taskContainerDelta : containers) {
+			if (!taskContainerDelta.isTransient()) {
+				synchronized (TaskListExternalizationParticipant.this) {
+					dirty = true;
+				}
+				manager.requestSave();
+				return;
+			}
 		}
-		manager.requestSave();
 	}
 
 	public void taskListRead() {
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeQueriesJob.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeQueriesJob.java
index 97094b370..76fa41dbc 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeQueriesJob.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeQueriesJob.java
@@ -196,37 +196,37 @@ public class SynchronizeQueriesJob extends SynchronizationJob {
 				event.setTasks(allTasks);
 				event.setNeedsPerformQueries(true);
 
-				try {
-					// hook into the connector for checking for changed tasks and have the connector mark tasks that need synchronization
-					if (firePreSynchronization(event, new SubProgressMonitor(monitor, 20))) {
-						// synchronize queries, tasks changed within query are added to set of tasks to be synchronized
-						synchronizeQueries(monitor, event);
-
-						// for background synchronizations all changed tasks are synchronized including the ones that are not part of a query
-						if (!isUser()) {
-							for (ITask task : allTasks) {
-								if (task.isStale()) {
-									tasksToBeSynchronized.add(task);
-									((AbstractTask) task).setSynchronizing(true);
-								}
+//				try {
+				// hook into the connector for checking for changed tasks and have the connector mark tasks that need synchronization
+				if (firePreSynchronization(event, new SubProgressMonitor(monitor, 20))) {
+					// synchronize queries, tasks changed within query are added to set of tasks to be synchronized
+					synchronizeQueries(monitor, event);
+
+					// for background synchronizations all changed tasks are synchronized including the ones that are not part of a query
+					if (!isUser()) {
+						for (ITask task : allTasks) {
+							if (task.isStale()) {
+								tasksToBeSynchronized.add(task);
+								((AbstractTask) task).setSynchronizing(true);
 							}
 						}
+					}
 
-						// synchronize tasks that were marked by the connector
-						if (!tasksToBeSynchronized.isEmpty()) {
-							Policy.checkCanceled(monitor);
-							monitor.subTask("Synchronizing " + tasksToBeSynchronized.size() + " changed tasks");
-							synchronizeTasks(new SubProgressMonitor(monitor, 40));
-						} else {
-							monitor.worked(40);
-						}
-
-						// hook into the connector for synchronization time stamp management
-						firePostSynchronization(event, new SubProgressMonitor(monitor, 10));
+					// synchronize tasks that were marked by the connector
+					if (!tasksToBeSynchronized.isEmpty()) {
+						Policy.checkCanceled(monitor);
+						monitor.subTask("Synchronizing " + tasksToBeSynchronized.size() + " changed tasks");
+						synchronizeTasks(new SubProgressMonitor(monitor, 40));
+					} else {
+						monitor.worked(40);
 					}
-				} finally {
-					taskList.notifyContainersUpdated(null);
+
+					// hook into the connector for synchronization time stamp management
+					firePostSynchronization(event, new SubProgressMonitor(monitor, 10));
 				}
+//				} finally {
+//					taskList.notifyElementsChanged(null);
+//				}
 			} finally {
 				Job.getJobManager().endRule(rule);
 			}
@@ -247,7 +247,7 @@ public class SynchronizeQueriesJob extends SynchronizationJob {
 			synchronizeQuery(repositoryQuery, event, new SubProgressMonitor(monitor, 20));
 
 			repositoryQuery.setSynchronizing(false);
-			taskList.notifyContainersUpdated(Collections.singleton(repositoryQuery));
+			taskList.notifySyncStateChanged(Collections.singleton(repositoryQuery));
 		}
 	}
 
@@ -325,8 +325,8 @@ public class SynchronizeQueriesJob extends SynchronizationJob {
 		for (RepositoryQuery repositoryQuery : queries) {
 			repositoryQuery.setSynchronizationStatus(status);
 			repositoryQuery.setSynchronizing(false);
+			taskList.notifyElementChanged(repositoryQuery);
 		}
-		taskList.notifyContainersUpdated(queries);
 	}
 
 }
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeTasksJob.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeTasksJob.java
index 0770d04fe..680152b40 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeTasksJob.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/internal/tasks/core/sync/SynchronizeTasksJob.java
@@ -86,7 +86,7 @@ public class SynchronizeTasksJob extends SynchronizationJob {
 		} catch (OperationCanceledException e) {
 			for (ITask task : tasks) {
 				((AbstractTask) task).setSynchronizing(false);
-				taskList.notifyTaskChanged(task, false);
+				taskList.notifyElementChanged(task);
 			}
 			return Status.CANCEL_STATUS;
 		} catch (Exception e) {
@@ -113,7 +113,7 @@ public class SynchronizeTasksJob extends SynchronizationJob {
 	private void synchronizeTask(IProgressMonitor monitor, ITask task) {
 		monitor.subTask("Receiving task " + task.getSummary());
 		((AbstractTask) task).setErrorStatus(null);
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 		try {
 			String taskId = task.getTaskId();
 			if (!isUser()) {
@@ -174,8 +174,8 @@ public class SynchronizeTasksJob extends SynchronizationJob {
 			((AbstractLegacyRepositoryConnector) connector).getLegacyTaskDataHandler().getMultiTaskData(repository,
 					Collections.unmodifiableSet(idToTask.keySet()), collector, monitor);
 		} else {
-			connector.getTaskDataHandler().getMultiTaskData(repository,
-					Collections.unmodifiableSet(idToTask.keySet()), collector, monitor);
+			connector.getTaskDataHandler().getMultiTaskData(repository, Collections.unmodifiableSet(idToTask.keySet()),
+					collector, monitor);
 		}
 
 	}
@@ -207,12 +207,7 @@ public class SynchronizeTasksJob extends SynchronizationJob {
 
 		task.setStale(false);
 		((AbstractTask) task).setSynchronizing(false);
-		if (task.getSynchronizationState() == SynchronizationState.INCOMING
-				|| task.getSynchronizationState() == SynchronizationState.CONFLICT) {
-			taskList.notifyTaskChanged(task, true);
-		} else {
-			taskList.notifyTaskChanged(task, false);
-		}
+		taskList.notifyElementChanged(task);
 	}
 
 	private void updateFromTaskData(TaskRepository taskRepository, ITask task, TaskData taskData) {
@@ -228,7 +223,7 @@ public class SynchronizeTasksJob extends SynchronizationJob {
 		if (!isUser()) {
 			((AbstractTask) task).setSynchronizing(false);
 		}
-		taskList.notifyTaskChanged(task, false);
+		taskList.notifyElementChanged(task);
 	}
 
 }
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/IRepositoryQuery.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/IRepositoryQuery.java
index 022fbf7d9..e3bb5b66a 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/IRepositoryQuery.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/IRepositoryQuery.java
@@ -8,7 +8,6 @@
 
 package org.eclipse.mylyn.tasks.core;
 
-
 /**
  * @since 3.0
  */
diff --git a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/TaskContainerDelta.java b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/TaskContainerDelta.java
index 835e7fef5..e301094ab 100644
--- a/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/TaskContainerDelta.java
+++ b/org.eclipse.mylyn.tasks.core/src/org/eclipse/mylyn/tasks/core/TaskContainerDelta.java
@@ -18,24 +18,17 @@ public final class TaskContainerDelta {
 
 	public enum Kind {
 		/**
-		 * One container added to another or to the root.
+		 * One container (source) added to another (target)
 		 */
 		ADDED,
 
 		/**
-		 * One container removed from another or from the root.
+		 * One container (source) removed from another (target)
 		 */
 		REMOVED,
 
 		/**
-		 * Container has changed, e.g. has new children, a task's priority or planning info. For tasks changed state
-		 * tends to be show in a view.
-		 */
-		CHANGED,
-
-		/**
-		 * The content of the container has changed, e.g. new data has been downloaded for a task from the repository.
-		 * For tasks content tends to be show in an editor.
+		 * The internal state of the container (target) has changed, e.g. attributes, summary, priority, etc
 		 */
 		CONTENT,
 
@@ -45,27 +38,66 @@ public final class TaskContainerDelta {
 		ROOT
 	}
 
-	private final ITaskElement container;
+	private final ITaskElement target;
+
+	private final ITaskElement source;
 
 	private final Kind kind;
 
+	private boolean isTransient;
+
 	/**
 	 * @since 3.0
 	 */
 	public TaskContainerDelta(ITaskElement container, Kind kind) {
-		this.container = container;
+		this.source = container;
+		this.target = null;
 		this.kind = kind;
 	}
 
 	/**
 	 * @since 3.0
 	 */
-	public ITaskElement getContainer() {
-		return container;
+	public TaskContainerDelta(ITaskElement source, ITaskElement target, Kind kind) {
+		this.source = source;
+		this.target = target;
+		this.kind = kind;
+	}
+
+	/**
+	 * The target is the container modified or the target destination for the <code>source</code> element
+	 * 
+	 * @since 3.0
+	 */
+	public ITaskElement getTarget() {
+		return target;
+	}
+
+	/**
+	 * The element being acted upon in relation to the <code>target</code>
+	 * 
+	 * @since 3.0
+	 */
+	public ITaskElement getSource() {
+		return source;
 	}
 
 	public Kind getKind() {
 		return kind;
 	}
 
+	/**
+	 * @since 3.0
+	 */
+	public void setTransient(boolean isTransient) {
+		this.isTransient = isTransient;
+	}
+
+	/**
+	 * @since 3.0
+	 */
+	public boolean isTransient() {
+		return isTransient;
+	}
+
 }