Disable the automatic snapshots for TestBug297635

Disable the automatic snapshots while running tests in TestBug297635 to
avoid random failures.

Fixes eclipse-platform#460

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/DelayedSnapshotJob.java

@@ -17,7 +17,10 @@
 import org.eclipse.core.internal.utils.Messages;
 import org.eclipse.core.internal.utils.Policy;
 import org.eclipse.core.resources.ISaveContext;
-import org.eclipse.core.runtime.*;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.jobs.Job;
 
 /**
@@ -28,6 +31,7 @@ public class DelayedSnapshotJob extends Job {
 	private static final String MSG_SNAPSHOT = Messages.resources_snapshot;
 	private SaveManager saveManager;
 	private Workspace workspace;
+	private volatile boolean suspended;
 
 	public DelayedSnapshotJob(SaveManager manager, Workspace workspace) {
 		super(MSG_SNAPSHOT);
@@ -44,7 +48,7 @@ public DelayedSnapshotJob(SaveManager manager, Workspace workspace) {
 	public IStatus run(IProgressMonitor monitor) {
 		if (monitor.isCanceled())
 			return Status.CANCEL_STATUS;
-		if (!workspace.isOpen()) {
+		if (!workspace.isOpen() || suspended) {
 			return Status.OK_STATUS;
 		}
 		try {
@@ -56,4 +60,22 @@ public IStatus run(IProgressMonitor monitor) {
 			saveManager.snapshotRequested = false;
 		}
 	}
+
+	/**
+	 * Suspend automatic snapshots until {@link #resume()} is called.
+	 *
+	 * @see #resume()
+	 */
+	void suspend() {
+		suspended = true;
+	}
+
+	/**
+	 * Resume automatic snapshots. This method does not schedule this Job.
+	 *
+	 * @see #suspend()
+	 */
+	void resume() {
+		suspended = false;
+	}
 }

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/SaveManager.java

@@ -1463,6 +1463,22 @@ public void shutdown(final IProgressMonitor monitor) {
 		snapshotJob.cancel();
 	}
 
+	/**
+	 * Tries to determine if the workspace has changes and calls
+	 * {@link #snapshotIfNeeded(boolean)}. If an exception occurs while trying to
+	 * determine whether or not the workspace has changes then the snapshot might be
+	 * taken anyway, the workspace will be simply assumed unchanged.
+	 */
+	private void snapshotIfNeeded() {
+		boolean workspaceHasTreeChanges = false;
+		try {
+			workspaceHasTreeChanges = workspace.hasTreeChanges();
+		} catch (CoreException e) {
+			Policy.log(e);
+		}
+		snapshotIfNeeded(workspaceHasTreeChanges);
+	}
+
 	/**
 	 * Performs a snapshot if one is deemed necessary.
 	 * Encapsulates rules for determining when a snapshot is needed.
@@ -2205,4 +2221,13 @@ protected void writeWorkspaceFields(DataOutputStream output, IProgressMonitor mo
 		// save the registered sync partners in the synchronizer
 		((Synchronizer) workspace.getSynchronizer()).savePartners(output);
 	}
+
+	public void suspendSnapshotJob() {
+		snapshotJob.suspend();
+	}
+
+	public void resumeSnapshotJob() {
+		snapshotJob.resume();
+		snapshotIfNeeded();
+	}
 }

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/Workspace.java

@@ -1578,11 +1578,7 @@ public void endOperation(ISchedulingRule rule, boolean build) throws CoreExcepti
 				// build() and snapshot() should not fail if they are called.
 				workManager.rebalanceNestedOperations();
 
-				//find out if any operation has potentially modified the tree
-				hasTreeChanges = workManager.shouldBuild();
-				//double check if the tree has actually changed
-				if (hasTreeChanges)
-					hasTreeChanges = operationTree != null && ElementTree.hasChanges(tree, operationTree, ResourceComparator.getBuildComparator(), true);
+				hasTreeChanges = hasTreeChanges();
 				broadcastPostChange();
 				// Request a snapshot if we are sufficiently out of date.
 				saveManager.snapshotIfNeeded(hasTreeChanges);
@@ -1601,6 +1597,13 @@ public void endOperation(ISchedulingRule rule, boolean build) throws CoreExcepti
 			buildManager.endTopLevel(hasTreeChanges);
 	}
 
+	boolean hasTreeChanges() throws CoreException {
+		return getWorkManager().shouldBuild() // find out if any operation has potentially modified the tree
+		//double check if the tree has actually changed
+				&& operationTree != null
+				&& ElementTree.hasChanges(tree, operationTree, ResourceComparator.getBuildComparator(), true);
+	}
+
 	/**
 	 * Flush the build order cache for the workspace.  The buildOrder cache contains the total
 	 * order of the build configurations in the workspace, including projects not mentioned in

resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/session/TestBug297635.java

@@ -55,6 +55,22 @@ public BundleContext getContext() {
 		return Platform.getBundle(PI_RESOURCES_TESTS).getBundleContext();
 	}
 
+	@Override
+	protected void setUp() throws Exception {
+		super.setUp();
+		getSaveManager().suspendSnapshotJob();
+	}
+
+	@Override
+	protected void tearDown() throws Exception {
+		super.tearDown();
+		getSaveManager().resumeSnapshotJob();
+	}
+
+	private SaveManager getSaveManager() {
+		return ((Workspace) getWorkspace()).getSaveManager();
+	}
+
 	public void testBug() throws Exception {
 		installBundle();
 
@@ -136,11 +152,11 @@ private Map<String, SavedState> getSavedStatesFromSaveManager()
 		// there
 		Field field = SaveManager.class.getDeclaredField("savedStates");
 		field.setAccessible(true);
-		return (Map<String, SavedState>) field.get(((Workspace) getWorkspace()).getSaveManager());
+		return (Map<String, SavedState>) field.get(getSaveManager());
 	}
 
 	private void saveSnapshot() throws CoreException {
-		((Workspace) getWorkspace()).getSaveManager().save(ISaveContext.SNAPSHOT, true, null, getMonitor());
+		getSaveManager().save(ISaveContext.SNAPSHOT, true, null, getMonitor());
 	}
 
 	private void assertStateTrees(SavedState savedState, boolean isNull)