Always run compare input calculation in background thread

Bug: 458251
Change-Id: I5a52025dfa59a2c28515d13f6f5161ad64769449
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>

3 files changed, 144 insertions, 56 deletions

diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/CompareUtils.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/CompareUtils.java
index 1828236d32..8ab20c553d 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/CompareUtils.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/CompareUtils.java
@@ -34,8 +34,12 @@ import org.eclipse.core.resources.mapping.ResourceTraversal;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.core.runtime.preferences.DefaultScope;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences.IPreferenceChangeListener;
@@ -79,6 +83,7 @@ import org.eclipse.jgit.treewalk.filter.TreeFilter;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.io.EolCanonicalizingInputStream;
 import org.eclipse.osgi.util.NLS;
+import org.eclipse.swt.widgets.Display;
 import org.eclipse.team.core.history.IFileRevision;
 import org.eclipse.team.ui.synchronize.SaveableCompareEditorInput;
 import org.eclipse.ui.IEditorInput;
@@ -86,6 +91,7 @@ import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IEditorReference;
 import org.eclipse.ui.IReusableEditor;
 import org.eclipse.ui.IWorkbenchPage;
+import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.actions.ActionFactory.IWorkbenchAction;
 
 /**
@@ -442,24 +448,70 @@ public class CompareUtils {
 	 * @param page
 	 *            If not {@null} try to re-use a compare editor on this
 	 *            page if any is available. Otherwise open a new one.
-	 * @throws IOException
-	 *             If HEAD or {@code refName} can't be resolved in the given
-	 *             repository.
 	 */
-	private static void compareWorkspaceWithRef(Repository repository,
-			IFile file, String refName, IWorkbenchPage page) throws IOException {
-		final RepositoryMapping mapping = RepositoryMapping.getMapping(file);
-		final String gitPath = mapping.getRepoRelativePath(file);
-		final ITypedElement base = SaveableCompareEditorInput
-				.createFileElement(file);
+	private static void compareWorkspaceWithRef(final Repository repository,
+			final IFile file, final String refName, final IWorkbenchPage page) {
+
+		Job job = new Job(UIText.CompareUtils_jobName) {
+
+			@Override
+			public IStatus run(IProgressMonitor monitor) {
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				final RepositoryMapping mapping = RepositoryMapping
+						.getMapping(file);
+				final String gitPath = mapping.getRepoRelativePath(file);
+				final ITypedElement base = SaveableCompareEditorInput
+						.createFileElement(file);
+
+				CompareEditorInput in;
+				try {
+					in = prepareCompareInput(repository, gitPath, base, refName);
+				} catch (IOException e) {
+					return Activator.createErrorStatus(
+							UIText.CompareWithRefAction_errorOnSynchronize, e);
+				}
+
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				openCompareEditorRunnable(page, in);
+				return Status.OK_STATUS;
+			}
+		};
+		job.setUser(true);
+		job.schedule();
+	}
 
-		CompareEditorInput in = prepareCompareInput(repository, gitPath, base,
-				refName);
+	/**
+	 * Opens compare editor in UI thread. Safe to start from background threads
+	 * too - in this case the operation will be started asynchronously in UI
+	 * thread.
+	 *
+	 * @param page
+	 *            can be null
+	 * @param in
+	 *            non null
+	 */
+	private static void openCompareEditorRunnable(
+			final IWorkbenchPage page,
+			final CompareEditorInput in) {
+		// safety check: make sure we open compare editor from UI thread
+		if (Display.getCurrent() == null) {
+			PlatformUI.getWorkbench().getDisplay().asyncExec(new Runnable() {
+				public void run() {
+					openCompareEditorRunnable(page, in);
+				}
+			});
+			return;
+		}
 
-		if (page != null)
+		if (page != null) {
 			openInCompare(page, in);
-		else
+		} else {
 			CompareUI.openCompareEditor(in);
+		}
 	}
 
 	/**
@@ -478,23 +530,39 @@ public class CompareUtils {
 	 * @param page
 	 *            If not {@null} try to re-use a compare editor on this
 	 *            page if any is available. Otherwise open a new one.
-	 * @throws IOException
-	 *             If HEAD or {@code refName} can't be resolved in the given
-	 *             repository.
 	 */
-	private static void compareLocalWithRef(Repository repository,
-			IPath location, String refName, IWorkbenchPage page)
-			throws IOException {
-		final String gitPath = getRepoRelativePath(location, repository);
-		final ITypedElement base = new LocalNonWorkspaceTypedElement(location);
+	private static void compareLocalWithRef(final Repository repository,
+			final IPath location, final String refName,
+			final IWorkbenchPage page) {
 
-		CompareEditorInput in = prepareCompareInput(repository, gitPath, base,
-				refName);
+		Job job = new Job(UIText.CompareUtils_jobName) {
 
-		if (page != null)
-			openInCompare(page, in);
-		else
-			CompareUI.openCompareEditor(in);
+			@Override
+			public IStatus run(IProgressMonitor monitor) {
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				final String gitPath = getRepoRelativePath(location, repository);
+				final ITypedElement base = new LocalNonWorkspaceTypedElement(
+						location);
+
+				CompareEditorInput in;
+				try {
+					in = prepareCompareInput(repository, gitPath, base, refName);
+				} catch (IOException e) {
+					return Activator.createErrorStatus(
+							UIText.CompareWithRefAction_errorOnSynchronize, e);
+				}
+
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				openCompareEditorRunnable(page, in);
+				return Status.OK_STATUS;
+			}
+		};
+		job.setUser(true);
+		job.schedule();
 	}
 
 	/*
@@ -671,11 +739,10 @@ public class CompareUtils {
 	 * @param page
 	 *            If not {@null} try to re-use a compare editor on this
 	 *            page if any is available. Otherwise open a new one.
-	 * @throws IOException
 	 */
 	public static void compare(IPath location, Repository repository,
 			String leftRev, String rightRev, boolean includeLocal,
-			IWorkbenchPage page) throws IOException {
+			IWorkbenchPage page) {
 		if (includeLocal)
 			compareLocalWithRef(repository, location, rightRev, page);
 		else {
@@ -685,8 +752,7 @@ public class CompareUtils {
 	}
 
 	private static void compareBetween(Repository repository, String gitPath,
-			String leftRev, String rightRev, IWorkbenchPage page)
-			throws IOException {
+			String leftRev, String rightRev, IWorkbenchPage page) {
 		compareBetween(repository, gitPath, gitPath, leftRev, rightRev, page);
 	}
 
@@ -710,34 +776,52 @@ public class CompareUtils {
 	 * @param page
 	 *            If not {@null} try to re-use a compare editor on this
 	 *            page if any is available. Otherwise open a new one.
-	 * @throws IOException
 	 */
-	private static void compareBetween(Repository repository,
-			String leftGitPath, String rightGitPath, String leftRev,
-			String rightRev, IWorkbenchPage page) throws IOException {
-		final ITypedElement left = getTypedElementFor(repository, leftGitPath,
-				leftRev);
-		final ITypedElement right = getTypedElementFor(repository,
-				rightGitPath,
-				rightRev);
-
-		final ITypedElement commonAncestor;
-		if (left != null && right != null && !GitFileRevision.INDEX.equals(leftRev)
-				&& !GitFileRevision.INDEX.equals(rightRev))
-			commonAncestor = getTypedElementForCommonAncestor(repository,
-					rightGitPath, leftRev, rightRev);
-		else
-			commonAncestor = null;
+	private static void compareBetween(final Repository repository,
+			final String leftGitPath, final String rightGitPath,
+			final String leftRev, final String rightRev,
+			final IWorkbenchPage page) {
 
-		final GitCompareFileRevisionEditorInput in = new GitCompareFileRevisionEditorInput(
-				left, right, commonAncestor, null);
-		in.getCompareConfiguration().setLeftLabel(leftRev);
-		in.getCompareConfiguration().setRightLabel(rightRev);
+		Job job = new Job(UIText.CompareUtils_jobName) {
 
-		if (page != null)
-			openInCompare(page, in);
-		else
-			CompareUI.openCompareEditor(in);
+			@Override
+			public IStatus run(IProgressMonitor monitor) {
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				final ITypedElement left;
+				final ITypedElement right;
+				try {
+					left = getTypedElementFor(repository, leftGitPath, leftRev);
+					right = getTypedElementFor(repository, rightGitPath,
+							rightRev);
+				} catch (IOException e) {
+					return Activator.createErrorStatus(
+							UIText.CompareWithRefAction_errorOnSynchronize, e);
+				}
+				final ITypedElement commonAncestor;
+				if (left != null && right != null
+						&& !GitFileRevision.INDEX.equals(leftRev)
+						&& !GitFileRevision.INDEX.equals(rightRev)) {
+					commonAncestor = getTypedElementForCommonAncestor(
+							repository, rightGitPath, leftRev, rightRev);
+				} else {
+					commonAncestor = null;
+				}
+
+				final GitCompareFileRevisionEditorInput in = new GitCompareFileRevisionEditorInput(
+						left, right, commonAncestor, null);
+				in.getCompareConfiguration().setLeftLabel(leftRev);
+				in.getCompareConfiguration().setRightLabel(rightRev);
+				if (monitor.isCanceled()) {
+					return Status.CANCEL_STATUS;
+				}
+				openCompareEditorRunnable(page, in);
+				return Status.OK_STATUS;
+			}
+		};
+		job.setUser(true);
+		job.schedule();
 	}
 
 	private static String getRepoRelativePath(IPath location,
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/UIText.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/UIText.java
index c80b53c0e7..668e62cf33 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/UIText.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/UIText.java
@@ -2503,6 +2503,9 @@ public class UIText extends NLS {
 	public static String CompareWithPreviousActionHandler_TitleRevisionNotFound;
 
 	/** */
+	public static String CompareUtils_jobName;
+
+	/** */
 	public static String CompareUtils_errorCommonAncestor;
 
 	/** */
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/uitext.properties b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/uitext.properties
index a34f27797a..771b840dea 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/uitext.properties
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/uitext.properties
@@ -304,6 +304,7 @@ CompareTreeView_NoInputText=No input
 CompareTreeView_RepositoryRootName=Repository root
 CompareTreeView_WorkspaceVersionText=Workspace
 CompareTreeView_CompareModeTooltip=Compare mode
+CompareUtils_jobName=Git Compare...
 CompareUtils_errorGettingEncoding=Getting encoding failed
 CompareUtils_errorGettingHeadCommit=Getting HEAD commit failed