1 files changed, 145 insertions, 0 deletions
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/history/GitHistoryWalk.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/history/GitHistoryWalk.java
new file mode 100644
index 0000000000..ec5fd7c7d5
--- /dev/null
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/history/GitHistoryWalk.java
@@ -0,0 +1,145 @@
+/*******************************************************************************
+ * Copyright (C) 2018, Thomas Wolf <thomas.wolf@paranor.ch>
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.egit.ui.internal.history;
+
+import java.io.IOException;
+import java.text.MessageFormat;
+
+import org.eclipse.egit.ui.Activator;
+import org.eclipse.egit.ui.UIPreferences;
+import org.eclipse.egit.ui.internal.UIText;
+import org.eclipse.jface.preference.IPreferenceStore;
+import org.eclipse.jgit.errors.IncorrectObjectTypeException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.lib.AnyObjectId;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.RefDatabase;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevObject;
+
+/**
+ * An {@link SWTWalk} that sets its start points on the first call to next()
+ * depending on the git history preferences. The point of doing so is to be sure
+ * that potentially expensive operations are done in the GerenrateHistoryJob and
+ * not in the UI thread.
+ */
+class GitHistoryWalk extends SWTWalk {
+
+	private boolean initialized = false;
+
+	private final AnyObjectId headId;
+
+	GitHistoryWalk(Repository repository, AnyObjectId headId) {
+		super(repository);
+		this.headId = headId;
+	}
+
+	@Override
+	public RevCommit next() throws MissingObjectException,
+			IncorrectObjectTypeException, IOException {
+		if (!initialized) {
+			initialize();
+		}
+		return super.next();
+	}
+
+	@Override
+	protected void reset(int retainFlags) {
+		super.reset(retainFlags);
+		initialized = false;
+	}
+
+	/**
+	 * Set the walk's start points as defined by the git history preferences.
+	 *
+	 * @throws IOException
+	 *             on errors
+	 */
+	private void initialize() throws IOException {
+		IPreferenceStore store = Activator.getDefault().getPreferenceStore();
+		RefDatabase db = getRepository().getRefDatabase();
+		try {
+			if (store.getBoolean(
+					UIPreferences.RESOURCEHISTORY_SHOW_ALL_BRANCHES)) {
+				markStartAllRefs(db, Constants.R_HEADS);
+				markStartAllRefs(db, Constants.R_REMOTES);
+				markStartAllRefs(db, Constants.R_TAGS);
+			}
+			if (store.getBoolean(
+					UIPreferences.RESOURCEHISTORY_SHOW_ADDITIONAL_REFS)) {
+				markStartAdditionalRefs(db);
+			}
+			if (store.getBoolean(UIPreferences.RESOURCEHISTORY_SHOW_NOTES)) {
+				markStartAllRefs(db, Constants.R_NOTES);
+			} else {
+				markUninteresting(db, Constants.R_NOTES);
+			}
+			markStart(parseCommit(headId));
+		} catch (IOException e) {
+			throw new IOException(MessageFormat.format(
+					UIText.GitHistoryPage_errorSettingStartPoints,
+					Activator.getDefault().getRepositoryUtil()
+							.getRepositoryName(getRepository())),
+					e);
+		}
+		initialized = true;
+	}
+
+	private void markStartAllRefs(RefDatabase db, String prefix)
+			throws IOException, IncorrectObjectTypeException {
+		for (Ref ref : db.getRefsByPrefix(prefix)) {
+			if (!ref.isSymbolic()) {
+				markStartRef(ref);
+			}
+		}
+	}
+
+	private void markStartAdditionalRefs(RefDatabase db)
+			throws IOException, IncorrectObjectTypeException {
+		for (Ref ref : db.getAdditionalRefs()) {
+			markStartRef(ref);
+		}
+	}
+
+	private void markStartRef(Ref ref)
+			throws IOException, IncorrectObjectTypeException {
+		try {
+			RevObject refTarget = parseAny(ref.getLeaf().getObjectId());
+			RevObject peeled = peel(refTarget);
+			if (peeled instanceof RevCommit) {
+				markStart((RevCommit) peeled);
+			}
+		} catch (MissingObjectException e) {
+			// If there is a ref which points to Nirvana then we should simply
+			// ignore this ref. We should not let a corrupt ref cause that the
+			// history view is not filled at all.
+		}
+	}
+
+	private void markUninteresting(RefDatabase db, String prefix)
+			throws IOException, IncorrectObjectTypeException {
+		for (Ref ref : db.getRefsByPrefix(prefix)) {
+			if (!ref.isSymbolic()) {
+				try {
+					RevObject refTarget = parseAny(ref.getLeaf().getObjectId());
+					if (refTarget instanceof RevCommit) {
+						markUninteresting((RevCommit) refTarget);
+					}
+				} catch (MissingObjectException e) {
+					// See above.
+				}
+			}
+		}
+	}
+
+}