Limit the number of commits in LogCommand output

Bug: 316680
Change-Id: I88cf7aac6b5763cc94421433dd4bbd42f81e0e69

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/LogCommandTest.java

@@ -88,4 +88,30 @@ public class LogCommandTest extends RepositoryTestCase {
 		assertTrue(commits.contains(log.next()));
 		assertFalse(log.hasNext());
 	}
+
+	@Test
+	public void logAllCommitsWithMaxCount() throws Exception {
+		List<RevCommit> commits = new ArrayList<RevCommit>();
+		Git git = Git.wrap(db);
+
+		writeTrashFile("Test.txt", "Hello world");
+		git.add().addFilepattern("Test.txt").call();
+		commits.add(git.commit().setMessage("commit#1").call());
+
+		writeTrashFile("Test1.txt", "Hello world!");
+		git.add().addFilepattern("Test1.txt").call();
+		commits.add(git.commit().setMessage("commit#2").call());
+
+		writeTrashFile("Test2.txt", "Hello world!!");
+		git.add().addFilepattern("Test2.txt").call();
+		commits.add(git.commit().setMessage("commit#3").call());
+
+		Iterator<RevCommit> log = git.log().all().setMaxCount(2).call()
+				.iterator();
+		assertTrue(log.hasNext());
+		assertTrue(commits.contains(log.next()));
+		assertTrue(log.hasNext());
+		assertTrue(commits.contains(log.next()));
+		assertFalse(log.hasNext());
+	}
 }

org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/MaxCountRevFilterTest.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2011, Tomasz Zarna <Tomasz.Zarna@pl.ibm.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.revwalk;
+
+import static org.junit.Assert.assertNull;
+
+import org.eclipse.jgit.revwalk.filter.MaxCountRevFilter;
+import org.junit.Test;
+
+public class MaxCountRevFilterTest extends RevWalkTestCase {
+	@Test
+	public void testMaxCountRevFilter() throws Exception {
+		final RevCommit a = commit();
+		final RevCommit b = commit(a);
+		final RevCommit c1 = commit(b);
+		final RevCommit c2 = commit(b);
+		final RevCommit d = commit(c1, c2);
+		final RevCommit e = commit(d);
+
+		rw.reset();
+		rw.setRevFilter(MaxCountRevFilter.create(3));
+		markStart(e);
+		assertCommit(e, rw.next());
+		assertCommit(d, rw.next());
+		assertCommit(c2, rw.next());
+		assertNull(rw.next());
+
+		rw.reset();
+		rw.setRevFilter(MaxCountRevFilter.create(0));
+		markStart(e);
+		assertNull(rw.next());
+	}
+
+	@Test
+	public void testMaxCountRevFilter0() throws Exception {
+		final RevCommit a = commit();
+		final RevCommit b = commit(a);
+
+		rw.reset();
+		rw.setRevFilter(MaxCountRevFilter.create(0));
+		markStart(b);
+		assertNull(rw.next());
+	}
+}

org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties

@@ -58,6 +58,7 @@ cannotListRefs=cannot list refs
 cannotLock=Cannot lock {0}
 cannotLockPackIn=Cannot lock pack in {0}
 cannotMatchOnEmptyString=Cannot match on empty string.
+maxCountMustBeNonNegative=max count must be >= 0
 cannotMoveIndexTo=Cannot move index to {0}
 cannotMovePackTo=Cannot move pack to {0}
 cannotOpenService=cannot open {0}

org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java

@@ -118,6 +118,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String cannotLock;
 	/***/ public String cannotLockPackIn;
 	/***/ public String cannotMatchOnEmptyString;
+	/***/ public String maxCountMustBeNonNegative;
 	/***/ public String cannotMoveIndexTo;
 	/***/ public String cannotMovePackTo;
 	/***/ public String cannotOpenService;

org.eclipse.jgit/src/org/eclipse/jgit/api/LogCommand.java

@@ -59,6 +59,7 @@ import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.filter.MaxCountRevFilter;
 import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
 import org.eclipse.jgit.treewalk.filter.PathFilter;
 import org.eclipse.jgit.treewalk.filter.PathFilterGroup;
@@ -85,6 +86,8 @@ public class LogCommand extends GitCommand<Iterable<RevCommit>> {
 
 	private final List<PathFilter> pathFilters = new ArrayList<PathFilter>();
 
+	private int maxCount = -1;
+
 	/**
 	 * @param repo
 	 */
@@ -108,6 +111,8 @@ public class LogCommand extends GitCommand<Iterable<RevCommit>> {
 		if (pathFilters.size() > 0)
 			walk.setTreeFilter(AndTreeFilter.create(
 					PathFilterGroup.create(pathFilters), TreeFilter.ANY_DIFF));
+		if (maxCount > -1)
+			walk.setRevFilter(MaxCountRevFilter.create(maxCount));
 		if (!startSpecified) {
 			try {
 				ObjectId headId = repo.resolve(Constants.HEAD);
@@ -247,6 +252,19 @@ public class LogCommand extends GitCommand<Iterable<RevCommit>> {
 		return this;
 	}
 
+	/**
+	 * Limit the number of commits to output
+	 *
+	 * @param maxCount
+	 *            the limit
+	 * @return {@code this}
+	 */
+	public LogCommand setMaxCount(int maxCount) {
+		checkCallable();
+		this.maxCount = maxCount;
+		return this;
+	}
+
 	private LogCommand add(boolean include, AnyObjectId start)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			JGitInternalException {

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/filter/MaxCountRevFilter.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2011, Tomasz Zarna <Tomasz.Zarna@pl.ibm.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.revwalk.filter;
+
+import java.io.IOException;
+
+import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.errors.IncorrectObjectTypeException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.errors.StopWalkException;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+/**
+ * Limits the number of commits output.
+ */
+public class MaxCountRevFilter extends RevFilter {
+
+	private int maxCount;
+
+	private int count;
+
+	/**
+	 * Create a new max count filter.
+	 *
+	 * @param maxCount
+	 *            the limit
+	 * @return a new filter
+	 */
+	public static RevFilter create(int maxCount) {
+		if (maxCount < 0)
+			throw new IllegalArgumentException(
+					JGitText.get().maxCountMustBeNonNegative);
+		return new MaxCountRevFilter(maxCount);
+	}
+
+	private MaxCountRevFilter(int maxCount) {
+		this.count = 0;
+		this.maxCount = maxCount;
+	}
+
+	@Override
+	public boolean include(RevWalk walker, RevCommit cmit)
+			throws StopWalkException, MissingObjectException,
+			IncorrectObjectTypeException, IOException {
+		count++;
+		if (count > maxCount)
+			throw StopWalkException.INSTANCE;
+		return true;
+	}
+
+	@Override
+	public RevFilter clone() {
+		return new MaxCountRevFilter(maxCount);
+	}
+}