RepoCommand: record manifest shallow recommendation in .gitmodules

Git core learned about the submodule.<name>.shallow option in
.gitmodules files, which is a recommendation to clone a submodule
shallow. A repo manifest may record a clone depth recommendation as
an optional field, which contains more information than a binary
shallow/nonshallow recommendation, so any attempted conversion may be
lossy. In practice the clone depth recommendation is either '1' or doesn't
exist, which is the binary behavior we have in Git core.

Change-Id: I51aa9cb6d1d9660dae6ab6d21ad7bae9bc5325e6
Signed-off-by: Stefan Beller <sbeller@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/gitrepo/RepoCommandTest.java

@@ -44,6 +44,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 import java.io.BufferedReader;
@@ -800,6 +801,53 @@ public void testRecordSubmoduleLabels() throws Exception {
 		}
 	}
 
+	@Test
+	public void testRecordShallowRecommendation() throws Exception {
+		try (
+				Repository remoteDb = createBareRepository();
+				Repository tempDb = createWorkRepository()) {
+			StringBuilder xmlContent = new StringBuilder();
+			xmlContent
+				.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n")
+				.append("<manifest>")
+				.append("<remote name=\"remote1\" fetch=\".\" />")
+				.append("<default revision=\"master\" remote=\"remote1\" />")
+				.append("<project path=\"shallow-please\" ")
+					.append("name=\"").append(defaultUri).append("\" ")
+					.append("clone-depth=\"1\" />")
+				.append("<project path=\"non-shallow\" ")
+					.append("name=\"").append(defaultUri).append("\" />")
+				.append("</manifest>");
+			JGitTestUtil.writeTrashFile(tempDb, "manifest.xml",
+				xmlContent.toString());
+
+			RepoCommand command = new RepoCommand(remoteDb);
+			command.setPath(tempDb.getWorkTree().getAbsolutePath() + "/manifest.xml")
+				.setURI(rootUri)
+				.setRecommendShallow(true)
+				.call();
+			// Clone it
+			File directory = createTempDirectory("testBareRepo");
+			try (Repository localDb = Git.cloneRepository()
+					.setDirectory(directory)
+					.setURI(remoteDb.getDirectory().toURI().toString()).call()
+					.getRepository();) {
+				// The .gitmodules file should exist
+				File gitmodules = new File(localDb.getWorkTree(),
+						".gitmodules");
+				assertTrue("The .gitmodules file should exist",
+						gitmodules.exists());
+				FileBasedConfig c = new FileBasedConfig(gitmodules,
+						FS.DETECTED);
+				c.load();
+				assertEquals("Recording shallow configuration should work", "true",
+						c.getString("submodule", "shallow-please", "shallow"));
+				assertNull("Recording non shallow configuration should work",
+						c.getString("submodule", "non-shallow", "shallow"));
+			}
+		}
+	}
+
 	@Test
 	public void testRemoteRevision() throws Exception {
 		StringBuilder xmlContent = new StringBuilder();

org.eclipse.jgit/src/org/eclipse/jgit/gitrepo/ManifestParser.java

@@ -192,6 +192,8 @@ public void startElement(
 					attributes.getValue("revision"), //$NON-NLS-1$
 					attributes.getValue("remote"), //$NON-NLS-1$
 					attributes.getValue("groups")); //$NON-NLS-1$
+			currentProject.setRecommendShallow(
+				attributes.getValue("clone-depth")); //$NON-NLS-1$
 		} else if ("remote".equals(qName)) { //$NON-NLS-1$
 			String alias = attributes.getValue("alias"); //$NON-NLS-1$
 			String fetch = attributes.getValue("fetch"); //$NON-NLS-1$

org.eclipse.jgit/src/org/eclipse/jgit/gitrepo/RepoCommand.java

@@ -113,6 +113,7 @@ public class RepoCommand extends GitCommand<RevCommit> {
 	private String targetBranch = Constants.HEAD;
 	private boolean recordRemoteBranch = false;
 	private boolean recordSubmoduleLabels = false;
+	private boolean recordShallowSubmodules = false;
 	private PersonIdent author;
 	private RemoteReader callback;
 	private InputStream inputStream;
@@ -362,6 +363,21 @@ public RepoCommand setRecordSubmoduleLabels(boolean enable) {
 		return this;
 	}
 
+	/**
+	 * Set whether the clone-depth field should be recorded as a shallow
+	 * recommendation in .gitmodules.
+	 * <p>
+	 * Not implemented for non-bare repositories.
+	 *
+	 * @param enable Whether to record the shallow recommendation.
+	 * @return this command
+	 * @since 4.4
+	 */
+	public RepoCommand setRecommendShallow(boolean enable) {
+		this.recordShallowSubmodules = enable;
+		return this;
+	}
+
 	/**
 	 * The progress monitor associated with the clone operation. By default,
 	 * this is set to <code>NullProgressMonitor</code>
@@ -471,7 +487,8 @@ public RevCommit call() throws GitAPIException {
 							proj.getPath(),
 							proj.getRevision(),
 							proj.getCopyFiles(),
-							proj.getGroups());
+							proj.getGroups(),
+							proj.getRecommendShallow());
 				}
 			} catch (GitAPIException | IOException e) {
 				throw new ManifestErrorException(e);
@@ -512,6 +529,16 @@ public RevCommit call() throws GitAPIException {
 							cfg.setString("submodule", name, "branch", //$NON-NLS-1$ //$NON-NLS-2$
 									proj.getRevision());
 						}
+
+						if (recordShallowSubmodules && proj.getRecommendShallow() != null) {
+							// The shallow recommendation is losing information.
+							// As the repo manifests stores the recommended
+							// depth in the 'clone-depth' field, while
+							// git core only uses a binary 'shallow = true/false'
+							// hint, we'll map any depth to 'shallow = true'
+							cfg.setBoolean("submodule", name, "shallow", //$NON-NLS-1$ //$NON-NLS-2$
+									true);
+						}
 					}
 					if (recordSubmoduleLabels) {
 						StringBuilder rec = new StringBuilder();
@@ -616,10 +643,10 @@ public RevCommit call() throws GitAPIException {
 	}
 
 	private void addSubmodule(String url, String name, String revision,
-			List<CopyFile> copyfiles, Set<String> groups)
+			List<CopyFile> copyfiles, Set<String> groups, String recommendShallow)
 			throws GitAPIException, IOException {
 		if (repo.isBare()) {
-			RepoProject proj = new RepoProject(url, name, revision, null, groups);
+			RepoProject proj = new RepoProject(url, name, revision, null, groups, recommendShallow);
 			proj.addCopyFiles(copyfiles);
 			bareProjects.add(proj);
 		} else {

org.eclipse.jgit/src/org/eclipse/jgit/gitrepo/RepoProject.java

@@ -70,6 +70,7 @@ public class RepoProject implements Comparable<RepoProject> {
 	private final String remote;
 	private final Set<String> groups;
 	private final List<CopyFile> copyfiles;
+	private String recommendShallow;
 	private String url;
 	private String defaultRevision;
 
@@ -138,7 +139,8 @@ public void copy() throws IOException {
 	 * @since 4.4
 	 */
 	public RepoProject(String name, String path, String revision,
-			String remote, Set<String> groups) {
+			String remote, Set<String> groups,
+			String recommendShallow) {
 		if (name == null) {
 			throw new NullPointerException();
 		}
@@ -150,6 +152,7 @@ public RepoProject(String name, String path, String revision,
 		this.revision = revision;
 		this.remote = remote;
 		this.groups = groups;
+		this.recommendShallow = recommendShallow;
 		copyfiles = new ArrayList<CopyFile>();
 	}
 
@@ -167,7 +170,7 @@ public RepoProject(String name, String path, String revision,
 	 */
 	public RepoProject(String name, String path, String revision,
 			String remote, String groups) {
-		this(name, path, revision, remote, new HashSet<String>());
+		this(name, path, revision, remote, new HashSet<String>(), null);
 		if (groups != null && groups.length() > 0)
 			this.setGroups(groups);
 	}
@@ -281,6 +284,25 @@ public Set<String> getGroups() {
 		return groups;
 	}
 
+	/**
+	 * Return the recommendation for shallowness.
+	 *
+	 * @return the String of "clone-depth"
+	 * @since 4.4
+	 */
+	public String getRecommendShallow() {
+		return recommendShallow;
+	}
+
+	/**
+	 * Sets the recommendation for shallowness.
+	 *
+	 * @since 4.4
+	 */
+	public void setRecommendShallow(String recommendShallow) {
+		this.recommendShallow = recommendShallow;
+	}
+
 	/**
 	 * Add a copy file configuration.
 	 *