This is a command line tool which can be used to import only
the commit graph of another Git repository, to help debug a
topology related bug, without actually needing a clone of the
problematic repository.
Signed-off-by: Shawn O. Pearce <spearce@xxxxxxxxxxx>
---
I used this yesterday to obtain a DAG from someone's private
repository and recreate the same structure on my own system,
to debug why RevWalk was busted in their case.
Its only meant for debugging weird cases, I can't see many
uses of it. But now that its written, maybe we should add
it to the project and keep it around.
.../services/org.spearce.jgit.pgm.TextBuiltin | 1 +
.../org/spearce/jgit/pgm/RebuildCommitGraph.java | 276 ++++++++++++++++++++
2 files changed, 277 insertions(+), 0 deletions(-)
create mode 100644 org.spearce.jgit.pgm/src/org/spearce/jgit/pgm/RebuildCommitGraph.java
diff --git a/org.spearce.jgit.pgm/src/META-INF/services/org.spearce.jgit.pgm.TextBuiltin b/org.spearce.jgit.pgm/src/META-INF/services/org.spearce.jgit.pgm.TextBuiltin
index 1ba29e6..9bba156 100644
--- a/org.spearce.jgit.pgm/src/META-INF/services/org.spearce.jgit.pgm.TextBuiltin
+++ b/org.spearce.jgit.pgm/src/META-INF/services/org.spearce.jgit.pgm.TextBuiltin
@@ -11,6 +11,7 @@ org.spearce.jgit.pgm.LsRemote
org.spearce.jgit.pgm.LsTree
org.spearce.jgit.pgm.MergeBase
org.spearce.jgit.pgm.Push
+org.spearce.jgit.pgm.RebuildCommitGraph
org.spearce.jgit.pgm.ReceivePack
org.spearce.jgit.pgm.RevList
org.spearce.jgit.pgm.Rm
diff --git a/org.spearce.jgit.pgm/src/org/spearce/jgit/pgm/RebuildCommitGraph.java b/org.spearce.jgit.pgm/src/org/spearce/jgit/pgm/RebuildCommitGraph.java
new file mode 100644
index 0000000..ccee997
--- /dev/null
+++ b/org.spearce.jgit.pgm/src/org/spearce/jgit/pgm/RebuildCommitGraph.java
@@ -0,0 +1,276 @@
+/*
+ * Copyright (C) 2009, Google Inc.
+ *
+ * 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 Git Development Community 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.spearce.jgit.pgm;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.Map;
+
+import org.kohsuke.args4j.Argument;
+import org.spearce.jgit.errors.MissingObjectException;
+import org.spearce.jgit.errors.ObjectWritingException;
+import org.spearce.jgit.lib.Commit;
+import org.spearce.jgit.lib.Constants;
+import org.spearce.jgit.lib.LockFile;
+import org.spearce.jgit.lib.ObjectId;
+import org.spearce.jgit.lib.ObjectWriter;
+import org.spearce.jgit.lib.PersonIdent;
+import org.spearce.jgit.lib.ProgressMonitor;
+import org.spearce.jgit.lib.Ref;
+import org.spearce.jgit.lib.RefUpdate;
+import org.spearce.jgit.lib.RefWriter;
+import org.spearce.jgit.lib.TextProgressMonitor;
+import org.spearce.jgit.lib.Tree;
+import org.spearce.jgit.revwalk.RevWalk;
+
+/**
+ * Recreates a repository from another one's commit graph.
+ * <p>
+ * <b>Do not run this on a repository unless you want to destroy it.</b>
+ * <p>
+ * To create the input files, in the source repository use:
+ *
+ * <pre>
+ * git for-each-ref >in.refs
+ * git log --all '--pretty=format:%H %ct %P' >in.dag
+ * </pre>
+ * <p>
+ * Run the rebuild in either an empty repository, or a clone of the source. Any
+ * missing commits (which might be the entire graph) will be created. All refs
+ * will be modified to match the input exactly, which means some refs may be
+ * deleted from the current repository.
+ * <p>
+ */
+class RebuildCommitGraph extends TextBuiltin {
+ @Argument(index = 0, required = true, metaVar = "REFS", usage = "for-each-ref output")
+ File refList;
+
+ @Argument(index = 1, required = true, metaVar = "DAG", usage = "log --all '--pretty=format:%H %ct %P' output")
+ File graph;
+
+ private final ProgressMonitor pm = new TextProgressMonitor();
+
+ private Map<ObjectId, ObjectId> rewrites = new HashMap<ObjectId, ObjectId>();
+
+ @Override
+ protected void run() throws Exception {
+ recreateCommitGraph();
+ detachHead();
+ deleteAllRefs();
+ recreateRefs();
+ }
+
+ private void recreateCommitGraph() throws IOException {
+ final RevWalk rw = new RevWalk(db);
+ final Map<ObjectId, ToRewrite> toRewrite = new HashMap<ObjectId, ToRewrite>();
+ List<ToRewrite> queue = new ArrayList<ToRewrite>();
+ final BufferedReader br = new BufferedReader(new InputStreamReader(
+ new FileInputStream(graph), Constants.CHARSET));
+ try {
+ String line;
+ while ((line = br.readLine()) != null) {
+ final String[] parts = line.split("[ \t]{1,}");
+ final ObjectId oldId = ObjectId.fromString(parts[0]);
+ try {
+ rw.parseCommit(oldId);
+ // We have it already. Don't rewrite it.
+ continue;
+ } catch (MissingObjectException mue) {
+ // Fall through and rewrite it.
+ }
+
+ final long time = Long.parseLong(parts[1]) * 1000L;
+ final ObjectId[] parents = new ObjectId[parts.length - 2];
+ for (int i = 0; i < parents.length; i++) {
+ parents[i] = ObjectId.fromString(parts[2 + i]);
+ }
+
+ final ToRewrite t = new ToRewrite(oldId, time, parents);
+ toRewrite.put(oldId, t);
+ queue.add(t);
+ }
+ } finally {
+ br.close();
+ }
+
+ pm.beginTask("Rewriting commits", queue.size());
+ final ObjectWriter ow = new ObjectWriter(db);
+ final ObjectId emptyTree = ow.writeTree(new Tree(db));
+ final PersonIdent me = new PersonIdent("jgit rebuild-commitgraph",
+ "rebuild-commitgraph@localhost");
+ while (!queue.isEmpty()) {
+ final ListIterator<ToRewrite> itr = queue
+ .listIterator(queue.size());
+ queue = new ArrayList<ToRewrite>();
+ REWRITE: while (itr.hasPrevious()) {
+ final ToRewrite t = itr.previous();
+ final ObjectId[] newParents = new ObjectId[t.oldParents.length];
+ for (int k = 0; k < t.oldParents.length; k++) {
+ final ToRewrite p = toRewrite.get(t.oldParents[k]);
+ if (p != null) {
+ if (p.newId == null) {
+ // Must defer until after the parent is rewritten.
+ queue.add(t);
+ continue REWRITE;
+ } else {
+ newParents[k] = p.newId;
+ }
+ } else {
+ // We have the old parent object. Use it.
+ //
+ newParents[k] = t.oldParents[k];
+ }
+ }
+
+ final Commit newc = new Commit(db);
+ newc.setTreeId(emptyTree);
+ newc.setAuthor(new PersonIdent(me, new Date(t.commitTime)));
+ newc.setCommitter(newc.getAuthor());
+ newc.setParentIds(newParents);
+ newc.setMessage("ORIGINAL " + t.oldId.name() + "\n");
+ t.newId = ow.writeCommit(newc);
+ rewrites.put(t.oldId, t.newId);
+ pm.update(1);
+ }
+ }
+ pm.endTask();
+ }
+
+ private static class ToRewrite {
+ final ObjectId oldId;
+
+ final long commitTime;
+
+ final ObjectId[] oldParents;
+
+ ObjectId newId;
+
+ ToRewrite(final ObjectId o, final long t, final ObjectId[] p) {
+ oldId = o;
+ commitTime = t;
+ oldParents = p;
+ }
+ }
+
+ private void detachHead() throws IOException {
+ final String head = db.getFullBranch();
+ final ObjectId id = db.resolve(Constants.HEAD);
+ if (!ObjectId.isId(head) && id != null) {
+ final LockFile lf;
+ lf = new LockFile(new File(db.getDirectory(), Constants.HEAD));
+ if (!lf.lock())
+ throw new IOException("Cannot lock HEAD");
+ lf.write(id);
+ if (!lf.commit())
+ throw new IOException("Cannot deatch HEAD");
+ }
+ }
+
+ private void deleteAllRefs() throws Exception {
+ final RevWalk rw = new RevWalk(db);
+ for (final Ref r : db.getAllRefs().values()) {
+ if (Constants.HEAD.equals(r.getName()))
+ continue;
+ final RefUpdate u = db.updateRef(r.getName());
+ u.setForceUpdate(true);
+ u.delete(rw);
+ }
+ }
+
+ private void recreateRefs() throws Exception {
+ final Map<String, Ref> refs = computeNewRefs();
+ new RefWriter(refs.values()) {
+ @Override
+ protected void writeFile(final String name, final byte[] content)
+ throws IOException {
+ final File file = new File(db.getDirectory(), name);
+ final LockFile lck = new LockFile(file);
+ if (!lck.lock())
+ throw new ObjectWritingException("Can't write " + file);
+ try {
+ lck.write(content);
+ } catch (IOException ioe) {
+ throw new ObjectWritingException("Can't write " + file);
+ }
+ if (!lck.commit())
+ throw new ObjectWritingException("Can't write " + file);
+ }
+ }.writePackedRefs();
+ }
+
+ private Map<String, Ref> computeNewRefs() throws IOException {
+ final RevWalk rw = new RevWalk(db);
+ final Map<String, Ref> refs = new HashMap<String, Ref>();
+ final BufferedReader br = new BufferedReader(new InputStreamReader(
+ new FileInputStream(refList), Constants.CHARSET));
+ try {
+ String line;
+ while ((line = br.readLine()) != null) {
+ final String[] parts = line.split("[ \t]{1,}");
+ final ObjectId origId = ObjectId.fromString(parts[0]);
+ final String type = parts[1];
+ final String name = parts[2];
+
+ ObjectId id = rewrites.get(origId);
+ if (id == null)
+ id = origId;
+ try {
+ rw.parseAny(id);
+ } catch (MissingObjectException mue) {
+ if (!Constants.TYPE_COMMIT.equals(type)) {
+ System.err.println("skipping " + type + " " + name);
+ continue;
+ }
+ throw new MissingObjectException(id, type);
+ }
+ refs.put(name, new Ref(Ref.Storage.PACKED, name, id));
+ }
+ } finally {
+ br.close();
+ }
+ return refs;
+ }
+}
--
1.6.2.288.gc3f22
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
