opendev/gerrit
Code Issues Proposed changes

AutoMerger: Support disabling writes to refs/cache-automerge/*

Browse Source 
It turns out that when the persistent diff cache (and eventually the
blame cache) is present, we never have to actually read the
refs/cache-automerge/* refs. When we need the commit/tree data for the
purposes of populating the cache, we can always just read that back
from the ObjectInserter that created it. This also means we can do
batch work like an online RebuildNoteDb without ever having to write
refs/cache-automerge/* refs.

Leave the default behavior of writing out the refs as people currently
expect that behavior, but we could potentially revisit that in the
future.

Change-Id: I8bad4de10c8ef6ac6fd5a8b2cf79fc3e3ef6f830
This commit is contained in:
Dave Borowitz
2016-04-25 13:03:42 -04:00
parent 937854a833
commit f5e6e04435
5 changed files with 163 additions and 142 deletions
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250
gerrit-server/src/main/java/com/google/gerrit/server/patch/AutoMerger.java
View File

@@ -18,6 +18,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.server.GerritPersonIdent;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.inject.Inject;
import org.eclipse.jgit.diff.Sequence;
@@ -25,6 +26,7 @@ import org.eclipse.jgit.dircache.DirCache;
import org.eclipse.jgit.dircache.DirCacheBuilder;
import org.eclipse.jgit.dircache.DirCacheEntry;
import org.eclipse.jgit.lib.CommitBuilder;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
@@ -52,9 +54,13 @@ public class AutoMerger {
private static final Logger log = LoggerFactory.getLogger(AutoMerger.class);
private final PersonIdent gerritIdent;
private final boolean save;
@Inject
AutoMerger(@GerritPersonIdent PersonIdent gerritIdent) {
AutoMerger(
@GerritServerConfig Config cfg,
@GerritPersonIdent PersonIdent gerritIdent) {
save = cfg.getBoolean("change", null, "cacheAutomerge", true);
this.gerritIdent = gerritIdent;
}
@@ -64,8 +70,9 @@ public class AutoMerger {
* @return auto-merge commit or {@code null} if an auto-merge commit
* couldn't be created. Headers of the returned RevCommit are parsed.
*/
public RevCommit merge(Repository repo, RevWalk rw, RevCommit merge,
ThreeWayMergeStrategy mergeStrategy) throws IOException {
public RevCommit merge(Repository repo, RevWalk rw, final ObjectInserter ins,
RevCommit merge, ThreeWayMergeStrategy mergeStrategy)
throws IOException {
rw.parseHeaders(merge);
String hash = merge.name();
String refName = RefNames.REFS_CACHE_AUTOMERGE
@@ -78,128 +85,126 @@ public class AutoMerger {
if (obj instanceof RevCommit) {
return (RevCommit) obj;
}
return commit(repo, rw, refName, obj, merge);
return commit(repo, rw, ins, refName, obj, merge);
}
ResolveMerger m = (ResolveMerger) mergeStrategy.newMerger(repo, true);
try (ObjectInserter ins = repo.newObjectInserter()) {
DirCache dc = DirCache.newInCore();
m.setDirCache(dc);
m.setObjectInserter(new ObjectInserter.Filter() {
@Override
protected ObjectInserter delegate() {
return ins;
}
@Override
public void flush() {
}
@Override
public void close() {
}
});
boolean couldMerge;
try {
couldMerge = m.merge(merge.getParents());
} catch (IOException e) {
// It is not safe to continue further down in this method as throwing
// an exception most likely means that the merge tree was not created
// and m.getMergeResults() is empty. This would mean that all paths are
// unmerged and Gerrit UI would show all paths in the patch list.
log.warn("Error attempting automerge " + refName, e);
return null;
DirCache dc = DirCache.newInCore();
m.setDirCache(dc);
m.setObjectInserter(new ObjectInserter.Filter() {
@Override
protected ObjectInserter delegate() {
return ins;
}
ObjectId treeId;
if (couldMerge) {
treeId = m.getResultTreeId();
} else {
RevCommit ours = merge.getParent(0);
RevCommit theirs = merge.getParent(1);
rw.parseBody(ours);
rw.parseBody(theirs);
String oursMsg = ours.getShortMessage();
String theirsMsg = theirs.getShortMessage();
String oursName = String.format("HEAD (%s %s)",
ours.abbreviate(6).name(),
oursMsg.substring(0, Math.min(oursMsg.length(), 60)));
String theirsName = String.format("BRANCH (%s %s)",
theirs.abbreviate(6).name(),
theirsMsg.substring(0, Math.min(theirsMsg.length(), 60)));
MergeFormatter fmt = new MergeFormatter();
Map<String, MergeResult<? extends Sequence>> r = m.getMergeResults();
Map<String, ObjectId> resolved = new HashMap<>();
for (Map.Entry<String, MergeResult<? extends Sequence>> entry : r.entrySet()) {
MergeResult<? extends Sequence> p = entry.getValue();
try (TemporaryBuffer buf =
new TemporaryBuffer.LocalFile(null, 10 * 1024 * 1024)) {
fmt.formatMerge(buf, p, "BASE", oursName, theirsName, UTF_8.name());
buf.close();
try (InputStream in = buf.openInputStream()) {
resolved.put(entry.getKey(), ins.insert(Constants.OBJ_BLOB, buf.length(), in));
}
}
}
DirCacheBuilder builder = dc.builder();
int cnt = dc.getEntryCount();
for (int i = 0; i < cnt;) {
DirCacheEntry entry = dc.getEntry(i);
if (entry.getStage() == 0) {
builder.add(entry);
i++;
continue;
}
int next = dc.nextEntry(i);
String path = entry.getPathString();
DirCacheEntry res = new DirCacheEntry(path);
if (resolved.containsKey(path)) {
// For a file with content merge conflict that we produced a result
// above on, collapse the file down to a single stage 0 with just
// the blob content, and a randomly selected mode (the lowest stage,
// which should be the merge base, or ours).
res.setFileMode(entry.getFileMode());
res.setObjectId(resolved.get(path));
} else if (next == i + 1) {
// If there is exactly one stage present, shouldn't be a conflict...
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
} else if (next == i + 2) {
// Two stages suggests a delete/modify conflict. Pick the higher
// stage as the automatic result.
entry = dc.getEntry(i + 1);
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
} else {
// 3 stage conflict, no resolve above
// Punt on the 3-stage conflict and show the base, for now.
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
}
builder.add(res);
i = next;
}
builder.finish();
treeId = dc.writeTree(ins);
@Override
public void flush() {
}
ins.flush();
return commit(repo, rw, refName, treeId, merge);
@Override
public void close() {
}
});
boolean couldMerge;
try {
couldMerge = m.merge(merge.getParents());
} catch (IOException e) {
// It is not safe to continue further down in this method as throwing
// an exception most likely means that the merge tree was not created
// and m.getMergeResults() is empty. This would mean that all paths are
// unmerged and Gerrit UI would show all paths in the patch list.
log.warn("Error attempting automerge " + refName, e);
return null;
}
ObjectId treeId;
if (couldMerge) {
treeId = m.getResultTreeId();
} else {
RevCommit ours = merge.getParent(0);
RevCommit theirs = merge.getParent(1);
rw.parseBody(ours);
rw.parseBody(theirs);
String oursMsg = ours.getShortMessage();
String theirsMsg = theirs.getShortMessage();
String oursName = String.format("HEAD (%s %s)",
ours.abbreviate(6).name(),
oursMsg.substring(0, Math.min(oursMsg.length(), 60)));
String theirsName = String.format("BRANCH (%s %s)",
theirs.abbreviate(6).name(),
theirsMsg.substring(0, Math.min(theirsMsg.length(), 60)));
MergeFormatter fmt = new MergeFormatter();
Map<String, MergeResult<? extends Sequence>> r = m.getMergeResults();
Map<String, ObjectId> resolved = new HashMap<>();
for (Map.Entry<String, MergeResult<? extends Sequence>> entry : r.entrySet()) {
MergeResult<? extends Sequence> p = entry.getValue();
try (TemporaryBuffer buf =
new TemporaryBuffer.LocalFile(null, 10 * 1024 * 1024)) {
fmt.formatMerge(buf, p, "BASE", oursName, theirsName, UTF_8.name());
buf.close();
try (InputStream in = buf.openInputStream()) {
resolved.put(entry.getKey(), ins.insert(Constants.OBJ_BLOB, buf.length(), in));
}
}
}
DirCacheBuilder builder = dc.builder();
int cnt = dc.getEntryCount();
for (int i = 0; i < cnt;) {
DirCacheEntry entry = dc.getEntry(i);
if (entry.getStage() == 0) {
builder.add(entry);
i++;
continue;
}
int next = dc.nextEntry(i);
String path = entry.getPathString();
DirCacheEntry res = new DirCacheEntry(path);
if (resolved.containsKey(path)) {
// For a file with content merge conflict that we produced a result
// above on, collapse the file down to a single stage 0 with just
// the blob content, and a randomly selected mode (the lowest stage,
// which should be the merge base, or ours).
res.setFileMode(entry.getFileMode());
res.setObjectId(resolved.get(path));
} else if (next == i + 1) {
// If there is exactly one stage present, shouldn't be a conflict...
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
} else if (next == i + 2) {
// Two stages suggests a delete/modify conflict. Pick the higher
// stage as the automatic result.
entry = dc.getEntry(i + 1);
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
} else {
// 3 stage conflict, no resolve above
// Punt on the 3-stage conflict and show the base, for now.
res.setFileMode(entry.getFileMode());
res.setObjectId(entry.getObjectId());
}
builder.add(res);
i = next;
}
builder.finish();
treeId = dc.writeTree(ins);
}
ins.flush();
return commit(repo, rw, ins, refName, treeId, merge);
}
private RevCommit commit(Repository repo, RevWalk rw, String refName,
ObjectId tree, RevCommit merge) throws IOException {
private RevCommit commit(Repository repo, RevWalk rw, ObjectInserter ins,
String refName, ObjectId tree, RevCommit merge) throws IOException {
rw.parseHeaders(merge);
// For maximum stability, choose a single ident using the committer time of
// the input commit, using the server name and timezone.
@@ -216,16 +221,15 @@ public class AutoMerger {
cb.addParentId(p);
}
ObjectId commitId;
try (ObjectInserter ins = repo.newObjectInserter()) {
commitId = ins.insert(cb);
commitId = ins.insert(cb);
if (save) {
ins.flush();
RefUpdate ru = repo.updateRef(refName);
ru.setNewObjectId(commitId);
ru.disableRefLog();
ru.forceUpdate();
}
RefUpdate ru = repo.updateRef(refName);
ru.setNewObjectId(commitId);
ru.disableRefLog();
ru.forceUpdate();
return rw.parseCommit(commitId);
}
}

11
gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListLoader.java
View File

@@ -136,11 +136,12 @@ public class PatchListLoader implements Callable<PatchList> {
private PatchList readPatchList(final PatchListKey key, final Repository repo)
throws IOException, PatchListNotAvailableException {
final RawTextComparator cmp = comparatorFor(key.getWhitespace());
try (ObjectReader reader = repo.newObjectReader();
try (ObjectInserter ins = repo.newObjectInserter();
ObjectReader reader = ins.newReader();
RevWalk rw = new RevWalk(reader);
DiffFormatter df = new DiffFormatter(DisabledOutputStream.INSTANCE)) {
final RevCommit b = rw.parseCommit(key.getNewId());
final RevObject a = aFor(key, repo, rw, b);
final RevObject a = aFor(key, repo, rw, ins, b);
if (a == null) {
// TODO(sop) Remove this case.
@@ -317,8 +318,8 @@ public class PatchListLoader implements Callable<PatchList> {
}
}
private RevObject aFor(final PatchListKey key,
final Repository repo, final RevWalk rw, final RevCommit b)
private RevObject aFor(PatchListKey key,
Repository repo, RevWalk rw, ObjectInserter ins, RevCommit b)
throws IOException {
if (key.getOldId() != null) {
return rw.parseAny(key.getOldId());
@@ -333,7 +334,7 @@ public class PatchListLoader implements Callable<PatchList> {
return r;
}
case 2:
return autoMerger.merge(repo, rw, b, mergeStrategy);
return autoMerger.merge(repo, rw, ins, b, mergeStrategy);
default:
// TODO(sop) handle an octopus merge.
return null;