opendev/gerrit
Code Issues Proposed changes

Merge "ChangeRebuilderImpl: Don't always drop updates when losing race"

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This commit is contained in:
David Pursehouse 2016-07-25 00:24:25 +00:00 committed by Gerrit Code Review
commit e845fc0e24
3 changed files with 29 additions and 4 deletions
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3
gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNotes.java
View File

@ -584,7 +584,8 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
//
// Parse notes from the staged result so we can return something useful
// to the caller instead of throwing.
log.debug("Rebuilding change {} failed", getChangeId());
log.debug("Rebuilding change {} failed: {}",
getChangeId(), e.getMessage());
args.metrics.autoRebuildFailureCount.increment(CHANGES);
rebuildResult = checkNotNull(r);
checkNotNull(r.newState());

27
gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeRebuilderImpl.java
View File

@ -176,6 +176,16 @@ public class ChangeRebuilderImpl extends ChangeRebuilder {
}
}
private static class ConflictingUpdateException extends OrmRuntimeException {
private static final long serialVersionUID = 1L;
ConflictingUpdateException(Change change, String expectedNoteDbState) {
super(String.format(
"Expected change %s to have noteDbState %s but was %s",
change.getId(), expectedNoteDbState, change.getNoteDbState()));
}
}
@Override
public Result rebuild(NoteDbUpdateManager manager,
ChangeBundle bundle) throws NoSuchChangeException, IOException,
@ -217,8 +227,13 @@ public class ChangeRebuilderImpl extends ChangeRebuilder {
db.changes().atomicUpdate(changeId, new AtomicUpdate<Change>() {
@Override
public Change update(Change change) {
if (!Objects.equals(oldNoteDbState, change.getNoteDbState())) {
String currNoteDbState = change.getNoteDbState();
if (Objects.equals(currNoteDbState, newNoteDbState)) {
// Another thread completed the same rebuild we were about to.
throw new AbortUpdateException();
} else if (!Objects.equals(oldNoteDbState, currNoteDbState)) {
// Another thread updated the state to something else.
throw new ConflictingUpdateException(change, oldNoteDbState);
}
change.setNoteDbState(newNoteDbState);
return change;
@ -233,7 +248,15 @@ public class ChangeRebuilderImpl extends ChangeRebuilder {
throw new OrmException(NoteDbUpdateManager.CHANGES_READ_ONLY);
}
} catch (AbortUpdateException e) {
// Drop this rebuild; another thread completed it.
// Drop this rebuild; another thread completed it. It's ok to not execute
// the update in this case, since the object referenced in the Result was
// flushed to the repo by whatever thread won the race.
} catch (ConflictingUpdateException e) {
// Rethrow as an OrmException so the caller knows to use staged results.
// Strictly speaking they are not completely up to date, but result we
// send to the caller is the same as if this rebuild had executed before
// the other thread.
throw new OrmException(e.getMessage());
}
return r;
}

3
gerrit-server/src/main/java/com/google/gerrit/server/notedb/DraftCommentNotes.java
View File

@ -206,7 +206,8 @@ public class DraftCommentNotes extends AbstractChangeNotes<DraftCommentNotes> {
repo.scanForRepoChanges();
} catch (OrmException | IOException e) {
// See ChangeNotes#rebuildAndOpen.
log.debug("Rebuilding change {} via drafts failed", getChangeId());
log.debug("Rebuilding change {} via drafts failed: {}",
getChangeId(), e.getMessage());
args.metrics.autoRebuildFailureCount.increment(CHANGES);
checkNotNull(r.staged());
return LoadHandle.create(