Remove ReadOnlyRepository

The purpose of this class was to provide a read-only view of a
repository during a BatchUpdate, so op implementations would not be able
to modify the repository except during the updateRepo phase. Now that we
use RepoView to limit the repository operations available to ops,
ReadOnlyRepository is no longer used.

Plus, it turns out to be difficult to implement ReadOnlyRepository
correctly, both because of the extremely broad Repository interface and
the way that it interacts with its ObjectDatabase/RefDatabase fields.
This was one of the motivating factors for implementing a highly
restricted RepoView subset in the first place.

Change-Id: I85950461a8b7ed5fe418b5553d295f61be8120f7

gerrit-server/src/main/java/com/google/gerrit/server/update/ReadOnlyRepository.java

@@ -1,180 +0,0 @@
-// Copyright (C) 2015 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.google.gerrit.server.update;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import java.io.IOException;
-import java.util.List;
-import java.util.Map;
-import org.eclipse.jgit.attributes.AttributesNodeProvider;
-import org.eclipse.jgit.lib.BaseRepositoryBuilder;
-import org.eclipse.jgit.lib.ObjectDatabase;
-import org.eclipse.jgit.lib.ObjectInserter;
-import org.eclipse.jgit.lib.ObjectReader;
-import org.eclipse.jgit.lib.Ref;
-import org.eclipse.jgit.lib.RefDatabase;
-import org.eclipse.jgit.lib.RefRename;
-import org.eclipse.jgit.lib.RefUpdate;
-import org.eclipse.jgit.lib.ReflogReader;
-import org.eclipse.jgit.lib.Repository;
-import org.eclipse.jgit.lib.StoredConfig;
-
-class ReadOnlyRepository extends Repository {
-  private static final String MSG = "Cannot modify a " + ReadOnlyRepository.class.getSimpleName();
-
-  private static BaseRepositoryBuilder<?, ?> builder(Repository r) {
-    checkNotNull(r);
-    BaseRepositoryBuilder<?, ?> builder =
-        new BaseRepositoryBuilder<>().setFS(r.getFS()).setGitDir(r.getDirectory());
-
-    if (!r.isBare()) {
-      builder.setWorkTree(r.getWorkTree()).setIndexFile(r.getIndexFile());
-    }
-    return builder;
-  }
-
-  private final Repository delegate;
-  private final RefDb refdb;
-  private final ObjDb objdb;
-
-  ReadOnlyRepository(Repository delegate) {
-    super(builder(delegate));
-    this.delegate = delegate;
-    this.refdb = new RefDb(delegate.getRefDatabase());
-    this.objdb = new ObjDb(delegate.getObjectDatabase());
-  }
-
-  @Override
-  public void create(boolean bare) throws IOException {
-    throw new UnsupportedOperationException(MSG);
-  }
-
-  @Override
-  public ObjectDatabase getObjectDatabase() {
-    return objdb;
-  }
-
-  @Override
-  public RefDatabase getRefDatabase() {
-    return refdb;
-  }
-
-  @Override
-  public StoredConfig getConfig() {
-    return delegate.getConfig();
-  }
-
-  @Override
-  public AttributesNodeProvider createAttributesNodeProvider() {
-    return delegate.createAttributesNodeProvider();
-  }
-
-  @Override
-  public void scanForRepoChanges() throws IOException {
-    delegate.scanForRepoChanges();
-  }
-
-  @Override
-  public void notifyIndexChanged() {
-    delegate.notifyIndexChanged();
-  }
-
-  @Override
-  public ReflogReader getReflogReader(String refName) throws IOException {
-    return delegate.getReflogReader(refName);
-  }
-
-  @Override
-  public String getGitwebDescription() throws IOException {
-    return delegate.getGitwebDescription();
-  }
-
-  private static class RefDb extends RefDatabase {
-    private final RefDatabase delegate;
-
-    private RefDb(RefDatabase delegate) {
-      this.delegate = checkNotNull(delegate);
-    }
-
-    @Override
-    public void create() throws IOException {
-      throw new UnsupportedOperationException(MSG);
-    }
-
-    @Override
-    public void close() {
-      delegate.close();
-    }
-
-    @Override
-    public boolean isNameConflicting(String name) throws IOException {
-      return delegate.isNameConflicting(name);
-    }
-
-    @Override
-    public RefUpdate newUpdate(String name, boolean detach) throws IOException {
-      throw new UnsupportedOperationException(MSG);
-    }
-
-    @Override
-    public RefRename newRename(String fromName, String toName) throws IOException {
-      throw new UnsupportedOperationException(MSG);
-    }
-
-    @Override
-    public Ref getRef(String name) throws IOException {
-      return delegate.getRef(name);
-    }
-
-    @Override
-    public Map<String, Ref> getRefs(String prefix) throws IOException {
-      return delegate.getRefs(prefix);
-    }
-
-    @Override
-    public List<Ref> getAdditionalRefs() throws IOException {
-      return delegate.getAdditionalRefs();
-    }
-
-    @Override
-    public Ref peel(Ref ref) throws IOException {
-      return delegate.peel(ref);
-    }
-  }
-
-  private static class ObjDb extends ObjectDatabase {
-    private final ObjectDatabase delegate;
-
-    private ObjDb(ObjectDatabase delegate) {
-      this.delegate = checkNotNull(delegate);
-    }
-
-    @Override
-    public ObjectInserter newInserter() {
-      throw new UnsupportedOperationException(MSG);
-    }
-
-    @Override
-    public ObjectReader newReader() {
-      return delegate.newReader();
-    }
-
-    @Override
-    public void close() {
-      delegate.close();
-    }
-  }
-}