Extract multiple commit prevention in DNS writers into a base class

This still retains the DnsWriter interface itself for better integration
with Dagger and to preserve the option of having a DNS writer that does
not have this requirement (e.g. because it is idempotent).

This also makes the commit check thread-safe, which is a nice-to-have.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=168451114
This commit is contained in:
mcilwain 2017-09-12 14:48:54 -07:00 committed by jianglai
parent f6e0d5fa0c
commit 51298aeabb
4 changed files with 49 additions and 32 deletions

View file

@ -0,0 +1,36 @@
// Copyright 2017 The Nomulus Authors. All Rights Reserved.
//
// 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 google.registry.dns.writer;
import static com.google.common.base.Preconditions.checkState;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A base implementation of {@link DnsWriter} that protects against multiple calls to commit().
*/
public abstract class BaseDnsWriter implements DnsWriter {
private final AtomicBoolean committedAlready = new AtomicBoolean(false);
@Override
public final void commit() {
checkState(committedAlready.compareAndSet(false, true), "commit() has already been called");
commitUnchecked();
}
/** Commits DNS updates. This can never be called more than once. */
protected abstract void commitUnchecked();
}