google-nomulus/java/google/registry/dns/DnsWriterProxy.java

// 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;

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.logging.FormattingLogger.getLoggerForCallerClass;

import com.google.common.collect.ImmutableMap;
import com.google.common.logging.FormattingLogger;
import google.registry.dns.writer.DnsWriter;
import google.registry.model.registry.Registry;
import java.util.Map;
import javax.inject.Inject;

/** Proxy for retrieving {@link DnsWriter} implementations. */
public final class DnsWriterProxy {

  private static final FormattingLogger logger = getLoggerForCallerClass();

  private final ImmutableMap<String, DnsWriter> dnsWriters;

  @Inject
  DnsWriterProxy(Map<String, DnsWriter> dnsWriters) {
    this.dnsWriters = ImmutableMap.copyOf(dnsWriters);
  }

  /**
   * Returns the instance of {@link DnsWriter} by class name.
   *
   * If the DnsWriter doesn't belong to this TLD, will return null.
   */
  public DnsWriter getByClassNameForTld(String className, String tld) {
    if (!Registry.get(tld).getDnsWriters().contains(className)) {
      logger.warningfmt(
          "Loaded potentially stale DNS writer %s which is not active on TLD %s.",
          className, tld);
      return null;
    }
    DnsWriter dnsWriter = dnsWriters.get(className);
    checkState(dnsWriter != null, "Could not load DnsWriter %s for TLD %s", className, tld);
    return dnsWriter;
  }
}