TransactionStateStorageProvider.java

/*
 * Copyright © 2012-2014 Cask Data, Inc.
 *
 * 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 co.cask.tephra.runtime;

import co.cask.tephra.TxConstants;
import co.cask.tephra.persist.NoOpTransactionStateStorage;
import co.cask.tephra.persist.TransactionStateStorage;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import com.google.inject.name.Names;
import org.apache.hadoop.conf.Configuration;

/**
 * A provider for {@link TransactionStateStorage} that provides different
 * {@link TransactionStateStorage} implementation based on configuration.
 */
@Singleton
public final class TransactionStateStorageProvider implements Provider<TransactionStateStorage> {

  private final Configuration cConf;
  private final Injector injector;

  @Inject
  TransactionStateStorageProvider(Configuration cConf, Injector injector) {
    this.cConf = cConf;
    this.injector = injector;
  }

  @Override
  public TransactionStateStorage get() {
    if (cConf.getBoolean(TxConstants.Manager.CFG_DO_PERSIST, true)) {
      return injector.getInstance(Key.get(TransactionStateStorage.class, Names.named("persist")));
    } else {
      return injector.getInstance(NoOpTransactionStateStorage.class);
    }
  }
}