/*
 * Druid - a distributed column store.
 * Copyright 2012 - 2015 Metamarkets Group 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 io.druid.common.aws;

import com.amazonaws.auth.AWSCredentialsProvider;

public class LazyFileSessionCredentialsProvider implements AWSCredentialsProvider
{
  private AWSCredentialsConfig config;
  private FileSessionCredentialsProvider provider;

  public LazyFileSessionCredentialsProvider(AWSCredentialsConfig config) {
    this.config = config;
  }

  private FileSessionCredentialsProvider getUnderlyingProvider() {
    if (provider == null) {
      synchronized (config) {
        if (provider == null) {
          provider = new FileSessionCredentialsProvider(config.getFileSessionCredentials());
        }
      }
    }
    return provider;
  }

  @Override
  public com.amazonaws.auth.AWSCredentials getCredentials()
  {
    return getUnderlyingProvider().getCredentials();
  }

  @Override
  public void refresh() {
    getUnderlyingProvider().refresh();
  }
}