content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.client.file.cache;
  
  import alluxio.AlluxioURI;
  import alluxio.client.file.DelegatingFileSystem;
  import alluxio.client.file.FileInStream;
  import alluxio.client.file.FileSystem;
  import alluxio.client.file.URIStatus;
  import alluxio.client.file.cache.filter.CacheFilter;
  import alluxio.conf.AlluxioConfiguration;
  import alluxio.exception.AlluxioException;
  import alluxio.grpc.OpenFilePOptions;
  
  import com.google.common.base.Preconditions;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.util.Optional;
  
  /**
   * A FileSystem implementation with a local cache.
   */
  public class LocalCacheFileSystem extends DelegatingFileSystem {
    private static final Logger LOG = LoggerFactory.getLogger(LocalCacheFileSystem.class);
    private final CacheManager mCacheManager;
    private final CacheFilter mCacheFilter;
    private final AlluxioConfiguration mConf;
  
    /**
     * @param cacheManage cache manager
     * @param fs a FileSystem instance to query on local cache miss
     * @param conf the configuration, only respected for the first call
     */
    public LocalCacheFileSystem(CacheManager cacheManage, FileSystem fs, AlluxioConfiguration conf) {
      super(fs);
      mCacheManager = Preconditions.checkNotNull(cacheManage, "cacheManager");
      mConf = Preconditions.checkNotNull(conf, "conf");
      mCacheFilter = CacheFilter.create(conf);
    }
  
    @Override
    public AlluxioConfiguration getConf() {
      return mDelegatedFileSystem.getConf();
    }
  
    @Override
    public FileInStream openFile(AlluxioURI path, OpenFilePOptions options)
        throws IOException, AlluxioException {
      if (mCacheManager == null || mCacheManager.state() == CacheManager.State.NOT_IN_USE) {
        return mDelegatedFileSystem.openFile(path, options);
      }
      return openFile(mDelegatedFileSystem.getStatus(path), options);
    }
  
    @Override
    public FileInStream openFile(URIStatus status, OpenFilePOptions options)
        throws IOException, AlluxioException {
      if (mCacheManager == null || mCacheManager.state() == CacheManager.State.NOT_IN_USE
          || !mCacheFilter.needsCache(status)) {
        return mDelegatedFileSystem.openFile(status, options);
      }
      return new LocalCacheFileInStream(status,
          uriStatus -> mDelegatedFileSystem.openFile(status, options), mCacheManager, mConf,
          Optional.empty());
    }
  }
  