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.underfs.kodo;
  
  import alluxio.util.CommonUtils;
  import alluxio.util.io.PathUtils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.security.DigestOutputStream;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.List;
  import java.util.UUID;
  import java.util.concurrent.atomic.AtomicBoolean;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * A stream for writing a file into Qiniu. The data will be persisted to a temporary directory on
   * the local disk and copied as a complete file when the {@link #close()} method is called.
   */
  @NotThreadSafe
  public class KodoOutputStream extends OutputStream {
  
    private static final Logger LOG = LoggerFactory.getLogger(KodoOutputStream.class);
  
    private final String mKey;
  
    private final File mFile;
  
    private final KodoClient mKodoClient;
  
    private OutputStream mLocalOutputStream;
  
    private MessageDigest mHash;
  
    /**
     * Flag to indicate this stream has been closed, to ensure close is only done once.
     */
    private AtomicBoolean mClosed = new AtomicBoolean(false);
  
    /**
     * Creates a name instance of {@link KodoOutputStream}.
     *
     * @param key the key of the file
     * @param kodoClient the client for Kodo
     * @param tmpDirs a list of temporary directories
     */
    public KodoOutputStream(String key, KodoClient kodoClient, List<String> tmpDirs)
        throws IOException {
      mKey = key;
      mKodoClient = kodoClient;
      mFile = new File(PathUtils.concatPath(CommonUtils.getTmpDir(tmpDirs), UUID.randomUUID()));
  
      try {
        mHash = MessageDigest.getInstance("MD5");
        mLocalOutputStream =
            new BufferedOutputStream(new DigestOutputStream(new FileOutputStream(mFile), mHash));
      } catch (NoSuchAlgorithmException e) {
        LOG.warn("Algorithm not available for MD5 hash.", e);
        mHash = null;
        mLocalOutputStream = new BufferedOutputStream(new FileOutputStream(mFile));
      }
    }
  
    @Override
    public void write(int b) throws IOException {
      mLocalOutputStream.write(b);
    }
  
    @Override
    public void write(byte[] b) throws IOException {
      mLocalOutputStream.write(b, 0, b.length);
    }
  
    @Override
    public void write(byte[] b, int off, int len) throws IOException {
      mLocalOutputStream.write(b, off, len);
    }
  
    @Override
    public void flush() throws IOException {
      mLocalOutputStream.flush();
    }
  
    /**
     * Closes this output stream. When an output stream is closed, the local temporary file is
     * uploaded to KODO Service. Once the file is uploaded, the temporary file is deleted.
     */
  
    @Override
    public void close() {
      if (mClosed.getAndSet(true)) {
        return;
      }
      try {
        mLocalOutputStream.close();
        mKodoClient.uploadFile(mKey, mFile);
      } catch (Exception e) {
        LOG.error("Failed to upload {}.", mKey, e);
      } finally {
        // Delete the temporary file on the local machine if the Kodo client completed the
        // upload or if the upload failed.
        if (!mFile.delete()) {
          LOG.error("Failed to delete temporary file @ {}", mFile.getPath());
        }
      }
    }
  }
  