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.oss;
  
  import alluxio.underfs.ContentHashable;
  import alluxio.util.CommonUtils;
  import alluxio.util.io.PathUtils;
  
  import com.aliyun.oss.OSS;
  import com.aliyun.oss.ServiceException;
  import com.aliyun.oss.model.ObjectMetadata;
  import com.google.common.base.Preconditions;
  import org.apache.commons.codec.binary.Base64;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.BufferedInputStream;
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  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.Optional;
  import java.util.UUID;
  import java.util.concurrent.atomic.AtomicBoolean;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * A stream for writing a file into OSS. 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 final class OSSOutputStream extends OutputStream implements ContentHashable {
    private static final Logger LOG = LoggerFactory.getLogger(OSSOutputStream.class);
  
    /** Bucket name of the Alluxio OSS bucket. */
    private final String mBucketName;
    /** Key of the file when it is uploaded to OSS. */
    private final String mKey;
    /** The local file that will be uploaded when the stream is closed. */
    private final File mFile;
    /** The oss client for OSS operations. */
    private final OSS mOssClient;
  
    /** The OutputStream to a local file where the file will be buffered until closed. */
    private OutputStream mLocalOutputStream;
    /** The MD5 hash of the file. */
    private MessageDigest mHash;
  
    /** Flag to indicate this stream has been closed, to ensure close is only done once. */
    private AtomicBoolean mClosed = new AtomicBoolean(false);
  
    private String mContentHash;
  
    /**
     * Creates a name instance of {@link OSSOutputStream}.
     *
     * @param bucketName the name of the bucket
     * @param key the key of the file
     * @param client the client for OSS
     * @param tmpDirs a list of temporary directories
     */
    public OSSOutputStream(String bucketName, String key, OSS client, List<String> tmpDirs)
        throws IOException {
      Preconditions.checkArgument(bucketName != null && !bucketName.isEmpty(),
          "Bucket name must not be null or empty.");
      Preconditions.checkArgument(key != null && !key.isEmpty(),
          "OSS path must not be null or empty.");
      Preconditions.checkArgument(client != null, "OSSClient must not be null.");
      mBucketName = bucketName;
      mKey = key;
      mOssClient = client;
  
      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));
      }
    }
  
    /**
     * Writes the given bytes to this output stream. Before close, the bytes are all written to local
     * file.
     *
     * @param b the bytes to write
     */
    @Override
    public void write(int b) throws IOException {
      mLocalOutputStream.write(b);
    }
  
    /**
     * Writes the given byte array to this output stream. Before close, the bytes are all written to
     * local file.
     *
     * @param b the byte array
     */
    @Override
    public void write(byte[] b) throws IOException {
      mLocalOutputStream.write(b, 0, b.length);
    }
  
    /**
     * Writes the given number of bytes from the given byte array starting at the given offset to this
     * output stream. Before close, the bytes are all written to local file.
     *
     * @param b the byte array
     * @param off the start offset in the data
     * @param len the number of bytes to write
     */
    @Override
    public void write(byte[] b, int off, int len) throws IOException {
      mLocalOutputStream.write(b, off, len);
    }
  
    /**
     * Flushes this output stream and forces any buffered output bytes to be written out. Before
     * close, the data are flushed to local file.
     */
    @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 OSS Service. Once the file is uploaded, the temporary file is deleted.
     */
    @Override
    public void close() throws IOException {
      if (mClosed.getAndSet(true)) {
        return;
      }
      mLocalOutputStream.close();
      try (BufferedInputStream in = new BufferedInputStream(new FileInputStream(mFile))) {
        ObjectMetadata objMeta = new ObjectMetadata();
        objMeta.setContentLength(mFile.length());
        if (mHash != null) {
          byte[] hashBytes = mHash.digest();
          objMeta.setContentMD5(new String(Base64.encodeBase64(hashBytes)));
        }
        mContentHash = mOssClient.putObject(mBucketName, mKey, in, objMeta).getETag();
      } catch (ServiceException e) {
        LOG.error("Failed to upload {}.", mKey);
        throw new IOException(e);
      } finally {
        // Delete the temporary file on the local machine if the OSS client completed the
        // upload or if the upload failed.
        if (!mFile.delete()) {
          LOG.error("Failed to delete temporary file @ {}", mFile.getPath());
        }
      }
    }
  
    @Override
    public Optional<String> getContentHash() {
      return Optional.ofNullable(mContentHash);
    }
  }
  