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.s3a;
  
  import alluxio.underfs.ContentHashable;
  import alluxio.util.CommonUtils;
  import alluxio.util.io.PathUtils;
  
  import com.amazonaws.services.s3.internal.Mimetypes;
  import com.amazonaws.services.s3.model.ObjectMetadata;
  import com.amazonaws.services.s3.model.PutObjectRequest;
  import com.amazonaws.services.s3.transfer.TransferManager;
  import com.amazonaws.util.Base64;
  import com.google.common.base.Preconditions;
  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.Optional;
  import java.util.UUID;
  import javax.annotation.concurrent.NotThreadSafe;
  
  /**
   * A stream for writing a file into S3. 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. The data
   * transfer is done using a {@link TransferManager} which manages the upload threads and handles
   * multipart upload.
   */
  @NotThreadSafe
  public class S3AOutputStream extends OutputStream implements ContentHashable {
    private static final Logger LOG = LoggerFactory.getLogger(S3AOutputStream.class);
  
    private final boolean mSseEnabled;
  
    /** Bucket name of the Alluxio S3 bucket. */
    private final String mBucketName;
  
    /** Key of the file when it is uploaded to S3. */
    protected final String mKey;
  
    /** The local file that will be uploaded when the stream is closed. */
    private final File mFile;
  
    /** Flag to indicate this stream has been closed, to ensure close is only done once. */
    private boolean mClosed = false;
  
    /**
     * A {@link TransferManager} to upload the file to S3 using Multipart Uploads. Multipart Uploads
     * involves uploading an object's data in parts instead of all at once, which can work around S3's
     * limit of 5GB on a single Object PUT operation.
     *
     * It is recommended (http://docs.aws.amazon.com/AmazonS3/latest/dev/UploadingObjects.html)
     * to upload file larger than 100MB using Multipart Uploads.
     */
    // TODO(calvin): Investigate if the lower level API can be more efficient.
    protected TransferManager mManager;
  
    /** The output stream to a local file where the file will be buffered until closed. */
    private OutputStream mLocalOutputStream;
  
    /** The MD5 hash of the file. */
    private MessageDigest mHash;
  
    private String mContentHash;
  
    /**
     * Constructs a new stream for writing a file.
     *
     * @param bucketName the name of the bucket
     * @param key the key of the file
     * @param manager the transfer manager to upload the file with
     * @param tmpDirs a list of temporary directories
     * @param sseEnabled whether or not server side encryption is enabled
     */
    public S3AOutputStream(String bucketName, String key, TransferManager manager,
        List<String> tmpDirs, boolean sseEnabled) throws IOException {
      Preconditions.checkArgument(bucketName != null && !bucketName.isEmpty(), "Bucket name must "
          + "not be null or empty.");
      mBucketName = bucketName;
      mKey = key;
      mManager = manager;
      mSseEnabled = sseEnabled;
      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();
    }
  
    @Override
    public void close() throws IOException {
      if (mClosed) {
        return;
      }
      mLocalOutputStream.close();
      String path = getUploadPath();
      try {
        // Generate the object metadata by setting server side encryption, md5 checksum, the file
        // length, and encoding as octet stream since no assumptions are made about the file type
        ObjectMetadata meta = new ObjectMetadata();
        if (mSseEnabled) {
          meta.setSSEAlgorithm(ObjectMetadata.AES_256_SERVER_SIDE_ENCRYPTION);
        }
        if (mHash != null) {
          meta.setContentMD5(new String(Base64.encode(mHash.digest())));
        }
        meta.setContentLength(mFile.length());
        meta.setContentType(Mimetypes.MIMETYPE_OCTET_STREAM);
  
        // Generate the put request and wait for the transfer manager to complete the upload
        PutObjectRequest putReq = new PutObjectRequest(mBucketName, path, mFile).withMetadata(meta);
        mContentHash = getTransferManager().upload(putReq).waitForUploadResult().getETag();
      } catch (Exception e) {
        LOG.error("Failed to upload {}", path, e);
        throw new IOException(e);
      } finally {
        // Delete the temporary file on the local machine if the transfer manager completed the
        // upload or if the upload failed.
        if (!mFile.delete()) {
          LOG.error("Failed to delete temporary file @ {}", mFile.getPath());
        }
        // Set the closed flag, close can be retried until mFile.delete is called successfully
        mClosed = true;
      }
    }
  
    /**
     * @return the path in S3 to upload the file to
     */
    protected String getUploadPath() {
      return mKey;
    }
  
    /**
     * @return return the transfer manager
     */
    protected TransferManager getTransferManager() {
      return mManager;
    }
  
    @Override
    public Optional<String> getContentHash() {
      return Optional.ofNullable(mContentHash);
    }
  }
  