Java tutorial
/* * 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.Configuration; import alluxio.Constants; import alluxio.PropertyKey; 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.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 { private static final Logger LOG = LoggerFactory.getLogger(Constants.LOGGER_TYPE); private static final boolean SSE_ENABLED = Configuration .getBoolean(PropertyKey.UNDERFS_S3A_SERVER_SIDE_ENCRYPTION_ENABLED); /** Bucket name of the Alluxio S3 bucket. */ private final String mBucketName; /** Key of the file when it is uploaded to S3. */ private 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. private final 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; /** * 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 * @throws IOException when a non-Alluxio related error occurs */ public S3AOutputStream(String bucketName, String key, TransferManager manager) throws IOException { Preconditions.checkArgument(bucketName != null && !bucketName.isEmpty(), "Bucket name must " + "not be null or empty."); mBucketName = bucketName; mKey = key; mManager = manager; mFile = new File(PathUtils.concatPath("/tmp", 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(); 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 (SSE_ENABLED) { meta.setSSEAlgorithm(ObjectMetadata.AES_256_SERVER_SIDE_ENCRYPTION); } if (mHash != null) { meta.setContentMD5(new String(Base64.encode(mHash.digest()))); } meta.setContentLength(mFile.length()); meta.setContentEncoding(Mimetypes.MIMETYPE_OCTET_STREAM); // Generate the put request and wait for the transfer manager to complete the upload, then // delete the temporary file on the local machine PutObjectRequest putReq = new PutObjectRequest(mBucketName, mKey, mFile).withMetadata(meta); mManager.upload(putReq).waitForUploadResult(); if (!mFile.delete()) { LOG.error("Failed to delete temporary file @ {}", mFile.getPath()); } } catch (Exception e) { LOG.error("Failed to upload {}. Temporary file @ {}", mKey, mFile.getPath()); throw new IOException(e); } // Set the closed flag, close can be retried until mFile.delete is called successfully mClosed = true; } }