hadoop-hdds/client/src/main/java/org/apache/hadoop/hdds/scm/storage/BlockOutputStream.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.hadoop.hdds.scm.storage;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import org.apache.hadoop.hdds.protocol.DatanodeDetails;
import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos;
import org.apache.hadoop.hdds.scm.XceiverClientReply;
import org.apache.hadoop.hdds.scm.container.common.helpers.StorageContainerException;
import org.apache.hadoop.hdds.scm.pipeline.Pipeline;
import org.apache.hadoop.ozone.common.Checksum;
import org.apache.hadoop.ozone.common.ChecksumData;
import org.apache.hadoop.ozone.common.OzoneChecksumException;
import org.apache.ratis.thirdparty.com.google.protobuf.ByteString;
import org.apache.hadoop.hdds.scm.XceiverClientManager;
import org.apache.hadoop.hdds.scm.XceiverClientSpi;
import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.ChecksumType;
import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.ChunkInfo;
import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.BlockData;
import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos.KeyValue;
import org.apache.hadoop.hdds.client.BlockID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicReference;

import static org.apache.hadoop.hdds.scm.storage.ContainerProtocolCalls
    .putBlockAsync;
import static org.apache.hadoop.hdds.scm.storage.ContainerProtocolCalls
    .writeChunkAsync;

/**
 * An {@link OutputStream} used by the REST service in combination with the
 * SCMClient to write the value of a key to a sequence
 * of container chunks.  Writes are buffered locally and periodically written to
 * the container as a new chunk.  In order to preserve the semantics that
 * replacement of a pre-existing key is atomic, each instance of the stream has
 * an internal unique identifier.  This unique identifier and a monotonically
 * increasing chunk index form a composite key that is used as the chunk name.
 * After all data is written, a putKey call creates or updates the corresponding
 * container key, and this call includes the full list of chunks that make up
 * the key data.  The list of chunks is updated all at once.  Therefore, a
 * concurrent reader never can see an intermediate state in which different
 * chunks of data from different versions of the key data are interleaved.
 * This class encapsulates all state management for buffering and writing
 * through to the container.
 */
public class BlockOutputStream extends OutputStream {
  public static final Logger LOG =
      LoggerFactory.getLogger(BlockOutputStream.class);

  private volatile BlockID blockID;

  private final BlockData.Builder containerBlockData;
  private XceiverClientManager xceiverClientManager;
  private XceiverClientSpi xceiverClient;
  private final ContainerProtos.ChecksumType checksumType;
  private final int bytesPerChecksum;
  private int chunkIndex;
  private int chunkSize;
  private final long streamBufferFlushSize;
  private final long streamBufferMaxSize;
  private BufferPool bufferPool;
  // The IOException will be set by response handling thread in case there is an
  // exception received in the response. If the exception is set, the next
  // request will fail upfront.
  private AtomicReference<IOException> ioException;
  private ExecutorService responseExecutor;

  // the effective length of data flushed so far
  private long totalDataFlushedLength;

  // effective data write attempted so far for the block
  private long writtenDataLength;

  // List containing buffers for which the putBlock call will
  // update the length in the datanodes. This list will just maintain
  // references to the buffers in the BufferPool which will be cleared
  // when the watchForCommit acknowledges a putBlock logIndex has been
  // committed on all datanodes. This list will be a  place holder for buffers
  // which got written between successive putBlock calls.
  private List<ByteBuffer> bufferList;

  // This object will maintain the commitIndexes and byteBufferList in order
  // Also, corresponding to the logIndex, the corresponding list of buffers will
  // be released from the buffer pool.
  private final CommitWatcher commitWatcher;

  private List<DatanodeDetails> failedServers;

  /**
   * Creates a new BlockOutputStream.
   *
   * @param blockID              block ID
   * @param xceiverClientManager client manager that controls client
   * @param pipeline             pipeline where block will be written
   * @param chunkSize            chunk size
   * @param bufferPool           pool of buffers
   * @param streamBufferFlushSize flush size
   * @param streamBufferMaxSize   max size of the currentBuffer
   * @param watchTimeout          watch timeout
   * @param checksumType          checksum type
   * @param bytesPerChecksum      Bytes per checksum
   */
  @SuppressWarnings("parameternumber")
  public BlockOutputStream(BlockID blockID,
      XceiverClientManager xceiverClientManager, Pipeline pipeline,
      int chunkSize, long streamBufferFlushSize, long streamBufferMaxSize,
      long watchTimeout, BufferPool bufferPool, ChecksumType checksumType,
      int bytesPerChecksum)
      throws IOException {
    this.blockID = blockID;
    this.chunkSize = chunkSize;
    KeyValue keyValue =
        KeyValue.newBuilder().setKey("TYPE").setValue("KEY").build();
    this.containerBlockData =
        BlockData.newBuilder().setBlockID(blockID.getDatanodeBlockIDProtobuf())
            .addMetadata(keyValue);
    this.xceiverClientManager = xceiverClientManager;
    this.xceiverClient = xceiverClientManager.acquireClient(pipeline);
    this.chunkIndex = 0;
    this.streamBufferFlushSize = streamBufferFlushSize;
    this.streamBufferMaxSize = streamBufferMaxSize;
    this.bufferPool = bufferPool;
    this.checksumType = checksumType;
    this.bytesPerChecksum = bytesPerChecksum;

    // A single thread executor handle the responses of async requests
    responseExecutor = Executors.newSingleThreadExecutor();
    commitWatcher = new CommitWatcher(bufferPool, xceiverClient, watchTimeout);
    bufferList = null;
    totalDataFlushedLength = 0;
    writtenDataLength = 0;
    failedServers = new ArrayList<>(0);
    ioException = new AtomicReference<>(null);
  }


  public BlockID getBlockID() {
    return blockID;
  }

  public long getTotalAckDataLength() {
    return commitWatcher.getTotalAckDataLength();
  }

  public long getWrittenDataLength() {
    return writtenDataLength;
  }

  public List<DatanodeDetails> getFailedServers() {
    return failedServers;
  }

  @VisibleForTesting
  public XceiverClientSpi getXceiverClient() {
    return xceiverClient;
  }

  @VisibleForTesting
  public long getTotalDataFlushedLength() {
    return totalDataFlushedLength;
  }

  @VisibleForTesting
  public BufferPool getBufferPool() {
    return bufferPool;
  }

  public IOException getIoException() {
    return ioException.get();
  }

  @VisibleForTesting
  public Map<Long, List<ByteBuffer>> getCommitIndex2flushedDataMap() {
    return commitWatcher.getCommitIndex2flushedDataMap();
  }

  @Override
  public void write(int b) throws IOException {
    checkOpen();
    byte[] buf = new byte[1];
    buf[0] = (byte) b;
    write(buf, 0, 1);
  }

  @Override
  public void write(byte[] b, int off, int len) throws IOException {
    checkOpen();
    if (b == null) {
      throw new NullPointerException();
    }
    if ((off < 0) || (off > b.length) || (len < 0) || ((off + len) > b.length)
        || ((off + len) < 0)) {
      throw new IndexOutOfBoundsException();
    }
    if (len == 0) {
      return;
    }

    while (len > 0) {
      int writeLen;
      // Allocate a buffer if needed. The buffer will be allocated only
      // once as needed and will be reused again for multiple blockOutputStream
      // entries.
      ByteBuffer  currentBuffer = bufferPool.allocateBufferIfNeeded();
      int pos = currentBuffer.position();
      writeLen =
          Math.min(chunkSize - pos % chunkSize, len);
      currentBuffer.put(b, off, writeLen);
      if (!currentBuffer.hasRemaining()) {
        writeChunk(currentBuffer);
      }
      off += writeLen;
      len -= writeLen;
      writtenDataLength += writeLen;
      if (shouldFlush()) {
        updateFlushLength();
        executePutBlock();
      }
      // Data in the bufferPool can not exceed streamBufferMaxSize
      if (isBufferPoolFull()) {
        handleFullBuffer();
      }
    }
  }

  private boolean shouldFlush() {
    return bufferPool.computeBufferData() % streamBufferFlushSize == 0;
  }

  private void updateFlushLength() {
    totalDataFlushedLength += writtenDataLength - totalDataFlushedLength;
  }

  private boolean isBufferPoolFull() {
    return bufferPool.computeBufferData() == streamBufferMaxSize;
  }
  /**
   * Will be called on the retryPath in case closedContainerException/
   * TimeoutException.
   * @param len length of data to write
   * @throws IOException if error occurred
   */

  // In this case, the data is already cached in the currentBuffer.
  public void writeOnRetry(long len) throws IOException {
    if (len == 0) {
      return;
    }
    int count = 0;
    Preconditions.checkArgument(len <= streamBufferMaxSize);
    while (len > 0) {
      long writeLen;
      writeLen = Math.min(chunkSize, len);
      if (writeLen == chunkSize) {
        writeChunk(bufferPool.getBuffer(count));
      }
      len -= writeLen;
      count++;
      writtenDataLength += writeLen;
      // we should not call isBufferFull/shouldFlush here.
      // The buffer might already be full as whole data is already cached in
      // the buffer. We should just validate
      // if we wrote data of size streamBufferMaxSize/streamBufferFlushSize to
      // call for handling full buffer/flush buffer condition.
      if (writtenDataLength % streamBufferFlushSize == 0) {
        // reset the position to zero as now we will be reading the
        // next buffer in the list
        updateFlushLength();
        executePutBlock();
      }
      if (writtenDataLength == streamBufferMaxSize) {
        handleFullBuffer();
      }
    }
  }

  /**
   * This is a blocking call. It will wait for the flush till the commit index
   * at the head of the commitIndex2flushedDataMap gets replicated to all or
   * majority.
   * @throws IOException
   */
  private void handleFullBuffer() throws IOException {
    try {
      checkOpen();
      if (!commitWatcher.getFutureMap().isEmpty()) {
        waitOnFlushFutures();
      }
    } catch (InterruptedException | ExecutionException e) {
      setIoException(e);
      adjustBuffersOnException();
      throw getIoException();
    }
    watchForCommit(true);
  }


  // It may happen that once the exception is encountered , we still might
  // have successfully flushed up to a certain index. Make sure the buffers
  // only contain data which have not been sufficiently replicated
  private void adjustBuffersOnException() {
    commitWatcher.releaseBuffersOnException();
  }

  /**
   * calls watchForCommit API of the Ratis Client. For Standalone client,
   * it is a no op.
   * @param bufferFull flag indicating whether bufferFull condition is hit or
   *              its called as part flush/close
   * @return minimum commit index replicated to all nodes
   * @throws IOException IOException in case watch gets timed out
   */
  private void watchForCommit(boolean bufferFull) throws IOException {
    checkOpen();
    try {
      XceiverClientReply reply = bufferFull ?
          commitWatcher.watchOnFirstIndex() : commitWatcher.watchOnLastIndex();
      if (reply != null) {
        List<DatanodeDetails> dnList = reply.getDatanodes();
        if (!dnList.isEmpty()) {
          Pipeline pipe = xceiverClient.getPipeline();

          LOG.warn("Failed to commit BlockId {} on {}. Failed nodes: {}",
              blockID, pipe, dnList);
          failedServers.addAll(dnList);
        }
      }
    } catch (IOException ioe) {
      setIoException(ioe);
      throw getIoException();
    }
  }

  private CompletableFuture<ContainerProtos.
      ContainerCommandResponseProto> executePutBlock()
      throws IOException {
    checkOpen();
    long flushPos = totalDataFlushedLength;
    Preconditions.checkNotNull(bufferList);
    List<ByteBuffer> byteBufferList = bufferList;
    bufferList = null;
    Preconditions.checkNotNull(byteBufferList);

    CompletableFuture<ContainerProtos.
        ContainerCommandResponseProto> flushFuture;
    try {
      XceiverClientReply asyncReply =
          putBlockAsync(xceiverClient, containerBlockData.build());
      CompletableFuture<ContainerProtos.ContainerCommandResponseProto> future =
          asyncReply.getResponse();
      flushFuture = future.thenApplyAsync(e -> {
        try {
          validateResponse(e);
        } catch (IOException sce) {
          throw new CompletionException(sce);
        }
        // if the ioException is not set, putBlock is successful
        if (getIoException() == null) {
          BlockID responseBlockID = BlockID.getFromProtobuf(
              e.getPutBlock().getCommittedBlockLength().getBlockID());
          Preconditions.checkState(blockID.getContainerBlockID()
              .equals(responseBlockID.getContainerBlockID()));
          // updates the bcsId of the block
          blockID = responseBlockID;
          if (LOG.isDebugEnabled()) {
            LOG.debug(
                "Adding index " + asyncReply.getLogIndex() + " commitMap size "
                    + commitWatcher.getCommitInfoMapSize() + " flushLength "
                    + flushPos + " numBuffers " + byteBufferList.size()
                    + " blockID " + blockID + " bufferPool size" + bufferPool
                    .getSize() + " currentBufferIndex " + bufferPool
                    .getCurrentBufferIndex());
          }
          // for standalone protocol, logIndex will always be 0.
          commitWatcher
              .updateCommitInfoMap(asyncReply.getLogIndex(), byteBufferList);
        }
        return e;
      }, responseExecutor).exceptionally(e -> {
        if (LOG.isDebugEnabled()) {
          LOG.debug(
              "putBlock failed for blockID " + blockID + " with exception " + e
                  .getLocalizedMessage());
        }
        CompletionException ce =  new CompletionException(e);
        setIoException(ce);
        throw ce;
      });
    } catch (IOException | InterruptedException | ExecutionException e) {
      throw new IOException(
          "Unexpected Storage Container Exception: " + e.toString(), e);
    }
    commitWatcher.getFutureMap().put(flushPos, flushFuture);
    return flushFuture;
  }

  @Override
  public void flush() throws IOException {
    if (xceiverClientManager != null && xceiverClient != null
        && bufferPool != null && bufferPool.getSize() > 0) {
      try {
        handleFlush();
      } catch (InterruptedException | ExecutionException e) {
        // just set the exception here as well in order to maintain sanctity of
        // ioException field
        setIoException(e);
        adjustBuffersOnException();
        throw getIoException();
      }
    }
  }


  private void writeChunk(ByteBuffer buffer)
      throws IOException {
    // This data in the buffer will be pushed to datanode and a reference will
    // be added to the bufferList. Once putBlock gets executed, this list will
    // be marked null. Hence, during first writeChunk call after every putBlock
    // call or during the first call to writeChunk here, the list will be null.

    if (bufferList == null) {
      bufferList = new ArrayList<>();
    }
    bufferList.add(buffer);
    // Please note : We are not flipping the slice when we write since
    // the slices are pointing the currentBuffer start and end as needed for
    // the chunk write. Also please note, Duplicate does not create a
    // copy of data, it only creates metadata that points to the data
    // stream.
    ByteBuffer chunk = buffer.duplicate();
    chunk.position(0);
    chunk.limit(buffer.position());
    writeChunkToContainer(chunk);
  }

  private void handleFlush()
      throws IOException, InterruptedException, ExecutionException {
    checkOpen();
    // flush the last chunk data residing on the currentBuffer
    if (totalDataFlushedLength < writtenDataLength) {
      ByteBuffer currentBuffer = bufferPool.getCurrentBuffer();
      Preconditions.checkArgument(currentBuffer.position() > 0);
      if (currentBuffer.position() != chunkSize) {
        writeChunk(currentBuffer);
      }
      // This can be a partially filled chunk. Since we are flushing the buffer
      // here, we just limit this buffer to the current position. So that next
      // write will happen in new buffer
      updateFlushLength();
      executePutBlock();
    }
    waitOnFlushFutures();
    watchForCommit(false);
    // just check again if the exception is hit while waiting for the
    // futures to ensure flush has indeed succeeded

    // irrespective of whether the commitIndex2flushedDataMap is empty
    // or not, ensure there is no exception set
    checkOpen();
  }

  @Override
  public void close() throws IOException {
    if (xceiverClientManager != null && xceiverClient != null
        && bufferPool != null && bufferPool.getSize() > 0) {
      try {
        handleFlush();
      } catch (InterruptedException | ExecutionException e) {
        setIoException(e);
        adjustBuffersOnException();
        throw getIoException();
      } finally {
        cleanup(false);
      }
      // TODO: Turn the below buffer empty check on when Standalone pipeline
      // is removed in the write path in tests
      // Preconditions.checkArgument(buffer.position() == 0);
      // bufferPool.checkBufferPoolEmpty();

    }
  }

  private void waitOnFlushFutures()
      throws InterruptedException, ExecutionException {
    CompletableFuture<Void> combinedFuture = CompletableFuture.allOf(
        commitWatcher.getFutureMap().values().toArray(
            new CompletableFuture[commitWatcher.getFutureMap().size()]));
    // wait for all the transactions to complete
    combinedFuture.get();
  }

  private void validateResponse(
      ContainerProtos.ContainerCommandResponseProto responseProto)
      throws IOException {
    try {
      // if the ioException is already set, it means a prev request has failed
      // just throw the exception. The current operation will fail with the
      // original error
      IOException exception = getIoException();
      if (exception != null) {
        throw exception;
      }
      ContainerProtocolCalls.validateContainerResponse(responseProto);
    } catch (StorageContainerException sce) {
      LOG.error("Unexpected Storage Container Exception: ", sce);
      setIoException(sce);
      throw sce;
    }
  }


  private void setIoException(Exception e) {
    if (getIoException() == null) {
      IOException exception =  new IOException(
          "Unexpected Storage Container Exception: " + e.toString(), e);
      ioException.compareAndSet(null, exception);
    }
  }

  public void cleanup(boolean invalidateClient) {
    if (xceiverClientManager != null) {
      xceiverClientManager.releaseClient(xceiverClient, invalidateClient);
    }
    xceiverClientManager = null;
    xceiverClient = null;
    commitWatcher.cleanup();
    if (bufferList !=  null) {
      bufferList.clear();
    }
    bufferList = null;
    responseExecutor.shutdown();
  }

  /**
   * Checks if the stream is open or exception has occured.
   * If not, throws an exception.
   *
   * @throws IOException if stream is closed
   */
  private void checkOpen() throws IOException {
    if (isClosed()) {
      throw new IOException("BlockOutputStream has been closed.");
    } else if (getIoException() != null) {
      adjustBuffersOnException();
      throw getIoException();
    }
  }

  public boolean isClosed() {
    return xceiverClient == null;
  }

  /**
   * Writes buffered data as a new chunk to the container and saves chunk
   * information to be used later in putKey call.
   *
   * @throws IOException if there is an I/O error while performing the call
   * @throws OzoneChecksumException if there is an error while computing
   * checksum
   */
  private void writeChunkToContainer(ByteBuffer chunk) throws IOException {
    int effectiveChunkSize = chunk.remaining();
    ByteString data = bufferPool.byteStringConversion().apply(chunk);
    Checksum checksum = new Checksum(checksumType, bytesPerChecksum);
    ChecksumData checksumData = checksum.computeChecksum(chunk);
    ChunkInfo chunkInfo = ChunkInfo.newBuilder()
        .setChunkName(blockID.getLocalID() + "_chunk_" + ++chunkIndex)
        .setOffset(0)
        .setLen(effectiveChunkSize)
        .setChecksumData(checksumData.getProtoBufMessage())
        .build();

    try {
      XceiverClientReply asyncReply =
          writeChunkAsync(xceiverClient, chunkInfo, blockID, data);
      CompletableFuture<ContainerProtos.ContainerCommandResponseProto> future =
          asyncReply.getResponse();
      future.thenApplyAsync(e -> {
        try {
          validateResponse(e);
        } catch (IOException sce) {
          future.completeExceptionally(sce);
        }
        return e;
      }, responseExecutor).exceptionally(e -> {
        if (LOG.isDebugEnabled()) {
          LOG.debug(
              "writing chunk failed " + chunkInfo.getChunkName() + " blockID "
                  + blockID + " with exception " + e.getLocalizedMessage());
        }
        CompletionException ce = new CompletionException(e);
        setIoException(ce);
        throw ce;
      });
    } catch (IOException | InterruptedException | ExecutionException e) {
      throw new IOException(
          "Unexpected Storage Container Exception: " + e.toString(), e);
    }
    if (LOG.isDebugEnabled()) {
      LOG.debug(
          "writing chunk " + chunkInfo.getChunkName() + " blockID " + blockID
              + " length " + effectiveChunkSize);
    }
    containerBlockData.addChunks(chunkInfo);
  }

  @VisibleForTesting
  public void setXceiverClient(XceiverClientSpi xceiverClient) {
    this.xceiverClient = xceiverClient;
  }
}