| /** |
| * 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.hdfs.server.datanode.fsdataset.impl; |
| |
| import java.io.BufferedInputStream; |
| import java.io.Closeable; |
| import java.io.DataInputStream; |
| import java.io.FileInputStream; |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.MappedByteBuffer; |
| import java.nio.channels.FileChannel; |
| import java.nio.channels.FileChannel.MapMode; |
| |
| import org.apache.commons.io.IOUtils; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.ChecksumException; |
| import org.apache.hadoop.hdfs.server.datanode.BlockMetadataHeader; |
| import org.apache.hadoop.io.nativeio.NativeIO; |
| import org.apache.hadoop.util.DataChecksum; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * Represents an HDFS block that is mmapped by the DataNode. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class MappableBlock implements Closeable { |
| private MappedByteBuffer mmap; |
| private final long length; |
| |
| MappableBlock(MappedByteBuffer mmap, long length) { |
| this.mmap = mmap; |
| this.length = length; |
| assert length > 0; |
| } |
| |
| public long getLength() { |
| return length; |
| } |
| |
| /** |
| * Load the block. |
| * |
| * mmap and mlock the block, and then verify its checksum. |
| * |
| * @param length The current length of the block. |
| * @param blockIn The block input stream. Should be positioned at the |
| * start. The caller must close this. |
| * @param metaIn The meta file input stream. Should be positioned at |
| * the start. The caller must close this. |
| * @param blockFileName The block file name, for logging purposes. |
| * |
| * @return The Mappable block. |
| */ |
| public static MappableBlock load(long length, |
| FileInputStream blockIn, FileInputStream metaIn, |
| String blockFileName) throws IOException { |
| MappableBlock mappableBlock = null; |
| MappedByteBuffer mmap = null; |
| FileChannel blockChannel = null; |
| try { |
| blockChannel = blockIn.getChannel(); |
| if (blockChannel == null) { |
| throw new IOException("Block InputStream has no FileChannel."); |
| } |
| mmap = blockChannel.map(MapMode.READ_ONLY, 0, length); |
| NativeIO.POSIX.getCacheManipulator().mlock(blockFileName, mmap, length); |
| verifyChecksum(length, metaIn, blockChannel, blockFileName); |
| mappableBlock = new MappableBlock(mmap, length); |
| } finally { |
| IOUtils.closeQuietly(blockChannel); |
| if (mappableBlock == null) { |
| if (mmap != null) { |
| NativeIO.POSIX.munmap(mmap); // unmapping also unlocks |
| } |
| } |
| } |
| return mappableBlock; |
| } |
| |
| /** |
| * Verifies the block's checksum. This is an I/O intensive operation. |
| */ |
| private static void verifyChecksum(long length, |
| FileInputStream metaIn, FileChannel blockChannel, String blockFileName) |
| throws IOException, ChecksumException { |
| // Verify the checksum from the block's meta file |
| // Get the DataChecksum from the meta file header |
| BlockMetadataHeader header = |
| BlockMetadataHeader.readHeader(new DataInputStream( |
| new BufferedInputStream(metaIn, BlockMetadataHeader |
| .getHeaderSize()))); |
| FileChannel metaChannel = null; |
| try { |
| metaChannel = metaIn.getChannel(); |
| if (metaChannel == null) { |
| throw new IOException("Block InputStream meta file has no FileChannel."); |
| } |
| DataChecksum checksum = header.getChecksum(); |
| final int bytesPerChecksum = checksum.getBytesPerChecksum(); |
| final int checksumSize = checksum.getChecksumSize(); |
| final int numChunks = (8*1024*1024) / bytesPerChecksum; |
| ByteBuffer blockBuf = ByteBuffer.allocate(numChunks*bytesPerChecksum); |
| ByteBuffer checksumBuf = ByteBuffer.allocate(numChunks*checksumSize); |
| // Verify the checksum |
| int bytesVerified = 0; |
| while (bytesVerified < length) { |
| Preconditions.checkState(bytesVerified % bytesPerChecksum == 0, |
| "Unexpected partial chunk before EOF"); |
| assert bytesVerified % bytesPerChecksum == 0; |
| int bytesRead = fillBuffer(blockChannel, blockBuf); |
| if (bytesRead == -1) { |
| throw new IOException("checksum verification failed: premature EOF"); |
| } |
| blockBuf.flip(); |
| // Number of read chunks, including partial chunk at end |
| int chunks = (bytesRead+bytesPerChecksum-1) / bytesPerChecksum; |
| checksumBuf.limit(chunks*checksumSize); |
| fillBuffer(metaChannel, checksumBuf); |
| checksumBuf.flip(); |
| checksum.verifyChunkedSums(blockBuf, checksumBuf, blockFileName, |
| bytesVerified); |
| // Success |
| bytesVerified += bytesRead; |
| blockBuf.clear(); |
| checksumBuf.clear(); |
| } |
| } finally { |
| IOUtils.closeQuietly(metaChannel); |
| } |
| } |
| |
| /** |
| * Reads bytes into a buffer until EOF or the buffer's limit is reached |
| */ |
| private static int fillBuffer(FileChannel channel, ByteBuffer buf) |
| throws IOException { |
| int bytesRead = channel.read(buf); |
| if (bytesRead < 0) { |
| //EOF |
| return bytesRead; |
| } |
| while (buf.remaining() > 0) { |
| int n = channel.read(buf); |
| if (n < 0) { |
| //EOF |
| return bytesRead; |
| } |
| bytesRead += n; |
| } |
| return bytesRead; |
| } |
| |
| @Override |
| public void close() { |
| if (mmap != null) { |
| NativeIO.POSIX.munmap(mmap); |
| mmap = null; |
| } |
| } |
| } |