org.apache.hadoop.hbase.io.hfile.HFileBlockIndex Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of hbase-server Show documentation
Show all versions of hbase-server Show documentation
Server functionality for HBase
/*
*
* 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.hbase.io.hfile;
import java.io.ByteArrayOutputStream;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValue.KVComparator;
import org.apache.hadoop.hbase.io.HeapSize;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
import org.apache.hadoop.hbase.io.hfile.HFile.CachingBlockReader;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.ClassSize;
import org.apache.hadoop.hbase.util.CompoundBloomFilterWriter;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.util.StringUtils;
/**
* Provides functionality to write ({@link BlockIndexWriter}) and read
* ({@link BlockIndexReader}) single-level and multi-level block indexes.
*
* Examples of how to use the block index writer can be found in
* {@link CompoundBloomFilterWriter} and {@link HFileWriterV2}. Examples of how
* to use the reader can be found in {@link HFileReaderV2} and
* TestHFileBlockIndex.
*/
@InterfaceAudience.Private
public class HFileBlockIndex {
private static final Log LOG = LogFactory.getLog(HFileBlockIndex.class);
static final int DEFAULT_MAX_CHUNK_SIZE = 128 * 1024;
/**
* The maximum size guideline for index blocks (both leaf, intermediate, and
* root). If not specified, DEFAULT_MAX_CHUNK_SIZE is used.
*/
public static final String MAX_CHUNK_SIZE_KEY = "hfile.index.block.max.size";
/**
* The number of bytes stored in each "secondary index" entry in addition to
* key bytes in the non-root index block format. The first long is the file
* offset of the deeper-level block the entry points to, and the int that
* follows is that block's on-disk size without including header.
*/
static final int SECONDARY_INDEX_ENTRY_OVERHEAD = Bytes.SIZEOF_INT
+ Bytes.SIZEOF_LONG;
/**
* Error message when trying to use inline block API in single-level mode.
*/
private static final String INLINE_BLOCKS_NOT_ALLOWED =
"Inline blocks are not allowed in the single-level-only mode";
/**
* The size of a meta-data record used for finding the mid-key in a
* multi-level index. Consists of the middle leaf-level index block offset
* (long), its on-disk size without header included (int), and the mid-key
* entry's zero-based index in that leaf index block.
*/
private static final int MID_KEY_METADATA_SIZE = Bytes.SIZEOF_LONG +
2 * Bytes.SIZEOF_INT;
/**
* The reader will always hold the root level index in the memory. Index
* blocks at all other levels will be cached in the LRU cache in practice,
* although this API does not enforce that.
*
* All non-root (leaf and intermediate) index blocks contain what we call a
* "secondary index": an array of offsets to the entries within the block.
* This allows us to do binary search for the entry corresponding to the
* given key without having to deserialize the block.
*/
public static class BlockIndexReader implements HeapSize {
/** Needed doing lookup on blocks. */
private final KVComparator comparator;
// Root-level data.
private byte[][] blockKeys;
private long[] blockOffsets;
private int[] blockDataSizes;
private int rootCount = 0;
// Mid-key metadata.
private long midLeafBlockOffset = -1;
private int midLeafBlockOnDiskSize = -1;
private int midKeyEntry = -1;
/** Pre-computed mid-key */
private AtomicReference midKey = new AtomicReference();
/**
* The number of levels in the block index tree. One if there is only root
* level, two for root and leaf levels, etc.
*/
private int searchTreeLevel;
/** A way to read {@link HFile} blocks at a given offset */
private CachingBlockReader cachingBlockReader;
public BlockIndexReader(final KVComparator c, final int treeLevel,
final CachingBlockReader cachingBlockReader) {
this(c, treeLevel);
this.cachingBlockReader = cachingBlockReader;
}
public BlockIndexReader(final KVComparator c, final int treeLevel)
{
comparator = c;
searchTreeLevel = treeLevel;
}
/**
* @return true if the block index is empty.
*/
public boolean isEmpty() {
return blockKeys.length == 0;
}
/**
* Verifies that the block index is non-empty and throws an
* {@link IllegalStateException} otherwise.
*/
public void ensureNonEmpty() {
if (blockKeys.length == 0) {
throw new IllegalStateException("Block index is empty or not loaded");
}
}
/**
* Return the data block which contains this key. This function will only
* be called when the HFile version is larger than 1.
*
* @param key the key we are looking for
* @param keyOffset the offset of the key in its byte array
* @param keyLength the length of the key
* @param currentBlock the current block, to avoid re-reading the same
* block
* @return reader a basic way to load blocks
* @throws IOException
*/
public HFileBlock seekToDataBlock(final byte[] key, int keyOffset,
int keyLength, HFileBlock currentBlock, boolean cacheBlocks,
boolean pread, boolean isCompaction)
throws IOException {
BlockWithScanInfo blockWithScanInfo = loadDataBlockWithScanInfo(key, keyOffset, keyLength,
currentBlock, cacheBlocks, pread, isCompaction);
if (blockWithScanInfo == null) {
return null;
} else {
return blockWithScanInfo.getHFileBlock();
}
}
/**
* Return the BlockWithScanInfo which contains the DataBlock with other scan info
* such as nextIndexedKey.
* This function will only be called when the HFile version is larger than 1.
*
* @param key the key we are looking for
* @param keyOffset the offset of the key in its byte array
* @param keyLength the length of the key
* @param currentBlock the current block, to avoid re-reading the same
* block
* @param cacheBlocks
* @param pread
* @param isCompaction
* @return the BlockWithScanInfo which contains the DataBlock with other scan info
* such as nextIndexedKey.
* @throws IOException
*/
public BlockWithScanInfo loadDataBlockWithScanInfo(final byte[] key, int keyOffset,
int keyLength, HFileBlock currentBlock, boolean cacheBlocks,
boolean pread, boolean isCompaction)
throws IOException {
int rootLevelIndex = rootBlockContainingKey(key, keyOffset, keyLength);
if (rootLevelIndex < 0 || rootLevelIndex >= blockOffsets.length) {
return null;
}
// the next indexed key
byte[] nextIndexedKey = null;
// Read the next-level (intermediate or leaf) index block.
long currentOffset = blockOffsets[rootLevelIndex];
int currentOnDiskSize = blockDataSizes[rootLevelIndex];
if (rootLevelIndex < blockKeys.length - 1) {
nextIndexedKey = blockKeys[rootLevelIndex + 1];
} else {
nextIndexedKey = HConstants.NO_NEXT_INDEXED_KEY;
}
int lookupLevel = 1; // How many levels deep we are in our lookup.
int index = -1;
HFileBlock block;
while (true) {
if (currentBlock != null && currentBlock.getOffset() == currentOffset)
{
// Avoid reading the same block again, even with caching turned off.
// This is crucial for compaction-type workload which might have
// caching turned off. This is like a one-block cache inside the
// scanner.
block = currentBlock;
} else {
// Call HFile's caching block reader API. We always cache index
// blocks, otherwise we might get terrible performance.
boolean shouldCache = cacheBlocks || (lookupLevel < searchTreeLevel);
BlockType expectedBlockType;
if (lookupLevel < searchTreeLevel - 1) {
expectedBlockType = BlockType.INTERMEDIATE_INDEX;
} else if (lookupLevel == searchTreeLevel - 1) {
expectedBlockType = BlockType.LEAF_INDEX;
} else {
// this also accounts for ENCODED_DATA
expectedBlockType = BlockType.DATA;
}
block = cachingBlockReader.readBlock(currentOffset,
currentOnDiskSize, shouldCache, pread, isCompaction, true,
expectedBlockType);
}
if (block == null) {
throw new IOException("Failed to read block at offset " +
currentOffset + ", onDiskSize=" + currentOnDiskSize);
}
// Found a data block, break the loop and check our level in the tree.
if (block.getBlockType().isData()) {
break;
}
// Not a data block. This must be a leaf-level or intermediate-level
// index block. We don't allow going deeper than searchTreeLevel.
if (++lookupLevel > searchTreeLevel) {
throw new IOException("Search Tree Level overflow: lookupLevel="+
lookupLevel + ", searchTreeLevel=" + searchTreeLevel);
}
// Locate the entry corresponding to the given key in the non-root
// (leaf or intermediate-level) index block.
ByteBuffer buffer = block.getBufferWithoutHeader();
index = locateNonRootIndexEntry(buffer, key, keyOffset, keyLength, comparator);
if (index == -1) {
throw new IOException("The key "
+ Bytes.toStringBinary(key, keyOffset, keyLength)
+ " is before the" + " first key of the non-root index block "
+ block);
}
currentOffset = buffer.getLong();
currentOnDiskSize = buffer.getInt();
// Only update next indexed key if there is a next indexed key in the current level
byte[] tmpNextIndexedKey = getNonRootIndexedKey(buffer, index + 1);
if (tmpNextIndexedKey != null) {
nextIndexedKey = tmpNextIndexedKey;
}
}
if (lookupLevel != searchTreeLevel) {
throw new IOException("Reached a data block at level " + lookupLevel +
" but the number of levels is " + searchTreeLevel);
}
// set the next indexed key for the current block.
BlockWithScanInfo blockWithScanInfo = new BlockWithScanInfo(block, nextIndexedKey);
return blockWithScanInfo;
}
/**
* An approximation to the {@link HFile}'s mid-key. Operates on block
* boundaries, and does not go inside blocks. In other words, returns the
* first key of the middle block of the file.
*
* @return the first key of the middle block
*/
public byte[] midkey() throws IOException {
if (rootCount == 0)
throw new IOException("HFile empty");
byte[] targetMidKey = this.midKey.get();
if (targetMidKey != null) {
return targetMidKey;
}
if (midLeafBlockOffset >= 0) {
if (cachingBlockReader == null) {
throw new IOException("Have to read the middle leaf block but " +
"no block reader available");
}
// Caching, using pread, assuming this is not a compaction.
HFileBlock midLeafBlock = cachingBlockReader.readBlock(
midLeafBlockOffset, midLeafBlockOnDiskSize, true, true, false, true,
BlockType.LEAF_INDEX);
ByteBuffer b = midLeafBlock.getBufferWithoutHeader();
int numDataBlocks = b.getInt();
int keyRelOffset = b.getInt(Bytes.SIZEOF_INT * (midKeyEntry + 1));
int keyLen = b.getInt(Bytes.SIZEOF_INT * (midKeyEntry + 2)) -
keyRelOffset;
int keyOffset = b.arrayOffset() +
Bytes.SIZEOF_INT * (numDataBlocks + 2) + keyRelOffset +
SECONDARY_INDEX_ENTRY_OVERHEAD;
targetMidKey = Arrays.copyOfRange(b.array(), keyOffset, keyOffset + keyLen);
} else {
// The middle of the root-level index.
targetMidKey = blockKeys[rootCount / 2];
}
this.midKey.set(targetMidKey);
return targetMidKey;
}
/**
* @param i from 0 to {@link #getRootBlockCount() - 1}
*/
public byte[] getRootBlockKey(int i) {
return blockKeys[i];
}
/**
* @param i from 0 to {@link #getRootBlockCount() - 1}
*/
public long getRootBlockOffset(int i) {
return blockOffsets[i];
}
/**
* @param i zero-based index of a root-level block
* @return the on-disk size of the root-level block for version 2, or the
* uncompressed size for version 1
*/
public int getRootBlockDataSize(int i) {
return blockDataSizes[i];
}
/**
* @return the number of root-level blocks in this block index
*/
public int getRootBlockCount() {
return rootCount;
}
/**
* Finds the root-level index block containing the given key.
*
* @param key
* Key to find
* @return Offset of block containing key (between 0 and the
* number of blocks - 1) or -1 if this file does not contain the
* request.
*/
public int rootBlockContainingKey(final byte[] key, int offset,
int length) {
int pos = Bytes.binarySearch(blockKeys, key, offset, length,
comparator);
// pos is between -(blockKeys.length + 1) to blockKeys.length - 1, see
// binarySearch's javadoc.
if (pos >= 0) {
// This means this is an exact match with an element of blockKeys.
assert pos < blockKeys.length;
return pos;
}
// Otherwise, pos = -(i + 1), where blockKeys[i - 1] < key < blockKeys[i],
// and i is in [0, blockKeys.length]. We are returning j = i - 1 such that
// blockKeys[j] <= key < blockKeys[j + 1]. In particular, j = -1 if
// key < blockKeys[0], meaning the file does not contain the given key.
int i = -pos - 1;
assert 0 <= i && i <= blockKeys.length;
return i - 1;
}
/**
* Adds a new entry in the root block index. Only used when reading.
*
* @param key Last key in the block
* @param offset file offset where the block is stored
* @param dataSize the uncompressed data size
*/
private void add(final byte[] key, final long offset, final int dataSize) {
blockOffsets[rootCount] = offset;
blockKeys[rootCount] = key;
blockDataSizes[rootCount] = dataSize;
rootCount++;
}
/**
* The indexed key at the ith position in the nonRootIndex. The position starts at 0.
* @param nonRootIndex
* @param i the ith position
* @return The indexed key at the ith position in the nonRootIndex.
*/
private byte[] getNonRootIndexedKey(ByteBuffer nonRootIndex, int i) {
int numEntries = nonRootIndex.getInt(0);
if (i < 0 || i >= numEntries) {
return null;
}
// Entries start after the number of entries and the secondary index.
// The secondary index takes numEntries + 1 ints.
int entriesOffset = Bytes.SIZEOF_INT * (numEntries + 2);
// Targetkey's offset relative to the end of secondary index
int targetKeyRelOffset = nonRootIndex.getInt(
Bytes.SIZEOF_INT * (i + 1));
// The offset of the target key in the blockIndex buffer
int targetKeyOffset = entriesOffset // Skip secondary index
+ targetKeyRelOffset // Skip all entries until mid
+ SECONDARY_INDEX_ENTRY_OVERHEAD; // Skip offset and on-disk-size
// We subtract the two consecutive secondary index elements, which
// gives us the size of the whole (offset, onDiskSize, key) tuple. We
// then need to subtract the overhead of offset and onDiskSize.
int targetKeyLength = nonRootIndex.getInt(Bytes.SIZEOF_INT * (i + 2)) -
targetKeyRelOffset - SECONDARY_INDEX_ENTRY_OVERHEAD;
int from = nonRootIndex.arrayOffset() + targetKeyOffset;
int to = from + targetKeyLength;
return Arrays.copyOfRange(nonRootIndex.array(), from, to);
}
/**
* Performs a binary search over a non-root level index block. Utilizes the
* secondary index, which records the offsets of (offset, onDiskSize,
* firstKey) tuples of all entries.
*
* @param key the key we are searching for offsets to individual entries in
* the blockIndex buffer
* @param keyOffset the offset of the key in its byte array
* @param keyLength the length of the key
* @param nonRootIndex the non-root index block buffer, starting with the
* secondary index. The position is ignored.
* @return the index i in [0, numEntries - 1] such that keys[i] <= key <
* keys[i + 1], if keys is the array of all keys being searched, or
* -1 otherwise
* @throws IOException
*/
static int binarySearchNonRootIndex(byte[] key, int keyOffset,
int keyLength, ByteBuffer nonRootIndex,
KVComparator comparator) {
int numEntries = nonRootIndex.getInt(0);
int low = 0;
int high = numEntries - 1;
int mid = 0;
// Entries start after the number of entries and the secondary index.
// The secondary index takes numEntries + 1 ints.
int entriesOffset = Bytes.SIZEOF_INT * (numEntries + 2);
// If we imagine that keys[-1] = -Infinity and
// keys[numEntries] = Infinity, then we are maintaining an invariant that
// keys[low - 1] < key < keys[high + 1] while narrowing down the range.
while (low <= high) {
mid = (low + high) >>> 1;
// Midkey's offset relative to the end of secondary index
int midKeyRelOffset = nonRootIndex.getInt(
Bytes.SIZEOF_INT * (mid + 1));
// The offset of the middle key in the blockIndex buffer
int midKeyOffset = entriesOffset // Skip secondary index
+ midKeyRelOffset // Skip all entries until mid
+ SECONDARY_INDEX_ENTRY_OVERHEAD; // Skip offset and on-disk-size
// We subtract the two consecutive secondary index elements, which
// gives us the size of the whole (offset, onDiskSize, key) tuple. We
// then need to subtract the overhead of offset and onDiskSize.
int midLength = nonRootIndex.getInt(Bytes.SIZEOF_INT * (mid + 2)) -
midKeyRelOffset - SECONDARY_INDEX_ENTRY_OVERHEAD;
// we have to compare in this order, because the comparator order
// has special logic when the 'left side' is a special key.
int cmp = comparator.compareFlatKey(key, keyOffset, keyLength,
nonRootIndex.array(), nonRootIndex.arrayOffset() + midKeyOffset,
midLength);
// key lives above the midpoint
if (cmp > 0)
low = mid + 1; // Maintain the invariant that keys[low - 1] < key
// key lives below the midpoint
else if (cmp < 0)
high = mid - 1; // Maintain the invariant that key < keys[high + 1]
else
return mid; // exact match
}
// As per our invariant, keys[low - 1] < key < keys[high + 1], meaning
// that low - 1 < high + 1 and (low - high) <= 1. As per the loop break
// condition, low >= high + 1. Therefore, low = high + 1.
if (low != high + 1) {
throw new IllegalStateException("Binary search broken: low=" + low
+ " " + "instead of " + (high + 1));
}
// OK, our invariant says that keys[low - 1] < key < keys[low]. We need to
// return i such that keys[i] <= key < keys[i + 1]. Therefore i = low - 1.
int i = low - 1;
// Some extra validation on the result.
if (i < -1 || i >= numEntries) {
throw new IllegalStateException("Binary search broken: result is " +
i + " but expected to be between -1 and (numEntries - 1) = " +
(numEntries - 1));
}
return i;
}
/**
* Search for one key using the secondary index in a non-root block. In case
* of success, positions the provided buffer at the entry of interest, where
* the file offset and the on-disk-size can be read.
*
* @param nonRootBlock a non-root block without header. Initial position
* does not matter.
* @param key the byte array containing the key
* @param keyOffset the offset of the key in its byte array
* @param keyLength the length of the key
* @return the index position where the given key was found,
* otherwise return -1 in the case the given key is before the first key.
*
*/
static int locateNonRootIndexEntry(ByteBuffer nonRootBlock, byte[] key,
int keyOffset, int keyLength, KVComparator comparator) {
int entryIndex = binarySearchNonRootIndex(key, keyOffset, keyLength,
nonRootBlock, comparator);
if (entryIndex != -1) {
int numEntries = nonRootBlock.getInt(0);
// The end of secondary index and the beginning of entries themselves.
int entriesOffset = Bytes.SIZEOF_INT * (numEntries + 2);
// The offset of the entry we are interested in relative to the end of
// the secondary index.
int entryRelOffset = nonRootBlock.getInt(Bytes.SIZEOF_INT
* (1 + entryIndex));
nonRootBlock.position(entriesOffset + entryRelOffset);
}
return entryIndex;
}
/**
* Read in the root-level index from the given input stream. Must match
* what was written into the root level by
* {@link BlockIndexWriter#writeIndexBlocks(FSDataOutputStream)} at the
* offset that function returned.
*
* @param in the buffered input stream or wrapped byte input stream
* @param numEntries the number of root-level index entries
* @throws IOException
*/
public void readRootIndex(DataInput in, final int numEntries)
throws IOException {
blockOffsets = new long[numEntries];
blockKeys = new byte[numEntries][];
blockDataSizes = new int[numEntries];
// If index size is zero, no index was written.
if (numEntries > 0) {
for (int i = 0; i < numEntries; ++i) {
long offset = in.readLong();
int dataSize = in.readInt();
byte[] key = Bytes.readByteArray(in);
add(key, offset, dataSize);
}
}
}
/**
* Read in the root-level index from the given input stream. Must match
* what was written into the root level by
* {@link BlockIndexWriter#writeIndexBlocks(FSDataOutputStream)} at the
* offset that function returned.
*
* @param blk the HFile block
* @param numEntries the number of root-level index entries
* @return the buffered input stream or wrapped byte input stream
* @throws IOException
*/
public DataInputStream readRootIndex(HFileBlock blk, final int numEntries) throws IOException {
DataInputStream in = blk.getByteStream();
readRootIndex(in, numEntries);
return in;
}
/**
* Read the root-level metadata of a multi-level block index. Based on
* {@link #readRootIndex(DataInput, int)}, but also reads metadata
* necessary to compute the mid-key in a multi-level index.
*
* @param blk the HFile block
* @param numEntries the number of root-level index entries
* @throws IOException
*/
public void readMultiLevelIndexRoot(HFileBlock blk,
final int numEntries) throws IOException {
DataInputStream in = readRootIndex(blk, numEntries);
// after reading the root index the checksum bytes have to
// be subtracted to know if the mid key exists.
int checkSumBytes = blk.totalChecksumBytes();
if ((in.available() - checkSumBytes) < MID_KEY_METADATA_SIZE) {
// No mid-key metadata available.
return;
}
midLeafBlockOffset = in.readLong();
midLeafBlockOnDiskSize = in.readInt();
midKeyEntry = in.readInt();
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("size=" + rootCount).append("\n");
for (int i = 0; i < rootCount; i++) {
sb.append("key=").append(KeyValue.keyToString(blockKeys[i]))
.append("\n offset=").append(blockOffsets[i])
.append(", dataSize=" + blockDataSizes[i]).append("\n");
}
return sb.toString();
}
@Override
public long heapSize() {
long heapSize = ClassSize.align(6 * ClassSize.REFERENCE +
2 * Bytes.SIZEOF_INT + ClassSize.OBJECT);
// Mid-key metadata.
heapSize += MID_KEY_METADATA_SIZE;
// Calculating the size of blockKeys
if (blockKeys != null) {
// Adding array + references overhead
heapSize += ClassSize.align(ClassSize.ARRAY + blockKeys.length
* ClassSize.REFERENCE);
// Adding bytes
for (byte[] key : blockKeys) {
heapSize += ClassSize.align(ClassSize.ARRAY + key.length);
}
}
if (blockOffsets != null) {
heapSize += ClassSize.align(ClassSize.ARRAY + blockOffsets.length
* Bytes.SIZEOF_LONG);
}
if (blockDataSizes != null) {
heapSize += ClassSize.align(ClassSize.ARRAY + blockDataSizes.length
* Bytes.SIZEOF_INT);
}
return ClassSize.align(heapSize);
}
}
/**
* Writes the block index into the output stream. Generate the tree from
* bottom up. The leaf level is written to disk as a sequence of inline
* blocks, if it is larger than a certain number of bytes. If the leaf level
* is not large enough, we write all entries to the root level instead.
*
* After all leaf blocks have been written, we end up with an index
* referencing the resulting leaf index blocks. If that index is larger than
* the allowed root index size, the writer will break it up into
* reasonable-size intermediate-level index block chunks write those chunks
* out, and create another index referencing those chunks. This will be
* repeated until the remaining index is small enough to become the root
* index. However, in most practical cases we will only have leaf-level
* blocks and the root index, or just the root index.
*/
public static class BlockIndexWriter implements InlineBlockWriter {
/**
* While the index is being written, this represents the current block
* index referencing all leaf blocks, with one exception. If the file is
* being closed and there are not enough blocks to complete even a single
* leaf block, no leaf blocks get written and this contains the entire
* block index. After all levels of the index were written by
* {@link #writeIndexBlocks(FSDataOutputStream)}, this contains the final
* root-level index.
*/
private BlockIndexChunk rootChunk = new BlockIndexChunk();
/**
* Current leaf-level chunk. New entries referencing data blocks get added
* to this chunk until it grows large enough to be written to disk.
*/
private BlockIndexChunk curInlineChunk = new BlockIndexChunk();
/**
* The number of block index levels. This is one if there is only root
* level (even empty), two if there a leaf level and root level, and is
* higher if there are intermediate levels. This is only final after
* {@link #writeIndexBlocks(FSDataOutputStream)} has been called. The
* initial value accounts for the root level, and will be increased to two
* as soon as we find out there is a leaf-level in
* {@link #blockWritten(long, int, int)}.
*/
private int numLevels = 1;
private HFileBlock.Writer blockWriter;
private byte[] firstKey = null;
/**
* The total number of leaf-level entries, i.e. entries referenced by
* leaf-level blocks. For the data block index this is equal to the number
* of data blocks.
*/
private long totalNumEntries;
/** Total compressed size of all index blocks. */
private long totalBlockOnDiskSize;
/** Total uncompressed size of all index blocks. */
private long totalBlockUncompressedSize;
/** The maximum size guideline of all multi-level index blocks. */
private int maxChunkSize;
/** Whether we require this block index to always be single-level. */
private boolean singleLevelOnly;
/** CacheConfig, or null if cache-on-write is disabled */
private CacheConfig cacheConf;
/** Name to use for computing cache keys */
private String nameForCaching;
/** Creates a single-level block index writer */
public BlockIndexWriter() {
this(null, null, null);
singleLevelOnly = true;
}
/**
* Creates a multi-level block index writer.
*
* @param blockWriter the block writer to use to write index blocks
* @param cacheConf used to determine when and how a block should be cached-on-write.
*/
public BlockIndexWriter(HFileBlock.Writer blockWriter,
CacheConfig cacheConf, String nameForCaching) {
if ((cacheConf == null) != (nameForCaching == null)) {
throw new IllegalArgumentException("Block cache and file name for " +
"caching must be both specified or both null");
}
this.blockWriter = blockWriter;
this.cacheConf = cacheConf;
this.nameForCaching = nameForCaching;
this.maxChunkSize = HFileBlockIndex.DEFAULT_MAX_CHUNK_SIZE;
}
public void setMaxChunkSize(int maxChunkSize) {
if (maxChunkSize <= 0) {
throw new IllegalArgumentException("Invald maximum index block size");
}
this.maxChunkSize = maxChunkSize;
}
/**
* Writes the root level and intermediate levels of the block index into
* the output stream, generating the tree from bottom up. Assumes that the
* leaf level has been inline-written to the disk if there is enough data
* for more than one leaf block. We iterate by breaking the current level
* of the block index, starting with the index of all leaf-level blocks,
* into chunks small enough to be written to disk, and generate its parent
* level, until we end up with a level small enough to become the root
* level.
*
* If the leaf level is not large enough, there is no inline block index
* anymore, so we only write that level of block index to disk as the root
* level.
*
* @param out FSDataOutputStream
* @return position at which we entered the root-level index.
* @throws IOException
*/
public long writeIndexBlocks(FSDataOutputStream out) throws IOException {
if (curInlineChunk != null && curInlineChunk.getNumEntries() != 0) {
throw new IOException("Trying to write a multi-level block index, " +
"but are " + curInlineChunk.getNumEntries() + " entries in the " +
"last inline chunk.");
}
// We need to get mid-key metadata before we create intermediate
// indexes and overwrite the root chunk.
byte[] midKeyMetadata = numLevels > 1 ? rootChunk.getMidKeyMetadata()
: null;
if (curInlineChunk != null) {
while (rootChunk.getRootSize() > maxChunkSize) {
rootChunk = writeIntermediateLevel(out, rootChunk);
numLevels += 1;
}
}
// write the root level
long rootLevelIndexPos = out.getPos();
{
DataOutput blockStream =
blockWriter.startWriting(BlockType.ROOT_INDEX);
rootChunk.writeRoot(blockStream);
if (midKeyMetadata != null)
blockStream.write(midKeyMetadata);
blockWriter.writeHeaderAndData(out);
}
// Add root index block size
totalBlockOnDiskSize += blockWriter.getOnDiskSizeWithoutHeader();
totalBlockUncompressedSize +=
blockWriter.getUncompressedSizeWithoutHeader();
if (LOG.isTraceEnabled()) {
LOG.trace("Wrote a " + numLevels + "-level index with root level at pos "
+ rootLevelIndexPos + ", " + rootChunk.getNumEntries()
+ " root-level entries, " + totalNumEntries + " total entries, "
+ StringUtils.humanReadableInt(this.totalBlockOnDiskSize) +
" on-disk size, "
+ StringUtils.humanReadableInt(totalBlockUncompressedSize) +
" total uncompressed size.");
}
return rootLevelIndexPos;
}
/**
* Writes the block index data as a single level only. Does not do any
* block framing.
*
* @param out the buffered output stream to write the index to. Typically a
* stream writing into an {@link HFile} block.
* @param description a short description of the index being written. Used
* in a log message.
* @throws IOException
*/
public void writeSingleLevelIndex(DataOutput out, String description)
throws IOException {
expectNumLevels(1);
if (!singleLevelOnly)
throw new IOException("Single-level mode is turned off");
if (rootChunk.getNumEntries() > 0)
throw new IOException("Root-level entries already added in " +
"single-level mode");
rootChunk = curInlineChunk;
curInlineChunk = new BlockIndexChunk();
if (LOG.isTraceEnabled()) {
LOG.trace("Wrote a single-level " + description + " index with "
+ rootChunk.getNumEntries() + " entries, " + rootChunk.getRootSize()
+ " bytes");
}
rootChunk.writeRoot(out);
}
/**
* Split the current level of the block index into intermediate index
* blocks of permitted size and write those blocks to disk. Return the next
* level of the block index referencing those intermediate-level blocks.
*
* @param out
* @param currentLevel the current level of the block index, such as the a
* chunk referencing all leaf-level index blocks
* @return the parent level block index, which becomes the root index after
* a few (usually zero) iterations
* @throws IOException
*/
private BlockIndexChunk writeIntermediateLevel(FSDataOutputStream out,
BlockIndexChunk currentLevel) throws IOException {
// Entries referencing intermediate-level blocks we are about to create.
BlockIndexChunk parent = new BlockIndexChunk();
// The current intermediate-level block index chunk.
BlockIndexChunk curChunk = new BlockIndexChunk();
for (int i = 0; i < currentLevel.getNumEntries(); ++i) {
curChunk.add(currentLevel.getBlockKey(i),
currentLevel.getBlockOffset(i), currentLevel.getOnDiskDataSize(i));
if (curChunk.getRootSize() >= maxChunkSize)
writeIntermediateBlock(out, parent, curChunk);
}
if (curChunk.getNumEntries() > 0) {
writeIntermediateBlock(out, parent, curChunk);
}
return parent;
}
private void writeIntermediateBlock(FSDataOutputStream out,
BlockIndexChunk parent, BlockIndexChunk curChunk) throws IOException {
long beginOffset = out.getPos();
DataOutputStream dos = blockWriter.startWriting(
BlockType.INTERMEDIATE_INDEX);
curChunk.writeNonRoot(dos);
byte[] curFirstKey = curChunk.getBlockKey(0);
blockWriter.writeHeaderAndData(out);
if (cacheConf != null) {
HFileBlock blockForCaching = blockWriter.getBlockForCaching(cacheConf);
cacheConf.getBlockCache().cacheBlock(new BlockCacheKey(nameForCaching,
beginOffset, DataBlockEncoding.NONE,
blockForCaching.getBlockType()), blockForCaching);
}
// Add intermediate index block size
totalBlockOnDiskSize += blockWriter.getOnDiskSizeWithoutHeader();
totalBlockUncompressedSize +=
blockWriter.getUncompressedSizeWithoutHeader();
// OFFSET is the beginning offset the chunk of block index entries.
// SIZE is the total byte size of the chunk of block index entries
// + the secondary index size
// FIRST_KEY is the first key in the chunk of block index
// entries.
parent.add(curFirstKey, beginOffset,
blockWriter.getOnDiskSizeWithHeader());
// clear current block index chunk
curChunk.clear();
curFirstKey = null;
}
/**
* @return how many block index entries there are in the root level
*/
public final int getNumRootEntries() {
return rootChunk.getNumEntries();
}
/**
* @return the number of levels in this block index.
*/
public int getNumLevels() {
return numLevels;
}
private void expectNumLevels(int expectedNumLevels) {
if (numLevels != expectedNumLevels) {
throw new IllegalStateException("Number of block index levels is "
+ numLevels + "but is expected to be " + expectedNumLevels);
}
}
/**
* Whether there is an inline block ready to be written. In general, we
* write an leaf-level index block as an inline block as soon as its size
* as serialized in the non-root format reaches a certain threshold.
*/
@Override
public boolean shouldWriteBlock(boolean closing) {
if (singleLevelOnly) {
throw new UnsupportedOperationException(INLINE_BLOCKS_NOT_ALLOWED);
}
if (curInlineChunk == null) {
throw new IllegalStateException("curInlineChunk is null; has shouldWriteBlock been " +
"called with closing=true and then called again?");
}
if (curInlineChunk.getNumEntries() == 0) {
return false;
}
// We do have some entries in the current inline chunk.
if (closing) {
if (rootChunk.getNumEntries() == 0) {
// We did not add any leaf-level blocks yet. Instead of creating a
// leaf level with one block, move these entries to the root level.
expectNumLevels(1);
rootChunk = curInlineChunk;
curInlineChunk = null; // Disallow adding any more index entries.
return false;
}
return true;
} else {
return curInlineChunk.getNonRootSize() >= maxChunkSize;
}
}
/**
* Write out the current inline index block. Inline blocks are non-root
* blocks, so the non-root index format is used.
*
* @param out
*/
@Override
public void writeInlineBlock(DataOutput out) throws IOException {
if (singleLevelOnly)
throw new UnsupportedOperationException(INLINE_BLOCKS_NOT_ALLOWED);
// Write the inline block index to the output stream in the non-root
// index block format.
curInlineChunk.writeNonRoot(out);
// Save the first key of the inline block so that we can add it to the
// parent-level index.
firstKey = curInlineChunk.getBlockKey(0);
// Start a new inline index block
curInlineChunk.clear();
}
/**
* Called after an inline block has been written so that we can add an
* entry referring to that block to the parent-level index.
*/
@Override
public void blockWritten(long offset, int onDiskSize, int uncompressedSize) {
// Add leaf index block size
totalBlockOnDiskSize += onDiskSize;
totalBlockUncompressedSize += uncompressedSize;
if (singleLevelOnly)
throw new UnsupportedOperationException(INLINE_BLOCKS_NOT_ALLOWED);
if (firstKey == null) {
throw new IllegalStateException("Trying to add second-level index " +
"entry with offset=" + offset + " and onDiskSize=" + onDiskSize +
"but the first key was not set in writeInlineBlock");
}
if (rootChunk.getNumEntries() == 0) {
// We are writing the first leaf block, so increase index level.
expectNumLevels(1);
numLevels = 2;
}
// Add another entry to the second-level index. Include the number of
// entries in all previous leaf-level chunks for mid-key calculation.
rootChunk.add(firstKey, offset, onDiskSize, totalNumEntries);
firstKey = null;
}
@Override
public BlockType getInlineBlockType() {
return BlockType.LEAF_INDEX;
}
/**
* Add one index entry to the current leaf-level block. When the leaf-level
* block gets large enough, it will be flushed to disk as an inline block.
*
* @param firstKey the first key of the data block
* @param blockOffset the offset of the data block
* @param blockDataSize the on-disk size of the data block ({@link HFile}
* format version 2), or the uncompressed size of the data block (
* {@link HFile} format version 1).
*/
public void addEntry(byte[] firstKey, long blockOffset, int blockDataSize)
{
curInlineChunk.add(firstKey, blockOffset, blockDataSize);
++totalNumEntries;
}
/**
* @throws IOException if we happened to write a multi-level index.
*/
public void ensureSingleLevel() throws IOException {
if (numLevels > 1) {
throw new IOException ("Wrote a " + numLevels + "-level index with " +
rootChunk.getNumEntries() + " root-level entries, but " +
"this is expected to be a single-level block index.");
}
}
/**
* @return true if we are using cache-on-write. This is configured by the
* caller of the constructor by either passing a valid block cache
* or null.
*/
@Override
public boolean getCacheOnWrite() {
return cacheConf != null && cacheConf.shouldCacheIndexesOnWrite();
}
/**
* The total uncompressed size of the root index block, intermediate-level
* index blocks, and leaf-level index blocks.
*
* @return the total uncompressed size of all index blocks
*/
public long getTotalUncompressedSize() {
return totalBlockUncompressedSize;
}
}
/**
* A single chunk of the block index in the process of writing. The data in
* this chunk can become a leaf-level, intermediate-level, or root index
* block.
*/
static class BlockIndexChunk {
/** First keys of the key range corresponding to each index entry. */
private final List blockKeys = new ArrayList();
/** Block offset in backing stream. */
private final List blockOffsets = new ArrayList();
/** On-disk data sizes of lower-level data or index blocks. */
private final List onDiskDataSizes = new ArrayList();
/**
* The cumulative number of sub-entries, i.e. entries on deeper-level block
* index entries. numSubEntriesAt[i] is the number of sub-entries in the
* blocks corresponding to this chunk's entries #0 through #i inclusively.
*/
private final List numSubEntriesAt = new ArrayList();
/**
* The offset of the next entry to be added, relative to the end of the
* "secondary index" in the "non-root" format representation of this index
* chunk. This is the next value to be added to the secondary index.
*/
private int curTotalNonRootEntrySize = 0;
/**
* The accumulated size of this chunk if stored in the root index format.
*/
private int curTotalRootSize = 0;
/**
* The "secondary index" used for binary search over variable-length
* records in a "non-root" format block. These offsets are relative to the
* end of this secondary index.
*/
private final List secondaryIndexOffsetMarks =
new ArrayList();
/**
* Adds a new entry to this block index chunk.
*
* @param firstKey the first key in the block pointed to by this entry
* @param blockOffset the offset of the next-level block pointed to by this
* entry
* @param onDiskDataSize the on-disk data of the block pointed to by this
* entry, including header size
* @param curTotalNumSubEntries if this chunk is the root index chunk under
* construction, this specifies the current total number of
* sub-entries in all leaf-level chunks, including the one
* corresponding to the second-level entry being added.
*/
void add(byte[] firstKey, long blockOffset, int onDiskDataSize,
long curTotalNumSubEntries) {
// Record the offset for the secondary index
secondaryIndexOffsetMarks.add(curTotalNonRootEntrySize);
curTotalNonRootEntrySize += SECONDARY_INDEX_ENTRY_OVERHEAD
+ firstKey.length;
curTotalRootSize += Bytes.SIZEOF_LONG + Bytes.SIZEOF_INT
+ WritableUtils.getVIntSize(firstKey.length) + firstKey.length;
blockKeys.add(firstKey);
blockOffsets.add(blockOffset);
onDiskDataSizes.add(onDiskDataSize);
if (curTotalNumSubEntries != -1) {
numSubEntriesAt.add(curTotalNumSubEntries);
// Make sure the parallel arrays are in sync.
if (numSubEntriesAt.size() != blockKeys.size()) {
throw new IllegalStateException("Only have key/value count " +
"stats for " + numSubEntriesAt.size() + " block index " +
"entries out of " + blockKeys.size());
}
}
}
/**
* The same as {@link #add(byte[], long, int, long)} but does not take the
* key/value into account. Used for single-level indexes.
*
* @see {@link #add(byte[], long, int, long)}
*/
public void add(byte[] firstKey, long blockOffset, int onDiskDataSize) {
add(firstKey, blockOffset, onDiskDataSize, -1);
}
public void clear() {
blockKeys.clear();
blockOffsets.clear();
onDiskDataSizes.clear();
secondaryIndexOffsetMarks.clear();
numSubEntriesAt.clear();
curTotalNonRootEntrySize = 0;
curTotalRootSize = 0;
}
/**
* Finds the entry corresponding to the deeper-level index block containing
* the given deeper-level entry (a "sub-entry"), assuming a global 0-based
* ordering of sub-entries.
*
*
* Implementation note. We are looking for i such that
* numSubEntriesAt[i - 1] <= k < numSubEntriesAt[i], because a deeper-level
* block #i (0-based) contains sub-entries # numSubEntriesAt[i - 1]'th
* through numSubEntriesAt[i] - 1, assuming a global 0-based ordering of
* sub-entries. i is by definition the insertion point of k in
* numSubEntriesAt.
*
* @param k sub-entry index, from 0 to the total number sub-entries - 1
* @return the 0-based index of the entry corresponding to the given
* sub-entry
*/
public int getEntryBySubEntry(long k) {
// We define mid-key as the key corresponding to k'th sub-entry
// (0-based).
int i = Collections.binarySearch(numSubEntriesAt, k);
// Exact match: cumulativeWeight[i] = k. This means chunks #0 through
// #i contain exactly k sub-entries, and the sub-entry #k (0-based)
// is in the (i + 1)'th chunk.
if (i >= 0)
return i + 1;
// Inexact match. Return the insertion point.
return -i - 1;
}
/**
* Used when writing the root block index of a multi-level block index.
* Serializes additional information allowing to efficiently identify the
* mid-key.
*
* @return a few serialized fields for finding the mid-key
* @throws IOException if could not create metadata for computing mid-key
*/
public byte[] getMidKeyMetadata() throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream(
MID_KEY_METADATA_SIZE);
DataOutputStream baosDos = new DataOutputStream(baos);
long totalNumSubEntries = numSubEntriesAt.get(blockKeys.size() - 1);
if (totalNumSubEntries == 0) {
throw new IOException("No leaf-level entries, mid-key unavailable");
}
long midKeySubEntry = (totalNumSubEntries - 1) / 2;
int midKeyEntry = getEntryBySubEntry(midKeySubEntry);
baosDos.writeLong(blockOffsets.get(midKeyEntry));
baosDos.writeInt(onDiskDataSizes.get(midKeyEntry));
long numSubEntriesBefore = midKeyEntry > 0
? numSubEntriesAt.get(midKeyEntry - 1) : 0;
long subEntryWithinEntry = midKeySubEntry - numSubEntriesBefore;
if (subEntryWithinEntry < 0 || subEntryWithinEntry > Integer.MAX_VALUE)
{
throw new IOException("Could not identify mid-key index within the "
+ "leaf-level block containing mid-key: out of range ("
+ subEntryWithinEntry + ", numSubEntriesBefore="
+ numSubEntriesBefore + ", midKeySubEntry=" + midKeySubEntry
+ ")");
}
baosDos.writeInt((int) subEntryWithinEntry);
if (baosDos.size() != MID_KEY_METADATA_SIZE) {
throw new IOException("Could not write mid-key metadata: size=" +
baosDos.size() + ", correct size: " + MID_KEY_METADATA_SIZE);
}
// Close just to be good citizens, although this has no effect.
baos.close();
return baos.toByteArray();
}
/**
* Writes the block index chunk in the non-root index block format. This
* format contains the number of entries, an index of integer offsets
* for quick binary search on variable-length records, and tuples of
* block offset, on-disk block size, and the first key for each entry.
*
* @param out
* @throws IOException
*/
void writeNonRoot(DataOutput out) throws IOException {
// The number of entries in the block.
out.writeInt(blockKeys.size());
if (secondaryIndexOffsetMarks.size() != blockKeys.size()) {
throw new IOException("Corrupted block index chunk writer: " +
blockKeys.size() + " entries but " +
secondaryIndexOffsetMarks.size() + " secondary index items");
}
// For each entry, write a "secondary index" of relative offsets to the
// entries from the end of the secondary index. This works, because at
// read time we read the number of entries and know where the secondary
// index ends.
for (int currentSecondaryIndex : secondaryIndexOffsetMarks)
out.writeInt(currentSecondaryIndex);
// We include one other element in the secondary index to calculate the
// size of each entry more easily by subtracting secondary index elements.
out.writeInt(curTotalNonRootEntrySize);
for (int i = 0; i < blockKeys.size(); ++i) {
out.writeLong(blockOffsets.get(i));
out.writeInt(onDiskDataSizes.get(i));
out.write(blockKeys.get(i));
}
}
/**
* @return the size of this chunk if stored in the non-root index block
* format
*/
int getNonRootSize() {
return Bytes.SIZEOF_INT // Number of entries
+ Bytes.SIZEOF_INT * (blockKeys.size() + 1) // Secondary index
+ curTotalNonRootEntrySize; // All entries
}
/**
* Writes this chunk into the given output stream in the root block index
* format. This format is similar to the {@link HFile} version 1 block
* index format, except that we store on-disk size of the block instead of
* its uncompressed size.
*
* @param out the data output stream to write the block index to. Typically
* a stream writing into an {@link HFile} block.
* @throws IOException
*/
void writeRoot(DataOutput out) throws IOException {
for (int i = 0; i < blockKeys.size(); ++i) {
out.writeLong(blockOffsets.get(i));
out.writeInt(onDiskDataSizes.get(i));
Bytes.writeByteArray(out, blockKeys.get(i));
}
}
/**
* @return the size of this chunk if stored in the root index block format
*/
int getRootSize() {
return curTotalRootSize;
}
/**
* @return the number of entries in this block index chunk
*/
public int getNumEntries() {
return blockKeys.size();
}
public byte[] getBlockKey(int i) {
return blockKeys.get(i);
}
public long getBlockOffset(int i) {
return blockOffsets.get(i);
}
public int getOnDiskDataSize(int i) {
return onDiskDataSizes.get(i);
}
public long getCumulativeNumKV(int i) {
if (i < 0)
return 0;
return numSubEntriesAt.get(i);
}
}
public static int getMaxChunkSize(Configuration conf) {
return conf.getInt(MAX_CHUNK_SIZE_KEY, DEFAULT_MAX_CHUNK_SIZE);
}
}