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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.index.sasi.disk;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.AbstractIterator;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.Pair;
import com.carrotsearch.hppc.LongArrayList;
import com.carrotsearch.hppc.LongSet;
import com.carrotsearch.hppc.cursors.LongCursor;
public abstract class AbstractTokenTreeBuilder implements TokenTreeBuilder
{
protected int numBlocks;
protected Node root;
protected InteriorNode rightmostParent;
protected Leaf leftmostLeaf;
protected Leaf rightmostLeaf;
protected long tokenCount = 0;
protected long treeMinToken;
protected long treeMaxToken;
public void add(TokenTreeBuilder other)
{
add(other.iterator());
}
public TokenTreeBuilder finish()
{
if (root == null)
constructTree();
return this;
}
public long getTokenCount()
{
return tokenCount;
}
public int serializedSize()
{
if (numBlocks == 1)
return BLOCK_HEADER_BYTES +
((int) tokenCount * BLOCK_ENTRY_BYTES) +
(((Leaf) root).overflowCollisionCount() * OVERFLOW_ENTRY_BYTES);
else
return numBlocks * BLOCK_BYTES;
}
public void write(DataOutputPlus out) throws IOException
{
ByteBuffer blockBuffer = ByteBuffer.allocate(BLOCK_BYTES);
Iterator levelIterator = root.levelIterator();
long childBlockIndex = 1;
while (levelIterator != null)
{
Node firstChild = null;
while (levelIterator.hasNext())
{
Node block = levelIterator.next();
if (firstChild == null && !block.isLeaf())
firstChild = ((InteriorNode) block).children.get(0);
if (block.isSerializable())
{
block.serialize(childBlockIndex, blockBuffer);
flushBuffer(blockBuffer, out, numBlocks != 1);
}
childBlockIndex += block.childCount();
}
levelIterator = (firstChild == null) ? null : firstChild.levelIterator();
}
}
protected abstract void constructTree();
protected void flushBuffer(ByteBuffer buffer, DataOutputPlus o, boolean align) throws IOException
{
// seek to end of last block before flushing
if (align)
alignBuffer(buffer, BLOCK_BYTES);
buffer.flip();
o.write(buffer);
buffer.clear();
}
protected abstract class Node
{
protected InteriorNode parent;
protected Node next;
protected Long nodeMinToken, nodeMaxToken;
public Node(Long minToken, Long maxToken)
{
nodeMinToken = minToken;
nodeMaxToken = maxToken;
}
public abstract boolean isSerializable();
public abstract void serialize(long childBlockIndex, ByteBuffer buf);
public abstract int childCount();
public abstract int tokenCount();
public Long smallestToken()
{
return nodeMinToken;
}
public Long largestToken()
{
return nodeMaxToken;
}
public Iterator levelIterator()
{
return new LevelIterator(this);
}
public boolean isLeaf()
{
return (this instanceof Leaf);
}
protected boolean isLastLeaf()
{
return this == rightmostLeaf;
}
protected boolean isRoot()
{
return this == root;
}
protected void updateTokenRange(long token)
{
nodeMinToken = nodeMinToken == null ? token : Math.min(nodeMinToken, token);
nodeMaxToken = nodeMaxToken == null ? token : Math.max(nodeMaxToken, token);
}
protected void serializeHeader(ByteBuffer buf)
{
Header header;
if (isRoot())
header = new RootHeader();
else if (!isLeaf())
header = new InteriorNodeHeader();
else
header = new LeafHeader();
header.serialize(buf);
alignBuffer(buf, BLOCK_HEADER_BYTES);
}
private abstract class Header
{
public void serialize(ByteBuffer buf)
{
buf.put(infoByte())
.putShort((short) (tokenCount()))
.putLong(nodeMinToken)
.putLong(nodeMaxToken);
}
protected abstract byte infoByte();
}
private class RootHeader extends Header
{
public void serialize(ByteBuffer buf)
{
super.serialize(buf);
writeMagic(buf);
buf.putLong(tokenCount)
.putLong(treeMinToken)
.putLong(treeMaxToken);
}
protected byte infoByte()
{
// if leaf, set leaf indicator and last leaf indicator (bits 0 & 1)
// if not leaf, clear both bits
return (byte) ((isLeaf()) ? 3 : 0);
}
protected void writeMagic(ByteBuffer buf)
{
switch (Descriptor.CURRENT_VERSION)
{
case Descriptor.VERSION_AB:
buf.putShort(AB_MAGIC);
break;
default:
break;
}
}
}
private class InteriorNodeHeader extends Header
{
// bit 0 (leaf indicator) & bit 1 (last leaf indicator) cleared
protected byte infoByte()
{
return 0;
}
}
private class LeafHeader extends Header
{
// bit 0 set as leaf indicator
// bit 1 set if this is last leaf of data
protected byte infoByte()
{
byte infoByte = 1;
infoByte |= (isLastLeaf()) ? (1 << LAST_LEAF_SHIFT) : 0;
return infoByte;
}
}
}
protected abstract class Leaf extends Node
{
protected LongArrayList overflowCollisions;
public Leaf(Long minToken, Long maxToken)
{
super(minToken, maxToken);
}
public int childCount()
{
return 0;
}
public int overflowCollisionCount() {
return overflowCollisions == null ? 0 : overflowCollisions.size();
}
protected void serializeOverflowCollisions(ByteBuffer buf)
{
if (overflowCollisions != null)
for (LongCursor offset : overflowCollisions)
buf.putLong(offset.value);
}
public void serialize(long childBlockIndex, ByteBuffer buf)
{
serializeHeader(buf);
serializeData(buf);
serializeOverflowCollisions(buf);
}
protected abstract void serializeData(ByteBuffer buf);
protected LeafEntry createEntry(final long tok, final LongSet offsets)
{
int offsetCount = offsets.size();
switch (offsetCount)
{
case 0:
throw new AssertionError("no offsets for token " + tok);
case 1:
long offset = offsets.toArray()[0];
if (offset > MAX_OFFSET)
throw new AssertionError("offset " + offset + " cannot be greater than " + MAX_OFFSET);
else if (offset <= Integer.MAX_VALUE)
return new SimpleLeafEntry(tok, offset);
else
return new FactoredOffsetLeafEntry(tok, offset);
case 2:
long[] rawOffsets = offsets.toArray();
if (rawOffsets[0] <= Integer.MAX_VALUE && rawOffsets[1] <= Integer.MAX_VALUE &&
(rawOffsets[0] <= Short.MAX_VALUE || rawOffsets[1] <= Short.MAX_VALUE))
return new PackedCollisionLeafEntry(tok, rawOffsets);
else
return createOverflowEntry(tok, offsetCount, offsets);
default:
return createOverflowEntry(tok, offsetCount, offsets);
}
}
private LeafEntry createOverflowEntry(final long tok, final int offsetCount, final LongSet offsets)
{
if (overflowCollisions == null)
overflowCollisions = new LongArrayList();
LeafEntry entry = new OverflowCollisionLeafEntry(tok, (short) overflowCollisions.size(), (short) offsetCount);
for (LongCursor o : offsets)
{
if (overflowCollisions.size() == OVERFLOW_TRAILER_CAPACITY)
throw new AssertionError("cannot have more than " + OVERFLOW_TRAILER_CAPACITY + " overflow collisions per leaf");
else
overflowCollisions.add(o.value);
}
return entry;
}
protected abstract class LeafEntry
{
protected final long token;
abstract public EntryType type();
abstract public int offsetData();
abstract public short offsetExtra();
public LeafEntry(final long tok)
{
token = tok;
}
public void serialize(ByteBuffer buf)
{
buf.putShort((short) type().ordinal())
.putShort(offsetExtra())
.putLong(token)
.putInt(offsetData());
}
}
// assumes there is a single offset and the offset is <= Integer.MAX_VALUE
protected class SimpleLeafEntry extends LeafEntry
{
private final long offset;
public SimpleLeafEntry(final long tok, final long off)
{
super(tok);
offset = off;
}
public EntryType type()
{
return EntryType.SIMPLE;
}
public int offsetData()
{
return (int) offset;
}
public short offsetExtra()
{
return 0;
}
}
// assumes there is a single offset and Integer.MAX_VALUE < offset <= MAX_OFFSET
// take the middle 32 bits of offset (or the top 32 when considering offset is max 48 bits)
// and store where offset is normally stored. take bottom 16 bits of offset and store in entry header
private class FactoredOffsetLeafEntry extends LeafEntry
{
private final long offset;
public FactoredOffsetLeafEntry(final long tok, final long off)
{
super(tok);
offset = off;
}
public EntryType type()
{
return EntryType.FACTORED;
}
public int offsetData()
{
return (int) (offset >>> Short.SIZE);
}
public short offsetExtra()
{
// exta offset is supposed to be an unsigned 16-bit integer
return (short) offset;
}
}
// holds an entry with two offsets that can be packed in an int & a short
// the int offset is stored where offset is normally stored. short offset is
// stored in entry header
private class PackedCollisionLeafEntry extends LeafEntry
{
private short smallerOffset;
private int largerOffset;
public PackedCollisionLeafEntry(final long tok, final long[] offs)
{
super(tok);
smallerOffset = (short) Math.min(offs[0], offs[1]);
largerOffset = (int) Math.max(offs[0], offs[1]);
}
public EntryType type()
{
return EntryType.PACKED;
}
public int offsetData()
{
return largerOffset;
}
public short offsetExtra()
{
return smallerOffset;
}
}
// holds an entry with three or more offsets, or two offsets that cannot
// be packed into an int & a short. the index into the overflow list
// is stored where the offset is normally stored. the number of overflowed offsets
// for the entry is stored in the entry header
private class OverflowCollisionLeafEntry extends LeafEntry
{
private final short startIndex;
private final short count;
public OverflowCollisionLeafEntry(final long tok, final short collisionStartIndex, final short collisionCount)
{
super(tok);
startIndex = collisionStartIndex;
count = collisionCount;
}
public EntryType type()
{
return EntryType.OVERFLOW;
}
public int offsetData()
{
return startIndex;
}
public short offsetExtra()
{
return count;
}
}
}
protected class InteriorNode extends Node
{
protected List tokens = new ArrayList<>(TOKENS_PER_BLOCK);
protected List children = new ArrayList<>(TOKENS_PER_BLOCK + 1);
protected int position = 0;
public InteriorNode()
{
super(null, null);
}
public boolean isSerializable()
{
return true;
}
public void serialize(long childBlockIndex, ByteBuffer buf)
{
serializeHeader(buf);
serializeTokens(buf);
serializeChildOffsets(childBlockIndex, buf);
}
public int childCount()
{
return children.size();
}
public int tokenCount()
{
return tokens.size();
}
public Long smallestToken()
{
return tokens.get(0);
}
protected void add(Long token, InteriorNode leftChild, InteriorNode rightChild)
{
int pos = tokens.size();
if (pos == TOKENS_PER_BLOCK)
{
InteriorNode sibling = split();
sibling.add(token, leftChild, rightChild);
}
else
{
if (leftChild != null)
children.add(pos, leftChild);
if (rightChild != null)
{
children.add(pos + 1, rightChild);
rightChild.parent = this;
}
updateTokenRange(token);
tokens.add(pos, token);
}
}
protected void add(Leaf node)
{
if (position == (TOKENS_PER_BLOCK + 1))
{
rightmostParent = split();
rightmostParent.add(node);
}
else
{
node.parent = this;
children.add(position, node);
position++;
// the first child is referenced only during bulk load. we don't take a value
// to store into the tree, one is subtracted since position has already been incremented
// for the next node to be added
if (position - 1 == 0)
return;
// tokens are inserted one behind the current position, but 2 is subtracted because
// position has already been incremented for the next add
Long smallestToken = node.smallestToken();
updateTokenRange(smallestToken);
tokens.add(position - 2, smallestToken);
}
}
protected InteriorNode split()
{
Pair splitResult = splitBlock();
Long middleValue = splitResult.left;
InteriorNode sibling = splitResult.right;
InteriorNode leftChild = null;
// create a new root if necessary
if (parent == null)
{
parent = new InteriorNode();
root = parent;
sibling.parent = parent;
leftChild = this;
numBlocks++;
}
parent.add(middleValue, leftChild, sibling);
return sibling;
}
protected Pair splitBlock()
{
final int splitPosition = TOKENS_PER_BLOCK - 2;
InteriorNode sibling = new InteriorNode();
sibling.parent = parent;
next = sibling;
Long middleValue = tokens.get(splitPosition);
for (int i = splitPosition; i < TOKENS_PER_BLOCK; i++)
{
if (i != TOKENS_PER_BLOCK && i != splitPosition)
{
long token = tokens.get(i);
sibling.updateTokenRange(token);
sibling.tokens.add(token);
}
Node child = children.get(i + 1);
child.parent = sibling;
sibling.children.add(child);
sibling.position++;
}
for (int i = TOKENS_PER_BLOCK; i >= splitPosition; i--)
{
if (i != TOKENS_PER_BLOCK)
tokens.remove(i);
if (i != splitPosition)
children.remove(i);
}
nodeMinToken = smallestToken();
nodeMaxToken = tokens.get(tokens.size() - 1);
numBlocks++;
return Pair.create(middleValue, sibling);
}
protected boolean isFull()
{
return (position >= TOKENS_PER_BLOCK + 1);
}
private void serializeTokens(ByteBuffer buf)
{
tokens.forEach(buf::putLong);
}
private void serializeChildOffsets(long childBlockIndex, ByteBuffer buf)
{
for (int i = 0; i < children.size(); i++)
buf.putLong((childBlockIndex + i) * BLOCK_BYTES);
}
}
public static class LevelIterator extends AbstractIterator
{
private Node currentNode;
LevelIterator(Node first)
{
currentNode = first;
}
public Node computeNext()
{
if (currentNode == null)
return endOfData();
Node returnNode = currentNode;
currentNode = returnNode.next;
return returnNode;
}
}
protected static void alignBuffer(ByteBuffer buffer, int blockSize)
{
long curPos = buffer.position();
if ((curPos & (blockSize - 1)) != 0) // align on the block boundary if needed
buffer.position((int) FBUtilities.align(curPos, blockSize));
}
}