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* 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.codec.prefixtree.encode.column;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.codec.prefixtree.PrefixTreeBlockMeta;
import org.apache.hadoop.hbase.codec.prefixtree.encode.tokenize.Tokenizer;
import org.apache.hadoop.hbase.codec.prefixtree.encode.tokenize.TokenizerNode;
import org.apache.hadoop.hbase.util.CollectionUtils;
import org.apache.hadoop.hbase.util.vint.UFIntTool;
import com.google.common.collect.Lists;
/**
* Takes the tokenized family or qualifier data and flattens it into a stream of bytes. The family
* section is written after the row section, and qualifier section after family section.
* <p/>
* The family and qualifier tries, or "column tries", are structured differently than the row trie.
* The trie cannot be reassembled without external data about the offsets of the leaf nodes, and
* these external pointers are stored in the nubs and leaves of the row trie. For each cell in a
* row, the row trie contains a list of offsets into the column sections (along with pointers to
* timestamps and other per-cell fields). These offsets point to the last column node/token that
* comprises the column name. To assemble the column name, the trie is traversed in reverse (right
* to left), with the rightmost tokens pointing to the start of their "parent" node which is the
* node to the left.
* <p/>
* This choice was made to reduce the size of the column trie by storing the minimum amount of
* offset data. As a result, to find a specific qualifier within a row, you must do a binary search
* of the column nodes, reassembling each one as you search. Future versions of the PrefixTree might
* encode the columns in both a forward and reverse trie, which would convert binary searches into
* more efficient trie searches which would be beneficial for wide rows.
*/
@InterfaceAudience.Private
public class ColumnSectionWriter {
public static final int EXPECTED_NUBS_PLUS_LEAVES = 100;
/****************** fields ****************************/
private PrefixTreeBlockMeta blockMeta;
private boolean familyVsQualifier;
private Tokenizer tokenizer;
private int numBytes = 0;
private ArrayList<TokenizerNode> nonLeaves;
private ArrayList<TokenizerNode> leaves;
private ArrayList<TokenizerNode> allNodes;
private ArrayList<ColumnNodeWriter> columnNodeWriters;
private List<Integer> outputArrayOffsets;
/*********************** construct *********************/
public ColumnSectionWriter() {
this.nonLeaves = Lists.newArrayList();
this.leaves = Lists.newArrayList();
this.outputArrayOffsets = Lists.newArrayList();
}
public ColumnSectionWriter(PrefixTreeBlockMeta blockMeta, Tokenizer builder,
boolean familyVsQualifier) {
this();// init collections
reconstruct(blockMeta, builder, familyVsQualifier);
}
public void reconstruct(PrefixTreeBlockMeta blockMeta, Tokenizer builder,
boolean familyVsQualifier) {
this.blockMeta = blockMeta;
this.tokenizer = builder;
this.familyVsQualifier = familyVsQualifier;
}
public void reset() {
numBytes = 0;
nonLeaves.clear();
leaves.clear();
outputArrayOffsets.clear();
}
/****************** methods *******************************/
public ColumnSectionWriter compile() {
if (familyVsQualifier) {
// do nothing. max family length fixed at Byte.MAX_VALUE
} else {
blockMeta.setMaxQualifierLength(tokenizer.getMaxElementLength());
}
tokenizer.setNodeFirstInsertionIndexes();
tokenizer.appendNodes(nonLeaves, true, false);
tokenizer.appendNodes(leaves, false, true);
allNodes = Lists.newArrayListWithCapacity(nonLeaves.size() + leaves.size());
allNodes.addAll(nonLeaves);
allNodes.addAll(leaves);
columnNodeWriters = Lists.newArrayListWithCapacity(CollectionUtils.nullSafeSize(allNodes));
for (int i = 0; i < allNodes.size(); ++i) {
TokenizerNode node = allNodes.get(i);
columnNodeWriters.add(new ColumnNodeWriter(blockMeta, node, familyVsQualifier));
}
// leaf widths are known at this point, so add them up
int totalBytesWithoutOffsets = 0;
for (int i = allNodes.size() - 1; i >= 0; --i) {
ColumnNodeWriter columnNodeWriter = columnNodeWriters.get(i);
// leaves store all but their first token byte
totalBytesWithoutOffsets += columnNodeWriter.getWidthUsingPlaceholderForOffsetWidth(0);
}
// figure out how wide our offset FInts are
int parentOffsetWidth = 0;
while (true) {
++parentOffsetWidth;
int numBytesFinder = totalBytesWithoutOffsets + parentOffsetWidth * allNodes.size();
if (numBytesFinder < UFIntTool.maxValueForNumBytes(parentOffsetWidth)) {
numBytes = numBytesFinder;
break;
}// it fits
}
if (familyVsQualifier) {
blockMeta.setFamilyOffsetWidth(parentOffsetWidth);
} else {
blockMeta.setQualifierOffsetWidth(parentOffsetWidth);
}
int forwardIndex = 0;
for (int i = 0; i < allNodes.size(); ++i) {
TokenizerNode node = allNodes.get(i);
ColumnNodeWriter columnNodeWriter = columnNodeWriters.get(i);
int fullNodeWidth = columnNodeWriter
.getWidthUsingPlaceholderForOffsetWidth(parentOffsetWidth);
node.setOutputArrayOffset(forwardIndex);
columnNodeWriter.setTokenBytes(node.getToken());
if (node.isRoot()) {
columnNodeWriter.setParentStartPosition(0);
} else {
columnNodeWriter.setParentStartPosition(node.getParent().getOutputArrayOffset());
}
forwardIndex += fullNodeWidth;
}
tokenizer.appendOutputArrayOffsets(outputArrayOffsets);
return this;
}
public void writeBytes(OutputStream os) throws IOException {
for (ColumnNodeWriter columnNodeWriter : columnNodeWriters) {
columnNodeWriter.writeBytes(os);
}
}
/************* get/set **************************/
public ArrayList<ColumnNodeWriter> getColumnNodeWriters() {
return columnNodeWriters;
}
public int getNumBytes() {
return numBytes;
}
public int getOutputArrayOffset(int sortedIndex) {
return outputArrayOffsets.get(sortedIndex);
}
public ArrayList<TokenizerNode> getNonLeaves() {
return nonLeaves;
}
public ArrayList<TokenizerNode> getLeaves() {
return leaves;
}
}