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Common 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;
import org.apache.hadoop.hbase.KeyValue.Type;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.yetus.audience.InterfaceStability;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hbase.thirdparty.com.google.common.primitives.Longs;
/**
* Compare two HBase cells. Do not use this method comparing -ROOT- or
* hbase:meta cells. Cells from these tables need a specialized comparator, one that
* takes account of the special formatting of the row where we have commas to delimit table from
* regionname, from row. See KeyValue for how it has a special comparator to do hbase:meta cells
* and yet another for -ROOT-.
* While using this comparator for {{@link #compareRows(Cell, Cell)} et al, the hbase:meta cells
* format should be taken into consideration, for which the instance of this comparator
* should be used. In all other cases the static APIs in this comparator would be enough
*/
@edu.umd.cs.findbugs.annotations.SuppressWarnings(
value="UNKNOWN",
justification="Findbugs doesn't like the way we are negating the result of a compare in below")
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class CellComparatorImpl implements CellComparator {
static final Logger LOG = LoggerFactory.getLogger(CellComparatorImpl.class);
/**
* Comparator for plain key/values; i.e. non-catalog table key/values. Works on Key portion
* of KeyValue only.
*/
public static final CellComparatorImpl COMPARATOR = new CellComparatorImpl();
/**
* A {@link CellComparatorImpl} for hbase:meta catalog table
* {@link KeyValue}s.
*/
public static final CellComparatorImpl META_COMPARATOR = new MetaCellComparator();
@Override
public int compare(Cell a, Cell b) {
return compare(a, b, false);
}
/**
* Compare cells.
* @param a
* @param b
* @param ignoreSequenceid True if we are to compare the key portion only and ignore
* the sequenceid. Set to false to compare key and consider sequenceid.
* @return 0 if equal, -1 if a < b, and +1 if a > b.
*/
public final int compare(final Cell a, final Cell b, boolean ignoreSequenceid) {
// row
int c = compareRows(a, b);
if (c != 0) return c;
c = compareWithoutRow(a, b);
if(c != 0) return c;
if (!ignoreSequenceid) {
// Negate following comparisons so later edits show up first
// mvccVersion: later sorts first
return Longs.compare(b.getSequenceId(), a.getSequenceId());
} else {
return c;
}
}
/**
* Compares the family and qualifier part of the cell
* @param left the left cell
* @param right the right cell
* @return 0 if both cells are equal, 1 if left cell is bigger than right, -1 otherwise
*/
public final int compareColumns(final Cell left, final Cell right) {
int diff = compareFamilies(left, right);
if (diff != 0) {
return diff;
}
return compareQualifiers(left, right);
}
/**
* Compare the families of left and right cell
* @param left
* @param right
* @return 0 if both cells are equal, 1 if left cell is bigger than right, -1 otherwise
*/
@Override
public final int compareFamilies(Cell left, Cell right) {
if (left instanceof ByteBufferExtendedCell && right instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getFamilyByteBuffer(),
((ByteBufferExtendedCell) left).getFamilyPosition(), left.getFamilyLength(),
((ByteBufferExtendedCell) right).getFamilyByteBuffer(),
((ByteBufferExtendedCell) right).getFamilyPosition(), right.getFamilyLength());
}
if (left instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getFamilyByteBuffer(),
((ByteBufferExtendedCell) left).getFamilyPosition(), left.getFamilyLength(),
right.getFamilyArray(), right.getFamilyOffset(), right.getFamilyLength());
}
if (right instanceof ByteBufferExtendedCell) {
// Notice how we flip the order of the compare here. We used to negate the return value but
// see what FindBugs says
// http://findbugs.sourceforge.net/bugDescriptions.html#RV_NEGATING_RESULT_OF_COMPARETO
// It suggest flipping the order to get same effect and 'safer'.
return ByteBufferUtils.compareTo(
left.getFamilyArray(), left.getFamilyOffset(), left.getFamilyLength(),
((ByteBufferExtendedCell)right).getFamilyByteBuffer(),
((ByteBufferExtendedCell)right).getFamilyPosition(), right.getFamilyLength());
}
return Bytes.compareTo(left.getFamilyArray(), left.getFamilyOffset(), left.getFamilyLength(),
right.getFamilyArray(), right.getFamilyOffset(), right.getFamilyLength());
}
/**
* Compare the qualifiers part of the left and right cells.
* @param left
* @param right
* @return 0 if both cells are equal, 1 if left cell is bigger than right, -1 otherwise
*/
@Override
public final int compareQualifiers(Cell left, Cell right) {
if (left instanceof ByteBufferExtendedCell && right instanceof ByteBufferExtendedCell) {
return ByteBufferUtils
.compareTo(((ByteBufferExtendedCell) left).getQualifierByteBuffer(),
((ByteBufferExtendedCell) left).getQualifierPosition(),
left.getQualifierLength(), ((ByteBufferExtendedCell) right).getQualifierByteBuffer(),
((ByteBufferExtendedCell) right).getQualifierPosition(),
right.getQualifierLength());
}
if (left instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getQualifierByteBuffer(),
((ByteBufferExtendedCell) left).getQualifierPosition(), left.getQualifierLength(),
right.getQualifierArray(), right.getQualifierOffset(), right.getQualifierLength());
}
if (right instanceof ByteBufferExtendedCell) {
// Notice how we flip the order of the compare here. We used to negate the return value but
// see what FindBugs says
// http://findbugs.sourceforge.net/bugDescriptions.html#RV_NEGATING_RESULT_OF_COMPARETO
// It suggest flipping the order to get same effect and 'safer'.
return ByteBufferUtils.compareTo(left.getQualifierArray(),
left.getQualifierOffset(), left.getQualifierLength(),
((ByteBufferExtendedCell)right).getQualifierByteBuffer(),
((ByteBufferExtendedCell)right).getQualifierPosition(), right.getQualifierLength());
}
return Bytes.compareTo(left.getQualifierArray(), left.getQualifierOffset(),
left.getQualifierLength(), right.getQualifierArray(), right.getQualifierOffset(),
right.getQualifierLength());
}
/**
* Compares the rows of the left and right cell.
* For the hbase:meta case this method is overridden such that it can handle hbase:meta cells.
* The caller should ensure using the appropriate comparator for hbase:meta.
* @param left
* @param right
* @return 0 if both cells are equal, 1 if left cell is bigger than right, -1 otherwise
*/
@Override
public int compareRows(final Cell left, final Cell right) {
// left and right can be exactly the same at the beginning of a row
if (left == right) {
return 0;
}
if (left instanceof ByteBufferExtendedCell && right instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getRowByteBuffer(),
((ByteBufferExtendedCell) left).getRowPosition(), left.getRowLength(),
((ByteBufferExtendedCell) right).getRowByteBuffer(),
((ByteBufferExtendedCell) right).getRowPosition(), right.getRowLength());
}
if (left instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getRowByteBuffer(),
((ByteBufferExtendedCell) left).getRowPosition(), left.getRowLength(),
right.getRowArray(), right.getRowOffset(), right.getRowLength());
}
if (right instanceof ByteBufferExtendedCell) {
// Notice how we flip the order of the compare here. We used to negate the return value but
// see what FindBugs says
// http://findbugs.sourceforge.net/bugDescriptions.html#RV_NEGATING_RESULT_OF_COMPARETO
// It suggest flipping the order to get same effect and 'safer'.
return ByteBufferUtils.compareTo(left.getRowArray(), left.getRowOffset(), left.getRowLength(),
((ByteBufferExtendedCell)right).getRowByteBuffer(),
((ByteBufferExtendedCell)right).getRowPosition(), right.getRowLength());
}
return Bytes.compareTo(left.getRowArray(), left.getRowOffset(), left.getRowLength(),
right.getRowArray(), right.getRowOffset(), right.getRowLength());
}
/**
* Compares the row part of the cell with a simple plain byte[] like the
* stopRow in Scan. This should be used with context where for hbase:meta
* cells the {{@link #META_COMPARATOR} should be used
*
* @param left
* the cell to be compared
* @param right
* the kv serialized byte[] to be compared with
* @param roffset
* the offset in the byte[]
* @param rlength
* the length in the byte[]
* @return 0 if both cell and the byte[] are equal, 1 if the cell is bigger
* than byte[], -1 otherwise
*/
@Override
public int compareRows(Cell left, byte[] right, int roffset, int rlength) {
if (left instanceof ByteBufferExtendedCell) {
return ByteBufferUtils.compareTo(((ByteBufferExtendedCell) left).getRowByteBuffer(),
((ByteBufferExtendedCell) left).getRowPosition(), left.getRowLength(), right,
roffset, rlength);
}
return Bytes.compareTo(left.getRowArray(), left.getRowOffset(), left.getRowLength(), right,
roffset, rlength);
}
@Override
public final int compareWithoutRow(final Cell left, final Cell right) {
// If the column is not specified, the "minimum" key type appears the
// latest in the sorted order, regardless of the timestamp. This is used
// for specifying the last key/value in a given row, because there is no
// "lexicographically last column" (it would be infinitely long). The
// "maximum" key type does not need this behavior.
// Copied from KeyValue. This is bad in that we can't do memcmp w/ special rules like this.
int lFamLength = left.getFamilyLength();
int rFamLength = right.getFamilyLength();
int lQualLength = left.getQualifierLength();
int rQualLength = right.getQualifierLength();
if (lFamLength + lQualLength == 0
&& left.getTypeByte() == Type.Minimum.getCode()) {
// left is "bigger", i.e. it appears later in the sorted order
return 1;
}
if (rFamLength + rQualLength == 0
&& right.getTypeByte() == Type.Minimum.getCode()) {
return -1;
}
if (lFamLength != rFamLength) {
// comparing column family is enough.
return compareFamilies(left, right);
}
// Compare cf:qualifier
int diff = compareColumns(left, right);
if (diff != 0) return diff;
diff = compareTimestamps(left, right);
if (diff != 0) return diff;
// Compare types. Let the delete types sort ahead of puts; i.e. types
// of higher numbers sort before those of lesser numbers. Maximum (255)
// appears ahead of everything, and minimum (0) appears after
// everything.
return (0xff & right.getTypeByte()) - (0xff & left.getTypeByte());
}
/**
* Compares cell's timestamps in DESCENDING order.
* The below older timestamps sorting ahead of newer timestamps looks
* wrong but it is intentional. This way, newer timestamps are first
* found when we iterate over a memstore and newer versions are the
* first we trip over when reading from a store file.
* @return 1 if left's timestamp < right's timestamp
* -1 if left's timestamp > right's timestamp
* 0 if both timestamps are equal
*/
@Override
public int compareTimestamps(final Cell left, final Cell right) {
return compareTimestamps(left.getTimestamp(), right.getTimestamp());
}
/**
* Compares timestamps in DESCENDING order.
* The below older timestamps sorting ahead of newer timestamps looks
* wrong but it is intentional. This way, newer timestamps are first
* found when we iterate over a memstore and newer versions are the
* first we trip over when reading from a store file.
* @return 1 if left timestamp < right timestamp
* -1 if left timestamp > right timestamp
* 0 if both timestamps are equal
*/
@Override
public int compareTimestamps(final long ltimestamp, final long rtimestamp) {
if (ltimestamp < rtimestamp) {
return 1;
} else if (ltimestamp > rtimestamp) {
return -1;
}
return 0;
}
/**
* A {@link CellComparatorImpl} for hbase:meta catalog table
* {@link KeyValue}s.
*/
public static class MetaCellComparator extends CellComparatorImpl {
@Override
public int compareRows(final Cell left, final Cell right) {
return compareRows(left.getRowArray(), left.getRowOffset(), left.getRowLength(),
right.getRowArray(), right.getRowOffset(), right.getRowLength());
}
@Override
public int compareRows(Cell left, byte[] right, int roffset, int rlength) {
return compareRows(left.getRowArray(), left.getRowOffset(), left.getRowLength(), right,
roffset, rlength);
}
private int compareRows(byte[] left, int loffset, int llength, byte[] right, int roffset,
int rlength) {
int leftDelimiter = Bytes.searchDelimiterIndex(left, loffset, llength, HConstants.DELIMITER);
int rightDelimiter = Bytes
.searchDelimiterIndex(right, roffset, rlength, HConstants.DELIMITER);
// Compare up to the delimiter
int lpart = (leftDelimiter < 0 ? llength : leftDelimiter - loffset);
int rpart = (rightDelimiter < 0 ? rlength : rightDelimiter - roffset);
int result = Bytes.compareTo(left, loffset, lpart, right, roffset, rpart);
if (result != 0) {
return result;
} else {
if (leftDelimiter < 0 && rightDelimiter >= 0) {
return -1;
} else if (rightDelimiter < 0 && leftDelimiter >= 0) {
return 1;
} else if (leftDelimiter < 0 && rightDelimiter < 0) {
return 0;
}
}
// Compare middle bit of the row.
// Move past delimiter
leftDelimiter++;
rightDelimiter++;
int leftFarDelimiter = Bytes.searchDelimiterIndexInReverse(left, leftDelimiter, llength
- (leftDelimiter - loffset), HConstants.DELIMITER);
int rightFarDelimiter = Bytes.searchDelimiterIndexInReverse(right, rightDelimiter, rlength
- (rightDelimiter - roffset), HConstants.DELIMITER);
// Now compare middlesection of row.
lpart = (leftFarDelimiter < 0 ? llength + loffset : leftFarDelimiter) - leftDelimiter;
rpart = (rightFarDelimiter < 0 ? rlength + roffset : rightFarDelimiter) - rightDelimiter;
result = Bytes.compareTo(left, leftDelimiter, lpart, right, rightDelimiter, rpart);
if (result != 0) {
return result;
} else {
if (leftDelimiter < 0 && rightDelimiter >= 0) {
return -1;
} else if (rightDelimiter < 0 && leftDelimiter >= 0) {
return 1;
} else if (leftDelimiter < 0 && rightDelimiter < 0) {
return 0;
}
}
// Compare last part of row, the rowid.
leftFarDelimiter++;
rightFarDelimiter++;
result = Bytes.compareTo(left, leftFarDelimiter, llength - (leftFarDelimiter - loffset),
right, rightFarDelimiter, rlength - (rightFarDelimiter - roffset));
return result;
}
}
}