/*
* Copyright (C) 2013 The Async HBase Authors. All rights reserved.
* This file is part of Async HBase.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the StumbleUpon nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package org.hbase.async;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.util.CharsetUtil;
import java.nio.charset.Charset;
import org.hbase.async.generated.ComparatorPB;
import org.hbase.async.generated.FilterPB;
import org.hbase.async.generated.HBasePB;
/**
* Filters rows based on an expression applied to the row key.
* <p>
* The regular expression will be applied on the server-side, on the row
* key. Rows for which the key doesn't match will not be returned to the
* scanner, which can be useful to carefully select which rows are matched
* when you can't just do a prefix match, and cut down the amount of data
* transfered on the network.
* <p>
* Don't use an expensive regular expression, because Java's implementation
* uses backtracking and matching will happen on the server side, potentially
* on many many row keys.
* See <a href="http://swtch.com/~rsc/regexp/regexp1.html">Regular Expression
* Matching Can Be Simple And Fast</a> for more details on regular expression
* performance (or lack thereof) and what "backtracking" means.
* <p>
* This means you need to <strong>be careful</strong> about using regular
* expressions supplied by users as that would allow them to easily DDoS
* HBase by sending prohibitively expensive regexps that would consume all
* CPU cycles and cause the entire HBase node to time out.
* @since 1.5
*/
public final class KeyRegexpFilter extends ScanFilter {
private static final byte[] ROWFILTER = Bytes.ISO88591("org.apache.hadoop"
+ ".hbase.filter.RowFilter");
private static final byte[] REGEXSTRINGCOMPARATOR = Bytes.ISO88591("org.apache.hadoop"
+ ".hbase.filter.RegexStringComparator");
private static final byte[] EQUAL = new byte[] { 'E', 'Q', 'U', 'A', 'L' };
private final byte[] regexp;
private final byte[] charset;
/**
* Sets a regular expression to filter results based on the row key.
* <p>
* This is equivalent to calling {@link #KeyRegexpFilter(String, Charset)}
* with the ISO-8859-1 charset in argument.
* @param regexp The regular expression with which to filter the row keys.
*/
public KeyRegexpFilter(final String regexp) {
this(regexp, CharsetUtil.ISO_8859_1);
}
/**
* Sets a regular expression to filter results based on the row key.
* @param regexp The regular expression with which to filter the row keys.
* @param charset The charset used to decode the bytes of the row key into a
* string. The RegionServer must support this charset, otherwise it will
* unexpectedly close the connection the first time you attempt to use this
* scanner.
* @see #KeyRegexpFilter(byte[], Charset)
*/
public KeyRegexpFilter(final String regexp, final Charset charset) {
this(Bytes.UTF8(regexp), charset);
}
/**
* Sets a regular expression to filter results based on the row key.
* <p>
* This is equivalent to calling {@link #KeyRegexpFilter(byte[], Charset)}
* with the ISO-8859-1 charset in argument.
* @param regexp The binary regular expression with which to filter
* the row keys.
*/
public KeyRegexpFilter(final byte[] regexp) {
this(regexp, CharsetUtil.ISO_8859_1);
}
/**
* Sets a regular expression to filter results based on the row key.
* @param regexp The regular expression with which to filter the row keys.
* @param charset The charset used to decode the bytes of the row key into a
* string. The RegionServer must support this charset, otherwise it will
* unexpectedly close the connection the first time you attempt to use this
* scanner.
*/
public KeyRegexpFilter(final byte[] regexp, final Charset charset) {
this.regexp = regexp;
this.charset = Bytes.UTF8(charset.name());
}
@Override
byte[] serialize() {
final ComparatorPB.Comparator.Builder comparator =
ComparatorPB.Comparator.newBuilder();
comparator.setNameBytes(Bytes.wrap(REGEXSTRINGCOMPARATOR));
final byte[] regex_cmp = ComparatorPB.RegexStringComparator.newBuilder()
.setPatternBytes(Bytes.wrap(regexp))
.setPatternFlags(0)
.setCharsetBytes(Bytes.wrap(charset))
.build()
.toByteArray();
comparator.setSerializedComparator(Bytes.wrap(regex_cmp));
final FilterPB.CompareFilter cmp = FilterPB.CompareFilter.newBuilder()
.setCompareOp(HBasePB.CompareType.EQUAL)
.setComparator(comparator.build())
.build();
return FilterPB.RowFilter.newBuilder()
.setCompareFilter(cmp)
.build()
.toByteArray();
}
@Override
byte[] name() {
return ROWFILTER;
}
@Override
void serializeOld(final ChannelBuffer buf) {
buf.writeByte((byte) ROWFILTER.length); // 1
buf.writeBytes(ROWFILTER); // 40
// writeUTF of the comparison operator
buf.writeShort(5); // 2
buf.writeBytes(EQUAL); // 5
// The comparator: a RegexStringComparator
buf.writeByte(54); // Code for WritableByteArrayComparable // 1
buf.writeByte(0); // Code for "this has no code". // 1
buf.writeByte((byte) REGEXSTRINGCOMPARATOR.length); // 1
buf.writeBytes(REGEXSTRINGCOMPARATOR); // 52
// writeUTF the regexp
buf.writeShort(regexp.length); // 2
buf.writeBytes(regexp); // regexp.length
// writeUTF the charset
buf.writeShort(charset.length); // 2
buf.writeBytes(charset); // charset.length
}
@Override
int predictSerializedSize() {
return 1 + 40 + 2 + 5 + 1 + 1 + 1 + 52
+ 2 + regexp.length + 2 + charset.length;
}
public String toString() {
return "KeyRegexpFilter(\"" + new String(regexp, CharsetUtil.UTF_8)
+ "\", " + new String(charset, CharsetUtil.UTF_8) + ')';
}
}