/**
* 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.filter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.DeserializationException;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.protobuf.generated.FilterProtos;
import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.BytesBytesPair;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
import com.google.protobuf.ByteString;
import com.google.protobuf.InvalidProtocolBufferException;
/**
* Filters data based on fuzzy row key. Performs fast-forwards during scanning.
* It takes pairs (row key, fuzzy info) to match row keys. Where fuzzy info is
* a byte array with 0 or 1 as its values:
* <ul>
* <li>
* 0 - means that this byte in provided row key is fixed, i.e. row key's byte at same position
* must match
* </li>
* <li>
* 1 - means that this byte in provided row key is NOT fixed, i.e. row key's byte at this
* position can be different from the one in provided row key
* </li>
* </ul>
*
*
* Example:
* Let's assume row key format is userId_actionId_year_month. Length of userId is fixed
* and is 4, length of actionId is 2 and year and month are 4 and 2 bytes long respectively.
*
* Let's assume that we need to fetch all users that performed certain action (encoded as "99")
* in Jan of any year. Then the pair (row key, fuzzy info) would be the following:
* row key = "????_99_????_01" (one can use any value instead of "?")
* fuzzy info = "\x01\x01\x01\x01\x00\x00\x00\x00\x01\x01\x01\x01\x00\x00\x00"
*
* I.e. fuzzy info tells the matching mask is "????_99_????_01", where at ? can be any value.
*
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class FuzzyRowFilter extends FilterBase {
private List<Pair<byte[], byte[]>> fuzzyKeysData;
private boolean done = false;
public FuzzyRowFilter(List<Pair<byte[], byte[]>> fuzzyKeysData) {
this.fuzzyKeysData = fuzzyKeysData;
}
// TODO: possible improvement: save which fuzzy row key to use when providing a hint
@Override
public ReturnCode filterKeyValue(KeyValue kv) {
byte[] rowKey = kv.getRow();
// assigning "worst" result first and looking for better options
SatisfiesCode bestOption = SatisfiesCode.NO_NEXT;
for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
SatisfiesCode satisfiesCode =
satisfies(rowKey, fuzzyData.getFirst(), fuzzyData.getSecond());
if (satisfiesCode == SatisfiesCode.YES) {
return ReturnCode.INCLUDE;
}
if (satisfiesCode == SatisfiesCode.NEXT_EXISTS) {
bestOption = SatisfiesCode.NEXT_EXISTS;
}
}
if (bestOption == SatisfiesCode.NEXT_EXISTS) {
return ReturnCode.SEEK_NEXT_USING_HINT;
}
// the only unhandled SatisfiesCode is NO_NEXT, i.e. we are done
done = true;
return ReturnCode.NEXT_ROW;
}
@Override
public KeyValue getNextKeyHint(KeyValue currentKV) {
byte[] rowKey = currentKV.getRow();
byte[] nextRowKey = null;
// Searching for the "smallest" row key that satisfies at least one fuzzy row key
for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
byte[] nextRowKeyCandidate = getNextForFuzzyRule(rowKey,
fuzzyData.getFirst(), fuzzyData.getSecond());
if (nextRowKeyCandidate == null) {
continue;
}
if (nextRowKey == null || Bytes.compareTo(nextRowKeyCandidate, nextRowKey) < 0) {
nextRowKey = nextRowKeyCandidate;
}
}
if (nextRowKey == null) {
// SHOULD NEVER happen
// TODO: is there a better way than throw exception? (stop the scanner?)
throw new IllegalStateException("No next row key that satisfies fuzzy exists when" +
" getNextKeyHint() is invoked." +
" Filter: " + this.toString() +
" currentKV: " + currentKV.toString());
}
return KeyValue.createFirstOnRow(nextRowKey);
}
@Override
public boolean filterAllRemaining() {
return done;
}
/**
* @return The filter serialized using pb
*/
public byte [] toByteArray() {
FilterProtos.FuzzyRowFilter.Builder builder =
FilterProtos.FuzzyRowFilter.newBuilder();
for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
BytesBytesPair.Builder bbpBuilder = BytesBytesPair.newBuilder();
bbpBuilder.setFirst(ByteString.copyFrom(fuzzyData.getFirst()));
bbpBuilder.setSecond(ByteString.copyFrom(fuzzyData.getSecond()));
builder.addFuzzyKeysData(bbpBuilder);
}
return builder.build().toByteArray();
}
/**
* @param pbBytes A pb serialized {@link FuzzyRowFilter} instance
* @return An instance of {@link FuzzyRowFilter} made from <code>bytes</code>
* @throws DeserializationException
* @see {@link #toByteArray()}
*/
public static FuzzyRowFilter parseFrom(final byte [] pbBytes)
throws DeserializationException {
FilterProtos.FuzzyRowFilter proto;
try {
proto = FilterProtos.FuzzyRowFilter.parseFrom(pbBytes);
} catch (InvalidProtocolBufferException e) {
throw new DeserializationException(e);
}
int count = proto.getFuzzyKeysDataCount();
ArrayList<Pair<byte[], byte[]>> fuzzyKeysData= new ArrayList<Pair<byte[], byte[]>>(count);
for (int i = 0; i < count; ++i) {
BytesBytesPair current = proto.getFuzzyKeysData(i);
byte[] keyBytes = current.getFirst().toByteArray();
byte[] keyMeta = current.getSecond().toByteArray();
fuzzyKeysData.add(new Pair<byte[], byte[]>(keyBytes, keyMeta));
}
return new FuzzyRowFilter(fuzzyKeysData);
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append("FuzzyRowFilter");
sb.append("{fuzzyKeysData=");
for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
sb.append('{').append(Bytes.toStringBinary(fuzzyData.getFirst())).append(":");
sb.append(Bytes.toStringBinary(fuzzyData.getSecond())).append('}');
}
sb.append("}, ");
return sb.toString();
}
// Utility methods
static enum SatisfiesCode {
// row satisfies fuzzy rule
YES,
// row doesn't satisfy fuzzy rule, but there's possible greater row that does
NEXT_EXISTS,
// row doesn't satisfy fuzzy rule and there's no greater row that does
NO_NEXT
}
static SatisfiesCode satisfies(byte[] row,
byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
return satisfies(row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
}
private static SatisfiesCode satisfies(byte[] row, int offset, int length,
byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
if (row == null) {
// do nothing, let scan to proceed
return SatisfiesCode.YES;
}
boolean nextRowKeyCandidateExists = false;
for (int i = 0; i < fuzzyKeyMeta.length && i < length; i++) {
// First, checking if this position is fixed and not equals the given one
boolean byteAtPositionFixed = fuzzyKeyMeta[i] == 0;
boolean fixedByteIncorrect = byteAtPositionFixed && fuzzyKeyBytes[i] != row[i + offset];
if (fixedByteIncorrect) {
// in this case there's another row that satisfies fuzzy rule and bigger than this row
if (nextRowKeyCandidateExists) {
return SatisfiesCode.NEXT_EXISTS;
}
// If this row byte is less than fixed then there's a byte array bigger than
// this row and which satisfies the fuzzy rule. Otherwise there's no such byte array:
// this row is simply bigger than any byte array that satisfies the fuzzy rule
boolean rowByteLessThanFixed = (row[i + offset] & 0xFF) < (fuzzyKeyBytes[i] & 0xFF);
return rowByteLessThanFixed ? SatisfiesCode.NEXT_EXISTS : SatisfiesCode.NO_NEXT;
}
// Second, checking if this position is not fixed and byte value is not the biggest. In this
// case there's a byte array bigger than this row and which satisfies the fuzzy rule. To get
// bigger byte array that satisfies the rule we need to just increase this byte
// (see the code of getNextForFuzzyRule below) by one.
// Note: if non-fixed byte is already at biggest value, this doesn't allow us to say there's
// bigger one that satisfies the rule as it can't be increased.
if (fuzzyKeyMeta[i] == 1 && !isMax(fuzzyKeyBytes[i])) {
nextRowKeyCandidateExists = true;
}
}
return SatisfiesCode.YES;
}
private static boolean isMax(byte fuzzyKeyByte) {
return (fuzzyKeyByte & 0xFF) == 255;
}
static byte[] getNextForFuzzyRule(byte[] row, byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
return getNextForFuzzyRule(row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
}
/**
* @return greater byte array than given (row) which satisfies the fuzzy rule if it exists,
* null otherwise
*/
private static byte[] getNextForFuzzyRule(byte[] row, int offset, int length,
byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
// To find out the next "smallest" byte array that satisfies fuzzy rule and "greater" than
// the given one we do the following:
// 1. setting values on all "fixed" positions to the values from fuzzyKeyBytes
// 2. if during the first step given row did not increase, then we increase the value at
// the first "non-fixed" position (where it is not maximum already)
// It is easier to perform this by using fuzzyKeyBytes copy and setting "non-fixed" position
// values than otherwise.
byte[] result = Arrays.copyOf(fuzzyKeyBytes,
length > fuzzyKeyBytes.length ? length : fuzzyKeyBytes.length);
int toInc = -1;
boolean increased = false;
for (int i = 0; i < result.length; i++) {
if (i >= fuzzyKeyMeta.length || fuzzyKeyMeta[i] == 1) {
result[i] = row[offset + i];
if (!isMax(row[i])) {
// this is "non-fixed" position and is not at max value, hence we can increase it
toInc = i;
}
} else if (i < fuzzyKeyMeta.length && fuzzyKeyMeta[i] == 0) {
if ((row[i + offset] & 0xFF) < (fuzzyKeyBytes[i] & 0xFF)) {
// if setting value for any fixed position increased the original array,
// we are OK
increased = true;
break;
}
if ((row[i + offset] & 0xFF) > (fuzzyKeyBytes[i] & 0xFF)) {
// if setting value for any fixed position makes array "smaller", then just stop:
// in case we found some non-fixed position to increase we will do it, otherwise
// there's no "next" row key that satisfies fuzzy rule and "greater" than given row
break;
}
}
}
if (!increased) {
if (toInc < 0) {
return null;
}
result[toInc]++;
// Setting all "non-fixed" positions to zeroes to the right of the one we increased so
// that found "next" row key is the smallest possible
for (int i = toInc + 1; i < result.length; i++) {
if (i >= fuzzyKeyMeta.length || fuzzyKeyMeta[i] == 1) {
result[i] = 0;
}
}
}
return result;
}
/**
* @param other
* @return true if and only if the fields of the filter that are serialized
* are equal to the corresponding fields in other. Used for testing.
*/
boolean areSerializedFieldsEqual(Filter o) {
if (o == this) return true;
if (!(o instanceof FuzzyRowFilter)) return false;
FuzzyRowFilter other = (FuzzyRowFilter)o;
if (this.fuzzyKeysData.size() != other.fuzzyKeysData.size()) return false;
for (int i = 0; i < fuzzyKeysData.size(); ++i) {
Pair<byte[], byte[]> thisData = this.fuzzyKeysData.get(i);
Pair<byte[], byte[]> otherData = other.fuzzyKeysData.get(i);
if (!(Bytes.equals(thisData.getFirst(), otherData.getFirst())
&& Bytes.equals(thisData.getSecond(), otherData.getSecond()))) {
return false;
}
}
return true;
}
}