/*
*
* 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 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 java.util.ArrayList;
import com.google.common.base.Preconditions;
import com.google.protobuf.InvalidProtocolBufferException;
/**
* A filter that will only return the key component of each KV (the value will
* be rewritten as empty).
* <p>
* This filter can be used to grab all of the keys without having to also grab
* the values.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class KeyOnlyFilter extends FilterBase {
boolean lenAsVal;
public KeyOnlyFilter() { this(false); }
public KeyOnlyFilter(boolean lenAsVal) { this.lenAsVal = lenAsVal; }
@Override
public KeyValue transform(KeyValue kv) {
return kv.createKeyOnly(this.lenAsVal);
}
public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
Preconditions.checkArgument((filterArguments.size() == 0 || filterArguments.size() == 1),
"Expected: 0 or 1 but got: %s", filterArguments.size());
KeyOnlyFilter filter = new KeyOnlyFilter();
if (filterArguments.size() == 1) {
filter.lenAsVal = ParseFilter.convertByteArrayToBoolean(filterArguments.get(0));
}
return filter;
}
/**
* @return The filter serialized using pb
*/
public byte [] toByteArray() {
FilterProtos.KeyOnlyFilter.Builder builder =
FilterProtos.KeyOnlyFilter.newBuilder();
builder.setLenAsVal(this.lenAsVal);
return builder.build().toByteArray();
}
/**
* @param pbBytes A pb serialized {@link KeyOnlyFilter} instance
* @return An instance of {@link KeyOnlyFilter} made from <code>bytes</code>
* @throws DeserializationException
* @see #toByteArray
*/
public static KeyOnlyFilter parseFrom(final byte [] pbBytes)
throws DeserializationException {
FilterProtos.KeyOnlyFilter proto;
try {
proto = FilterProtos.KeyOnlyFilter.parseFrom(pbBytes);
} catch (InvalidProtocolBufferException e) {
throw new DeserializationException(e);
}
return new KeyOnlyFilter(proto.getLenAsVal());
}
/**
* @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 KeyOnlyFilter)) return false;
KeyOnlyFilter other = (KeyOnlyFilter)o;
return this.lenAsVal == other.lenAsVal;
}
}