/*
* Copyright 2010 The Apache Software Foundation
*
* 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.hbase.KeyValue;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import com.google.common.base.Preconditions;
/**
* Simple filter that returns first N columns on row only.
* This filter was written to test filters in Get and as soon as it gets
* its quota of columns, {@link #filterAllRemaining()} returns true. This
* makes this filter unsuitable as a Scan filter.
*/
public class ColumnCountGetFilter extends FilterBase {
private int limit = 0;
private int count = 0;
/**
* Used during serialization.
* Do not use.
*/
public ColumnCountGetFilter() {
super();
}
public ColumnCountGetFilter(final int n) {
Preconditions.checkArgument(n >= 0, "limit be positive %s", n);
this.limit = n;
}
public int getLimit() {
return limit;
}
@Override
public boolean filterAllRemaining() {
return this.count > this.limit;
}
@Override
public ReturnCode filterKeyValue(KeyValue v) {
this.count++;
return filterAllRemaining() ? ReturnCode.SKIP: ReturnCode.INCLUDE;
}
@Override
public void reset() {
this.count = 0;
}
public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
Preconditions.checkArgument(filterArguments.size() == 1,
"Expected 1 but got: %s", filterArguments.size());
int limit = ParseFilter.convertByteArrayToInt(filterArguments.get(0));
return new ColumnCountGetFilter(limit);
}
@Override
public void readFields(DataInput in) throws IOException {
this.limit = in.readInt();
}
@Override
public void write(DataOutput out) throws IOException {
out.writeInt(this.limit);
}
}