com.metamx.common.collect.CountingMap Maven / Gradle / Ivy
/*
* Copyright 2011,2012 Metamarkets Group Inc.
*
* Licensed 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 com.metamx.common.collect;
import com.google.common.base.Function;
import com.google.common.collect.Maps;
import java.util.AbstractMap;
import java.util.HashMap;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
// Can't find a good way to abstract over which counter representation is used,
// so I just pick Long/MutableLong.
public class CountingMap extends AbstractMap
{
private final HashMap counts = new HashMap<>();
public void add(K k, Long n)
{
if (!counts.containsKey(k)) {
counts.put(k, new AtomicLong(0));
}
counts.get(k).addAndGet(n);
}
public Set> entrySet()
{
return Maps.transformValues(
counts,
new Function()
{
@Override
public Long apply(AtomicLong n)
{
return n.get();
}
}
).entrySet();
}
}