--- /dev/null
+package org.apache.lucene.facet.search;
+
+import java.util.Arrays;
+
+/**
+ * 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.
+ */
+
+/**
+ * An IntArrayAllocator is an object which manages counter array objects
+ * of a certain length. These counter arrays are needed temporarily during
+ * faceted search (see {@link FacetsAccumulator} and can be reused across searches
+ * instead of being allocated afresh on every search.
+ * <P>
+ * An IntArrayAllocator is thread-safe.
+ *
+ * @lucene.experimental
+ */
+public final class IntArrayAllocator extends TemporaryObjectAllocator<int[]> {
+
+ // An IntArrayAllocater deals with integer arrays of a fixed length.
+ private int length;
+
+ /**
+ * Construct an allocator for counter arrays of length <CODE>length</CODE>,
+ * keeping around a pool of up to <CODE>maxArrays</CODE> old arrays.
+ * <P>
+ * Note that the pool size only restricts the number of arrays that hang
+ * around when not needed, but <I>not</I> the maximum number of arrays
+ * that are allocated when actually is use: If a number of concurrent
+ * threads ask for an allocation, all of them will get a counter array,
+ * even if their number is greater than maxArrays. If an application wants
+ * to limit the number of concurrent threads making allocations, it needs
+ * to do so on its own - for example by blocking new threads until the
+ * existing ones have finished.
+ * <P>
+ * In particular, when maxArrays=0, this object behaves as a trivial
+ * allocator, always allocating a new array and never reusing an old one.
+ */
+ public IntArrayAllocator(int length, int maxArrays) {
+ super(maxArrays);
+ this.length = length;
+ }
+
+ @Override
+ public int[] create() {
+ return new int[length];
+ }
+
+ @Override
+ public void clear(int[] array) {
+ Arrays.fill(array, 0);
+ }
+
+}