/* * SPDX-License-Identifier: Apache-2.0 * * The OpenSearch Contributors require contributions made to * this file be licensed under the Apache-2.0 license or a * compatible open source license. */ /* * Licensed to Elasticsearch under one or more contributor * license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright * ownership. Elasticsearch 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. */ /* * Modifications Copyright OpenSearch Contributors. See * GitHub history for details. */ package org.opensearch.common.util.concurrent; import java.util.concurrent.BlockingQueue; /** * Extends the {@code SizeBlockingQueue} to add the {@code adjustCapacity} method, which will adjust * the capacity by a certain amount towards a maximum or minimum. * * @opensearch.internal */ final class ResizableBlockingQueue<E> extends SizeBlockingQueue<E> { private volatile int capacity; ResizableBlockingQueue(BlockingQueue<E> queue, int initialCapacity) { super(queue, initialCapacity); this.capacity = initialCapacity; } @Override public int capacity() { return this.capacity; } @Override public int remainingCapacity() { return Math.max(0, this.capacity()); } /** Resize the limit for the queue, returning the new size limit */ public synchronized int adjustCapacity(int optimalCapacity, int adjustmentAmount, int minCapacity, int maxCapacity) { assert adjustmentAmount > 0 : "adjustment amount should be a positive value"; assert optimalCapacity >= 0 : "desired capacity cannot be negative"; assert minCapacity >= 0 : "cannot have min capacity smaller than 0"; assert maxCapacity >= minCapacity : "cannot have max capacity smaller than min capacity"; if (optimalCapacity == capacity) { // Yahtzee! return this.capacity; } if (optimalCapacity > capacity + adjustmentAmount) { // adjust up final int newCapacity = Math.min(maxCapacity, capacity + adjustmentAmount); this.capacity = newCapacity; return newCapacity; } else if (optimalCapacity < capacity - adjustmentAmount) { // adjust down final int newCapacity = Math.max(minCapacity, capacity - adjustmentAmount); this.capacity = newCapacity; return newCapacity; } else { return this.capacity; } } }