| /* |
| * 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.cassandra.utils.concurrent; |
| |
| import java.util.ArrayDeque; |
| import java.util.Collection; |
| import java.util.Objects; |
| import java.util.function.Supplier; |
| |
| |
| interface LightweightRecyclerPoolHolder<T> |
| { |
| ArrayDeque<T> get(); |
| } |
| |
| /** |
| * A simple thread local object reuse facility with limited capacity and no attempt at rebalancing pooling between |
| * threads. This is meant to be put in place where churn is high, but single object allocation and footprint are not |
| * so high to justify a more sophisticated approach. |
| * |
| * @param <T> |
| * @see ThreadLocals#createLightweightRecycler(int) |
| */ |
| public interface LightweightRecycler<T> extends LightweightRecyclerPoolHolder<T> |
| { |
| /** |
| * @return a reusable instance, or null if none is available |
| */ |
| default T reuse() |
| { |
| return get().pollFirst(); |
| } |
| |
| /** |
| * @return a reusable instance, or allocate one via the provided supplier |
| */ |
| default T reuseOrAllocate(Supplier<T> supplier) |
| { |
| final T reuse = reuse(); |
| return reuse != null ? reuse : supplier.get(); |
| } |
| |
| /** |
| * @param t to be recycled, if t is a collection it will be cleared before recycling, but not cleared if not |
| * recycled |
| * @return true if t was recycled, false otherwise |
| */ |
| default boolean tryRecycle(T t) |
| { |
| Objects.requireNonNull(t); |
| |
| final ArrayDeque<T> pool = get(); |
| if (pool.size() < capacity()) |
| { |
| if (t instanceof Collection) |
| ((Collection<?>) t).clear(); |
| pool.offerFirst(t); |
| return true; |
| } |
| else |
| { |
| return false; |
| } |
| } |
| |
| /** |
| * @return current count of available instances for reuse |
| */ |
| default int available() |
| { |
| return get().size(); |
| } |
| |
| |
| /** |
| * @return maximum capacity of the recycler |
| */ |
| int capacity(); |
| } |