1 /*
2 * Copyright 2019 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.util.internal;
17
18 import io.netty.util.Recycler;
19
20 /**
21 * Light-weight object pool.
22 *
23 * @param <T> the type of the pooled object
24 */
25 public abstract class ObjectPool<T> {
26
27 ObjectPool() { }
28
29 /**
30 * Get a {@link Object} from the {@link ObjectPool}. The returned {@link Object} may be created via
31 * {@link ObjectCreator#newObject(Handle)} if no pooled {@link Object} is ready to be reused.
32 */
33 public abstract T get();
34
35 /**
36 * Handle for an pooled {@link Object} that will be used to notify the {@link ObjectPool} once it can
37 * reuse the pooled {@link Object} again.
38 * @param <T>
39 */
40 public interface Handle<T> {
41 /**
42 * Recycle the {@link Object} if possible and so make it ready to be reused.
43 */
44 void recycle(T self);
45 }
46
47 /**
48 * Creates a new Object which references the given {@link Handle} and calls {@link Handle#recycle(Object)} once
49 * it can be re-used.
50 *
51 * @param <T> the type of the pooled object
52 */
53 public interface ObjectCreator<T> {
54
55 /**
56 * Creates an returns a new {@link Object} that can be used and later recycled via
57 * {@link Handle#recycle(Object)}.
58 *
59 * @param handle can NOT be null.
60 */
61 T newObject(Handle<T> handle);
62 }
63
64 /**
65 * Creates a new {@link ObjectPool} which will use the given {@link ObjectCreator} to create the {@link Object}
66 * that should be pooled.
67 */
68 public static <T> ObjectPool<T> newPool(final ObjectCreator<T> creator) {
69 return new RecyclerObjectPool<T>(ObjectUtil.checkNotNull(creator, "creator"));
70 }
71
72 private static final class RecyclerObjectPool<T> extends ObjectPool<T> {
73 private final Recycler<T> recycler;
74
75 RecyclerObjectPool(final ObjectCreator<T> creator) {
76 recycler = new Recycler<T>() {
77 @Override
78 protected T newObject(Handle<T> handle) {
79 return creator.newObject(handle);
80 }
81 };
82 }
83
84 @Override
85 public T get() {
86 return recycler.get();
87 }
88 }
89 }