1 /*
2 * Copyright 2012 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;
17
18 /**
19 * Holds {@link Attribute}s which can be accessed via {@link AttributeKey}.
20 *
21 * Implementations must be Thread-safe.
22 */
23 public interface AttributeMap {
24 /**
25 * Get the {@link Attribute} for the given {@link AttributeKey}. This method will never return null, but may return
26 * an {@link Attribute} which does not have a value set yet.
27 */
28 <T> Attribute<T> attr(AttributeKey<T> key);
29
30 /**
31 * Returns {@code true} if and only if the given {@link Attribute} exists in this {@link AttributeMap}.
32 */
33 <T> boolean hasAttr(AttributeKey<T> key);
34 }