1 /*
2 * Copyright 2016 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.resolver.dns;
17
18 import io.netty.channel.EventLoop;
19 import io.netty.handler.codec.dns.DnsRecord;
20
21 import java.net.InetAddress;
22 import java.util.List;
23
24 /**
25 * A cache for DNS resolution entries.
26 */
27 public interface DnsCache {
28
29 /**
30 * Clears all the resolved addresses cached by this resolver.
31 *
32 * @see #clear(String)
33 */
34 void clear();
35
36 /**
37 * Clears the resolved addresses of the specified host name from the cache of this resolver.
38 *
39 * @return {@code true} if and only if there was an entry for the specified host name in the cache and
40 * it has been removed by this method
41 */
42 boolean clear(String hostname);
43
44 /**
45 * Return the cached entries for the given hostname.
46 * @param hostname the hostname
47 * @param additionals the additional records
48 * @return the cached entries
49 */
50 List<? extends DnsCacheEntry> get(String hostname, DnsRecord[] additionals);
51
52 /**
53 * Create a new {@link DnsCacheEntry} and cache a resolved address for a given hostname.
54 * @param hostname the hostname
55 * @param additionals the additional records
56 * @param address the resolved address
57 * @param originalTtl the TTL as returned by the DNS server
58 * @param loop the {@link EventLoop} used to register the TTL timeout
59 * @return The {@link DnsCacheEntry} corresponding to this cache entry.
60 */
61 DnsCacheEntry cache(String hostname, DnsRecord[] additionals, InetAddress address, long originalTtl,
62 EventLoop loop);
63
64 /**
65 * Cache the resolution failure for a given hostname.
66 * Be aware this <strong>won't</strong> be called with timeout / cancel / transport exceptions.
67 *
68 * @param hostname the hostname
69 * @param additionals the additional records
70 * @param cause the resolution failure
71 * @param loop the {@link EventLoop} used to register the TTL timeout
72 * @return The {@link DnsCacheEntry} corresponding to this cache entry, or {@code null} if this cache doesn't
73 * support caching failed responses.
74 */
75 DnsCacheEntry cache(String hostname, DnsRecord[] additionals, Throwable cause, EventLoop loop);
76 }