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 * http://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 org.jboss.netty.handler.execution;
17
18
19 import java.util.concurrent.Executor;
20 import java.util.concurrent.ExecutorService;
21
22 import org.jboss.netty.util.ExternalResourceReleasable;
23
24 /**
25 * A special {@link Executor} which allows to chain a series of
26 * {@link Executor}s and {@link ChannelEventRunnableFilter}.
27 */
28 public class ChainedExecutor implements Executor, ExternalResourceReleasable {
29
30 private final Executor cur;
31 private final Executor next;
32 private final ChannelEventRunnableFilter filter;
33
34 /**
35 * Create a new {@link ChainedExecutor} which will used the given
36 * {@link ChannelEventRunnableFilter} to see if the {@link #cur} {@link Executor} should get
37 * used. Otherwise it will pass the work to the {@link #next} {@link Executor}
38 *
39 * @param filter the {@link ChannelEventRunnableFilter} which will be used to check if the
40 * {@link ChannelEventRunnable} should be passed to the cur or next {@link Executor}
41 * @param cur the {@link Executor} to use if the {@link ChannelEventRunnableFilter} match
42 * @param next the {@link Executor} to use if the {@link ChannelEventRunnableFilter} does not match
43 */
44 public ChainedExecutor(ChannelEventRunnableFilter filter, Executor cur, Executor next) {
45 if (filter == null) {
46 throw new NullPointerException("filter");
47 }
48 if (cur == null) {
49 throw new NullPointerException("cur");
50 }
51 if (next == null) {
52 throw new NullPointerException("next");
53 }
54
55 this.filter = filter;
56 this.cur = cur;
57 this.next = next;
58 }
59
60 /**
61 * Execute the passed {@link ChannelEventRunnable} with the current {@link Executor} if the
62 * {@link ChannelEventRunnableFilter} match. Otherwise pass it to the next {@link Executor} in
63 * the chain.
64 */
65 public void execute(Runnable command) {
66 assert command instanceof ChannelEventRunnable;
67 if (filter.filter((ChannelEventRunnable) command)) {
68 cur.execute(command);
69 } else {
70 next.execute(command);
71 }
72 }
73
74 public void releaseExternalResources() {
75 if (cur instanceof ExecutorService) {
76 ((ExecutorService) cur).shutdown();
77 }
78 if (next instanceof ExecutorService) {
79 ((ExecutorService) next).shutdown();
80 }
81 releaseExternal(cur);
82 releaseExternal(next);
83 }
84
85
86 private static void releaseExternal(Executor executor) {
87 if (executor instanceof ExternalResourceReleasable) {
88 ((ExternalResourceReleasable) executor).releaseExternalResources();
89 }
90 }
91 }