1 /*
2 * Copyright (C) 2010, Google Inc.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.events;
45
46 import java.util.List;
47 import java.util.concurrent.ConcurrentHashMap;
48 import java.util.concurrent.ConcurrentMap;
49 import java.util.concurrent.CopyOnWriteArrayList;
50
51 /** Manages a thread-safe list of {@link RepositoryListener}s. */
52 public class ListenerList {
53 private final ConcurrentMap<Class<? extends RepositoryListener>, CopyOnWriteArrayList<ListenerHandle>> lists = new ConcurrentHashMap<Class<? extends RepositoryListener>, CopyOnWriteArrayList<ListenerHandle>>();
54
55 /**
56 * Register an IndexChangedListener.
57 *
58 * @param listener
59 * the listener implementation.
60 * @return handle to later remove the listener.
61 */
62 public ListenerHandle addIndexChangedListener(IndexChangedListener listener) {
63 return addListener(IndexChangedListener.class, listener);
64 }
65
66 /**
67 * Register a RefsChangedListener.
68 *
69 * @param listener
70 * the listener implementation.
71 * @return handle to later remove the listener.
72 */
73 public ListenerHandle addRefsChangedListener(RefsChangedListener listener) {
74 return addListener(RefsChangedListener.class, listener);
75 }
76
77 /**
78 * Register a ConfigChangedListener.
79 *
80 * @param listener
81 * the listener implementation.
82 * @return handle to later remove the listener.
83 */
84 public ListenerHandle addConfigChangedListener(
85 ConfigChangedListener listener) {
86 return addListener(ConfigChangedListener.class, listener);
87 }
88
89 /**
90 * Add a listener to the list.
91 *
92 * @param <T>
93 * the type of listener being registered.
94 * @param type
95 * type of listener being registered.
96 * @param listener
97 * the listener instance.
98 * @return a handle to later remove the registration, if desired.
99 */
100 public <T extends RepositoryListener> ListenerHandle addListener(
101 Class<T> type, T listener) {
102 ListenerHandle handle = new ListenerHandle(this, type, listener);
103 add(handle);
104 return handle;
105 }
106
107 /**
108 * Dispatch an event to all interested listeners.
109 * <p>
110 * Listeners are selected by the type of listener the event delivers to.
111 *
112 * @param event
113 * the event to deliver.
114 */
115 @SuppressWarnings("unchecked")
116 public void dispatch(RepositoryEvent event) {
117 List<ListenerHandle> list = lists.get(event.getListenerType());
118 if (list != null) {
119 for (ListenerHandle handle : list)
120 event.dispatch(handle.listener);
121 }
122 }
123
124 private void add(ListenerHandle handle) {
125 List<ListenerHandle> list = lists.get(handle.type);
126 if (list == null) {
127 CopyOnWriteArrayList<ListenerHandle> newList;
128
129 newList = new CopyOnWriteArrayList<ListenerHandle>();
130 list = lists.putIfAbsent(handle.type, newList);
131 if (list == null)
132 list = newList;
133 }
134 list.add(handle);
135 }
136
137 void remove(ListenerHandle handle) {
138 List<ListenerHandle> list = lists.get(handle.type);
139 if (list != null)
140 list.remove(handle);
141 }
142 }