Broadcaster.java revision 8a985d24ce9a38f40ed88fecbdcd0e75e3a68f44 
1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * 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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.os;
18
19/** @hide */
20public class Broadcaster
21{
22    public Broadcaster()
23    {
24    }
25
26    /**
27     *  Sign up for notifications about something.
28     *
29     *  When this broadcaster pushes a message with senderWhat in the what field,
30     *  target will be sent a copy of that message with targetWhat in the what field.
31     */
32    public void request(int senderWhat, Handler target, int targetWhat)
33    {
34        synchronized (this) {
35            Registration r = null;
36            if (mReg == null) {
37                r = new Registration();
38                r.senderWhat = senderWhat;
39                r.targets = new Handler[1];
40                r.targetWhats = new int[1];
41                r.targets[0] = target;
42                r.targetWhats[0] = targetWhat;
43                mReg = r;
44                r.next = r;
45                r.prev = r;
46            } else {
47                // find its place in the map
48                Registration start = mReg;
49                r = start;
50                do {
51                    if (r.senderWhat >= senderWhat) {
52                        break;
53                    }
54                    r = r.next;
55                } while (r != start);
56                int n;
57                if (r.senderWhat != senderWhat) {
58                    // we didn't find a senderWhat match, but r is right
59                    // after where it goes
60                    Registration reg = new Registration();
61                    reg.senderWhat = senderWhat;
62                    reg.targets = new Handler[1];
63                    reg.targetWhats = new int[1];
64                    reg.next = r;
65                    reg.prev = r.prev;
66                    r.prev.next = reg;
67                    r.prev = reg;
68
69                    if (r == mReg && r.senderWhat > reg.senderWhat) {
70                        mReg = reg;
71                    }
72
73                    r = reg;
74                    n = 0;
75                } else {
76                    n = r.targets.length;
77                    Handler[] oldTargets = r.targets;
78                    int[] oldWhats = r.targetWhats;
79                    // check for duplicates, and don't do it if we are dup.
80                    for (int i=0; i<n; i++) {
81                        if (oldTargets[i] == target && oldWhats[i] == targetWhat) {
82                            return;
83                        }
84                    }
85                    r.targets = new Handler[n+1];
86                    System.arraycopy(oldTargets, 0, r.targets, 0, n);
87                    r.targetWhats = new int[n+1];
88                    System.arraycopy(oldWhats, 0, r.targetWhats, 0, n);
89                }
90                r.targets[n] = target;
91                r.targetWhats[n] = targetWhat;
92            }
93        }
94    }
95
96    /**
97     * Unregister for notifications for this senderWhat/target/targetWhat tuple.
98     */
99    public void cancelRequest(int senderWhat, Handler target, int targetWhat)
100    {
101        synchronized (this) {
102            Registration start = mReg;
103            Registration r = start;
104
105            if (r == null) {
106                return;
107            }
108
109            do {
110                if (r.senderWhat >= senderWhat) {
111                    break;
112                }
113                r = r.next;
114            } while (r != start);
115
116            if (r.senderWhat == senderWhat) {
117                Handler[] targets = r.targets;
118                int[] whats = r.targetWhats;
119                int oldLen = targets.length;
120                for (int i=0; i<oldLen; i++) {
121                    if (targets[i] == target && whats[i] == targetWhat) {
122                        r.targets = new Handler[oldLen-1];
123                        r.targetWhats = new int[oldLen-1];
124                        if (i > 0) {
125                            System.arraycopy(targets, 0, r.targets, 0, i);
126                            System.arraycopy(whats, 0, r.targetWhats, 0, i);
127                        }
128
129                        int remainingLen = oldLen-i-1;
130                        if (remainingLen != 0) {
131                            System.arraycopy(targets, i+1, r.targets, i,
132                                    remainingLen);
133                            System.arraycopy(whats, i+1, r.targetWhats, i,
134                                    remainingLen);
135                        }
136                        break;
137                    }
138                }
139            }
140        }
141    }
142
143    /**
144     * For debugging purposes, print the registrations to System.out
145     */
146    public void dumpRegistrations()
147    {
148        synchronized (this) {
149            Registration start = mReg;
150            System.out.println("Broadcaster " + this + " {");
151            if (start != null) {
152                Registration r = start;
153                do {
154                    System.out.println("    senderWhat=" + r.senderWhat);
155                    int n = r.targets.length;
156                    for (int i=0; i<n; i++) {
157                        System.out.println("        [" + r.targetWhats[i]
158                                        + "] " + r.targets[i]);
159                    }
160                    r = r.next;
161                } while (r != start);
162            }
163            System.out.println("}");
164        }
165    }
166
167    /**
168     * Send out msg.  Anyone who has registered via the request() method will be
169     * sent the message.
170     */
171    public void broadcast(Message msg)
172    {
173        synchronized (this) {
174            if (mReg == null) {
175                return;
176            }
177
178            int senderWhat = msg.what;
179            Registration start = mReg;
180            Registration r = start;
181            do {
182                if (r.senderWhat >= senderWhat) {
183                    break;
184                }
185                r = r.next;
186            } while (r != start);
187            if (r.senderWhat == senderWhat) {
188                Handler[] targets = r.targets;
189                int[] whats = r.targetWhats;
190                int n = targets.length;
191                for (int i=0; i<n; i++) {
192                    Handler target = targets[i];
193                    Message m = Message.obtain();
194                    m.copyFrom(msg);
195                    m.what = whats[i];
196                    target.sendMessage(m);
197                }
198            }
199        }
200    }
201
202    private class Registration
203    {
204        Registration next;
205        Registration prev;
206
207        int senderWhat;
208        Handler[] targets;
209        int[] targetWhats;
210    }
211    private Registration mReg;
212}
213