summaryrefslogtreecommitdiffstats
path: root/src/com/android/launcher3/DeferredHandler.java
blob: 92ecf964388c259c826559eccb6c2f589e386d88 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.launcher3;

import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.MessageQueue;
import android.util.Pair;
import java.util.LinkedList;
import java.util.ListIterator;

/**
 * Queue of things to run on a looper thread.  Items posted with {@link #post} will not
 * be actually enqued on the handler until after the last one has run, to keep from
 * starving the thread.
 *
 * This class is fifo.
 */
public class DeferredHandler {
    private LinkedList<Pair<Runnable, Integer>> mQueue = new LinkedList<Pair<Runnable, Integer>>();
    private MessageQueue mMessageQueue = Looper.myQueue();
    private Impl mHandler = new Impl();

    private class Impl extends Handler implements MessageQueue.IdleHandler {
        public void handleMessage(Message msg) {
            Pair<Runnable, Integer> p;
            Runnable r;
            synchronized (mQueue) {
                if (mQueue.size() == 0) {
                    return;
                }
                p = mQueue.removeFirst();
                r = p.first;
            }
            r.run();
            synchronized (mQueue) {
                scheduleNextLocked();
            }
        }

        public boolean queueIdle() {
            handleMessage(null);
            return false;
        }
    }

    private class IdleRunnable implements Runnable {
        Runnable mRunnable;

        IdleRunnable(Runnable r) {
            mRunnable = r;
        }

        public void run() {
            mRunnable.run();
        }
    }

    public DeferredHandler() {
    }

    /** Schedule runnable to run after everything that's on the queue right now. */
    public void post(Runnable runnable) {
        post(runnable, 0);
    }
    public void post(Runnable runnable, int type) {
        synchronized (mQueue) {
            mQueue.add(new Pair<Runnable, Integer>(runnable, type));
            if (mQueue.size() == 1) {
                scheduleNextLocked();
            }
        }
    }

    /** Schedule runnable to run when the queue goes idle. */
    public void postIdle(final Runnable runnable) {
        postIdle(runnable, 0);
    }
    public void postIdle(final Runnable runnable, int type) {
        post(new IdleRunnable(runnable), type);
    }

    public void cancelRunnable(Runnable runnable) {
        synchronized (mQueue) {
            while (mQueue.remove(runnable)) { }
        }
    }
    public void cancelAllRunnablesOfType(int type) {
        synchronized (mQueue) {
            ListIterator<Pair<Runnable, Integer>> iter = mQueue.listIterator();
            Pair<Runnable, Integer> p;
            while (iter.hasNext()) {
                p = iter.next();
                if (p.second == type) {
                    iter.remove();
                }
            }
        }
    }

    public void cancel() {
        synchronized (mQueue) {
            mQueue.clear();
        }
    }

    /** Runs all queued Runnables from the calling thread. */
    public void flush() {
        LinkedList<Pair<Runnable, Integer>> queue = new LinkedList<Pair<Runnable, Integer>>();
        synchronized (mQueue) {
            queue.addAll(mQueue);
            mQueue.clear();
        }
        for (Pair<Runnable, Integer> p : queue) {
            p.first.run();
        }
    }

    void scheduleNextLocked() {
        if (mQueue.size() > 0) {
            Pair<Runnable, Integer> p = mQueue.getFirst();
            Runnable peek = p.first;
            if (peek instanceof IdleRunnable) {
                mMessageQueue.addIdleHandler(mHandler);
            } else {
                mHandler.sendEmptyMessage(1);
            }
        }
    }
}