1/*
2 * Copyright (C) 2011 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 com.android.emailcommon.utility;
18
19import com.google.common.annotations.VisibleForTesting;
20
21import android.os.Handler;
22
23import java.util.ArrayList;
24import java.util.LinkedList;
25
26/**
27 * Class that helps post {@link Runnable}s to a {@link Handler}, and cancel pending ones
28 * at once.
29 */
30public class DelayedOperations {
31    private final Handler mHandler;
32
33    @VisibleForTesting
34    final LinkedList<QueuedOperation> mPendingOperations = new LinkedList<QueuedOperation>();
35
36    private class QueuedOperation implements Runnable {
37        private final Runnable mActualRannable;
38
39        public QueuedOperation(Runnable actualRannable) {
40            mActualRannable = actualRannable;
41        }
42
43        @Override
44        public void run() {
45            mPendingOperations.remove(this);
46            mActualRannable.run();
47        }
48
49        public void cancel() {
50            mPendingOperations.remove(this);
51            cancelRunnable(this);
52        }
53    }
54
55    public DelayedOperations(Handler handler) {
56        mHandler = handler;
57    }
58
59    /**
60     * Post a {@link Runnable} to the handler.  Equivalent to {@link Handler#post(Runnable)}.
61     */
62    public void post(Runnable r) {
63        final QueuedOperation qo = new QueuedOperation(r);
64        mPendingOperations.add(qo);
65        postRunnable(qo);
66    }
67
68    /**
69     * Cancel a runnable that's been posted with {@link #post(Runnable)}.
70     *
71     * Equivalent to {@link Handler#removeCallbacks(Runnable)}.
72     */
73    public void removeCallbacks(Runnable r) {
74        QueuedOperation found = null;
75        for (QueuedOperation qo : mPendingOperations) {
76            if (qo.mActualRannable == r) {
77                found = qo;
78                break;
79            }
80        }
81        if (found != null) {
82            found.cancel();
83        }
84    }
85
86    /**
87     * Cancel all pending {@link Runnable}s.
88     */
89    public void removeCallbacks() {
90        // To avoid ConcurrentModificationException
91        final ArrayList<QueuedOperation> temp = new ArrayList<QueuedOperation>(mPendingOperations);
92        for (QueuedOperation qo : temp) {
93            qo.cancel();
94        }
95    }
96
97    /** Overridden by test, as Handler is not mockable. */
98    void postRunnable(Runnable r) {
99        mHandler.post(r);
100    }
101
102    /** Overridden by test, as Handler is not mockable. */
103    void cancelRunnable(Runnable r) {
104        mHandler.removeCallbacks(r);
105    }
106}
107