1/*
2 * Copyright (C) 2017 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.internal.telephony;
18
19import static org.junit.Assert.assertTrue;
20import static org.mockito.ArgumentMatchers.any;
21import static org.mockito.ArgumentMatchers.anyLong;
22import static org.mockito.Mockito.doAnswer;
23import static org.mockito.Mockito.times;
24import static org.mockito.Mockito.verify;
25
26import android.os.Handler;
27import android.os.Looper;
28import android.support.test.runner.AndroidJUnit4;
29
30import com.android.internal.telephony.ims.ImsTestBase;
31
32import org.junit.After;
33import org.junit.Before;
34import org.junit.Test;
35import org.junit.runner.RunWith;
36import org.mockito.Mock;
37@RunWith(AndroidJUnit4.class)
38public class ExponentialBackoffTest extends ImsTestBase {
39
40    private static final int START_DELAY_MS = 10;
41    private static final int MAXIMUM_DELAY_MS = 1000;
42    private static final int MULTIPLIER = 2;
43
44    private ExponentialBackoff mBackoffUnderTest;
45    private Handler mHandler = new Handler(Looper.getMainLooper());
46    @Mock private Runnable mRunnable;
47    @Mock private ExponentialBackoff.HandlerAdapter mHandlerAdapter;
48
49    @Before
50    public void setUp() throws Exception {
51        super.setUp();
52        mBackoffUnderTest = new ExponentialBackoff(
53                START_DELAY_MS, MAXIMUM_DELAY_MS, MULTIPLIER, mHandler, mRunnable);
54        mBackoffUnderTest.setHandlerAdapter(mHandlerAdapter);
55        doAnswer(invocation -> mHandler.postDelayed((Runnable) invocation.getArguments()[0],
56                        (long) invocation.getArguments()[1])
57        ).when(mHandlerAdapter).postDelayed(any(Runnable.class), anyLong());
58        doAnswer(invocation -> {
59            mHandler.removeCallbacks((Runnable) invocation.getArguments()[0]);
60            return null;
61        }).when(mHandlerAdapter).removeCallbacks(any(Runnable.class));
62    }
63
64    @After
65    public void tearDown() {
66        mBackoffUnderTest.stop();
67    }
68
69    @Test
70    public void testStartBackoff() {
71        mBackoffUnderTest.start();
72        long delay = mBackoffUnderTest.getCurrentDelay();
73        waitForHandlerActionDelayed(mHandler, delay, 2 * delay);
74
75        // The runnable is executed after timeout event occurred.
76        verify(mRunnable).run();
77    }
78
79    @Test
80    public void testStopBackoff() {
81        mBackoffUnderTest.start();
82
83        mBackoffUnderTest.stop();
84        // removeCallbacks is called during start() and stop()
85        verify(mHandlerAdapter, times(2)).removeCallbacks(mRunnable);
86    }
87
88    @Test
89    public void testDelayIncreasedExponentially() {
90        mBackoffUnderTest.start();
91        // guarantee START_DELAY_MS * 2 ^ i <= MAXIMUM_DELAY_MS
92        for (int i = 1; i < 5; i++) {
93            mBackoffUnderTest.notifyFailed();
94            long delay = mBackoffUnderTest.getCurrentDelay();
95            long minDelay = (long) (START_DELAY_MS * Math.pow(MULTIPLIER, i - 1));
96            long maxDelay = (long) (START_DELAY_MS * Math.pow(MULTIPLIER, i));
97            assertTrue("delay = " + delay + " minDelay = " + minDelay, delay >= minDelay);
98            assertTrue("delay = " + delay + " maxDelay = " + maxDelay, delay <= maxDelay);
99        }
100    }
101
102    @Test
103    public void testDelayShouldNotExceededTheMaximumLimit() {
104        mBackoffUnderTest.start();
105        // guarantee START_DELAY_MS * 2 ^ 30 > MAXIMUM_DELAY_MS
106        for (int i = 1; i < 30; i++) {
107            mBackoffUnderTest.notifyFailed();
108        }
109        long delay = mBackoffUnderTest.getCurrentDelay();
110        assertTrue(
111                "delay = " + delay + " maximumDelay = " + MAXIMUM_DELAY_MS,
112                delay <= MAXIMUM_DELAY_MS);
113    }
114}
115