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.car;
18
19import android.car.hardware.CarSensorManager;
20import android.os.IBinder;
21import java.util.LinkedList;
22
23/**
24 * This class wraps a set of listeners of a given type of event, grouped by event-transmission rate.
25 * This is logic that is common to different services that need to receive and rebroadcast events.
26 * @param  The type of event listener.
27 */
28public class Listeners<ClientType extends com.android.car.Listeners.IListener> {
29    public interface IListener extends IBinder.DeathRecipient {
30        void release();
31    }
32
33    public static class ClientWithRate<ClientType extends IListener> {
34        private final ClientType mClient;
35        /** rate requested from client */
36        private int mRate;
37
38        ClientWithRate(ClientType client, int rate) {
39            mClient = client;
40            mRate = rate;
41        }
42
43        @Override
44        public boolean equals(Object o) {
45            //TODO(egranata): is this truly necessary?
46            if (o instanceof ClientWithRate &&
47                mClient == ((ClientWithRate) o).mClient) {
48                return true;
49            }
50            return false;
51        }
52
53        @Override
54        public int hashCode() {
55            return mClient.hashCode();
56        }
57
58        int getRate() {
59            return mRate;
60        }
61
62        void setRate(int rate) {
63            mRate = rate;
64        }
65
66        ClientType getClient() {
67            return mClient;
68        }
69    }
70
71    private final LinkedList<ClientWithRate<ClientType>> mClients = new LinkedList<>();
72    /** rate sent to car */
73    private int mRate;
74
75    Listeners(int rate) {
76        mRate = rate;
77    }
78
79    int getRate() {
80        return mRate;
81    }
82
83    void setRate(int rate) {
84        mRate = rate;
85    }
86
87    /** update rate from existing clients and return true if rate is changed. */
88    boolean updateRate() {
89        //TODO(egranata): we might need to support other rate ranges
90        int fastestRate = CarSensorManager.SENSOR_RATE_NORMAL;
91        for (ClientWithRate<ClientType> clientWithRate: mClients) {
92            int clientRate = clientWithRate.getRate();
93            if (clientRate < fastestRate) {
94                fastestRate = clientRate;
95            }
96        }
97        if (mRate != fastestRate) {
98            mRate = fastestRate;
99            return true;
100        }
101        return false;
102    }
103
104    void addClientWithRate(ClientWithRate<ClientType> clientWithRate) {
105        mClients.add(clientWithRate);
106    }
107
108    void removeClientWithRate(ClientWithRate<ClientType> clientWithRate) {
109        mClients.remove(clientWithRate);
110    }
111
112    int getNumberOfClients() {
113        return mClients.size();
114    }
115
116    Iterable<ClientWithRate<ClientType>> getClients() {
117        return mClients;
118    }
119
120    ClientWithRate<ClientType> findClientWithRate(ClientType client) {
121        for (ClientWithRate<ClientType> clientWithRate: mClients) {
122            if (clientWithRate.getClient() == client) {
123                return clientWithRate;
124            }
125        }
126        return null;
127    }
128
129    void release() {
130        for (ClientWithRate<ClientType> clientWithRate: mClients) {
131            clientWithRate.getClient().release();
132        }
133        mClients.clear();
134    }
135}
136