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
19import android.util.Slog;
20
21import com.google.android.collect.Maps;
22
23import java.util.HashMap;
24import java.util.concurrent.TimeoutException;
25
26/**
27 * Controls and utilities for low-level {@code init} services.
28 *
29 * @hide
30 */
31public class SystemService {
32
33    private static HashMap<String, State> sStates = Maps.newHashMap();
34
35    /**
36     * State of a known {@code init} service.
37     */
38    public enum State {
39        RUNNING("running"),
40        STOPPING("stopping"),
41        STOPPED("stopped"),
42        RESTARTING("restarting");
43
44        State(String state) {
45            sStates.put(state, this);
46        }
47    }
48
49    private static Object sPropertyLock = new Object();
50
51    static {
52        SystemProperties.addChangeCallback(new Runnable() {
53            @Override
54            public void run() {
55                synchronized (sPropertyLock) {
56                    sPropertyLock.notifyAll();
57                }
58            }
59        });
60    }
61
62    /** Request that the init daemon start a named service. */
63    public static void start(String name) {
64        SystemProperties.set("ctl.start", name);
65    }
66
67    /** Request that the init daemon stop a named service. */
68    public static void stop(String name) {
69        SystemProperties.set("ctl.stop", name);
70    }
71
72    /** Request that the init daemon restart a named service. */
73    public static void restart(String name) {
74        SystemProperties.set("ctl.restart", name);
75    }
76
77    /**
78     * Return current state of given service.
79     */
80    public static State getState(String service) {
81        final String rawState = SystemProperties.get("init.svc." + service);
82        final State state = sStates.get(rawState);
83        if (state != null) {
84            return state;
85        } else {
86            return State.STOPPED;
87        }
88    }
89
90    /**
91     * Check if given service is {@link State#STOPPED}.
92     */
93    public static boolean isStopped(String service) {
94        return State.STOPPED.equals(getState(service));
95    }
96
97    /**
98     * Check if given service is {@link State#RUNNING}.
99     */
100    public static boolean isRunning(String service) {
101        return State.RUNNING.equals(getState(service));
102    }
103
104    /**
105     * Wait until given service has entered specific state.
106     */
107    public static void waitForState(String service, State state, long timeoutMillis)
108            throws TimeoutException {
109        final long endMillis = SystemClock.elapsedRealtime() + timeoutMillis;
110        while (true) {
111            synchronized (sPropertyLock) {
112                final State currentState = getState(service);
113                if (state.equals(currentState)) {
114                    return;
115                }
116
117                if (SystemClock.elapsedRealtime() >= endMillis) {
118                    throw new TimeoutException("Service " + service + " currently " + currentState
119                            + "; waited " + timeoutMillis + "ms for " + state);
120                }
121
122                try {
123                    sPropertyLock.wait(timeoutMillis);
124                } catch (InterruptedException e) {
125                }
126            }
127        }
128    }
129
130    /**
131     * Wait until any of given services enters {@link State#STOPPED}.
132     */
133    public static void waitForAnyStopped(String... services)  {
134        while (true) {
135            synchronized (sPropertyLock) {
136                for (String service : services) {
137                    if (State.STOPPED.equals(getState(service))) {
138                        return;
139                    }
140                }
141
142                try {
143                    sPropertyLock.wait();
144                } catch (InterruptedException e) {
145                }
146            }
147        }
148    }
149}
150