6734b9f680
Do this on a periodic basis as well as when the AUTO_TIME setting changes to true. If we recently acquired NITZ time from the telephony provider, then don't override with NTP time.
298 lines
11 KiB
Java
298 lines
11 KiB
Java
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server;
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import com.android.internal.telephony.TelephonyIntents;
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import android.app.AlarmManager;
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import android.app.PendingIntent;
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import android.content.BroadcastReceiver;
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import android.content.ContentResolver;
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import android.content.Context;
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import android.content.Intent;
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import android.content.IntentFilter;
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import android.database.ContentObserver;
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import android.net.SntpClient;
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import android.os.Handler;
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import android.os.HandlerThread;
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import android.os.Looper;
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import android.os.Message;
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import android.os.SystemClock;
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import android.provider.Settings;
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import android.util.Log;
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import android.util.Slog;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.util.Properties;
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/**
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* Monitors the network time and updates the system time if it is out of sync
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* and there hasn't been any NITZ update from the carrier recently.
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* If looking up the network time fails for some reason, it tries a few times with a short
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* interval and then resets to checking on longer intervals.
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* <p>
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* If the user enables AUTO_TIME, it will check immediately for the network time, if NITZ wasn't
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* available.
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* </p>
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*/
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public class NetworkTimeUpdateService {
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private static final String TAG = "NetworkTimeUpdateService";
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private static final boolean DBG = false;
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private static final int EVENT_AUTO_TIME_CHANGED = 1;
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private static final int EVENT_POLL_NETWORK_TIME = 2;
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/** Normal polling frequency */
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private static final long POLLING_INTERVAL_MS = 24L * 60 * 60 * 1000; // 24 hrs
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/** Try-again polling interval, in case the network request failed */
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private static final long POLLING_INTERVAL_SHORTER_MS = 60 * 1000L; // 60 seconds
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/** Number of times to try again */
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private static final int TRY_AGAIN_TIMES_MAX = 3;
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/** How long to wait for the NTP server to respond. */
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private static final int MAX_NTP_FETCH_WAIT_MS = 20 * 1000;
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/** If the time difference is greater than this threshold, then update the time. */
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private static final int TIME_ERROR_THRESHOLD_MS = 5 * 1000;
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private static final String ACTION_POLL =
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"com.android.server.NetworkTimeUpdateService.action.POLL";
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private static final String PROPERTIES_FILE = "/etc/gps.conf";
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private static int POLL_REQUEST = 0;
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private static final long NOT_SET = -1;
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private long mNitzTimeSetTime = NOT_SET;
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// TODO: Have a way to look up the timezone we are in
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private long mNitzZoneSetTime = NOT_SET;
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private Context mContext;
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// NTP lookup is done on this thread and handler
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private Handler mHandler;
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private HandlerThread mThread;
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private AlarmManager mAlarmManager;
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private PendingIntent mPendingPollIntent;
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private SettingsObserver mSettingsObserver;
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// Address of the NTP server
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private String mNtpServer;
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// The last time that we successfully fetched the NTP time.
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private long mLastNtpFetchTime = NOT_SET;
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// Keeps track of how many quick attempts were made to fetch NTP time.
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// During bootup, the network may not have been up yet, or it's taking time for the
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// connection to happen.
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private int mTryAgainCounter;
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public NetworkTimeUpdateService(Context context) {
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mContext = context;
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mAlarmManager = (AlarmManager) mContext.getSystemService(Context.ALARM_SERVICE);
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Intent pollIntent = new Intent(ACTION_POLL, null);
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mPendingPollIntent = PendingIntent.getBroadcast(mContext, POLL_REQUEST, pollIntent, 0);
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}
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/** Initialize the receivers and initiate the first NTP request */
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public void systemReady() {
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mNtpServer = getNtpServerAddress();
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if (mNtpServer == null) {
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Slog.e(TAG, "NTP server address not found, not syncing to NTP time");
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return;
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}
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registerForTelephonyIntents();
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registerForAlarms();
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mThread = new HandlerThread(TAG);
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mThread.start();
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mHandler = new MyHandler(mThread.getLooper());
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// Check the network time on the new thread
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mHandler.obtainMessage(EVENT_POLL_NETWORK_TIME).sendToTarget();
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mSettingsObserver = new SettingsObserver(mHandler, EVENT_AUTO_TIME_CHANGED);
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mSettingsObserver.observe(mContext);
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}
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private String getNtpServerAddress() {
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String serverAddress = null;
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FileInputStream stream = null;
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try {
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Properties properties = new Properties();
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File file = new File(PROPERTIES_FILE);
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stream = new FileInputStream(file);
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properties.load(stream);
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serverAddress = properties.getProperty("NTP_SERVER", null);
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} catch (IOException e) {
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Slog.e(TAG, "Could not open GPS configuration file " + PROPERTIES_FILE);
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} finally {
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if (stream != null) {
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try {
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stream.close();
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} catch (Exception e) {}
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}
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}
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return serverAddress;
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}
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private void registerForTelephonyIntents() {
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IntentFilter intentFilter = new IntentFilter();
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intentFilter.addAction(TelephonyIntents.ACTION_NETWORK_SET_TIME);
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intentFilter.addAction(TelephonyIntents.ACTION_NETWORK_SET_TIMEZONE);
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mContext.registerReceiver(mNitzReceiver, intentFilter);
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}
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private void registerForAlarms() {
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mContext.registerReceiver(
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new BroadcastReceiver() {
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@Override
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public void onReceive(Context context, Intent intent) {
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mHandler.obtainMessage(EVENT_POLL_NETWORK_TIME).sendToTarget();
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}
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}, new IntentFilter(ACTION_POLL));
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}
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private void onPollNetworkTime(int event) {
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// If Automatic time is not set, don't bother.
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if (!isAutomaticTimeRequested()) return;
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final long refTime = SystemClock.elapsedRealtime();
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// If NITZ time was received less than POLLING_INTERVAL_MS time ago,
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// no need to sync to NTP.
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if (mNitzTimeSetTime != NOT_SET && refTime - mNitzTimeSetTime < POLLING_INTERVAL_MS) {
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resetAlarm(POLLING_INTERVAL_MS);
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return;
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}
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final long currentTime = System.currentTimeMillis();
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if (DBG) Log.d(TAG, "System time = " + currentTime);
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// Get the NTP time
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if (mLastNtpFetchTime == NOT_SET || refTime >= mLastNtpFetchTime + POLLING_INTERVAL_MS
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|| event == EVENT_AUTO_TIME_CHANGED) {
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if (DBG) Log.d(TAG, "Before Ntp fetch");
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long ntp = getNtpTime();
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if (DBG) Log.d(TAG, "Ntp = " + ntp);
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if (ntp > 0) {
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mTryAgainCounter = 0;
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mLastNtpFetchTime = SystemClock.elapsedRealtime();
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if (Math.abs(ntp - currentTime) > TIME_ERROR_THRESHOLD_MS) {
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// Set the system time
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if (DBG) Log.d(TAG, "Ntp time to be set = " + ntp);
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// Make sure we don't overflow, since it's going to be converted to an int
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if (ntp / 1000 < Integer.MAX_VALUE) {
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SystemClock.setCurrentTimeMillis(ntp);
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}
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} else {
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if (DBG) Log.d(TAG, "Ntp time is close enough = " + ntp);
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}
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} else {
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// Try again shortly
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mTryAgainCounter++;
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if (mTryAgainCounter <= TRY_AGAIN_TIMES_MAX) {
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resetAlarm(POLLING_INTERVAL_SHORTER_MS);
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} else {
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// Try much later
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mTryAgainCounter = 0;
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resetAlarm(POLLING_INTERVAL_MS);
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}
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return;
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}
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}
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resetAlarm(POLLING_INTERVAL_MS);
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}
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/**
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* Cancel old alarm and starts a new one for the specified interval.
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*
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* @param interval when to trigger the alarm, starting from now.
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*/
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private void resetAlarm(long interval) {
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mAlarmManager.cancel(mPendingPollIntent);
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long now = SystemClock.elapsedRealtime();
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long next = now + interval;
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mAlarmManager.set(AlarmManager.ELAPSED_REALTIME, next, mPendingPollIntent);
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}
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private long getNtpTime() {
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SntpClient client = new SntpClient();
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if (client.requestTime(mNtpServer, MAX_NTP_FETCH_WAIT_MS)) {
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return client.getNtpTime();
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} else {
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return 0;
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}
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}
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/**
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* Checks if the user prefers to automatically set the time.
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*/
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private boolean isAutomaticTimeRequested() {
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return Settings.System.getInt(mContext.getContentResolver(), Settings.System.AUTO_TIME, 0)
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!= 0;
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}
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/** Receiver for Nitz time events */
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private BroadcastReceiver mNitzReceiver = new BroadcastReceiver() {
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@Override
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public void onReceive(Context context, Intent intent) {
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String action = intent.getAction();
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if (TelephonyIntents.ACTION_NETWORK_SET_TIME.equals(action)) {
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mNitzTimeSetTime = SystemClock.elapsedRealtime();
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} else if (TelephonyIntents.ACTION_NETWORK_SET_TIMEZONE.equals(action)) {
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mNitzZoneSetTime = SystemClock.elapsedRealtime();
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}
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}
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};
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/** Handler to do the network accesses on */
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private class MyHandler extends Handler {
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public MyHandler(Looper l) {
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super(l);
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}
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@Override
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public void handleMessage(Message msg) {
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switch (msg.what) {
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case EVENT_AUTO_TIME_CHANGED:
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case EVENT_POLL_NETWORK_TIME:
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onPollNetworkTime(msg.what);
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break;
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}
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}
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}
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/** Observer to watch for changes to the AUTO_TIME setting */
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private static class SettingsObserver extends ContentObserver {
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private int mMsg;
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private Handler mHandler;
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SettingsObserver(Handler handler, int msg) {
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super(handler);
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mHandler = handler;
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mMsg = msg;
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}
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void observe(Context context) {
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ContentResolver resolver = context.getContentResolver();
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resolver.registerContentObserver(Settings.System.getUriFor(Settings.System.AUTO_TIME),
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false, this);
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}
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@Override
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public void onChange(boolean selfChange) {
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mHandler.obtainMessage(mMsg).sendToTarget();
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}
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}
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}
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