/*
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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 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.ConnectivityManager;
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import android.net.ConnectivityManager.NetworkCallback;
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import android.net.Network;
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import android.os.Binder;
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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.PowerManager;
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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.NtpTrustedTime;
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import android.util.TimeUtils;
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import com.android.internal.telephony.TelephonyIntents;
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import com.android.internal.util.DumpUtils;
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import java.io.FileDescriptor;
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import java.io.PrintWriter;
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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 OldNetworkTimeUpdateService extends Binder implements 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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private static final int EVENT_NETWORK_CHANGED = 3;
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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 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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private Network mDefaultNetwork = null;
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private final Context mContext;
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private final NtpTrustedTime mTime;
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private final AlarmManager mAlarmManager;
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private final ConnectivityManager mCM;
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private final PendingIntent mPendingPollIntent;
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private final PowerManager.WakeLock mWakeLock;
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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 SettingsObserver mSettingsObserver;
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private NetworkTimeUpdateCallback mNetworkTimeUpdateCallback;
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// Normal polling frequency
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private final long mPollingIntervalMs;
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// Try-again polling interval, in case the network request failed
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private final long mPollingIntervalShorterMs;
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// Number of times to try again
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private final int mTryAgainTimesMax;
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// If the time difference is greater than this threshold, then update the time.
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private final int mTimeErrorThresholdMs;
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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 OldNetworkTimeUpdateService(Context context) {
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mContext = context;
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mTime = NtpTrustedTime.getInstance(context);
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mAlarmManager = mContext.getSystemService(AlarmManager.class);
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mCM = mContext.getSystemService(ConnectivityManager.class);
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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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mPollingIntervalMs = mContext.getResources().getInteger(
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com.android.internal.R.integer.config_ntpPollingInterval);
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mPollingIntervalShorterMs = mContext.getResources().getInteger(
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com.android.internal.R.integer.config_ntpPollingIntervalShorter);
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mTryAgainTimesMax = mContext.getResources().getInteger(
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com.android.internal.R.integer.config_ntpRetry);
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mTimeErrorThresholdMs = mContext.getResources().getInteger(
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com.android.internal.R.integer.config_ntpThreshold);
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mWakeLock = context.getSystemService(PowerManager.class).newWakeLock(
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PowerManager.PARTIAL_WAKE_LOCK, TAG);
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}
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@Override
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public void systemRunning() {
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registerForTelephonyIntents();
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registerForAlarms();
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HandlerThread thread = new HandlerThread(TAG);
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thread.start();
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mHandler = new MyHandler(thread.getLooper());
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mNetworkTimeUpdateCallback = new NetworkTimeUpdateCallback();
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mCM.registerDefaultNetworkCallback(mNetworkTimeUpdateCallback, mHandler);
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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 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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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. Similarly, if we don't
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// have any default network, don't bother.
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if (mDefaultNetwork == null) return;
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mWakeLock.acquire();
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try {
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onPollNetworkTimeUnderWakeLock(event);
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} finally {
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mWakeLock.release();
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}
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}
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private void onPollNetworkTimeUnderWakeLock(int event) {
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// Force an NTP fix when outdated
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if (mTime.getCacheAge() >= mPollingIntervalMs) {
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if (DBG) Log.d(TAG, "Stale NTP fix; forcing refresh");
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mTime.forceRefresh();
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}
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if (mTime.getCacheAge() < mPollingIntervalMs) {
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// Obtained fresh fix; schedule next normal update
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resetAlarm(mPollingIntervalMs);
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if (isAutomaticTimeRequested()) {
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updateSystemClock(event);
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}
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} else {
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// No fresh fix; schedule retry
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mTryAgainCounter++;
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if (mTryAgainTimesMax < 0 || mTryAgainCounter <= mTryAgainTimesMax) {
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resetAlarm(mPollingIntervalShorterMs);
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} else {
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// Try much later
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mTryAgainCounter = 0;
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resetAlarm(mPollingIntervalMs);
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}
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}
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}
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private long getNitzAge() {
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if (mNitzTimeSetTime == NOT_SET) {
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return Long.MAX_VALUE;
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} else {
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return SystemClock.elapsedRealtime() - mNitzTimeSetTime;
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}
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}
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/**
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* Consider updating system clock based on current NTP fix, if requested by
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* user, significant enough delta, and we don't have a recent NITZ.
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*/
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private void updateSystemClock(int event) {
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final boolean forceUpdate = (event == EVENT_AUTO_TIME_CHANGED);
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if (!forceUpdate) {
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if (getNitzAge() < mPollingIntervalMs) {
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if (DBG) Log.d(TAG, "Ignoring NTP update due to recent NITZ");
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return;
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}
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final long skew = Math.abs(mTime.currentTimeMillis() - System.currentTimeMillis());
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if (skew < mTimeErrorThresholdMs) {
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if (DBG) Log.d(TAG, "Ignoring NTP update due to low skew");
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return;
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}
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}
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SystemClock.setCurrentTimeMillis(mTime.currentTimeMillis());
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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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/**
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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.Global.getInt(
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mContext.getContentResolver(), Settings.Global.AUTO_TIME, 0) != 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 (DBG) Log.d(TAG, "Received " + action);
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if (TelephonyIntents.ACTION_NETWORK_SET_TIME.equals(action)) {
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mNitzTimeSetTime = 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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case EVENT_NETWORK_CHANGED:
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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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private class NetworkTimeUpdateCallback extends NetworkCallback {
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@Override
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public void onAvailable(Network network) {
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Log.d(TAG, String.format("New default network %s; checking time.", network));
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mDefaultNetwork = network;
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// Running on mHandler so invoke directly.
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onPollNetworkTime(EVENT_NETWORK_CHANGED);
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}
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@Override
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public void onLost(Network network) {
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if (network.equals(mDefaultNetwork)) mDefaultNetwork = null;
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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.Global.getUriFor(Settings.Global.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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@Override
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protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
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if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
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pw.print("PollingIntervalMs: ");
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TimeUtils.formatDuration(mPollingIntervalMs, pw);
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pw.print("\nPollingIntervalShorterMs: ");
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TimeUtils.formatDuration(mPollingIntervalShorterMs, pw);
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pw.println("\nTryAgainTimesMax: " + mTryAgainTimesMax);
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pw.print("TimeErrorThresholdMs: ");
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TimeUtils.formatDuration(mTimeErrorThresholdMs, pw);
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pw.println("\nTryAgainCounter: " + mTryAgainCounter);
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pw.println("NTP cache age: " + mTime.getCacheAge());
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pw.println("NTP cache certainty: " + mTime.getCacheCertainty());
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pw.println();
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}
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}
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