Add more behavior to TimeDetectorService (4980bbcd) · Commits · e / os / android_frameworks_base

core/java/android/util/TimestampedValue.java

+8 −0

Original line number	Diff line number	Diff line
		@@ -126,4 +126,12 @@ public final class TimestampedValue<T> {
		dest.writeLong(timestampedValue.mReferenceTimeMillis);
		dest.writeValue(timestampedValue.mValue);
		}

		/**
		* Returns the difference in milliseconds between two instance's reference times.
		*/
		public static long referenceTimeDifference(
		@NonNull TimestampedValue<?> one, @NonNull TimestampedValue<?> two) {
		return one.mReferenceTimeMillis - two.mReferenceTimeMillis;
		}
		}

core/tests/coretests/src/android/util/TimestampedValueTest.java

+10 −0

Original line number	Diff line number	Diff line
		@@ -116,4 +116,14 @@ public class TimestampedValueTest {
		parcel.recycle();
		}
		}

		@Test
		public void testReferenceTimeDifference() {
		TimestampedValue<Long> value1 = new TimestampedValue<>(1000, 123L);
		assertEquals(0, TimestampedValue.referenceTimeDifference(value1, value1));

		TimestampedValue<Long> value2 = new TimestampedValue<>(1, 321L);
		assertEquals(999, TimestampedValue.referenceTimeDifference(value1, value2));
		assertEquals(-999, TimestampedValue.referenceTimeDifference(value2, value1));
		}
		}

services/core/java/com/android/server/timedetector/SimpleTimeDetectorStrategy.java

+184 −9

Original line number	Diff line number	Diff line
		@@ -20,38 +20,213 @@ import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.app.AlarmManager;
		import android.app.timedetector.TimeSignal;
		import android.content.Intent;
		import android.util.Slog;
		import android.util.TimestampedValue;

		import com.android.internal.telephony.TelephonyIntents;

		import java.io.FileDescriptor;
		import java.io.PrintWriter;

		/**
		* A placeholder implementation of TimeDetectorStrategy that passes NITZ suggestions immediately
		* to {@link AlarmManager}.
		* An implementation of TimeDetectorStrategy that passes only NITZ suggestions to
		* {@link AlarmManager}. The TimeDetectorService handles thread safety: all calls to
		* this class can be assumed to be single threaded (though the thread used may vary).
		*/
		// @NotThreadSafe
		public final class SimpleTimeDetectorStrategy implements TimeDetectorStrategy {

		private final static String TAG = "timedetector.SimpleTimeDetectorStrategy";

		private Callback mHelper;
		/**
		* CLOCK_PARANOIA: The maximum difference allowed between the expected system clock time and the
		* actual system clock time before a warning is logged. Used to help identify situations where
		* there is something other than this class setting the system clock.
		*/
		private static final long SYSTEM_CLOCK_PARANOIA_THRESHOLD_MILLIS = 2 * 1000;

		// @NonNull after initialize()
		private Callback mCallback;

		// NITZ state.
		@Nullable private TimestampedValue<Long> mLastNitzTime;


		// Information about the last time signal received: Used when toggling auto-time.
		@Nullable private TimestampedValue<Long> mLastSystemClockTime;
		private boolean mLastSystemClockTimeSendNetworkBroadcast;

		// System clock state.
		@Nullable private TimestampedValue<Long> mLastSystemClockTimeSet;

		@Override
		public void initialize(@NonNull Callback callback) {
		mHelper = callback;
		mCallback = callback;
		}

		@Override
		public void suggestTime(@NonNull TimeSignal timeSignal) {
		if (!TimeSignal.SOURCE_ID_NITZ.equals(timeSignal.getSourceId())) {
		Slog.w(TAG, "Ignoring signal from unknown source: " + timeSignal);
		Slog.w(TAG, "Ignoring signal from unsupported source: " + timeSignal);
		return;
		}

		mHelper.setTime(timeSignal.getUtcTime());
		// NITZ logic

		TimestampedValue<Long> newNitzUtcTime = timeSignal.getUtcTime();
		boolean nitzTimeIsValid = validateNewNitzTime(newNitzUtcTime, mLastNitzTime);
		if (!nitzTimeIsValid) {
		return;
		}
		// Always store the last NITZ value received, regardless of whether we go on to use it to
		// update the system clock. This is so that we can validate future NITZ signals.
		mLastNitzTime = newNitzUtcTime;

		// System clock update logic.

		// Historically, Android has sent a telephony broadcast only when setting the time using
		// NITZ.
		final boolean sendNetworkBroadcast =
		TimeSignal.SOURCE_ID_NITZ.equals(timeSignal.getSourceId());

		final TimestampedValue<Long> newUtcTime = newNitzUtcTime;
		setSystemClockIfRequired(newUtcTime, sendNetworkBroadcast);
		}

		private static boolean validateNewNitzTime(TimestampedValue<Long> newNitzUtcTime,
		TimestampedValue<Long> lastNitzTime) {

		if (lastNitzTime != null) {
		long referenceTimeDifference =
		TimestampedValue.referenceTimeDifference(newNitzUtcTime, lastNitzTime);
		if (referenceTimeDifference < 0 \|\| referenceTimeDifference > Integer.MAX_VALUE) {
		// Out of order or bogus.
		Slog.w(TAG, "validateNewNitzTime: Bad NITZ signal received."
		+ " referenceTimeDifference=" + referenceTimeDifference
		+ " lastNitzTime=" + lastNitzTime
		+ " newNitzUtcTime=" + newNitzUtcTime);
		return false;
		}
		}
		return true;
		}

		private void setSystemClockIfRequired(
		TimestampedValue<Long> time, boolean sendNetworkBroadcast) {

		// Store the last candidate we've seen in all cases so we can set the system clock
		// when/if time detection is enabled.
		mLastSystemClockTime = time;
		mLastSystemClockTimeSendNetworkBroadcast = sendNetworkBroadcast;

		if (!mCallback.isTimeDetectionEnabled()) {
		Slog.d(TAG, "setSystemClockIfRequired: Time detection is not enabled. time=" + time);
		return;
		}

		mCallback.acquireWakeLock();
		try {
		long elapsedRealtimeMillis = mCallback.elapsedRealtimeMillis();
		long actualTimeMillis = mCallback.systemClockMillis();

		// CLOCK_PARANOIA : Check to see if this class owns the clock or if something else
		// may be setting the clock.
		if (mLastSystemClockTimeSet != null) {
		long expectedTimeMillis = TimeDetectorStrategy.getTimeAt(
		mLastSystemClockTimeSet, elapsedRealtimeMillis);
		long absSystemClockDifference = Math.abs(expectedTimeMillis - actualTimeMillis);
		if (absSystemClockDifference > SYSTEM_CLOCK_PARANOIA_THRESHOLD_MILLIS) {
		Slog.w(TAG, "System clock has not tracked elapsed real time clock. A clock may"
		+ " be inaccurate or something unexpectedly set the system clock."
		+ " elapsedRealtimeMillis=" + elapsedRealtimeMillis
		+ " expectedTimeMillis=" + expectedTimeMillis
		+ " actualTimeMillis=" + actualTimeMillis);
		}
		}

		final String reason = "New time signal";
		adjustAndSetDeviceSystemClock(
		time, sendNetworkBroadcast, elapsedRealtimeMillis, actualTimeMillis, reason);
		} finally {
		mCallback.releaseWakeLock();
		}
		}

		@Override
		public void handleAutoTimeDetectionToggle(boolean enabled) {
		// If automatic time detection is enabled we update the system clock instantly if we can.
		// Conversely, if automatic time detection is disabled we leave the clock as it is.
		if (enabled) {
		if (mLastSystemClockTime != null) {
		// Only send the network broadcast if the last candidate would have caused one.
		final boolean sendNetworkBroadcast = mLastSystemClockTimeSendNetworkBroadcast;

		mCallback.acquireWakeLock();
		try {
		long elapsedRealtimeMillis = mCallback.elapsedRealtimeMillis();
		long actualTimeMillis = mCallback.systemClockMillis();

		final String reason = "Automatic time detection enabled.";
		adjustAndSetDeviceSystemClock(mLastSystemClockTime, sendNetworkBroadcast,
		elapsedRealtimeMillis, actualTimeMillis, reason);
		} finally {
		mCallback.releaseWakeLock();
		}
		}
		} else {
		// CLOCK_PARANOIA: We are losing "control" of the system clock so we cannot predict what
		// it should be in future.
		mLastSystemClockTimeSet = null;
		}
		}

		@Override
		public void dump(@NonNull FileDescriptor fd, @NonNull PrintWriter pw, @Nullable String[] args) {
		// No state to dump.
		public void dump(@NonNull PrintWriter pw, @Nullable String[] args) {
		pw.println("mLastNitzTime=" + mLastNitzTime);
		pw.println("mLastSystemClockTimeSet=" + mLastSystemClockTimeSet);
		pw.println("mLastSystemClockTime=" + mLastSystemClockTime);
		pw.println("mLastSystemClockTimeSendNetworkBroadcast="
		+ mLastSystemClockTimeSendNetworkBroadcast);
		}

		private void adjustAndSetDeviceSystemClock(
		TimestampedValue<Long> newTime, boolean sendNetworkBroadcast,
		long elapsedRealtimeMillis, long actualSystemClockMillis, String reason) {

		// Adjust for the time that has elapsed since the signal was received.
		long newSystemClockMillis = TimeDetectorStrategy.getTimeAt(newTime, elapsedRealtimeMillis);

		// Check if the new signal would make sufficient difference to the system clock. If it's
		// below the threshold then ignore it.
		long absTimeDifference = Math.abs(newSystemClockMillis - actualSystemClockMillis);
		long systemClockUpdateThreshold = mCallback.systemClockUpdateThresholdMillis();
		if (absTimeDifference < systemClockUpdateThreshold) {
		Slog.d(TAG, "adjustAndSetDeviceSystemClock: Not setting system clock. New time and"
		+ " system clock are close enough."
		+ " elapsedRealtimeMillis=" + elapsedRealtimeMillis
		+ " newTime=" + newTime
		+ " reason=" + reason
		+ " systemClockUpdateThreshold=" + systemClockUpdateThreshold
		+ " absTimeDifference=" + absTimeDifference);
		return;
		}

		Slog.d(TAG, "Setting system clock using time=" + newTime
		+ " reason=" + reason
		+ " elapsedRealtimeMillis=" + elapsedRealtimeMillis
		+ " newTimeMillis=" + newSystemClockMillis);
		mCallback.setSystemClock(newSystemClockMillis);

		// CLOCK_PARANOIA : Record the last time this class set the system clock.
		mLastSystemClockTimeSet = newTime;

		if (sendNetworkBroadcast) {
		// Send a broadcast that telephony code used to send after setting the clock.
		// TODO Remove this broadcast as soon as there are no remaining listeners.
		Intent intent = new Intent(TelephonyIntents.ACTION_NETWORK_SET_TIME);
		intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING);
		intent.putExtra("time", newSystemClockMillis);
		mCallback.sendStickyBroadcast(intent);
		}
		}
		}

services/core/java/com/android/server/timedetector/TimeDetectorService.java

+54 −13

Original line number	Diff line number	Diff line
		@@ -20,24 +20,29 @@ import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.app.timedetector.ITimeDetectorService;
		import android.app.timedetector.TimeSignal;
		import android.content.ContentResolver;
		import android.content.Context;
		import android.database.ContentObserver;
		import android.os.Binder;
		import android.provider.Settings;

		import com.android.internal.annotations.GuardedBy;
		import com.android.internal.annotations.VisibleForTesting;
		import com.android.internal.util.DumpUtils;
		import com.android.server.FgThread;
		import com.android.server.SystemService;
		import com.android.server.timedetector.TimeDetectorStrategy.Callback;

		import java.io.FileDescriptor;
		import java.io.PrintWriter;
		import java.util.Objects;

		public final class TimeDetectorService extends ITimeDetectorService.Stub {

		private static final String TAG = "timedetector.TimeDetectorService";

		public static class Lifecycle extends SystemService {

		public Lifecycle(Context context) {
		public Lifecycle(@NonNull Context context) {
		super(context);
		}

		@@ -51,31 +56,65 @@ public final class TimeDetectorService extends ITimeDetectorService.Stub {
		}
		}

		private final Context mContext;
		private final TimeDetectorStrategy mTimeDetectorStrategy;
		@NonNull private final Context mContext;
		@NonNull private final Callback mCallback;

		// The lock used when call the strategy to ensure thread safety.
		@NonNull private final Object mStrategyLock = new Object();

		@GuardedBy("mStrategyLock")
		@NonNull private final TimeDetectorStrategy mTimeDetectorStrategy;

		private static TimeDetectorService create(@NonNull Context context) {
		final TimeDetectorStrategy timeDetector = new SimpleTimeDetectorStrategy();
		final TimeDetectorStrategyCallbackImpl callback =
		new TimeDetectorStrategyCallbackImpl(context);
		timeDetector.initialize(callback);

		TimeDetectorService timeDetectorService =
		new TimeDetectorService(context, callback, timeDetector);

		// Wire up event listening.
		ContentResolver contentResolver = context.getContentResolver();
		contentResolver.registerContentObserver(
		Settings.Global.getUriFor(Settings.Global.AUTO_TIME), true,
		new ContentObserver(FgThread.getHandler()) {
		public void onChange(boolean selfChange) {
		timeDetectorService.handleAutoTimeDetectionToggle();
		}
		});

		private static TimeDetectorService create(Context context) {
		TimeDetectorStrategy timeDetector = new SimpleTimeDetectorStrategy();
		timeDetector.initialize(new TimeDetectorStrategyCallbackImpl(context));
		return new TimeDetectorService(context, timeDetector);
		return timeDetectorService;
		}

		@VisibleForTesting
		public TimeDetectorService(@NonNull Context context,
		public TimeDetectorService(@NonNull Context context, @NonNull Callback callback,
		@NonNull TimeDetectorStrategy timeDetectorStrategy) {
		mContext = Objects.requireNonNull(context);
		mCallback = Objects.requireNonNull(callback);
		mTimeDetectorStrategy = Objects.requireNonNull(timeDetectorStrategy);
		}

		@Override
		public void suggestTime(@NonNull TimeSignal timeSignal) {
		enforceSetTimePermission();
		Objects.requireNonNull(timeSignal);

		long callerIdToken = Binder.clearCallingIdentity();
		long idToken = Binder.clearCallingIdentity();
		try {
		synchronized (mStrategyLock) {
		mTimeDetectorStrategy.suggestTime(timeSignal);
		}
		} finally {
		Binder.restoreCallingIdentity(callerIdToken);
		Binder.restoreCallingIdentity(idToken);
		}
		}

		@VisibleForTesting
		public void handleAutoTimeDetectionToggle() {
		synchronized (mStrategyLock) {
		final boolean timeDetectionEnabled = mCallback.isTimeDetectionEnabled();
		mTimeDetectorStrategy.handleAutoTimeDetectionToggle(timeDetectionEnabled);
		}
		}

		@@ -84,7 +123,9 @@ public final class TimeDetectorService extends ITimeDetectorService.Stub {
		@Nullable String[] args) {
		if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;

		mTimeDetectorStrategy.dump(fd, pw, args);
		synchronized (mStrategyLock) {
		mTimeDetectorStrategy.dump(pw, args);
		}
		}

		private void enforceSetTimePermission() {

services/core/java/com/android/server/timedetector/TimeDetectorStrategy.java

+44 −4

Original line number	Diff line number	Diff line
		@@ -19,26 +19,66 @@ package com.android.server.timedetector;
		import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.app.timedetector.TimeSignal;
		import android.content.Intent;
		import android.util.TimestampedValue;

		import java.io.FileDescriptor;
		import java.io.PrintWriter;

		/**
		* The interface for classes that implement the time detection algorithm used by the
		* TimeDetectorService.
		* TimeDetectorService. The TimeDetectorService handles thread safety: all calls to implementations
		* of this interface can be assumed to be single threaded (though the thread used may vary).
		*
		* @hide
		*/
		// @NotThreadSafe
		public interface TimeDetectorStrategy {

		/**
		* The interface used by the strategy to interact with the surrounding service.
		*/
		interface Callback {
		void setTime(TimestampedValue<Long> time);

		/**
		* The absolute threshold below which the system clock need not be updated. i.e. if setting
		* the system clock would adjust it by less than this (either backwards or forwards) then it
		* need not be set.
		*/
		int systemClockUpdateThresholdMillis();

		/** Returns true if automatic time detection is enabled. */
		boolean isTimeDetectionEnabled();

		/** Acquire a suitable wake lock. Must be followed by {@link #releaseWakeLock()} */
		void acquireWakeLock();

		/** Returns the elapsedRealtimeMillis clock value. The WakeLock must be held. */
		long elapsedRealtimeMillis();

		/** Returns the system clock value. The WakeLock must be held. */
		long systemClockMillis();

		/** Sets the device system clock. The WakeLock must be held. */
		void setSystemClock(long newTimeMillis);

		/** Release the wake lock acquired by a call to {@link #acquireWakeLock()}. */
		void releaseWakeLock();

		/** Send the supplied intent as a stick broadcast. */
		void sendStickyBroadcast(@NonNull Intent intent);
		}

		/** Initialize the strategy. */
		void initialize(@NonNull Callback callback);

		/** Process the suggested time. */
		void suggestTime(@NonNull TimeSignal timeSignal);
		void dump(@NonNull FileDescriptor fd, @NonNull PrintWriter pw, @Nullable String[] args);

		/** Handle the auto-time setting being toggled on or off. */
		void handleAutoTimeDetectionToggle(boolean enabled);

		/** Dump debug information. */
		void dump(@NonNull PrintWriter pw, @Nullable String[] args);

		// Utility methods below are to be moved to a better home when one becomes more obvious.