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Improve Location object.

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Add getElapsedRealtimeNano():

Currently Location just has getTime() and setTime() based on UTC time.
This is entirely unreliable since it is not guaranteed monotonic.
There is a lot of code that compares fix age based on deltas -
and it is all broken in the case of a system clock change. System
clock can change when switching cellular networks (and in some
cases when switching towers).

Document the meaning of getAccuracy():
It is the horizontal, 95% confidence radius.

Make some fields mandatory if they are reported by a LocationProvider:

All Locations returned by a LocationProvider must include at the
minimum a lat, long, timestamps, and accuracy. This is necessary
to perform fused location. There are no public API's for applications
to feed locations into a location provider so this should not cause
any breakage.

If a LocationProvider does not fill in enough fields on a Location
object then it is dropped, and logged.

Bug: 4305998
Change-Id: I7df77125d8a64e174d7bc8c2708661b4f33461ea
This commit is contained in:
Nick Pelly
2012-07-18 13:13:37 -07:00
parent b8acd060d4
commit 2eeeec248a
7 changed files with 137 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
api/current.txt
View File

@@ -10504,6 +10504,7 @@ package android.location {
method public float getAccuracy();
method public double getAltitude();
method public float getBearing();
method public long getElapsedRealtimeNano();
method public android.os.Bundle getExtras();
method public double getLatitude();
method public double getLongitude();
@@ -10523,6 +10524,7 @@ package android.location {
method public void setAccuracy(float);
method public void setAltitude(double);
method public void setBearing(float);
method public void setElapsedRealtimeNano(long);
method public void setExtras(android.os.Bundle);
method public void setLatitude(double);
method public void setLongitude(double);

107
location/java/android/location/Location.java
View File

@@ -19,6 +19,7 @@ package android.location;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.SystemClock;
import android.util.Printer;
import java.text.DecimalFormat;
@@ -59,6 +60,7 @@ public class Location implements Parcelable {
private String mProvider;
private long mTime = 0;
private long mElapsedRealtimeNano = 0;
private double mLatitude = 0.0;
private double mLongitude = 0.0;
private boolean mHasAltitude = false;
@@ -84,6 +86,7 @@ public class Location implements Parcelable {
public void dump(Printer pw, String prefix) {
pw.println(prefix + "mProvider=" + mProvider + " mTime=" + mTime);
pw.println(prefix + "mElapsedRealtimeNano=" + mElapsedRealtimeNano);
pw.println(prefix + "mLatitude=" + mLatitude + " mLongitude=" + mLongitude);
pw.println(prefix + "mHasAltitude=" + mHasAltitude + " mAltitude=" + mAltitude);
pw.println(prefix + "mHasSpeed=" + mHasSpeed + " mSpeed=" + mSpeed);
@@ -118,6 +121,7 @@ public class Location implements Parcelable {
public void set(Location l) {
mProvider = l.mProvider;
mTime = l.mTime;
mElapsedRealtimeNano = l.mElapsedRealtimeNano;
mLatitude = l.mLatitude;
mLongitude = l.mLongitude;
mHasAltitude = l.mHasAltitude;
@@ -137,6 +141,7 @@ public class Location implements Parcelable {
public void reset() {
mProvider = null;
mTime = 0;
mElapsedRealtimeNano = 0;
mLatitude = 0;
mLongitude = 0;
mHasAltitude = false;
@@ -467,23 +472,62 @@ public class Location implements Parcelable {
}
/**
* Returns the UTC time of this fix, in milliseconds since January 1,
* Return the UTC time of this fix, in milliseconds since January 1,
* 1970.
* <p>Note that the UTC time on a device is not monotonic: it
* can jump forwards or backwards unpredictably. So always use
* {@link #getElapsedRealtimeNano()} when calculating time deltas.
* <p>On the other hand, {@link #getTime()} is useful for presenting
* a human readable time to the user, or for carefully comparing
* location fixes across reboot or across devices.
* <p>This method will always return a valid timestamp on
* Locations generated by a {@link LocationProvider}.
*
* @return time of fix, in milliseconds since January 1, 1970.
*/
public long getTime() {
return mTime;
}
/**
* Sets the UTC time of this fix, in milliseconds since January 1,
* Set the UTC time of this fix, in milliseconds since January 1,
* 1970.
*
* @param time UTC time of this fix, in milliseconds since January 1, 1970
*/
public void setTime(long time) {
mTime = time;
}
/**
* Returns the latitude of this fix.
* Return the time of this fix, in elapsed real-time since system boot.
* <p>This value can be reliably compared to
* {@link android.os.SystemClock#elapsedRealtimeNano()},
* to calculate the age of a fix, and to compare Location fixes, since
* elapsed real-time is guaranteed monotonic for each system boot, and
* continues to increment even when the system is in deep sleep.
* <p>This method will always return a valid timestamp on
* Locations generated by a {@link LocationProvider}.
*
* @return elapsed real-time of fix, in nanoseconds since system boot.
*/
public long getElapsedRealtimeNano() {
return mElapsedRealtimeNano;
}
/**
* Set the time of this fix, in elapsed real-time since system boot.
*
* @param time elapsed real-time of fix, in nanoseconds since system boot.
*/
public void setElapsedRealtimeNano(long time) {
mElapsedRealtimeNano = time;
}
/**
* Return the latitude of this fix.
* <p>This method will always return a valid latitude on
* Locations generated by a {@link LocationProvider}.
*/
public double getLatitude() {
return mLatitude;
@@ -497,7 +541,9 @@ public class Location implements Parcelable {
}
/**
* Returns the longitude of this fix.
* Return the longitude of this fix.
* <p>This method will always return a valid longitude on
* Locations generated by a {@link LocationProvider}.
*/
public double getLongitude() {
return mLongitude;
@@ -619,16 +665,27 @@ public class Location implements Parcelable {
}
/**
* Returns true if the provider is able to report accuracy information,
* false otherwise. The default implementation returns false.
* Return true if this Location has an associated accuracy.
* <p>All Location objects generated by a {@link LocationProvider}
* will have an accuracy.
*/
public boolean hasAccuracy() {
return mHasAccuracy;
}
/**
* Returns the accuracy of the fix in meters. If hasAccuracy() is false,
* 0.0 is returned.
* Return the accuracy of this Location fix.
* <p>Accuracy is measured in meters, and indicates the
* radius of 95% confidence.
* In other words, there is a 95% probability that the
* true location is within a circle centered at the reported
* location, with radius of the reported accuracy.
* <p>This is only a measure of horizontal accuracy, and does
* not indicate the accuracy of bearing, velocity or altitude
* if those are included in this Location.
* <p>If {@link #hasAccuracy} is false, 0.0 is returned.
* <p>All Location object generated by a {@link LocationProvider}
* will have a valid accuracy.
*/
public float getAccuracy() {
return mAccuracy;
@@ -652,6 +709,37 @@ public class Location implements Parcelable {
mHasAccuracy = false;
}
/**
* Return true if this Location object has enough data set to
* be considered a valid fix from a {@link LocationProvider}.
* @see #makeComplete
* @hide
*/
public boolean isComplete() {
if (mProvider == null) return false;
if (!mHasAccuracy) return false;
if (mTime == 0) return false;
if (mElapsedRealtimeNano == 0) return false;
return true;
}
/**
* Helper to fill in incomplete fields.
* Only use this to assist in backwards compatibility
* with Location objects received from applications.
* @see #isComplete
* @hide
*/
public void makeComplete() {
if (mProvider == null) mProvider = "?";
if (!mHasAccuracy) {
mHasAccuracy = true;
mAccuracy = 100.0f;
}
if (mTime == 0) mTime = System.currentTimeMillis();
if (mElapsedRealtimeNano == 0) mElapsedRealtimeNano = SystemClock.elapsedRealtimeNano();
}
/**
* Returns additional provider-specific information about the
* location fix as a Bundle. The keys and values are determined
@@ -681,6 +769,7 @@ public class Location implements Parcelable {
@Override public String toString() {
return "Location[mProvider=" + mProvider +
",mTime=" + mTime +
",mElapsedRealtimeNano=" + mElapsedRealtimeNano +
",mLatitude=" + mLatitude +
",mLongitude=" + mLongitude +
",mHasAltitude=" + mHasAltitude +
@@ -700,6 +789,7 @@ public class Location implements Parcelable {
String provider = in.readString();
Location l = new Location(provider);
l.mTime = in.readLong();
l.mElapsedRealtimeNano = in.readLong();
l.mLatitude = in.readDouble();
l.mLongitude = in.readDouble();
l.mHasAltitude = in.readInt() != 0;
@@ -726,6 +816,7 @@ public class Location implements Parcelable {
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeString(mProvider);
parcel.writeLong(mTime);
parcel.writeLong(mElapsedRealtimeNano);
parcel.writeDouble(mLatitude);
parcel.writeDouble(mLongitude);
parcel.writeInt(mHasAltitude ? 1 : 0);

21
location/java/android/location/LocationManager.java
View File

@@ -19,11 +19,13 @@ package android.location;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Looper;
import android.os.RemoteException;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.Log;
import com.android.internal.location.DummyLocationProvider;
@@ -1220,8 +1222,11 @@ public class LocationManager {
}
/**
* Sets a mock location for the given provider. This location will be used in place
* of any actual location from the provider.
* Sets a mock location for the given provider.
* <p>This location will be used in place of any actual location from the provider.
* The location object must have a minimum number of fields set to be
* considered a valid LocationProvider Location, as per documentation
* on {@link Location} class.
*
* @param provider the provider name
* @param loc the mock location
@@ -1230,8 +1235,20 @@ public class LocationManager {
* or the {@link android.provider.Settings.Secure#ALLOW_MOCK_LOCATION
* Settings.Secure.ALLOW_MOCK_LOCATION}} system setting is not enabled
* @throws IllegalArgumentException if no provider with the given name exists
* @throws IllegalArgumentException if the location is incomplete
*/
public void setTestProviderLocation(String provider, Location loc) {
if (!loc.isComplete()) {
if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN) {
// for backwards compatibility, allow mock locations that are incomplete
Log.w(TAG, "Incomplete Location object", new Throwable());
loc.makeComplete();
} else {
throw new IllegalArgumentException(
"Location object not complete. Missing timestamps or accuracy?");
}
}
try {
mService.setTestProviderLocation(provider, loc);
} catch (RemoteException ex) {

8
services/java/com/android/server/LocationManagerService.java
View File

@@ -1532,6 +1532,11 @@ public class LocationManagerService extends ILocationManager.Stub implements Run
throw new SecurityException("Requires INSTALL_LOCATION_PROVIDER permission");
}
if (!location.isComplete()) {
Log.w(TAG, "Dropping incomplete location: " + location);
return;
}
mLocationHandler.removeMessages(MESSAGE_LOCATION_CHANGED, location);
Message m = Message.obtain(mLocationHandler, MESSAGE_LOCATION_CHANGED, location);
m.arg1 = (passive ? 1 : 0);
@@ -1588,7 +1593,8 @@ public class LocationManagerService extends ILocationManager.Stub implements Run
// Check whether sufficient time has passed
long minTime = record.mMinTime;
if (loc.getTime() - lastLoc.getTime() < minTime - MAX_PROVIDER_SCHEDULING_JITTER) {
long delta = (loc.getElapsedRealtimeNano() - lastLoc.getElapsedRealtimeNano()) / 1000000L;
if (delta < minTime - MAX_PROVIDER_SCHEDULING_JITTER) {
return false;
}

6
services/java/com/android/server/UiModeManagerService.java
View File

@@ -308,7 +308,7 @@ class UiModeManagerService extends IUiModeManager.Stub {
/* if new location is older than the current one, the devices hasn't
* moved.
*/
if (location.getTime() < mLocation.getTime()) {
if (location.getElapsedRealtimeNano() < mLocation.getElapsedRealtimeNano()) {
return false;
}
@@ -764,7 +764,8 @@ class UiModeManagerService extends IUiModeManager.Stub {
mLocationManager.getLastKnownLocation(providers.next());
// pick the most recent location
if (location == null || (lastKnownLocation != null &&
location.getTime() < lastKnownLocation.getTime())) {
location.getElapsedRealtimeNano() <
lastKnownLocation.getElapsedRealtimeNano())) {
location = lastKnownLocation;
}
}
@@ -781,6 +782,7 @@ class UiModeManagerService extends IUiModeManager.Stub {
location.setLatitude(0);
location.setAccuracy(417000.0f);
location.setTime(System.currentTimeMillis());
location.setElapsedRealtimeNano(SystemClock.elapsedRealtimeNano());
}
synchronized (mLock) {
mLocation = location;

3
services/java/com/android/server/location/GpsLocationProvider.java
View File

@@ -1078,6 +1078,9 @@ public class GpsLocationProvider implements LocationProviderInterface {
mLocation.setLatitude(latitude);
mLocation.setLongitude(longitude);
mLocation.setTime(timestamp);
// It would be nice to push the elapsed real-time timestamp
// further down the stack, but this is still useful
mLocation.setElapsedRealtimeNano(SystemClock.elapsedRealtimeNano());
}
if ((flags & LOCATION_HAS_ALTITUDE) == LOCATION_HAS_ALTITUDE) {
mLocation.setAltitude(altitude);

4
services/java/com/android/server/location/LocationBasedCountryDetector.java
View File

@@ -114,7 +114,9 @@ public class LocationBasedCountryDetector extends CountryDetectorBase {
for (String provider : providers) {
Location lastKnownLocation = mLocationManager.getLastKnownLocation(provider);
if (lastKnownLocation != null) {
if (bestLocation == null || bestLocation.getTime() < lastKnownLocation.getTime()) {
if (bestLocation == null ||
bestLocation.getElapsedRealtimeNano() <
lastKnownLocation.getElapsedRealtimeNano()) {
bestLocation = lastKnownLocation;
}
}