Merge branch 'master' into refactor-lollipop-defer

CHANGELOG.md

@@ -3,11 +3,15 @@
 
 Enhancements:
 
+- Add ability to circumvent prohibition against scans running for > 30 minutes on Android N.
+  (#529, David G. Young)
 - Add support for running the beacon scanning service in a separate process and working with
   application setups that have more than one process. (#479, David G. Young)
 
 Bug Fixes:
 
+- Fix Google Play submission errors by no longer using uses-permission-sdk-23 in
+  Manifest (#527, David G. Young)
 - Fix failure to restart scanning in some cases after bluetooth has been off but then is turned
   back on. (#519, David G. Young)
 - Fix failure to stop scanning when unbinding from service or when the between scan period

src/main/AndroidManifest.xml

@@ -5,7 +5,7 @@
     <uses-permission android:name="android.permission.BLUETOOTH" android:required="false"/>
     <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:required="false"/>
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
-    <uses-permission-sdk-23 android:name="android.permission.ACCESS_COARSE_LOCATION"/>
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
 
     <application>
         <receiver android:name="org.altbeacon.beacon.startup.StartupBroadcastReceiver">

src/main/java/org/altbeacon/beacon/service/BeaconService.java

@@ -29,9 +29,12 @@
 import android.app.PendingIntent;
 import android.app.Service;
 import android.bluetooth.BluetoothDevice;
+import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageItemInfo;
+import android.content.pm.PackageManager;
 import android.os.AsyncTask;
 import android.os.Binder;
 import android.os.Build;
@@ -240,6 +243,15 @@ public void onCreate() {
             LogManager.i(TAG, "beaconService PID is "+processUtils.getPid()+" with process name "+processUtils.getProcessName());
         }
 
+        try {
+            PackageItemInfo info = this.getPackageManager().getServiceInfo(new ComponentName(this, BeaconService.class), PackageManager.GET_META_DATA);
+            if (info != null && info.metaData != null && info.metaData.get("longScanForcingEnabled") != null &&
+                    info.metaData.get("longScanForcingEnabled").toString().equals("true")) {
+                LogManager.i(TAG, "longScanForcingEnabled to keep scans going on Android N for > 30 minutes");
+                mCycledScanner.setLongScanForcingEnabled(true);
+            }
+        } catch (PackageManager.NameNotFoundException e) {}
+
         reloadParsers();
 
         defaultDistanceCalculator =  new ModelSpecificDistanceCalculator(this, BeaconManager.getDistanceModelUpdateUrl());

src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScanner.java

@@ -28,14 +28,20 @@
 
 @TargetApi(18)
 public abstract class CycledLeScanner {
+    public static final long ANDROID_N_MAX_SCAN_DURATION_MILLIS = 30 * 60 * 1000l; // 30 minutes
     private static final String TAG = "CycledLeScanner";
     private BluetoothAdapter mBluetoothAdapter;
 
     private long mLastScanCycleStartTime = 0l;
     private long mLastScanCycleEndTime = 0l;
     protected long mNextScanCycleStartTime = 0l;
     private long mScanCycleStopTime = 0l;
-
+    // This is the last time this class actually commanded the OS
+    // to start scanning.
+    private long mCurrentScanStartTime = 0l;
+    // True if the app has explicitly requested long running scans that
+    // may go beyond what is normally allowed on Android N.
+    private boolean mLongScanForcingEnabled = false;
     private boolean mScanning;
     protected boolean mScanningPaused;
     private boolean mScanCyclerStarted = false;
@@ -136,6 +142,15 @@ public static CycledLeScanner createScanner(Context context, long scanPeriod, lo
 
     }
 
+    /**
+     * Enables the scanner to go to extra lengths to keep scans going for longer than would
+     * otherwise be allowed.  Useful only for Android N and higher.
+     * @param enabled
+     */
+    public void setLongScanForcingEnabled(boolean enabled) {
+        mLongScanForcingEnabled = enabled;
+    }
+
     /**
      * Tells the cycler the scan rate and whether it is in operating in background mode.
      * Background mode flag  is used only with the Android 5.0 scanning implementations to switch
@@ -272,6 +287,7 @@ protected void scanLeDevice(final Boolean enable) {
                                         }
                                         try {
                                             if (android.os.Build.VERSION.SDK_INT < 23 || checkLocationPermission()) {
+                                                mCurrentScanStartTime = SystemClock.elapsedRealtime();
                                                 startScan();
                                             }
                                         } catch (Exception e) {
@@ -290,7 +306,9 @@ protected void scanLeDevice(final Boolean enable) {
                         LogManager.e(e, TAG, "Exception starting Bluetooth scan.  Perhaps Bluetooth is disabled or unavailable?");
                     }
                 } else {
-                    LogManager.d(TAG, "We are already scanning");
+                    LogManager.d(TAG, "We are already scanning and have been for "+(
+                            SystemClock.elapsedRealtime() - mCurrentScanStartTime
+                            )+" millis");
                 }
                 mScanCycleStopTime = (SystemClock.elapsedRealtime() + mScanPeriod);
                 scheduleScanCycleStop();
@@ -301,6 +319,7 @@ protected void scanLeDevice(final Boolean enable) {
                 mScanning = false;
                 mScanCyclerStarted = false;
                 stopScan();
+                mCurrentScanStartTime = 0l;
                 mLastScanCycleEndTime = SystemClock.elapsedRealtime();
                 // Clear any queued schedule tasks as we're done scanning
                 mScanHandler.removeCallbacksAndMessages(null);
@@ -353,7 +372,9 @@ private void finishScanCycle() {
                         // so it is best avoided.  If we know the device has detected to distinct
                         // packets in the same cycle, we will not restart scanning and just keep it
                         // going.
-                        if (!mDistinctPacketsDetectedPerScan || mBetweenScanPeriod != 0) {
+                        if (!mDistinctPacketsDetectedPerScan ||
+                                mBetweenScanPeriod != 0 ||
+                                mustStopScanToPreventAndroidNScanTimeout()) {
                             long now = SystemClock.elapsedRealtime();
                             if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.N &&
                                     mBetweenScanPeriod+mScanPeriod < ANDROID_N_MIN_SCAN_CYCLE_MILLIS &&
@@ -488,4 +509,35 @@ private boolean checkLocationPermission() {
     private boolean checkPermission(final String permission) {
         return mContext.checkPermission(permission, android.os.Process.myPid(), android.os.Process.myUid()) == PackageManager.PERMISSION_GRANTED;
     }
+
+    /**
+     * On Android N and later, a scan that runs for more than 30 minutes will be automatically
+     * stopped by the OS and converted to an "opportunistic" scan, meaning that they will only yield
+     * detections if another app is scanning.  This is inteneded to save battery.  This can be
+     * prevented by stopping scanning and restarting.  This method returns true if:
+     *   * this is Android N or later
+     *   * we are close to the 30 minute boundary since the last scan started
+     *   * The app developer has explicitly enabled long-running scans
+     * @return true if we must stop scanning to prevent
+     */
+    private boolean mustStopScanToPreventAndroidNScanTimeout() {
+        long timeOfNextScanCycleEnd = SystemClock.elapsedRealtime() +  mBetweenScanPeriod +
+                mScanPeriod;
+        boolean timeoutAtRisk = android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.N &&
+                mCurrentScanStartTime > 0 &&
+                (timeOfNextScanCycleEnd - mCurrentScanStartTime > ANDROID_N_MAX_SCAN_DURATION_MILLIS);
+
+        if (timeoutAtRisk) {
+            LogManager.d(TAG, "The next scan cycle would go over the Android N max duration.");
+            if  (mLongScanForcingEnabled) {
+                LogManager.d(TAG, "Stopping scan to prevent Android N scan timeout.");
+                return true;
+            }
+            else {
+                LogManager.w(TAG, "Allowing a long running scan to be stopped by the OS.  To " +
+                        "prevent this, set longScanForcingEnabled in the AndroidBeaconLibrary.");
+            }
+        }
+        return false;
+    }
 }