Start and stop BLE scans from a background thread to prevent blocking…

… the UI (issue AltBeacon#136)
herow-io · Oct 24, 2016 · c59223b · c59223b
1 parent e4afd02
commit c59223b
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Showing 4 changed files with 104 additions and 44 deletions.
diff --git a/src/main/java/org/altbeacon/beacon/service/BeaconService.java b/src/main/java/org/altbeacon/beacon/service/BeaconService.java
@@ -273,6 +273,7 @@ public void onDestroy() {
         LogManager.i(TAG, "onDestroy called.  stopping scanning");
         handler.removeCallbacksAndMessages(null);
         mCycledScanner.stop();
+        mCycledScanner.destroy();
         monitoringStatus.stopStatusPreservation();
     }
 

diff --git a/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScanner.java b/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScanner.java
@@ -12,6 +12,8 @@
 import android.content.pm.PackageManager;
 import android.os.Build;
 import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Looper;
 import android.os.SystemClock;
 
 import org.altbeacon.beacon.BeaconManager;
@@ -40,7 +42,10 @@ public abstract class CycledLeScanner {
     private long mScanPeriod;
 
     protected long mBetweenScanPeriod;
-    protected final Handler mHandler = new Handler();
+
+    protected final Handler mHandler = new Handler(Looper.getMainLooper());
+    protected final Handler mScanHandler;
+    private final HandlerThread mScanThread;
 
     protected final BluetoothCrashResolver mBluetoothCrashResolver;
     protected final CycledLeScanCallback mCycledLeScanCallback;
@@ -57,6 +62,10 @@ protected CycledLeScanner(Context context, long scanPeriod, long betweenScanPeri
         mCycledLeScanCallback = cycledLeScanCallback;
         mBluetoothCrashResolver = crashResolver;
         mBackgroundFlag = backgroundFlag;
+
+        mScanThread = new HandlerThread("CycledLeScannerThread");
+        mScanThread.start();
+        mScanHandler = new Handler(mScanThread.getLooper());
     }
 
     public static CycledLeScanner createScanner(Context context, long scanPeriod, long betweenScanPeriod, boolean backgroundFlag, CycledLeScanCallback cycledLeScanCallback, BluetoothCrashResolver crashResolver) {
@@ -156,6 +165,10 @@ public void stop() {
         }
     }
 
+    public void destroy() {
+        mScanThread.quit();
+    }
+
     protected abstract void stopScan();
 
     protected abstract boolean deferScanIfNeeded();

diff --git a/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScannerForJellyBeanMr2.java b/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScannerForJellyBeanMr2.java
@@ -18,17 +18,9 @@ public CycledLeScannerForJellyBeanMr2(Context context, long scanPeriod, long bet
         super(context, scanPeriod, betweenScanPeriod, backgroundFlag, cycledLeScanCallback, crashResolver);
     }
 
-    @SuppressWarnings("deprecation")
     @Override
     protected void stopScan() {
-        try {
-            BluetoothAdapter bluetoothAdapter = getBluetoothAdapter();
-            if (bluetoothAdapter != null) {
-                bluetoothAdapter.stopLeScan(getLeScanCallback());
-            }
-        } catch (Exception e) {
-            LogManager.e(e, TAG, "Internal Android exception scanning for beacons");
-        }
+        postStopLeScan();
     }
 
     @Override
@@ -54,19 +46,57 @@ public void run() {
         return false;
     }
 
-    @SuppressWarnings("deprecation")
     @Override
     protected void startScan() {
-        getBluetoothAdapter().startLeScan(getLeScanCallback());
+        postStartLeScan();
     }
 
-    @SuppressWarnings("deprecation")
     @Override
     protected void finishScan() {
-        getBluetoothAdapter().stopLeScan(getLeScanCallback());
+        postStopLeScan();
         mScanningPaused = true;
     }
 
+    private void postStartLeScan() {
+        final BluetoothAdapter bluetoothAdapter = getBluetoothAdapter();
+        if (bluetoothAdapter == null) {
+            return;
+        }
+        final BluetoothAdapter.LeScanCallback leScanCallback = getLeScanCallback();
+        mScanHandler.removeCallbacksAndMessages(null);
+        mScanHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    //noinspection deprecation
+                    bluetoothAdapter.startLeScan(leScanCallback);
+                } catch (Exception e) {
+                    LogManager.e(e, TAG, "Internal Android exception in startLeScan()");
+                }
+            }
+        });
+    }
+
+    private void postStopLeScan() {
+        final BluetoothAdapter bluetoothAdapter = getBluetoothAdapter();
+        if (bluetoothAdapter == null) {
+            return;
+        }
+        final BluetoothAdapter.LeScanCallback leScanCallback = getLeScanCallback();
+        mScanHandler.removeCallbacksAndMessages(null);
+        mScanHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    //noinspection deprecation
+                    bluetoothAdapter.stopLeScan(leScanCallback);
+                } catch (Exception e) {
+                    LogManager.e(e, TAG, "Internal Android exception in stopLeScan()");
+                }
+            }
+        });
+    }
+
     private BluetoothAdapter.LeScanCallback getLeScanCallback() {
         if (leScanCallback == null) {
             leScanCallback =

diff --git a/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScannerForLollipop.java b/src/main/java/org/altbeacon/beacon/service/scanner/CycledLeScannerForLollipop.java
@@ -8,7 +8,6 @@
 import android.bluetooth.le.ScanResult;
 import android.bluetooth.le.ScanSettings;
 import android.content.Context;
-import android.os.Build;
 import android.os.ParcelUuid;
 import android.os.SystemClock;
 
@@ -39,20 +38,7 @@ public CycledLeScannerForLollipop(Context context, long scanPeriod, long between
 
     @Override
     protected void stopScan() {
-        try {
-            if (getScanner() != null) {
-                try {
-                    getScanner().stopScan((android.bluetooth.le.ScanCallback) getNewLeScanCallback());
-                }
-                catch (NullPointerException npe) {
-                    // Necessary because of https://code.google.com/p/android/issues/detail?id=160503
-                    LogManager.e(TAG, "Cannot stop scan.  Unexpected NPE.", npe);
-                }
-            }
-        }
-        catch (IllegalStateException e) {
-            LogManager.w(TAG, "Cannot stop scan.  Bluetooth may be turned off.");
-        }
+        postStopLeScan();
     }
 
     /*
@@ -181,21 +167,7 @@ protected void startScan() {
             settings = (new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)).build();
         }
 
-        try {
-            if (getScanner() != null) {
-                ScanCallback callback = getNewLeScanCallback();
-                try {
-                    getScanner().startScan(filters, settings, callback);
-                }
-                catch (NullPointerException npe) {
-                    // Necessary because of https://code.google.com/p/android/issues/detail?id=160503
-                    LogManager.w(TAG, "Cannot start scan.  Unexpected NPE.", npe);
-                }
-            }
-        }
-        catch (IllegalStateException e) {
-            LogManager.w(TAG, "Cannot start scan.  Bluetooth may be turned off.");
-        }
+        postStartLeScan(filters, settings);
     }
 
     @Override
@@ -205,6 +177,50 @@ protected void finishScan() {
         mScanningPaused = true;
     }
 
+    private void postStartLeScan(final List<ScanFilter> filters, final ScanSettings settings) {
+        final BluetoothLeScanner scanner = getScanner();
+        if (scanner == null) {
+            return;
+        }
+        final ScanCallback scanCallback = getNewLeScanCallback();
+        mScanHandler.removeCallbacksAndMessages(null);
+        mScanHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    scanner.startScan(filters, settings, scanCallback);
+                } catch (IllegalStateException e) {
+                    LogManager.w(TAG, "Cannot start scan. Bluetooth may be turned off.");
+                } catch (NullPointerException npe) {
+                    // Necessary because of https://code.google.com/p/android/issues/detail?id=160503
+                    LogManager.e(TAG, "Cannot start scan. Unexpected NPE.", npe);
+                }
+            }
+        });
+    }
+
+    private void postStopLeScan() {
+        final BluetoothLeScanner scanner = getScanner();
+        if (scanner == null) {
+            return;
+        }
+        final ScanCallback scanCallback = getNewLeScanCallback();
+        mScanHandler.removeCallbacksAndMessages(null);
+        mScanHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    scanner.stopScan(scanCallback);
+                } catch (IllegalStateException e) {
+                    LogManager.w(TAG, "Cannot stop scan. Bluetooth may be turned off.");
+                } catch (NullPointerException npe) {
+                    // Necessary because of https://code.google.com/p/android/issues/detail?id=160503
+                    LogManager.e(TAG, "Cannot stop scan. Unexpected NPE.", npe);
+                }
+            }
+        });
+    }
+
     private BluetoothLeScanner getScanner() {
         if (mScanner == null) {
             LogManager.d(TAG, "Making new Android L scanner");