bluetooth: android: Initial Low Energy Discovery Sessions.

device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java

Index: device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java
diff --git a/device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java b/device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java
index 3c8b26521f600895c60f8deadbf46b72bfc27f73..4c45e0a920406bd88587433761447dc980ebc8fe 100644
--- a/device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java
+++ b/device/bluetooth/android/java/src/org/chromium/device/bluetooth/BluetoothAdapter.java
@@ -5,66 +5,113 @@
 package org.chromium.device.bluetooth;
 
 import android.Manifest;
+import android.annotation.TargetApi;
+import android.bluetooth.le.ScanCallback;
+import android.bluetooth.le.ScanResult;
+import android.bluetooth.le.ScanSettings;
 import android.content.Context;
 import android.content.ContextWrapper;
 import android.content.pm.PackageManager;
+import android.os.Build;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.base.Log;
 
+import java.util.List;
+
 /**
  * Exposes android.bluetooth.BluetoothAdapter as necessary for C++
  * device::BluetoothAdapterAndroid.
  */
 @JNINamespace("device")
+@TargetApi(Build.VERSION_CODES.LOLLIPOP)
 final class BluetoothAdapter {
     private static final String TAG = Log.makeTag("Bluetooth");
 
-    private final boolean mHasBluetoothPermission;
+    private long mNativeBluetoothAdapterAndroid;
+    private final boolean mHasBluetoothCapability;
     private android.bluetooth.BluetoothAdapter mAdapter;
+    private int mNumDiscoverySessions;
+    private ScanCallback mLeScanCallback;
+
+    // ---------------------------------------------------------------------------------------------
+    // Construction and handler for C++ object destruction.
 
     @CalledByNative
-    private static BluetoothAdapter create(Context context) {
-        return new BluetoothAdapter(context);
+    private static BluetoothAdapter create(Context context, long nativeBluetoothAdapterAndroid) {
+        return new BluetoothAdapter(context, nativeBluetoothAdapterAndroid);
     }
 
     @CalledByNative
-    private static BluetoothAdapter createWithoutPermissionForTesting(Context context) {
+    private static BluetoothAdapter createWithoutPermissionForTesting(
+            Context context, long nativeBluetoothAdapterAndroid) {
         Context contextWithoutPermission = new ContextWrapper(context) {
             @Override
             public int checkCallingOrSelfPermission(String permission) {
                 return PackageManager.PERMISSION_DENIED;
             }
         };
-        return new BluetoothAdapter(contextWithoutPermission);
+        return new BluetoothAdapter(contextWithoutPermission, nativeBluetoothAdapterAndroid);
     }
 
     // Constructs a BluetoothAdapter.
-    private BluetoothAdapter(Context context) {
-        mHasBluetoothPermission =
+    private BluetoothAdapter(Context context, long nativeBluetoothAdapterAndroid) {
+        mNativeBluetoothAdapterAndroid = nativeBluetoothAdapterAndroid;
+        final boolean hasMinAPI = Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
+        final boolean hasPermissions =
                 context.checkCallingOrSelfPermission(Manifest.permission.BLUETOOTH)
                         == PackageManager.PERMISSION_GRANTED
                 && context.checkCallingOrSelfPermission(Manifest.permission.BLUETOOTH_ADMIN)
                         == PackageManager.PERMISSION_GRANTED;
-        if (!mHasBluetoothPermission) {
-            Log.w(TAG,
-                    "Bluetooth API disabled; BLUETOOTH and BLUETOOTH_ADMIN permissions required.");
+        final boolean hasLowEnergyFeature =
+                Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2
+                && context.getPackageManager().hasSystemFeature(
+                           PackageManager.FEATURE_BLUETOOTH_LE);
+        mHasBluetoothCapability = hasMinAPI && hasPermissions && hasLowEnergyFeature;

[armansito, 2015/05/28 04:04:11]

The code is self explanatory but can you add a comment explaining why BT classic
won't be supported?

[scheib, 2015/06/30 17:55:14]

Done.

+        if (!mHasBluetoothCapability) {
+            if (!hasMinAPI) {
+                Log.i(TAG, "Bluetooth API disabled; SDK version (%d) too low.",
+                        Build.VERSION.SDK_INT);
+            } else if (!hasPermissions) {
+                Log.w(TAG, "Bluetooth API disabled; BLUETOOTH and BLUETOOTH_ADMIN permissions "
+                                + "required.");
+            } else if (!hasLowEnergyFeature) {
+                Log.i(TAG, "Bluetooth API disabled; Low Energy not supported on system.");
+            }
             return;
         }
 
         mAdapter = android.bluetooth.BluetoothAdapter.getDefaultAdapter();
-        if (mAdapter == null) Log.i(TAG, "No adapter found.");
+        if (mAdapter == null) {
+            Log.i(TAG, "No adapter found.");
+        } else {
+            Log.i(TAG, "BluetoothAdapter successfully constructed.");
+        }
     }
 
+    /**
+     * Shuts down any ongoing scan, removes reference to the C++ object.
+     */
     @CalledByNative
-    private boolean hasBluetoothPermission() {
-        return mHasBluetoothPermission;
+    private void onBluetoothAdapterAndroidDestruction() {
+        stopScan();
+        mNativeBluetoothAdapterAndroid = 0;
     }
 
     // ---------------------------------------------------------------------------------------------
-    // BluetoothAdapterAndroid.h interface:
+    // BluetoothAdapterAndroid Methods exposed :
 
+    // ---------------------------------------------------------------------------------------------
+    // BluetoothAdapterAndroid methods implemented in java:
+
+    // Implements BluetoothAdapterAndroid::HasBluetoothCapability.
+    @CalledByNative
+    private boolean hasBluetoothCapability() {
+        return mHasBluetoothCapability;
+    }
+
+    // Implements BluetoothAdapterAndroid::GetAddress.
     @CalledByNative
     private String getAddress() {
         if (isPresent()) {
@@ -74,6 +121,7 @@ final class BluetoothAdapter {
         }
     }
 
+    // Implements BluetoothAdapterAndroid::GetName.
     @CalledByNative
     private String getName() {
         if (isPresent()) {
@@ -83,16 +131,19 @@ final class BluetoothAdapter {
         }
     }
 
+    // Implements BluetoothAdapterAndroid::IsPresent.
     @CalledByNative
     private boolean isPresent() {
         return mAdapter != null;
     }
 
+    // Implements BluetoothAdapterAndroid::IsPowered.
     @CalledByNative
     private boolean isPowered() {
         return isPresent() && mAdapter.isEnabled();
     }
 
+    // Implements BluetoothAdapterAndroid::IsDiscoverable.
     @CalledByNative
     private boolean isDiscoverable() {
         return isPresent()
@@ -100,8 +151,123 @@ final class BluetoothAdapter {
                 == android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
     }
 
+    // Implements BluetoothAdapterAndroid::IsDiscovering.
     @CalledByNative
     private boolean isDiscovering() {
         return isPresent() && mAdapter.isDiscovering();
     }
+
+    // Implements BluetoothAdapterAndroid::AddDiscoverySession.
+    @CalledByNative
+    private boolean addDiscoverySession() {
+        if (!isPowered()) {
+            Log.d(TAG, "addDiscoverySession: Fails: !isPowered");
+            return false;
+        }
+
+        mNumDiscoverySessions++;
+        Log.d(TAG, "addDiscoverySession: Now %d sessions", mNumDiscoverySessions);
+        if (mNumDiscoverySessions > 1) {
+            return true;
+        }
+
+        return startScan();

[armansito, 2015/05/28 04:04:11]

If startScan() fails, won't you need to decrement the count?

[scheib, 2015/06/30 17:55:14]

Done.

+    }
+
+    // Implements BluetoothAdapterAndroid::RemoveDiscoverySession.
+    @CalledByNative
+    private boolean removeDiscoverySession() {
+        if (mNumDiscoverySessions == 0) {
+            assert false;
+            Log.w(TAG, "removeDiscoverySession: No scan in progress.");
+            return false;
+        }
+
+        --mNumDiscoverySessions;
+
+        if (mNumDiscoverySessions == 0) {
+            Log.d(TAG, "removeDiscoverySession: Stopping scan.");
+            return stopScan();
+        } else {
+            Log.d(TAG, "removeDiscoverySession: Now %d sessions", mNumDiscoverySessions);
+        }
+        return true;
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // Implementation details:
+
+    /**
+     * Starts a Low Energy scan.
+     * @return True on success.
+     */
+    private boolean startScan() {
+        // ScanSettings Note: SCAN_FAILED_FEATURE_UNSUPPORTED is caused (at least on some devices)
+        // if setReportDelay() is used or if SCAN_MODE_LOW_LATENCY isn't used.
+        ScanSettings scanSettings =
+                new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY).build();
+
+        assert mLeScanCallback == null;
+        mLeScanCallback = new DiscoveryScanCallback();
+
+        try {
+            mAdapter.getBluetoothLeScanner().startScan(
+                    null /* filters */, scanSettings, mLeScanCallback);
+        } catch (IllegalArgumentException e) {
+            Log.e(TAG, "Cannot start scan: " + e);
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Stops the Low Energy scan.
+     * @return True if a scan was in progress.
+     */
+    private boolean stopScan() {
+        if (mLeScanCallback == null) {
+            return false;
+        }
+        mAdapter.getBluetoothLeScanner().stopScan(mLeScanCallback);
+        mLeScanCallback = null;
+        return true;
+    }
+
+    /**
+     * Implements callbacks used during a Low Energy scan by notifying upon
+     * devices discovered or detecting a scan failure.
+     */
+    private class DiscoveryScanCallback extends ScanCallback {
+        @Override
+        public void onBatchScanResults(List<ScanResult> results) {
+            Log.v(TAG, "onBatchScanResults");
+        }
+
+        @Override
+        public void onScanResult(int callbackType, ScanResult result) {
+            Log.v(TAG, "onScanResult %s %s", result.getDevice().getAddress(),
+                    result.getDevice().getName());
+        }
+
+        @Override
+        public void onScanFailed(int errorCode) {
+            Log.w(TAG, "onScanFailed: %d", errorCode);
+            // DISCUSS IN CODE REVIEW.
+            //
+            // TODO(scheib): Current device/bluetooth API doesn't support a way to communicate
+            // this asynchronous failure. If there was a way to communicate asynchronous
+            // success, then the response to AddDiscoverySession would be delayed until then or
+            // this error. But without only the error we must presume success.
+            //
+            //
+            // NEED ISSUE NUMBER.
+            nativeOnScanFailed(mNativeBluetoothAdapterAndroid);

[armansito, 2015/05/28 04:04:11]

I'm fine with this, as long as you're updating the all the discovery sessions
AND setting the reference count to zero (though I don't see the latter part
here).

[scheib, 2015/06/30 17:55:14]

Done.

+        }
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // BluetoothAdapterAndroid C++ methods declared for access from java:
+
+    // Binds to BluetoothAdapterAndroid::OnScanFailed.
+    private native void nativeOnScanFailed(long nativeBluetoothAdapterAndroid);
 }