bluetooth: android: Initial Low Energy Discovery Sessions.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.device.bluetooth;
 
 import android.Manifest;
+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")
 final class BluetoothAdapter {
     private static final String TAG = Log.makeTag("Bluetooth");
 
-    private final boolean mHasBluetoothPermission;
+    private final boolean mHasBluetoothCapability;
     private android.bluetooth.BluetoothAdapter mAdapter;
+    private int mNumDiscoverySessions = 0;
+    private ScanCallback mLeScanCallback;
+
+    // ---------------------------------------------------------------------------------------------
+    // Construction:
 
     @CalledByNative
     private static BluetoothAdapter create(Context context) {
         return new BluetoothAdapter(context);
     }
 
     @CalledByNative
     private static BluetoothAdapter createWithoutPermissionForTesting(Context context) {
         Context contextWithoutPermission = new ContextWrapper(context) {
             @Override
             public int checkCallingOrSelfPermission(String permission) {
                 return PackageManager.PERMISSION_DENIED;
             }
         };
         return new BluetoothAdapter(contextWithoutPermission);
     }
 
     // Constructs a BluetoothAdapter.
     private BluetoothAdapter(Context context) {
-        mHasBluetoothPermission =
+        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 =
+                context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE);
+        mHasBluetoothCapability = hasMinAPI && hasPermissions && hasLowEnergyFeature;
+        if (!mHasBluetoothCapability) {
+            if (!hasMinAPI) {
+                Log.i(TAG, "Bluetooth API disabled; SDK version (%d) too low.",

[ortuno, 2015/05/21 16:48:53]

You are logging a lot of stuff. We should probably ask tedchoc if this is OK.

[scheib, 2015/05/22 01:26:46]

I've moved the verbose bits to .d and .v, which aren't enabled by default and
also removed included in release builds:
https://chromium.googlesource.com/chromium/src/+/master/base/android/java/src...

+                        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.");
-    }
-
-    @CalledByNative
-    private boolean hasBluetoothPermission() {
-        return mHasBluetoothPermission;
+        if (mAdapter == null) {
+            Log.i(TAG, "No adapter found.");
+        } else {
+            Log.i(TAG, "BluetoothAdapter successfully constructed.");
+        }
     }
 
     // ---------------------------------------------------------------------------------------------
-    // BluetoothAdapterAndroid.h interface:
+    // Accessors @CalledByNative for BluetoothAdapterAndroid:
+
+    @CalledByNative
+    private boolean hasBluetoothCapability() {
+        return mHasBluetoothCapability;
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // BluetoothAdapterAndroid interface @CalledByNative for BluetoothAdapterAndroid:
 
     @CalledByNative
     private String getAddress() {
         if (isPresent()) {
             return mAdapter.getAddress();
         } else {
             return "";
         }
     }
 
@@ skipping 20 matching lines @@
     private boolean isDiscoverable() {
         return isPresent()
                 && mAdapter.getScanMode()
                 == android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
     }
 
     @CalledByNative
     private boolean isDiscovering() {
         return isPresent() && mAdapter.isDiscovering();
     }
+
+    @CalledByNative
+    private boolean addDiscoverySession() {

[ortuno, 2015/05/21 16:48:53]

nit: Add a comment for this function.

[scheib, 2015/05/22 01:26:46]

Done.

+        if (!isPowered()) {
+            Log.i(TAG, "addDiscoverySession: Fails: !isPowered");
+            return false;
+        }
+
+        if (mNumDiscoverySessions > 0) {
+            Log.i(TAG, "addDiscoverySession: Already scanning.");
+            return true;
+        }
+        Log.i(TAG, "addDiscoverySession");
+        mNumDiscoverySessions++;
+
+        ScanSettings.Builder scanSettingsBuilder = new ScanSettings.Builder();

[ortuno, 2015/05/21 16:48:53]

I would refactor this a bit:

ScanSettings scanSettings = new ScanSettings.Builder()
    .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
    .build();

[scheib, 2015/05/22 01:26:46]

Done.

[scheib, 2015/05/22 01:26:46]

Done.

+        // Note: SCAN_FAILED_FEATURE_UNSUPPORTED is caused (at least on some
+        // devices) if scanSettingsBuilder.setReportDelay() is set or if
+        // SCAN_MODE_LOW_LATENCY isn't used.
+        scanSettingsBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY);
+
+        if (mLeScanCallback == null) mLeScanCallback = new DiscoveryScanCallback();

[ortuno, 2015/05/21 16:48:53]

I think you need braces here:

https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.1.1-brac...

[scheib, 2015/05/22 01:26:45]

Done.

+        mAdapter.getBluetoothLeScanner().startScan(
+                null /* filters */, scanSettingsBuilder.build(), mLeScanCallback);
+        return true;
+    }
+
+    @CalledByNative
+    private boolean removeDiscoverySession() {
+        Log.i(TAG, "removeDiscoverySession");
+        switch (--mNumDiscoverySessions) {

[ortuno, 2015/05/21 16:48:53]

nit: I think it would be clearer this way:

if (mNumDiscoverySessions == 0) {
  assert false;
  Log.w(TAG, "removeDiscoverySession: No scan in progress.");
  return false;
}

if (mNumDiscoverySessions == 1) {
  mAdapter.getBluetoothLeScanner().stopScan(mLeScanCallback);
}

--mNumDiscoverySessions

return true;

[scheib, 2015/05/22 01:26:46]

Done.

+            case -1:
+                assert false;
+                Log.w(TAG, "removeDiscoverySession: No scan in progress.");
+                mNumDiscoverySessions = 0;
+                return false;
+            case 0:
+                mAdapter.getBluetoothLeScanner().stopScan(mLeScanCallback);
+        }
+        return true;
+    }
+
+    // ---------------------------------------------------------------------------------------------
+    // Implementation details:
+
+    private class DiscoveryScanCallback extends ScanCallback {
+        @Override
+        public void onBatchScanResults(List<ScanResult> results) {
+            Log.i(TAG, "onBatchScanResults");
+        }
+
+        @Override
+        public void onScanResult(int callbackType, ScanResult result) {
+            Log.i(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.
+        }
+    }
 }