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Commit 85f95b25 authored by Myles Watson's avatar Myles Watson
Browse files

RemoteDevices: Optimize adding new remote devices 



RemoteDevices keeps track of the Bluetooth devices which have been
seen since the Bluetooth stack was initialized.  Each time a remote
device is discovered, it is added to a hash map.  When the size of the
hash map grows beyond a few hundred devices, the performance degrades.

This patch:
 - creates the address string once per search
  reducing the average search time with 300 devices from ~20ms to ~1ms
 - uses the hash of the address string to search
  further reducing the time with 1200 devices from ~2ms to ~1ms

HashMap<BluetoothDevice, DeviceProperties> became
 HashMap<String, DeviceProperties>

mDevice now stores the BluetoothDevice in each instance of
DeviceProperties.

TEST: Used System.nanoTime() to measure the elapsed time of
      getDeviceProperties()
Bug: 30828758

Change-Id: Id44886143fb2910955294341d4938d638c72f7f9
Signed-off-by: default avatarMyles Watson <mylesgw@google.com>
(cherry picked from commit 1fb90c4f25ba33b0f951e6ac092d05f85d355e2f)
parent ba488f10

android/app/src/com/android/bluetooth/btservice/RemoteDevices.java

+19 −12
Original line number Diff line number Diff line
@@ -45,13 +45,13 @@ final class RemoteDevices { 
    private static final int UUID_INTENT_DELAY = 6000;

    private static final int MESSAGE_UUID_INTENT = 1;



    private HashMap<BluetoothDevice, DeviceProperties> mDevices;

    private HashMap<String, DeviceProperties> mDevices;



    RemoteDevices(AdapterService service) {

        mAdapter = BluetoothAdapter.getDefaultAdapter();

        mAdapterService = service;

        mSdpTracker = new ArrayList<BluetoothDevice>();

        mDevices = new HashMap<BluetoothDevice, DeviceProperties>();

        mDevices = new HashMap<String, DeviceProperties>();

    }
@@ -70,26 +70,23 @@ final class RemoteDevices { 


    DeviceProperties getDeviceProperties(BluetoothDevice device) {

        synchronized (mDevices) {

            return mDevices.get(device);

            return mDevices.get(device.getAddress());

        }

    }



    BluetoothDevice getDevice(byte[] address) {

        for (BluetoothDevice dev : mDevices.keySet()) {

            if (dev.getAddress().equals(Utils.getAddressStringFromByte(address))) {

                return dev;

            }

        }

        DeviceProperties prop = mDevices.get(Utils.getAddressStringFromByte(address));

        if (prop == null)

           return null;

        return prop.getDevice();

    }



    DeviceProperties addDeviceProperties(byte[] address) {

        synchronized (mDevices) {

            DeviceProperties prop = new DeviceProperties();

            BluetoothDevice device =

                    mAdapter.getRemoteDevice(Utils.getAddressStringFromByte(address));

            prop.mDevice = mAdapter.getRemoteDevice(Utils.getAddressStringFromByte(address));

            prop.mAddress = address;

            mDevices.put(device, prop);

            mDevices.put(Utils.getAddressStringFromByte(address), prop);

            return prop;

        }

    }
@@ -103,6 +100,7 @@ final class RemoteDevices { 
        private int mDeviceType;

        private String mAlias;

        private int mBondState;

        private BluetoothDevice mDevice;



        DeviceProperties() {

            mBondState = BluetoothDevice.BOND_NONE;
@@ -144,6 +142,15 @@ final class RemoteDevices { 
            }

        }



        /**

         * @return the mDevice

         */

        BluetoothDevice getDevice() {

            synchronized (mObject) {

                return mDevice;

            }

        }



        /**

         * @return mRssi

         */