Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 90d53f23 authored by Robert Wu's avatar Robert Wu
Browse files

Accumulate Bluetooth MIDI packets until ready 

Bluetooth MIDI uses a packet encoder to encode and send packets.
When a caller calls send too quickly, the Bluetooth characteristic
is not ready and BluetoothPacketEncoder waits for a packet that
never arrives.

With this change, if the sender sends a couple packets before the
connection is ready, they will be added to a queue. Once the
Bluetooth characteristic is avaliable, this queue will be sent
with the next packet. This way, we can remove this infinite loop.

Bug: 64598842
Test: Added code to Phil's MidiBtlePairing app to send data to a
bluetooth MIDI device repeatedly after pairing. Verified that packets
don't get sent correctly before the change and that packets do get
sent correctly with this change.

Change-Id: Ib261d871752e83a2150980cd50acb56ee318b034
parent 3688b228

media/packages/BluetoothMidiService/src/com/android/bluetoothmidiservice/BluetoothMidiDevice.java

+14 −4
Original line number Diff line number Diff line
@@ -211,10 +211,10 @@ public final class BluetoothMidiDevice { 
        }



        @Override

        public void writePacket(byte[] buffer, int count) {

        public boolean writePacket(byte[] buffer, int count) {

            if (mCharacteristic == null) {

                Log.w(TAG, "not ready to send packet yet");

                return;

                return false;

            }



            // Cache the previous buffer for writePacket so buffers aren't
@@ -223,12 +223,22 @@ public final class BluetoothMidiDevice { 
                mCachedBuffer = new byte[count];

            }

            System.arraycopy(buffer, 0, mCachedBuffer, 0, count);

            mCharacteristic.setValue(mCachedBuffer);

            if (!mCharacteristic.setValue(mCachedBuffer)) {

                Log.w(TAG, "could not set characteristic value");

                return false;

            }



            if (DEBUG) {

                logByteArray("Sent ", mCharacteristic.getValue(), 0,

                       mCharacteristic.getValue().length);

            }

            mBluetoothGatt.writeCharacteristic(mCharacteristic);



            if (!mBluetoothGatt.writeCharacteristic(mCharacteristic)) {

                Log.w(TAG, "could not write characteristic to Bluetooth GATT");

                return false;

            }



            return true;

        }

    }

media/packages/BluetoothMidiService/src/com/android/bluetoothmidiservice/BluetoothPacketEncoder.java

+42 −2
Original line number Diff line number Diff line
@@ -17,11 +17,14 @@ 
package com.android.bluetoothmidiservice;



import android.media.midi.MidiReceiver;

import android.util.Log;



import com.android.internal.midi.MidiConstants;

import com.android.internal.midi.MidiFramer;



import java.io.IOException;

import java.util.ArrayDeque;

import java.util.Queue;



/**

 * This class accumulates MIDI messages to form a MIDI packet.
@@ -52,6 +55,8 @@ public class BluetoothPacketEncoder extends PacketEncoder { 


    private final Object mLock = new Object();



    private Queue<byte[]> mFailedToSendQueue = new ArrayDeque<byte[]>();



    // This receives normalized data from mMidiFramer and accumulates it into a packet buffer

    private final MidiReceiver mFramedDataReceiver = new MidiReceiver() {

        @Override
@@ -59,6 +64,8 @@ public class BluetoothPacketEncoder extends PacketEncoder { 
                throws IOException {



            synchronized (mLock) {

                flushFailedToSendQueueLocked();



                int milliTimestamp = (int)(timestamp / MILLISECOND_NANOS) & MILLISECOND_MASK;

                byte status = msg[offset];

                boolean isSysExStart = (status == MidiConstants.STATUS_SYSTEM_EXCLUSIVE);
@@ -227,11 +234,44 @@ public class BluetoothPacketEncoder extends PacketEncoder { 
        }



        if (mAccumulatedBytes > 0) {

            mPacketReceiver.writePacket(mAccumulationBuffer, mAccumulatedBytes);

            boolean wasSendSuccessful = mPacketReceiver.writePacket(mAccumulationBuffer,

                    mAccumulatedBytes);



            if (!wasSendSuccessful) {

                byte[] failedBuffer = new byte[mAccumulatedBytes];

                System.arraycopy(mAccumulationBuffer, 0, failedBuffer, 0, mAccumulatedBytes);

                mFailedToSendQueue.add(failedBuffer);

                Log.d(TAG, "Enqueued data into failed queue.");

            }



            mAccumulatedBytes = 0;

            mPacketTimestamp = 0;

            mRunningStatus = 0;

            mWritePending = true;

            mWritePending = wasSendSuccessful;

        }

    }



    private void flushFailedToSendQueueLocked() {

        while (!mFailedToSendQueue.isEmpty()) {

            while (mWritePending) {

                try {

                    mLock.wait();

                } catch (InterruptedException e) {

                    // try again

                    continue;

                }

            }

            byte[] currentBuffer = mFailedToSendQueue.element();



            boolean wasSendSuccessful = mPacketReceiver.writePacket(currentBuffer,

                    currentBuffer.length);

            mWritePending = wasSendSuccessful;

            if (wasSendSuccessful) {

                mFailedToSendQueue.remove();

                Log.d(TAG, "Dequeued data from failed queue.");

            } else {

                return;

            }

        }

    }

}

media/packages/BluetoothMidiService/src/com/android/bluetoothmidiservice/PacketEncoder.java

+2 −1
Original line number Diff line number Diff line
@@ -30,8 +30,9 @@ public abstract class PacketEncoder extends MidiReceiver { 
        /** Called to write an accumulated packet.

         * @param buffer the packet buffer to write

         * @param count the number of bytes in the packet buffer to write

         * @return whether the operation was successful

         */

        public void writePacket(byte[] buffer, int count);

        boolean writePacket(byte[] buffer, int count);

    }



    /**

media/packages/BluetoothMidiService/tests/unit/src/com/android/bluetoothmidiservice/BluetoothMidiCodecTest.java

+2 −1
Original line number Diff line number Diff line
@@ -114,7 +114,7 @@ public class BluetoothMidiCodecTest { 
        // TODO Should this block?

        // Store the packets and then write them from a periodic task.

        @Override

        public void writePacket(byte[] buffer, int count) {

        public boolean writePacket(byte[] buffer, int count) {

            Log.d(TAG, "writePacket() passed " + MidiFramer.formatMidiData(buffer, 0, count));

            byte[] packet = new byte[count];

            System.arraycopy(buffer, 0, packet, 0, count);
@@ -124,6 +124,7 @@ public class BluetoothMidiCodecTest { 
                assertEquals(null, e);

            }

            Log.d(TAG, "writePacket() returns");

            return true;

        }



        void test(final byte[][] midi)

media/packages/BluetoothMidiService/tests/unit/src/com/android/bluetoothmidiservice/BluetoothMidiEncoderTest.java

+2 −1
Original line number Diff line number Diff line
@@ -42,11 +42,12 @@ public class BluetoothMidiEncoderTest { 
    static class AccumulatingPacketReceiver implements PacketEncoder.PacketReceiver {

        ArrayList<byte[]> mBuffers = new ArrayList<byte[]>();



        public void writePacket(byte[] buffer, int count) {

        public boolean writePacket(byte[] buffer, int count) {

            byte[] actualRow = new byte[count];

            Log.d(TAG, "writePacket() passed " + MidiFramer.formatMidiData(buffer, 0, count));

            System.arraycopy(buffer, 0, actualRow, 0, count);

            mBuffers.add(actualRow);

            return true;

        }



        byte[][] getBuffers() {