From d338c3c8f8063a85fb82042affd6d197f5793be3 Mon Sep 17 00:00:00 2001
From: Robert Wu <robertwu@google.com>
Date: Mon, 21 Mar 2022 15:29:02 +0000
Subject: [PATCH] USB MIDI: Create encoder per output port

UsbMidiEncoder is not thread-safe. Therefore, each output port
should use its own encoder.

Bug: 225884009
Test: MidiKeyboard/MidiScope on both MIDI 2.0 and MIDI 1.0 paths.
Test: Verified M-Audio Keyboard with only input has the correct logs.
Change-Id: I43bd7381982403766b7f37c22d55ef5d19013120
---
 .../android/server/usb/UsbDirectMidiDevice.java    | 11 +++++++++--
 .../android/server/usb/UsbMidiPacketConverter.java | 14 +++++++++++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/services/usb/java/com/android/server/usb/UsbDirectMidiDevice.java b/services/usb/java/com/android/server/usb/UsbDirectMidiDevice.java
index 0fa79df3e008d..04c52f7253e95 100644
--- a/services/usb/java/com/android/server/usb/UsbDirectMidiDevice.java
+++ b/services/usb/java/com/android/server/usb/UsbDirectMidiDevice.java
@@ -84,7 +84,7 @@ public final class UsbDirectMidiDevice implements Closeable {
     private final Object mLock = new Object();
     private boolean mIsOpen;
 
-    private final UsbMidiPacketConverter mUsbMidiPacketConverter = new UsbMidiPacketConverter();
+    private UsbMidiPacketConverter mUsbMidiPacketConverter;
 
     private final MidiDeviceServer.Callback mCallback = new MidiDeviceServer.Callback() {
 
@@ -264,6 +264,11 @@ public final class UsbDirectMidiDevice implements Closeable {
         Log.d(TAG, "openLocked()");
         UsbManager manager = mContext.getSystemService(UsbManager.class);
 
+        // Converting from raw MIDI to USB MIDI is not thread-safe.
+        // UsbMidiPacketConverter creates a converter from raw MIDI
+        // to USB MIDI for each USB output.
+        mUsbMidiPacketConverter = new UsbMidiPacketConverter(mNumOutputs);
+
         mUsbDeviceConnections = new ArrayList<UsbDeviceConnection>(mUsbInterfaces.size());
         mInputUsbEndpoints = new ArrayList<ArrayList<UsbEndpoint>>(mUsbInterfaces.size());
         mOutputUsbEndpoints = new ArrayList<ArrayList<UsbEndpoint>>(mUsbInterfaces.size());
@@ -415,7 +420,7 @@ public final class UsbDirectMidiDevice implements Closeable {
                             } else {
                                 convertedArray =
                                         mUsbMidiPacketConverter.rawMidiToUsbMidi(
-                                                 event.data, event.count);
+                                                 event.data, event.count, portFinal);
                             }
 
                             if (DEBUG) {
@@ -518,6 +523,8 @@ public final class UsbDirectMidiDevice implements Closeable {
         mInputUsbEndpoints = null;
         mOutputUsbEndpoints = null;
 
+        mUsbMidiPacketConverter = null;
+
         mIsOpen = false;
     }
 
diff --git a/services/usb/java/com/android/server/usb/UsbMidiPacketConverter.java b/services/usb/java/com/android/server/usb/UsbMidiPacketConverter.java
index 7c93c7668fa22..56bb23681741f 100644
--- a/services/usb/java/com/android/server/usb/UsbMidiPacketConverter.java
+++ b/services/usb/java/com/android/server/usb/UsbMidiPacketConverter.java
@@ -74,8 +74,15 @@ public class UsbMidiPacketConverter {
     private static final byte SYSEX_START_EXCLUSIVE = (byte) 0xF0;
     private static final byte SYSEX_END_EXCLUSIVE = (byte) 0xF7;
 
-    private UsbMidiEncoder mUsbMidiEncoder = new UsbMidiEncoder();
     private UsbMidiDecoder mUsbMidiDecoder = new UsbMidiDecoder();
+    private UsbMidiEncoder[] mUsbMidiEncoders;
+
+    public UsbMidiPacketConverter(int numEncoders) {
+        mUsbMidiEncoders = new UsbMidiEncoder[numEncoders];
+        for (int i = 0; i < numEncoders; i++) {
+            mUsbMidiEncoders[i] = new UsbMidiEncoder();
+        }
+    }
 
     /**
      * Converts a USB MIDI array into a raw MIDI array.
@@ -93,10 +100,11 @@ public class UsbMidiPacketConverter {
      *
      * @param midiBytes the raw MIDI bytes to convert
      * @param size the size of usbMidiBytes
+     * @param encoderId which encoder to use
      * @return byte array of USB MIDI packets
      */
-    public byte[] rawMidiToUsbMidi(byte[] midiBytes, int size) {
-        return mUsbMidiEncoder.encode(midiBytes, size);
+    public byte[] rawMidiToUsbMidi(byte[] midiBytes, int size, int encoderId) {
+        return mUsbMidiEncoders[encoderId].encode(midiBytes, size);
     }
 
     private class UsbMidiDecoder {