Revert "android platform channels: moved to direct buffers for c <-> java interop (#26331)" (#26470)

This reverts commit a6eb224.

Author: zanderso

shell/platform/android/io/flutter/embedding/engine/FlutterJNI.java

@@ -814,7 +814,7 @@ public void setPlatformMessageHandler(@Nullable PlatformMessageHandler platformM
   @SuppressWarnings("unused")
   @VisibleForTesting
   public void handlePlatformMessage(
-      @NonNull final String channel, ByteBuffer message, final int replyId) {
+      @NonNull final String channel, byte[] message, final int replyId) {
     if (platformMessageHandler != null) {
       platformMessageHandler.handleMessageFromDart(channel, message, replyId);
     }
@@ -825,7 +825,7 @@ public void handlePlatformMessage(
   // Called by native to respond to a platform message that we sent.
   // TODO(mattcarroll): determine if reply is nonull or nullable
   @SuppressWarnings("unused")
-  private void handlePlatformMessageResponse(int replyId, ByteBuffer reply) {
+  private void handlePlatformMessageResponse(int replyId, byte[] reply) {
     if (platformMessageHandler != null) {
       platformMessageHandler.handlePlatformMessageResponse(replyId, reply);
     }

shell/platform/android/io/flutter/embedding/engine/dart/DartMessenger.java

@@ -75,18 +75,14 @@ public void send(
 
   @Override
   public void handleMessageFromDart(
-      @NonNull final String channel, @Nullable ByteBuffer message, final int replyId) {
+      @NonNull final String channel, @Nullable byte[] message, final int replyId) {
     Log.v(TAG, "Received message from Dart over channel '" + channel + "'");
     BinaryMessenger.BinaryMessageHandler handler = messageHandlers.get(channel);
     if (handler != null) {
       try {
         Log.v(TAG, "Deferring to registered handler to process message.");
-        handler.onMessage(message, new Reply(flutterJNI, replyId));
-        if (message != null && message.isDirect()) {
-          // This ensures that if a user retains an instance to the ByteBuffer and it happens to
-          // be direct they will get a deterministic error.
-          message.limit(0);
-        }
+        final ByteBuffer buffer = (message == null ? null : ByteBuffer.wrap(message));
+        handler.onMessage(buffer, new Reply(flutterJNI, replyId));
       } catch (Exception ex) {
         Log.e(TAG, "Uncaught exception in binary message listener", ex);
         flutterJNI.invokePlatformMessageEmptyResponseCallback(replyId);
@@ -100,18 +96,13 @@ public void handleMessageFromDart(
   }
 
   @Override
-  public void handlePlatformMessageResponse(int replyId, @Nullable ByteBuffer reply) {
+  public void handlePlatformMessageResponse(int replyId, @Nullable byte[] reply) {
     Log.v(TAG, "Received message reply from Dart.");
     BinaryMessenger.BinaryReply callback = pendingReplies.remove(replyId);
     if (callback != null) {
       try {
         Log.v(TAG, "Invoking registered callback for reply from Dart.");
-        callback.reply(reply);
-        if (reply != null && reply.isDirect()) {
-          // This ensures that if a user retains an instance to the ByteBuffer and it happens to
-          // be direct they will get a deterministic error.
-          reply.limit(0);
-        }
+        callback.reply(reply == null ? null : ByteBuffer.wrap(reply));
       } catch (Exception ex) {
         Log.e(TAG, "Uncaught exception in binary message reply handler", ex);
       } catch (Error err) {

shell/platform/android/io/flutter/embedding/engine/dart/PlatformMessageHandler.java

@@ -6,12 +6,11 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import java.nio.ByteBuffer;
 
 /** Handler that receives messages from Dart code. */
 public interface PlatformMessageHandler {
   void handleMessageFromDart(
-      @NonNull final String channel, @Nullable ByteBuffer message, final int replyId);
+      @NonNull final String channel, @Nullable byte[] message, final int replyId);
 
-  void handlePlatformMessageResponse(int replyId, @Nullable ByteBuffer reply);
+  void handlePlatformMessageResponse(int replyId, @Nullable byte[] reply);
 }

shell/platform/android/io/flutter/plugin/common/BinaryCodec.java

@@ -18,31 +18,8 @@
 public final class BinaryCodec implements MessageCodec<ByteBuffer> {
   // This codec must match the Dart codec of the same name in package flutter/services.
   public static final BinaryCodec INSTANCE = new BinaryCodec();
-  /**
-   * A BinaryCodec that returns direct ByteBuffers from `decodeMessage` for better performance.
-   *
-   * @see BinaryCodec.BinaryCodec(boolean)
-   */
-  public static final BinaryCodec INSTANCE_DIRECT = new BinaryCodec(true);
 
-  private final boolean returnsDirectByteBufferFromDecoding;
-
-  private BinaryCodec() {
-    this.returnsDirectByteBufferFromDecoding = false;
-  }
-
-  /**
-   * A constructor for BinaryCodec.
-   *
-   * @param returnsDirectByteBufferFromDecoding `true` means that the Codec will return direct
-   *     ByteBuffers from `decodeMessage`. Direct ByteBuffers will have better performance but will
-   *     be invalid beyond the scope of the `decodeMessage` call. `false` means Flutter will copy
-   *     the encoded message to Java's memory, so the ByteBuffer will be valid beyond the
-   *     decodeMessage call, at the cost of a copy.
-   */
-  private BinaryCodec(boolean returnsDirectByteBufferFromDecoding) {
-    this.returnsDirectByteBufferFromDecoding = returnsDirectByteBufferFromDecoding;
-  }
+  private BinaryCodec() {}
 
   @Override
   public ByteBuffer encodeMessage(ByteBuffer message) {
@@ -51,13 +28,6 @@ public ByteBuffer encodeMessage(ByteBuffer message) {
 
   @Override
   public ByteBuffer decodeMessage(ByteBuffer message) {
-    if (returnsDirectByteBufferFromDecoding) {
-      return message;
-    } else {
-      ByteBuffer result = ByteBuffer.allocate(message.capacity());
-      result.put(message);
-      result.rewind();
-      return result;
-    }
+    return message;
   }
 }

shell/platform/android/io/flutter/plugin/common/MessageCodec.java

@@ -26,10 +26,6 @@ public interface MessageCodec<T> {
   /**
    * Decodes the specified message from binary.
    *
-   * <p><b>Warning:</b> The ByteBuffer is "direct" and it won't be valid beyond this call. Storing
-   * the ByteBuffer and using it later and will lead to a {@code java.nio.BufferUnderflowException}.
-   * If you want to retain the data you'll need to copy it.
-   *
    * @param message the {@link ByteBuffer} message, possibly null.
    * @return a T value representation of the bytes between the given buffer's current position and
    *     its limit, or null, if message is null.

shell/platform/android/platform_view_android_jni_impl.cc

@@ -828,16 +828,15 @@ bool RegisterApi(JNIEnv* env) {
 
   g_handle_platform_message_method =
       env->GetMethodID(g_flutter_jni_class->obj(), "handlePlatformMessage",
-                       "(Ljava/lang/String;Ljava/nio/ByteBuffer;I)V");
+                       "(Ljava/lang/String;[BI)V");
 
   if (g_handle_platform_message_method == nullptr) {
     FML_LOG(ERROR) << "Could not locate handlePlatformMessage method";
     return false;
   }
 
   g_handle_platform_message_response_method = env->GetMethodID(
-      g_flutter_jni_class->obj(), "handlePlatformMessageResponse",
-      "(ILjava/nio/ByteBuffer;)V");
+      g_flutter_jni_class->obj(), "handlePlatformMessageResponse", "(I[B)V");
 
   if (g_handle_platform_message_response_method == nullptr) {
     FML_LOG(ERROR) << "Could not locate handlePlatformMessageResponse method";
@@ -1108,10 +1107,11 @@ void PlatformViewAndroidJNIImpl::FlutterViewHandlePlatformMessage(
       fml::jni::StringToJavaString(env, message->channel());
 
   if (message->hasData()) {
-    fml::jni::ScopedJavaLocalRef<jobject> message_array(
-        env, env->NewDirectByteBuffer(
-                 const_cast<uint8_t*>(message->data().GetMapping()),
-                 message->data().GetSize()));
+    fml::jni::ScopedJavaLocalRef<jbyteArray> message_array(
+        env, env->NewByteArray(message->data().GetSize()));
+    env->SetByteArrayRegion(
+        message_array.obj(), 0, message->data().GetSize(),
+        reinterpret_cast<const jbyte*>(message->data().GetMapping()));
     env->CallVoidMethod(java_object.obj(), g_handle_platform_message_method,
                         java_channel.obj(), message_array.obj(), responseId);
   } else {
@@ -1141,9 +1141,10 @@ void PlatformViewAndroidJNIImpl::FlutterViewHandlePlatformMessageResponse(
                         nullptr);
   } else {
     // Convert the vector to a Java byte array.
-    fml::jni::ScopedJavaLocalRef<jobject> data_array(
-        env, env->NewDirectByteBuffer(const_cast<uint8_t*>(data->GetMapping()),
-                                      data->GetSize()));
+    fml::jni::ScopedJavaLocalRef<jbyteArray> data_array(
+        env, env->NewByteArray(data->GetSize()));
+    env->SetByteArrayRegion(data_array.obj(), 0, data->GetSize(),
+                            reinterpret_cast<const jbyte*>(data->GetMapping()));
 
     env->CallVoidMethod(java_object.obj(),
                         g_handle_platform_message_response_method, responseId,

shell/platform/android/test/io/flutter/embedding/engine/dart/DartMessengerTest.java

@@ -1,13 +1,11 @@
 package io.flutter.embedding.engine.dart;
 
-import static junit.framework.TestCase.assertEquals;
 import static junit.framework.TestCase.assertNotNull;
 import static junit.framework.TestCase.assertTrue;
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
 
 import io.flutter.embedding.engine.FlutterJNI;
-import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.BinaryMessenger.BinaryMessageHandler;
 import java.nio.ByteBuffer;
 import org.junit.Test;
@@ -48,80 +46,9 @@ public void itHandlesErrors() {
         .onMessage(any(ByteBuffer.class), any(DartMessenger.Reply.class));
 
     messenger.setMessageHandler("test", throwingHandler);
-    messenger.handleMessageFromDart("test", ByteBuffer.allocate(0), 0);
+    messenger.handleMessageFromDart("test", new byte[] {}, 0);
     assertNotNull(reportingHandler.latestException);
     assertTrue(reportingHandler.latestException instanceof AssertionError);
     currentThread.setUncaughtExceptionHandler(savedHandler);
   }
-
-  @Test
-  public void givesDirectByteBuffer() {
-    // Setup test.
-    final FlutterJNI fakeFlutterJni = mock(FlutterJNI.class);
-    final DartMessenger messenger = new DartMessenger(fakeFlutterJni);
-    final String channel = "foobar";
-    final boolean[] wasDirect = {false};
-    final BinaryMessenger.BinaryMessageHandler handler =
-        (message, reply) -> {
-          wasDirect[0] = message.isDirect();
-        };
-    messenger.setMessageHandler(channel, handler);
-    final ByteBuffer message = ByteBuffer.allocateDirect(4 * 2);
-    message.rewind();
-    message.putChar('a');
-    message.putChar('b');
-    message.putChar('c');
-    message.putChar('d');
-    messenger.handleMessageFromDart(channel, message, /*replyId=*/ 123);
-    assertTrue(wasDirect[0]);
-  }
-
-  @Test
-  public void directByteBufferLimitZeroAfterUsage() {
-    // Setup test.
-    final FlutterJNI fakeFlutterJni = mock(FlutterJNI.class);
-    final DartMessenger messenger = new DartMessenger(fakeFlutterJni);
-    final String channel = "foobar";
-    final ByteBuffer[] byteBuffers = {null};
-    final int bufferSize = 4 * 2;
-    final BinaryMessenger.BinaryMessageHandler handler =
-        (message, reply) -> {
-          byteBuffers[0] = message;
-          assertEquals(bufferSize, byteBuffers[0].limit());
-        };
-    messenger.setMessageHandler(channel, handler);
-    final ByteBuffer message = ByteBuffer.allocateDirect(bufferSize);
-    message.rewind();
-    message.putChar('a');
-    message.putChar('b');
-    message.putChar('c');
-    message.putChar('d');
-    messenger.handleMessageFromDart(channel, message, /*replyId=*/ 123);
-    assertNotNull(byteBuffers[0]);
-    assertTrue(byteBuffers[0].isDirect());
-    assertEquals(0, byteBuffers[0].limit());
-  }
-
-  @Test
-  public void directByteBufferLimitZeroAfterReply() {
-    // Setup test.
-    final FlutterJNI fakeFlutterJni = mock(FlutterJNI.class);
-    final DartMessenger messenger = new DartMessenger(fakeFlutterJni);
-    final ByteBuffer message = ByteBuffer.allocateDirect(4 * 2);
-    final String channel = "foobar";
-    message.rewind();
-    message.putChar('a');
-    message.putChar('b');
-    message.putChar('c');
-    message.putChar('d');
-    final ByteBuffer[] byteBuffers = {null};
-    BinaryMessenger.BinaryReply callback =
-        (reply) -> {
-          assertTrue(reply.isDirect());
-          byteBuffers[0] = reply;
-        };
-    messenger.send(channel, null, callback);
-    messenger.handlePlatformMessageResponse(1, message);
-    assertEquals(0, byteBuffers[0].limit());
-  }
 }

shell/platform/android/test/io/flutter/plugin/platform/PlatformViewsControllerTest.java

@@ -630,10 +630,12 @@ public void checkInputConnectionProxy__falseIfViewIsNull() {
     assertFalse(shouldProxying);
   }
 
-  private static ByteBuffer encodeMethodCall(MethodCall call) {
+  private static byte[] encodeMethodCall(MethodCall call) {
     final ByteBuffer buffer = StandardMethodCodec.INSTANCE.encodeMethodCall(call);
     buffer.rewind();
-    return buffer;
+    final byte[] dest = new byte[buffer.remaining()];
+    buffer.get(dest);
+    return dest;
   }
 
   private static void createPlatformView(