Use efficient operations when copying bytes between Dart and Java

pkgs/cronet_http/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.0-jni
+
+* Use more efficient operations when copying bytes between Java and Dart.
+
 ## 0.3.0-jni
 
 * Switch to using `package:jnigen` for bindings to Cronet

pkgs/cronet_http/lib/src/cronet_client.dart

@@ -22,6 +22,7 @@ import 'package:jni/jni.dart';
 import 'jni/jni_bindings.dart' as jb;
 
 final _digitRegex = RegExp(r'^\d+$');
+const _bufferSize = 10 * 1024; // The size of the Cronet read buffer.
 
 /// The type of caching to use when making HTTP requests.
 enum CacheMode {
@@ -138,7 +139,7 @@ Map<String, String> _cronetToClientHeaders(
 jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
     BaseRequest request, Completer<StreamedResponse> responseCompleter) {
   StreamController<List<int>>? responseStream;
-  jb.ByteBuffer? byteBuffer;
+  JByteBuffer? jByteBuffer;
   var numRedirects = 0;
 
   // The order of callbacks generated by Cronet is documented here:
@@ -175,8 +176,8 @@ jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
         headers: responseHeaders,
       ));
 
-      byteBuffer = jb.ByteBuffer.allocateDirect(1024 * 1024);
-      urlRequest.read(byteBuffer!);
+      jByteBuffer = JByteBuffer.allocateDirect(_bufferSize);
+      urlRequest.read(jByteBuffer!.castTo(const jb.$ByteBufferType()));
     },
     onRedirectReceived: (urlRequest, responseInfo, newLocationUrl) {
       if (!request.followRedirects) {
@@ -204,20 +205,15 @@ jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
     },
     onReadCompleted: (urlRequest, responseInfo, byteBuffer) {
       byteBuffer.flip();
+      responseStream!
+          .add(jByteBuffer!.asUint8List().sublist(0, byteBuffer.remaining()));
 
-      final remaining = byteBuffer.remaining();
-      final data = Uint8List(remaining);
-      // TODO: Use a more efficient approach when
-      // https://github.com/dart-lang/jnigen/issues/387 is fixed.
-      for (var i = 0; i < remaining; ++i) {
-        data[i] = byteBuffer.get1(i);
-      }
-      responseStream!.add(data);
       byteBuffer.clear();
       urlRequest.read(byteBuffer);
     },
     onSucceeded: (urlRequest, responseInfo) {
       responseStream!.sink.close();
+      jByteBuffer?.release();
     },
     onFailed: (urlRequest, responseInfo, cronetException) {
       final error = ClientException(
@@ -228,6 +224,7 @@ jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
         responseStream!.addError(error);
         responseStream!.close();
       }
+      jByteBuffer?.release();
     },
   ));
 }
@@ -333,14 +330,10 @@ class CronetClient extends BaseClient {
     headers.forEach((k, v) => builder.addHeader(k.toJString(), v.toJString()));
 
     if (body.isNotEmpty) {
-      // TODO: Use a more efficient approach when
-      // https://github.com/dart-lang/jnigen/issues/387 is fixed.
-      final bodyBytes = JArray(jbyte.type, body.length);
-      for (var i = 0; i < body.length; ++i) {
-        bodyBytes[i] = body[i];
-      }
+      final bodyBuffer =
+          body.toJByteBuffer().castTo(const jb.$ByteBufferType());
       builder.setUploadDataProvider(
-          jb.UploadDataProviders.create4(bodyBytes), _executor);
+          jb.UploadDataProviders.create2(bodyBuffer), _executor);
     }
     builder.build().start();
     return responseCompleter.future;