Use efficient operations when copying bytes between Dart and Java (#1019)

Author: brianquinlan

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/android/build.gradle

@@ -43,6 +43,16 @@ android {
     defaultConfig {
         minSdkVersion 16
     }
+
+    defaultConfig {
+        consumerProguardFiles 'consumer-rules.pro'
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
 }
 
 dependencies {

pkgs/cronet_http/android/consumer-rules.pro

@@ -0,0 +1 @@
+-keep class io.flutter.plugins.cronet_http.** { *; }

pkgs/cronet_http/example/android/app/build.gradle

@@ -67,4 +67,7 @@ flutter {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    // ""com.google.android.gms:play-services-cronet" is only present so that
+    // `jnigen` will work. Applications should not include this line.
+    implementation "com.google.android.gms:play-services-cronet:18.0.1"
 }

pkgs/cronet_http/jnigen.yaml

@@ -7,8 +7,6 @@ android_sdk_config:
   add_gradle_deps: true
   android_example: 'example/'
 
-suspend_fun_to_async: true
-
 output:
   bindings_type: dart_only
   dart:
@@ -18,8 +16,6 @@ output:
 classes:
   - 'io.flutter.plugins.cronet_http.UrlRequestCallbackProxy'
   - 'java.net.URL'
-  - 'java.nio.Buffer'
-  - 'java.nio.ByteBuffer'
   - 'java.util.concurrent.Executors'
   - 'org.chromium.net.CronetEngine'
   - 'org.chromium.net.CronetException'

pkgs/cronet_http/lib/src/cronet_client.dart

@@ -14,14 +14,14 @@
 library;
 
 import 'dart:async';
-import 'dart:typed_data';
 
 import 'package:http/http.dart';
 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 +138,7 @@ 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 +175,8 @@ jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
         headers: responseHeaders,
       ));
 
-      byteBuffer = jb.ByteBuffer.allocateDirect(1024 * 1024);
-      urlRequest.read(byteBuffer!);
+      jByteBuffer = JByteBuffer.allocateDirect(_bufferSize);
+      urlRequest.read(jByteBuffer!);
     },
     onRedirectReceived: (urlRequest, responseInfo, newLocationUrl) {
       if (!request.followRedirects) {
@@ -204,20 +204,15 @@ 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 +223,7 @@ jb.UrlRequestCallbackProxy_UrlRequestCallbackInterface _urlRequestCallbacks(
         responseStream!.addError(error);
         responseStream!.close();
       }
+      jByteBuffer?.release();
     },
   ));
 }
@@ -333,14 +329,8 @@ 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];
-      }
       builder.setUploadDataProvider(
-          jb.UploadDataProviders.create4(bodyBytes), _executor);
+          jb.UploadDataProviders.create2(body.toJByteBuffer()), _executor);
     }
     builder.build().start();
     return responseCompleter.future;