将Rust + Flutter + Kotlin集成到移动应用程序中

Question

下周将为Rust 2018和Flutter 1.0启动importat,我想用构建一个使用Rust作为业务逻辑的应用程序和Flutter作为用户界面,可以在Android和iOS上运行,我构建了一个并在Android上测试它它工作正常.

我只是想知道如何衡量性能并将其与原生Android/iOS应用进行比较.

应用流程是:

1. 主要在Flutter中,即通过platform_channel调用本机函数
2. 本机函数通过JNI调用生锈库(JNI包装器需要调用生锈库)

结构如下:

使用的代码是:

main.dart:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const platform = const MethodChannel('samples.flutter.io/battery');

  String _batteryLevel = 'Unknown battery level.';

  Future<void> _getBatteryLevel() async {
    String batteryLevel;
    try {
      final String hello = await platform.invokeMethod('getText');
      final int result = await platform.invokeMethod('getBatteryLevel');

      batteryLevel = '$hello Battery level at $result %.';
    } on PlatformException catch (e) {
      batteryLevel = "Failed to get battery level: '${e.message}'.";
    }

    setState(() {
      _batteryLevel = batteryLevel;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            RaisedButton(
              child: Text('Get Battery Level'),
              onPressed: _getBatteryLevel,
            ),
            Text(_batteryLevel),
          ],
        ),
      ),
    );
  }
}

JNI wrapper - RustGreetings.kt

package com.mozilla.greetings

class RustGreetings {
    companion object {
        init {
            System.loadLibrary("greetings")
        }
    }

    private external fun greeting(pattern: String): String

    fun sayHello(to: String): String = greeting(to)
}

Android的主要活动是:

package com.example.batterylevel

import android.os.Bundle
import io.flutter.app.FlutterActivity
import io.flutter.plugins.GeneratedPluginRegistrant
import io.flutter.plugin.common.MethodChannel

import android.content.Context
import android.content.ContextWrapper
import android.content.Intent
import android.content.IntentFilter
import android.os.BatteryManager
import android.os.Build.VERSION
import android.os.Build.VERSION_CODES

import lib.Library
import com.mozilla.greetings.RustGreetings

class MainActivity: FlutterActivity() {
  private val CHANNEL = "samples.flutter.io/battery"

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    GeneratedPluginRegistrant.registerWith(this)

    MethodChannel(flutterView, CHANNEL).setMethodCallHandler { call, result ->
      if (call.method == "getText") {
        result.success(getText())
      } else if (call.method == "getBatteryLevel") {
       // result.success(getText())
        val batteryLevel = getBatteryLevel()

        if (batteryLevel != -1) {
          result.success(batteryLevel)
        } else {
          result.error("UNAVAILABLE", "Battery level not available.", null)
        }
      }
      else {

        result.notImplemented()
      }
    }
  }

  private fun getBatteryLevel(): Int {
    val batteryLevel: Int
    if (VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
      val batteryManager = getSystemService(Context.BATTERY_SERVICE) as BatteryManager
      batteryLevel = batteryManager.getIntProperty(BatteryManager.BATTERY_PROPERTY_CAPACITY)
    } else {
      val intent = ContextWrapper(applicationContext).registerReceiver(null, IntentFilter(Intent.ACTION_BATTERY_CHANGED))
      batteryLevel = intent!!.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) * 100 / intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1)
    }
    return batteryLevel
  }

  private fun getText(): String {
    val x = Library().someLibraryMethod()
    val g = RustGreetings()
    val r = g.sayHello("My $x Rust")
    return r
  }
}

在Android中gradle.build我刚刚添加了以下内容,因为我有兴趣检查添加kotlin JVM库并使其与移动应用程序中的Rust库进行交互的影响:

dependencies {
    implementation(files("src/main/libs/lib.jar"))
}

我的问题是:如何检查每个进程在被另一个进程执行或调用时的性能和影响

Answer 1

随着 Dart 中ffi的引入，事情变得更加流畅，性能也更好，因为现在直接使用 Dart/Rust 进行交互，而不需要 Dart/Kotlin/Rust 或 Dart/Swift/Rust 循环，下面是一个简单的示例：

第一的src/lib.rs

#[no_mangle]
pub extern fn rust_fn(x: i32) -> i32 {   
    println!("Hello from rust\nI'll return: {}", x.pow(2));
    x.pow(2)
 }

和Cargo.toml

[package]
name = "Double_in_Rost"
version = "0.1.0"
authors = ["Hasan Yousef"]
edition = "2018"

[lib]
name = "rust_lib"
crate-type = ["dylib"] # could be `staticlib` as well

[dependencies]

运行cargo build --release会生成target\release\rust_lib.dll复制/粘贴到Dart应用程序根目录

编写 Dart 代码如下：

[package]
name = "Double_in_Rost"
version = "0.1.0"
authors = ["Hasan Yousef"]
edition = "2018"

[lib]
name = "rust_lib"
crate-type = ["dylib"] # could be `staticlib` as well

[dependencies]