Basic Rust-based foreground service

app/build.gradle

@@ -29,3 +29,13 @@ android {
 dependencies {
 
 }
+apply plugin: 'org.mozilla.rust-android-gradle.rust-android'
+
+cargo {
+    module  = "../wgserv"
+    libname = "wgserv"
+    // targets = ["arm", "arm64", "x86", "x86_64"]
+    targets = ["arm64"]
+    apiLevel = 21
+    profile = "release"
+}

app/src/main/java/org/vi_server/wgserver/MainActivity.java

@@ -8,6 +8,7 @@
 import android.os.Bundle;
 import android.widget.Button;
 import android.widget.EditText;
+import android.widget.TextView;
 
 public class MainActivity extends Activity {
 
@@ -26,22 +27,41 @@ protected void onCreate(Bundle savedInstanceState) {
                 EditText t = findViewById(R.id.tConfig);
                 String config = t.getText().toString();
 
-                intent.putExtra("config", config);
+                long instance = Native.create();
+                String ret = Native.setConfig(instance, config);
 
-                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-                    ctx.startForegroundService(intent);
+                TextView s = findViewById(R.id.tStatus);
+                if (ret != null && !ret.isEmpty()) {
+                    s.setText(ret);
                 } else {
-                    ctx.startService(intent);
+                    intent.putExtra("instance", instance);
+
+                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                        ctx.startForegroundService(intent);
+                    } else {
+                        ctx.startService(intent);
+                    }
+                    s.setText("started");
                 }
+
             });
         }
         {
             Button b = findViewById(R.id.bStop);
             b.setOnClickListener(view -> {
+                TextView s = findViewById(R.id.tStatus);
                 Intent intent = new Intent(ctx, Serv.class);
                 ctx.stopService(intent);
+                s.setText("stopped");
             });
         }
 
+        {
+            Button b = findViewById(R.id.bSampleConfig);
+            b.setOnClickListener(view -> {
+                EditText t = findViewById(R.id.tConfig);
+                t.setText(Native.getSampleConfig());
+            });
+        }
     }
 }

app/src/main/java/org/vi_server/wgserver/Native.java

@@ -0,0 +1,23 @@
+package org.vi_server.wgserver;
+
+public class Native {
+    static {
+        System.loadLibrary("wgserv");
+    }
+
+    public static native long create();
+
+    /// Empty or null string = no error
+    public static native String setConfig(long instance, String toml_config);
+
+    /// Block thread and start it for real
+    ///
+    /// Empty or null string means no error
+    public static native String run(long instance);
+
+    /// Stop and deallocate the instance
+    /// May be called from other thread
+    public static native void destroy(long instance);
+
+    public static native String getSampleConfig();
+}

app/src/main/java/org/vi_server/wgserver/Serv.java

@@ -10,11 +10,13 @@
 import android.os.Build;
 import android.os.IBinder;
 import android.os.PowerManager;
+import android.util.Log;
 
 public class Serv extends Service {
     private static final String CHANNEL_DEFAULT_IMPORTANCE = "default";
     private static final int ONGOING_NOTIFICATION_ID = 1;
     private static Notification.Builder nb;
+    private static long instance = 0;
     private static PowerManager.WakeLock wl;
 
     @Override
@@ -29,7 +31,15 @@ public void onCreate() {
 
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
-        String config = intent.getStringExtra("config");
+        if (instance != 0) {
+            Native.destroy(instance);
+        }
+        instance = intent.getLongExtra("instance", 0);
+        if (instance == 0) {
+            this.stopForeground(true);
+            this.stopSelf();
+            return super.onStartCommand(intent, flags, startId);
+        }
 
         Intent notificationIntent = new Intent(this, MainActivity.class);
         PendingIntent pendingIntent =
@@ -47,9 +57,6 @@ public int onStartCommand(Intent intent, int flags, int startId) {
 
         CharSequence notiftext = getText(R.string.service_desc);
 
-        boolean failed = false;
-
-        // start here
 
         nb = new Notification.Builder(this)
                 .setContentTitle(getText(R.string.app_name))
@@ -60,24 +67,26 @@ public int onStartCommand(Intent intent, int flags, int startId) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             nb.setChannelId(CHANNEL_DEFAULT_IMPORTANCE);
         }
-        if (failed) {
-            nb.setContentText("Failed to start service");
-        }
+
         Notification notification = nb.build();
 
         startForeground(ONGOING_NOTIFICATION_ID, notification);
 
-        if (failed) {
-            this.stopForeground(true);
-            this.stopSelf();
-            return super.onStartCommand(intent, flags, startId);
-        }
-
         PowerManager pm = (PowerManager)this.getSystemService(
                 Context.POWER_SERVICE);
         wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "wgserver:wl");
         wl.acquire();
 
+        new Thread(() -> {
+            String ret2 = Native.run(instance);
+            if (ret2 == null || ret2.isEmpty()) {
+                Log.i("WgServer","Background thread exited without signaling failure");
+            } else {
+                Log.w("WgServer", "Background thread existed with error: " + ret2);
+            }
+            this.stopSelf();
+        }).start();
+
         return super.onStartCommand(intent, flags, startId);
     }
 
@@ -88,6 +97,10 @@ public void onDestroy() {
             wl.release();
             wl = null;
         }
+        if (instance != 0) {
+            Native.destroy(instance);
+            instance=0;
+        }
         super.onDestroy();
     }
 }

app/src/main/res/layout/activity_main.xml

@@ -15,14 +15,21 @@
         <Button
             android:id="@+id/bStart"
             android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
+            android:layout_height="30pt"
             android:text="Start" />
 
         <Button
             android:id="@+id/bStop"
             android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
+            android:layout_height="30pt"
             android:text="Stop" />
+
+        <Button
+            android:id="@+id/bSampleConfig"
+            android:layout_width="wrap_content"
+            android:layout_height="30pt"
+            android:layout_weight="1"
+            android:text="Sample config" />
     </LinearLayout>
 
     <EditText
@@ -34,4 +41,15 @@
         android:gravity="start|top"
         android:inputType="textMultiLine" />
 
+    <Space
+        android:layout_width="match_parent"
+        android:layout_height="4pt"
+        android:background="#F51F9000" />
+
+    <TextView
+        android:id="@+id/tStatus"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="idle" />
+
 </LinearLayout>

build.gradle

@@ -1,4 +1,13 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
+buildscript {
+    repositories {
+        maven {
+            url "https://plugins.gradle.org/m2/"
+        }
+    }
+    dependencies {
+        classpath 'org.mozilla.rust-android-gradle:plugin:0.9.3'
+    }
+}
 plugins {
     id 'com.android.application' version '7.3.1' apply false
     id 'com.android.library' version '7.3.1' apply false

wgserv/.gitignore

@@ -0,0 +1 @@
+target/