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Merge pull request #143 from powersync-ja/background-sync-example
Demo: Add example using a foreground service for synchronization
2 parents 953c3b4 + 9991199 commit bca578f

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‎demos/supabase-todolist/README.md

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## Run the app
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Choose a run configuration for the Android or iOS target in Android Studio and run it.
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For Android, this demo contains two Android apps:
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- [`androidApp/`](androidApp/): This is a regular compose UI app using PowerSync.
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- [`androidBackgroundSync/`](androidBackgroundSync/): This example differs from the regular app in
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that it uses a foreground service managing the synchronization process. The service is started
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in the main activity and keeps running even after the app is closed.
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For more notes on background sync, see [this document](docs/BackgroundSync.md).

‎demos/supabase-todolist/androidBackgroundSync/.gitignore

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/build

‎demos/supabase-todolist/androidBackgroundSync/build.gradle.kts

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plugins {
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alias(libs.plugins.androidApplication)
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alias(libs.plugins.kotlinAndroid)
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alias(libs.plugins.compose.compiler)
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id("org.jetbrains.compose")
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alias(libs.plugins.kotlin.atomicfu)
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}
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android {
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namespace = "com.powersync.demo.backgroundsync"
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compileSdk = 35
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defaultConfig {
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applicationId = "com.powersync.demo.backgroundsync"
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minSdk = 28
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targetSdk = 35
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versionCode = 1
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versionName = "1.0"
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testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
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}
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buildTypes {
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release {
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isMinifyEnabled = false
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proguardFiles(
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getDefaultProguardFile("proguard-android-optimize.txt"),
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"proguard-rules.pro"
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)
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}
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}
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compileOptions {
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sourceCompatibility = JavaVersion.VERSION_11
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targetCompatibility = JavaVersion.VERSION_11
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}
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kotlinOptions {
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jvmTarget = "11"
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}
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buildFeatures {
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compose = true
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}
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}
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dependencies {
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// When copying this example, replace "latest.release" with the current version available
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// at: https://central.sonatype.com/artifact/com.powersync/connector-supabase
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implementation("com.powersync:connector-supabase:latest.release")
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implementation(projects.shared)
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implementation(compose.material)
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implementation(libs.androidx.core)
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implementation(libs.androidx.activity.compose)
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implementation(libs.androidx.lifecycle.service)
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implementation(libs.compose.lifecycle)
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implementation(libs.compose.ui.tooling.preview)
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implementation(libs.koin.android)
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implementation(libs.koin.compose.viewmodel)
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}

‎demos/supabase-todolist/androidBackgroundSync/proguard-rules.pro

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# Add project specific ProGuard rules here.
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# You can control the set of applied configuration files using the
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# proguardFiles setting in build.gradle.
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#
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# For more details, see
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# http://developer.android.com/guide/developing/tools/proguard.html
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# If your project uses WebView with JS, uncomment the following
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# and specify the fully qualified class name to the JavaScript interface
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# class:
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#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
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# public *;
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#}
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# Uncomment this to preserve the line number information for
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# debugging stack traces.
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#-keepattributes SourceFile,LineNumberTable
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# If you keep the line number information, uncomment this to
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# hide the original source file name.
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#-renamesourcefileattribute SourceFile

‎demos/supabase-todolist/androidBackgroundSync/src/main/AndroidManifest.xml

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<?xml version="1.0" encoding="utf-8"?>
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<manifest xmlns:android="http://schemas.android.com/apk/res/android">
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<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
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<uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC"/>
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<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
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<uses-permission android:name="android.permission.INTERNET" />
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<application
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android:allowBackup="true"
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android:icon="@mipmap/ic_launcher"
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android:label="@string/app_name"
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android:roundIcon="@mipmap/ic_launcher_round"
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android:supportsRtl="true"
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android:networkSecurityConfig="@xml/network_security_config"
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android:name=".MainApplication"
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android:theme="@style/Theme.Supabasetodolist">
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<activity
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android:name=".MainActivity"
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android:exported="true"
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android:label="@string/app_name"
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android:theme="@style/Theme.Supabasetodolist">
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<intent-filter>
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<action android:name="android.intent.action.MAIN" />
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<category android:name="android.intent.category.LAUNCHER" />
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</intent-filter>
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</activity>
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<service android:name=".SyncService" android:exported="false" android:foregroundServiceType="dataSync" />
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</application>
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</manifest>

‎demos/supabase-todolist/androidBackgroundSync/src/main/java/com/powersync/demo/backgroundsync/MainActivity.kt

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package com.powersync.demo.backgroundsync
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import android.content.Intent
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import android.os.Bundle
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import androidx.activity.ComponentActivity
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import androidx.activity.compose.setContent
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import androidx.activity.enableEdgeToEdge
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import androidx.compose.foundation.layout.WindowInsets
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import androidx.compose.foundation.layout.fillMaxSize
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import androidx.compose.foundation.layout.systemBars
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import androidx.compose.foundation.layout.windowInsetsPadding
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import androidx.compose.material.MaterialTheme
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import androidx.compose.material.Surface
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import androidx.compose.ui.Modifier
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import androidx.lifecycle.lifecycleScope
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import com.powersync.connector.supabase.SupabaseConnector
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import com.powersync.demos.AppContent
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import io.github.jan.supabase.auth.status.SessionStatus
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import kotlinx.coroutines.launch
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import org.koin.android.ext.android.inject
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import org.koin.compose.KoinContext
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class MainActivity : ComponentActivity() {
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private val connector: SupabaseConnector by inject()
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override fun onCreate(savedInstanceState: Bundle?) {
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super.onCreate(savedInstanceState)
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enableEdgeToEdge()
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lifecycleScope.launch {
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// Watch the authentication state and start a sync foreground service once the user logs
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// in.
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connector.sessionStatus.collect {
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if (it is SessionStatus.Authenticated) {
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startForegroundService(Intent().apply {
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setClass(this@MainActivity, SyncService::class.java)
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})
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}
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}
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}
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setContent {
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// We've already started Koin from our application class to be able to use the database
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// outside of the UI here. So, use KoinContext and AppContent instead of the App()
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// composable that would set up its own context.
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KoinContext {
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MaterialTheme {
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Surface(color = MaterialTheme.colors.background) {
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AppContent(
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modifier=Modifier.fillMaxSize().windowInsetsPadding(WindowInsets.systemBars)
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)
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}
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}
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}
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}
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}
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}

‎demos/supabase-todolist/androidBackgroundSync/src/main/java/com/powersync/demo/backgroundsync/MainApplication.kt

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package com.powersync.demo.backgroundsync
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import android.app.Application
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import com.powersync.DatabaseDriverFactory
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import com.powersync.demos.AuthOptions
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import com.powersync.demos.sharedAppModule
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import org.koin.android.ext.koin.androidContext
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import org.koin.android.ext.koin.androidLogger
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import org.koin.core.context.startKoin
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import org.koin.core.module.dsl.singleOf
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import org.koin.dsl.module
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class MainApplication : Application() {
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override fun onCreate() {
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super.onCreate()
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startKoin {
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androidLogger()
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androidContext(this@MainApplication)
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modules(sharedAppModule, module {
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single { AuthOptions(connectFromViewModel = false) }
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singleOf(::DatabaseDriverFactory)
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})
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}
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}
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}

‎demos/supabase-todolist/androidBackgroundSync/src/main/java/com/powersync/demo/backgroundsync/SyncService.kt

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package com.powersync.demo.backgroundsync
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import android.app.Notification
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import android.content.Intent
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import android.content.pm.ServiceInfo
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import android.os.Build
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import androidx.core.app.NotificationChannelCompat
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import androidx.core.app.NotificationManagerCompat
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import androidx.core.app.ServiceCompat
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import androidx.lifecycle.LifecycleService
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import androidx.lifecycle.lifecycleScope
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import co.touchlab.kermit.Logger
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import com.powersync.PowerSyncDatabase
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import com.powersync.connector.supabase.SupabaseConnector
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import com.powersync.sync.SyncStatusData
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import io.github.jan.supabase.auth.status.SessionStatus
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import kotlinx.atomicfu.atomic
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import kotlinx.coroutines.CancellationException
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import kotlinx.coroutines.launch
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import org.koin.android.ext.android.inject
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class SyncService: LifecycleService() {
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private val connector: SupabaseConnector by inject()
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private val database: PowerSyncDatabase by inject()
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private var holdsServiceLock = false
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private val notificationManager get()= NotificationManagerCompat.from(this)
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override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
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super.onStartCommand(intent, flags, startId)
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holdsServiceLock = SERVICE_RUNNING.compareAndSet(false, true)
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if (!holdsServiceLock) {
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stopSelf()
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return START_NOT_STICKY
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}
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createNotificationChannel()
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ServiceCompat.startForeground(
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this,
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startId,
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buildNotification(),
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if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
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ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC
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} else {
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0
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}
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)
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lifecycleScope.launch {
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database.currentStatus.asFlow().collect {
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try {
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Logger.i("Sync service received status $it")
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notificationManager.notify(startId, buildNotification(it))
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} catch (e: SecurityException) {
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Logger.d("Ignoring security exception when updating notification", e)
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}
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}
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}
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lifecycleScope.launch {
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connector.sessionStatus.collect {
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when (it) {
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is SessionStatus.Authenticated -> {
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database.connect(connector)
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}
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is SessionStatus.NotAuthenticated -> {
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database.disconnectAndClear()
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Logger.i("Stopping sync service, user logged out")
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return@collect
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}
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else -> {
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// Ignore
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}
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}
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}
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}.invokeOnCompletion {
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if (it !is CancellationException) {
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this.lifecycle.currentState
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stopSelf(startId)
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}
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}
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return START_NOT_STICKY
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}
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override fun onTimeout(startId: Int, fgsType: Int) {
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// Background sync was running for too long without the app ever being open...
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stopSelf(startId)
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}
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override fun onDestroy() {
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if (holdsServiceLock) {
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SERVICE_RUNNING.value = false
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}
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super.onDestroy()
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}
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private fun createNotificationChannel() {
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val channel = NotificationChannelCompat.Builder(CHANNEL_ID, NotificationManagerCompat.IMPORTANCE_LOW)
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.setName(getString(R.string.background_channel_name))
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.build()
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notificationManager.createNotificationChannel(channel)
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}
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private fun buildNotification(state: SyncStatusData? = null): Notification = Notification.Builder(this, CHANNEL_ID).apply {
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setContentTitle(getString(R.string.sync_notification_title))
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setSmallIcon(R.drawable.ic_launcher_foreground)
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if (state != null) {
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if (state.uploading || state.downloading) {
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setProgress(0, 0, true)
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}
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}
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}.build()
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private companion object {
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val CHANNEL_ID = "background_sync"
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val SERVICE_RUNNING = atomic(false)
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}
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}

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