improve long polling service reliability

app/src/main/kotlin/dev/meloda/fast/presentation/MainActivity.kt

@@ -137,7 +137,8 @@ class MainActivity : AppCompatActivity() {
                     }
                 }
 
-                LaunchedEffect(longPollStateToApply) {
+                LifecycleResumeEffect(longPollStateToApply) {
+                    Log.d("LongPollMainActivity", "longPollStateToApply: $longPollStateToApply")
                     if (longPollStateToApply != LongPollState.Background) {
                         if (longPollStateToApply.isLaunched() && longPollCurrentState.isLaunched()
                             && longPollCurrentState != longPollStateToApply
@@ -151,6 +152,8 @@ class MainActivity : AppCompatActivity() {
                             inBackground = longPollStateToApply == LongPollState.Background
                         )
                     }
+
+                    onPauseOrDispose {}
                 }
 
                 val sendOnline by userSettings.sendOnlineStatus.collectAsStateWithLifecycle()
@@ -299,12 +302,19 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private val longPollingServiceIntent by lazy {
+        Intent(this, LongPollingService::class.java)
+    }
+    private val onlineServiceIntent by lazy {
+        Intent(this, OnlineService::class.java)
+    }
+
     private fun toggleLongPollService(
         enable: Boolean,
         inBackground: Boolean = AppSettings.Experimental.longPollInBackground
     ) {
         if (enable) {
-            val longPollIntent = Intent(this, LongPollingService::class.java)
+            val longPollIntent = longPollingServiceIntent
 
             if (inBackground) {
                 ContextCompat.startForegroundService(this, longPollIntent)
@@ -312,15 +322,15 @@ class MainActivity : AppCompatActivity() {
                 startService(longPollIntent)
             }
         } else {
-            stopService(Intent(this, LongPollingService::class.java))
+            stopService(longPollingServiceIntent)
         }
     }
 
     private fun toggleOnlineService(enable: Boolean) {
         if (enable) {
-            startService(Intent(this, OnlineService::class.java))
+            startService(onlineServiceIntent)
         } else {
-            stopService(Intent(this, OnlineService::class.java))
+            stopService(onlineServiceIntent)
         }
     }
 

app/src/main/kotlin/dev/meloda/fast/service/longpolling/LongPollingService.kt

@@ -30,11 +30,13 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import org.koin.android.ext.android.inject
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.resume
 import kotlin.coroutines.suspendCoroutine
+import kotlin.time.Duration.Companion.seconds
 
 class LongPollingService : Service() {
 
@@ -42,20 +44,9 @@ class LongPollingService : Service() {
 
     private val job = SupervisorJob()
 
-    private val exceptionHandler = CoroutineExceptionHandler { _, throwable ->
-        Log.e(TAG, "error: $throwable")
-
-        if (throwable !is NoAccessTokenException) {
-            throwable.printStackTrace()
-        }
-
-        if (throwable is LongPollException) {
-            // TODO: 23-Mar-25, Danil Nikolaev: restart LongPoll
-            return@CoroutineExceptionHandler
-        }
-
-        longPollController.updateCurrentState(LongPollState.Exception)
-        longPollController.setStateToApply(LongPollState.Exception)
+    private val exceptionHandler =
+        CoroutineExceptionHandler { _, throwable ->
+            handleError(throwable)
         }
 
     private val coroutineContext: CoroutineContext
@@ -68,6 +59,8 @@ class LongPollingService : Service() {
 
     private var currentJob: Job? = null
 
+    private val inBackground get() = AppSettings.Experimental.longPollInBackground
+
     override fun onCreate() {
         super.onCreate()
         Log.d(STATE_TAG, "onCreate()")
@@ -81,21 +74,12 @@ class LongPollingService : Service() {
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
         if (startId > 1) return START_STICKY
 
-        val inBackground = AppSettings.Experimental.longPollInBackground
-
         Log.d(
             STATE_TAG,
             "onStartCommand: asForeground: $inBackground; flags: $flags; startId: $startId;\ninstance: $this"
         )
 
-        if (currentJob != null) {
-            currentJob?.cancel()
-            currentJob = null
-        }
-
-        coroutineScope.launch {
-            currentJob = startPolling().also { it.join() }
-        }
+        startJob()
 
         val openCategorySettingsIntent = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS)
@@ -113,11 +97,6 @@ class LongPollingService : Service() {
             PendingIntent.FLAG_IMMUTABLE
         )
 
-        longPollController.updateCurrentState(
-            if (inBackground) LongPollState.Background
-            else LongPollState.InApp
-        )
-
         if (inBackground) {
             val notification =
                 NotificationsUtils.createNotification(
@@ -139,17 +118,33 @@ class LongPollingService : Service() {
         return START_STICKY
     }
 
+    private fun startJob() {
+        if (currentJob != null) {
+            currentJob?.cancel()
+            currentJob = null
+        }
+
+        coroutineScope.launch {
+            currentJob = startPolling().also { it.join() }
+        }
+    }
+
     private fun startPolling(): Job {
         if (job.isCompleted || job.isCancelled) {
-            Log.d(STATE_TAG, "job is completed or cancelled")
+            Log.d(STATE_TAG, "Job is completed or cancelled")
             throw Exception("Job is over")
         }
 
-        Log.d(STATE_TAG, "job started")
+        Log.d(STATE_TAG, "Starting job...")
 
         return coroutineScope.launch(coroutineContext) {
+            longPollController.updateCurrentState(
+                if (inBackground) LongPollState.Background
+                else LongPollState.InApp
+            )
+
             if (UserConfig.accessToken.isEmpty()) {
-                throw NoAccessTokenException
+                throw NoAccessTokenException()
             }
 
             var serverInfo = getServerInfo()
@@ -251,10 +246,24 @@ class LongPollingService : Service() {
         }
     }
 
+    private fun handleError(throwable: Throwable) {
+        Log.e(TAG, "error: $throwable")
+
+        if (throwable !is NoAccessTokenException) {
+            throwable.printStackTrace()
+        }
+
+        coroutineScope.launch {
+            delay(5.seconds)
+            startJob()
+        }
+
+        longPollController.updateCurrentState(LongPollState.Exception)
+    }
+
     override fun onDestroy() {
         Log.d(STATE_TAG, "onDestroy")
         longPollController.updateCurrentState(LongPollState.Stopped)
-        updatesParser.clearListeners()
         try {
             AppSettings.edit { putBoolean(KEY_LONG_POLL_WAS_DESTROYED, true) }
             job.cancel()
@@ -281,4 +290,4 @@ class LongPollingService : Service() {
 }
 
 private data class LongPollException(override val message: String) : Throwable()
-private data object NoAccessTokenException : Throwable()
+private class NoAccessTokenException : Throwable()