add a configurable reconnect option for websocket

app/src/main/kotlin/com/github/gotify/service/WebSocketConnection.kt

@@ -12,6 +12,10 @@ import com.github.gotify.client.model.Message
 import java.util.Calendar
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicLong
+import kotlin.math.pow
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
 import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
 import okhttp3.OkHttpClient
 import okhttp3.Request
@@ -24,7 +28,9 @@ internal class WebSocketConnection(
     private val baseUrl: String,
     settings: SSLSettings,
     private val token: String?,
-    private val alarmManager: AlarmManager
+    private val alarmManager: AlarmManager,
+    private val reconnectDelay: Duration,
+    private val exponentialBackoff: Boolean
 ) {
     companion object {
         private val ID = AtomicLong(0)
@@ -128,19 +134,19 @@ internal class WebSocketConnection(
         state = State.Disconnected
     }
 
-    fun scheduleReconnectNow(seconds: Long) = scheduleReconnect(ID.get(), seconds)
+    fun scheduleReconnectNow(scheduleIn: Duration) = scheduleReconnect(ID.get(), scheduleIn)
 
     @Synchronized
-    fun scheduleReconnect(id: Long, seconds: Long) {
+    fun scheduleReconnect(id: Long, scheduleIn: Duration) {
         if (state == State.Connecting || state == State.Connected) {
             return
         }
         state = State.Scheduled
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-            Logger.info("WebSocket: scheduling a restart in $seconds second(s) (via alarm manager)")
+            Logger.info("WebSocket: scheduling a restart in $scheduleIn (via alarm manager)")
             val future = Calendar.getInstance()
-            future.add(Calendar.SECOND, seconds.toInt())
+            future.add(Calendar.SECOND, scheduleIn.inWholeSeconds.toInt())
 
             alarmManagerCallback?.run(alarmManager::cancel)
             val cb = OnAlarmListener { syncExec(id) { start() } }
@@ -153,11 +159,11 @@ internal class WebSocketConnection(
                 null
             )
         } else {
-            Logger.info("WebSocket: scheduling a restart in $seconds second(s)")
+            Logger.info("WebSocket: scheduling a restart in $scheduleIn")
             handlerCallback?.run(reconnectHandler::removeCallbacks)
             val cb = Runnable { syncExec(id) { start() } }
             handlerCallback = cb
-            reconnectHandler.postDelayed(cb, TimeUnit.SECONDS.toMillis(seconds))
+            reconnectHandler.postDelayed(cb, scheduleIn.inWholeMilliseconds)
         }
     }
 
@@ -204,10 +210,15 @@ internal class WebSocketConnection(
                 closed()
 
                 errorCount++
-                val minutes = (errorCount * 2 - 1).coerceAtMost(20)
 
-                onFailure.execute(response?.message ?: "unreachable", minutes)
-                scheduleReconnect(id, TimeUnit.MINUTES.toSeconds(minutes.toLong()))
+                var scheduleIn = reconnectDelay
+                if (exponentialBackoff) {
+                    scheduleIn *= 2.0.pow(errorCount - 1)
+                }
+                scheduleIn = scheduleIn.coerceIn(5.seconds..20.minutes)
+
+                onFailure.execute(response?.message ?: "unreachable", scheduleIn)
+                scheduleReconnect(id, scheduleIn)
             }
             super.onFailure(webSocket, t, response)
         }
@@ -221,7 +232,7 @@ internal class WebSocketConnection(
     }
 
     internal fun interface OnNetworkFailureRunnable {
-        fun execute(status: String, minutes: Int)
+        fun execute(status: String, reconnectIn: Duration)
     }
 
     internal enum class State {

app/src/main/kotlin/com/github/gotify/service/WebSocketService.kt

@@ -40,6 +40,11 @@ import com.github.gotify.messages.MessagesActivity
 import io.noties.markwon.Markwon
 import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.atomic.AtomicLong
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.DurationUnit
+import kotlin.time.toDuration
 import org.tinylog.kotlin.Logger
 
 internal class WebSocketService : Service() {
@@ -110,16 +115,29 @@ internal class WebSocketService : Service() {
 
         val cm = getSystemService(CONNECTIVITY_SERVICE) as ConnectivityManager
         val alarmManager = getSystemService(ALARM_SERVICE) as AlarmManager
+        val sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
+        val reconnectDelay =
+            sharedPreferences.getString(
+                getString(R.string.setting_key_reconnect_delay),
+                null
+            )?.toIntOrNull()?.toDuration(DurationUnit.SECONDS) ?: 1.minutes
+
+        val exponentialBackoff = sharedPreferences.getBoolean(
+            getString(R.string.setting_key_exponential_backoff),
+            true
+        )
 
         connection = WebSocketConnection(
             settings.url,
             settings.sslSettings(),
             settings.token,
-            alarmManager
+            alarmManager,
+            reconnectDelay,
+            exponentialBackoff
         )
             .onOpen { onOpen() }
             .onClose { onClose() }
-            .onFailure { status, minutes -> onFailure(status, minutes) }
+            .onFailure { status, reconnectIn -> onFailure(status, reconnectIn) }
             .onMessage { message -> onMessage(message) }
             .onReconnected { notifyMissedNotifications() }
             .start()
@@ -180,16 +198,14 @@ internal class WebSocketService : Service() {
     }
 
     private fun doReconnect() {
-        connection?.scheduleReconnectNow(15)
+        connection?.scheduleReconnectNow(15.seconds)
     }
 
-    private fun onFailure(status: String, minutes: Int) {
+    private fun onFailure(status: String, reconnectIn: Duration) {
         val title = getString(R.string.websocket_error, status)
-        val intervalUnit = resources
-            .getQuantityString(R.plurals.websocket_retry_interval, minutes, minutes)
         showForegroundNotification(
             title,
-            "${getString(R.string.websocket_reconnect)} $intervalUnit"
+            getString(R.string.websocket_reconnect, reconnectIn.toString())
         )
     }
 

app/src/main/kotlin/com/github/gotify/settings/SettingsActivity.kt

@@ -21,6 +21,7 @@ import androidx.preference.SwitchPreferenceCompat
 import com.github.gotify.R
 import com.github.gotify.Utils
 import com.github.gotify.databinding.SettingsActivityBinding
+import com.github.gotify.service.WebSocketService
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 
 internal class SettingsActivity :
@@ -74,6 +75,34 @@ internal class SettingsActivity :
                     getString(R.string.setting_key_notification_channels)
                 )?.isEnabled = true
             }
+            findPreference<androidx.preference.EditTextPreference>(
+                getString(R.string.setting_key_reconnect_delay)
+            )?.onPreferenceChangeListener =
+                Preference.OnPreferenceChangeListener { _, newValue ->
+                    val value = (newValue as String).trim().toIntOrNull() ?: 60
+                    if (value !in 5..1200) {
+                        Utils.showSnackBar(
+                            requireActivity(),
+                            "Please enter a value between 5 and 1200"
+                        )
+                        return@OnPreferenceChangeListener false
+                    }
+
+                    requestWebSocketRestart()
+                    true
+                }
+            findPreference<SwitchPreferenceCompat>(
+                getString(R.string.setting_key_exponential_backoff)
+            )?.onPreferenceChangeListener =
+                Preference.OnPreferenceChangeListener { _, _ ->
+                    requestWebSocketRestart()
+                    true
+                }
+        }
+
+        private fun requestWebSocketRestart() {
+            val intent = Intent(requireContext(), WebSocketService::class.java)
+            requireContext().startService(intent)
         }
 
         override fun onViewCreated(view: View, savedInstanceState: Bundle?) {

app/src/main/res/values/arrays.xml

@@ -34,6 +34,7 @@
     </string-array>
     <string name="time_format_value_absolute">time_format_absolute</string>
     <string name="time_format_value_relative">time_format_relative</string>
+
     <bool name="notification_channels">false</bool>
     <bool name="exclude_from_recent">false</bool>
     <bool name="prompt_onreceive_intent">true</bool>

app/src/main/res/values/strings.xml

@@ -115,11 +115,14 @@
     <string name="action_dialog_button_cancel">Cancel</string>
 
     <string name="websocket_error">Error %s (see logs)</string>
-    <string name="websocket_reconnect">Trying to reconnect</string>
-    <plurals name="websocket_retry_interval">
-        <item quantity="one">in %d minute</item>
-        <item quantity="other">in %d minutes</item>
-    </plurals>
+    <string name="websocket_reconnect">Trying to reconnect in %s</string>
+    <string name="setting_reconnect_delay">Reconnect Delay (Seconds)</string>
+    <string name="setting_key_reconnect_delay">reconnect_delay</string>
+    <string name="setting_connection">Connection</string>
+    <string name="setting_reconnect_interval_summary">Delay between reconnect attempts</string>
+    <string name="setting_exponential_backoff_title">Exponential Backoff</string>
+    <string name="setting_exponential_backoff_summary">Exponentially increase the reconnect delay for each reconnect attempt</string>
+    <string name="setting_key_exponential_backoff">reconnect_exponential_backoff</string>
 
     <string name="notification_channel_title_foreground">Gotify foreground notification</string>
     <string name="notification_channel_title_min">Min priority messages (&lt;1)</string>

app/src/main/res/xml/root_preferences.xml

@@ -51,4 +51,18 @@
             android:summary="@string/setting_summary_prompt_onreceive_intent" />
     </PreferenceCategory>
 
+    <PreferenceCategory app:title="@string/setting_connection">
+        <EditTextPreference
+            android:defaultValue="60"
+            android:inputType="numberSigned"
+            android:key="@string/setting_key_reconnect_delay"
+            android:title="@string/setting_reconnect_delay"
+            android:summary="@string/setting_reconnect_interval_summary" />
+        <SwitchPreferenceCompat
+            android:key="@string/setting_key_exponential_backoff"
+            android:title="@string/setting_exponential_backoff_title"
+            android:summary="@string/setting_exponential_backoff_summary"
+            android:defaultValue="true" />
+    </PreferenceCategory>
+
 </PreferenceScreen>