Restart SSE connection in listenForItemChange() when not alive

When restarting openHAB existing SSE connections may look like they are still intact to the client, but no further events are received. Thus restart a connection when no ALIVE events are received anymore.

Signed-off-by: mueller-ma <mueller-ma@users.noreply.github.com>

Author: mueller-ma

mobile/src/main/java/org/openhab/habdroid/util/ItemClient.kt

@@ -20,8 +20,10 @@ import javax.xml.parsers.DocumentBuilderFactory
 import javax.xml.parsers.ParserConfigurationException
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
 import org.json.JSONArray
 import org.json.JSONException
 import org.json.JSONObject
@@ -119,10 +121,33 @@ object ItemClient {
         )
         var eventSubscription = createSubscription()
 
+        suspend fun restartSubscription() {
+            try {
+                eventSubscription.cancel()
+            } catch (e: Exception) {
+                Log.e(TAG, "Error cancelling SSE subscription for item $item", e)
+            }
+            delay(5.seconds)
+            eventSubscription = createSubscription()
+        }
+
+        var watchdogJob: Job? = null
+
+        fun resetAliveWatchdog() {
+            watchdogJob?.cancel()
+            watchdogJob = scope.launch {
+                delay(30.seconds) // ALIVE event is sent every 10 seconds
+                Log.d(TAG, "No events received for item $item, restarting subscription")
+                restartSubscription()
+            }
+        }
+        resetAliveWatchdog()
+
         try {
             while (scope.isActive) {
                 try {
                     val event = JSONObject(eventSubscription.getNextEvent())
+                    resetAliveWatchdog()
                     if (event.optString("type") == "ALIVE") {
                         Log.d(TAG, "Got ALIVE event for item $item")
                         continue
@@ -144,9 +169,7 @@ object ItemClient {
                     Log.e(TAG, "Failed parsing JSON of state change event for item $item", e)
                 } catch (e: HttpClient.SseFailureException) {
                     Log.e(TAG, "SSE failure for item $item", e)
-                    eventSubscription.cancel()
-                    delay(5.seconds)
-                    eventSubscription = createSubscription()
+                    restartSubscription()
                 }
             }
         } finally {