Fix/initial scheduling of global update (#1416)

* Fix setting initial global update delay

In case no update has run yet, and the "last automated update" defaulted to 0, the calculation always resulted in a multiple of the interval.

This resulted for e.g., interval 24, to always be scheduled at 00:00.
For e.g., interval 6, it was always one of the following times: 00:00, 06:00, 12:00, 18:00; depending on the current system time.

* Delete the existing "last automated update time"

So that the update will be triggered based on the time the server got started again after the update.

* Extract migrations into separate functions

* Cleanup migration execution logic

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/update/IUpdater.kt

@@ -8,6 +8,8 @@ import suwayomi.tachidesk.manga.model.dataclass.MangaDataClass
 interface IUpdater {
     fun getLastUpdateTimestamp(): Long
 
+    fun deleteLastAutomatedUpdateTimestamp()
+
     fun addCategoriesToUpdateQueue(
         categories: List<CategoryDataClass>,
         clear: Boolean?,

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/update/Updater.kt

@@ -116,10 +116,24 @@ class Updater : IUpdater {
 
     override fun getLastUpdateTimestamp(): Long = preferences.getLong(lastUpdateKey, 0)
 
+    fun saveLastUpdateTimestamp() {
+        preferences.edit().putLong(lastUpdateKey, System.currentTimeMillis()).apply()
+    }
+
+    fun getLastAutomatedUpdateTimestamp(): Long = preferences.getLong(lastAutomatedUpdateKey, 0)
+
+    fun saveLastAutomatedUpdateTimestamp() {
+        preferences.edit().putLong(lastAutomatedUpdateKey, System.currentTimeMillis()).apply()
+    }
+
+    override fun deleteLastAutomatedUpdateTimestamp() {
+        preferences.edit().remove(lastAutomatedUpdateKey).apply()
+    }
+
     private fun autoUpdateTask() {
         try {
-            val lastAutomatedUpdate = preferences.getLong(lastAutomatedUpdateKey, 0)
-            preferences.edit().putLong(lastAutomatedUpdateKey, System.currentTimeMillis()).apply()
+            val lastAutomatedUpdate = getLastAutomatedUpdateTimestamp()
+            saveLastAutomatedUpdateTimestamp()
 
             if (getStatus().isRunning) {
                 logger.debug { "Global update is already in progress" }
@@ -150,12 +164,23 @@ class Updater : IUpdater {
             serverConfig.globalUpdateInterval.value.hours
                 .coerceAtLeast(6.hours)
                 .inWholeMilliseconds
-        val lastAutomatedUpdate = preferences.getLong(lastAutomatedUpdateKey, 0)
-        val timeToNextExecution = (updateInterval - (System.currentTimeMillis() - lastAutomatedUpdate)).mod(updateInterval)
+        val lastAutomatedUpdate = getLastAutomatedUpdateTimestamp()
+        val isInitialScheduling = lastAutomatedUpdate == 0L
+
+        val timeToNextExecution =
+            if (!isInitialScheduling) {
+                (updateInterval - (System.currentTimeMillis() - lastAutomatedUpdate)).mod(updateInterval)
+            } else {
+                updateInterval
+            }
+
+        if (isInitialScheduling) {
+            saveLastAutomatedUpdateTimestamp()
+        }
 
         val wasPreviousUpdateTriggered =
             System.currentTimeMillis() - (
-                if (lastAutomatedUpdate > 0) lastAutomatedUpdate else System.currentTimeMillis()
+                if (!isInitialScheduling) lastAutomatedUpdate else System.currentTimeMillis()
             ) < updateInterval
         if (!wasPreviousUpdateTriggered) {
             GlobalScope.launch {
@@ -316,7 +341,7 @@ class Updater : IUpdater {
         clear: Boolean?,
         forceAll: Boolean,
     ) {
-        preferences.edit().putLong(lastUpdateKey, System.currentTimeMillis()).apply()
+        saveLastUpdateTimestamp()
 
         if (clear == true) {
             reset()