fix cache cleanup deleting more statuses than it should (#2348)

* fix cache cleanup deleting more statuses than it should

* reset LOAD_AT_ONCE

* improve tests

* move cache clean code back to ViewModel

app/src/main/java/com/keylesspalace/tusky/appstore/CacheUpdater.kt

@@ -6,12 +6,11 @@ import com.keylesspalace.tusky.db.AppDatabase
 import io.reactivex.rxjava3.core.Single
 import io.reactivex.rxjava3.disposables.Disposable
 import io.reactivex.rxjava3.schedulers.Schedulers
-import java.util.concurrent.TimeUnit
 import javax.inject.Inject
 
 class CacheUpdater @Inject constructor(
     eventHub: EventHub,
-    accountManager: AccountManager,
+    private val accountManager: AccountManager,
     private val appDatabase: AppDatabase,
     gson: Gson
 ) {
@@ -21,11 +20,6 @@ class CacheUpdater @Inject constructor(
     init {
         val timelineDao = appDatabase.timelineDao()
 
-        Schedulers.io().scheduleDirect {
-            val olderThan = System.currentTimeMillis() - CLEANUP_INTERVAL
-            appDatabase.timelineDao().cleanup(olderThan)
-        }
-
         disposable = eventHub.events.subscribe { event ->
             val accountId = accountManager.activeAccount?.id ?: return@subscribe
             when (event) {
@@ -61,8 +55,4 @@ class CacheUpdater @Inject constructor(
             .subscribeOn(Schedulers.io())
             .subscribe()
     }
-
-    companion object {
-        val CLEANUP_INTERVAL = TimeUnit.DAYS.toMillis(14)
-    }
 }

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/CachedTimelineViewModel.kt

@@ -43,11 +43,14 @@ import com.keylesspalace.tusky.network.TimelineCases
 import com.keylesspalace.tusky.util.dec
 import com.keylesspalace.tusky.util.inc
 import com.keylesspalace.tusky.viewdata.StatusViewData
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.rx3.await
 import retrofit2.HttpException
 import javax.inject.Inject
+import kotlin.time.DurationUnit
+import kotlin.time.toDuration
 
 /**
  * TimelineViewModel that caches all statuses in a local database
@@ -81,6 +84,16 @@ class CachedTimelineViewModel @Inject constructor(
         }
         .cachedIn(viewModelScope)
 
+    init {
+        viewModelScope.launch {
+            delay(5.toDuration(DurationUnit.SECONDS)) // delay so the db is not locked during initial ui refresh
+            accountManager.activeAccount?.id?.let { accountId ->
+                db.timelineDao().cleanup(accountId, MAX_STATUSES_IN_CACHE)
+                db.timelineDao().cleanupAccounts(accountId)
+            }
+        }
+    }
+
     override fun updatePoll(newPoll: Poll, status: StatusViewData.Concrete) {
         // handled by CacheUpdater
     }
@@ -207,4 +220,8 @@ class CachedTimelineViewModel @Inject constructor(
             }
         }
     }
+
+    companion object {
+        private const val MAX_STATUSES_IN_CACHE = 1000
+    }
 }

app/src/main/java/com/keylesspalace/tusky/components/timeline/viewmodel/TimelineViewModel.kt

@@ -43,7 +43,6 @@ import com.keylesspalace.tusky.settings.PrefKeys
 import com.keylesspalace.tusky.viewdata.StatusViewData
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.rx3.asFlow
 import kotlinx.coroutines.rx3.await

app/src/main/java/com/keylesspalace/tusky/db/TimelineDao.kt

@@ -98,8 +98,29 @@ AND serverId = :statusId"""
     )
     abstract fun delete(accountId: Long, statusId: String)
 
-    @Query("""DELETE FROM TimelineStatusEntity WHERE createdAt < :olderThan""")
-    abstract fun cleanup(olderThan: Long)
+    /**
+     * Cleans the TimelineStatusEntity table from old status entries.
+     * @param accountId id of the account for which to clean statuses
+     * @param limit how many statuses to keep
+     */
+    @Query(
+        """DELETE FROM TimelineStatusEntity WHERE timelineUserId = :accountId AND serverId NOT IN
+        (SELECT serverId FROM TimelineStatusEntity WHERE timelineUserId = :accountId ORDER BY LENGTH(serverId) DESC, serverId DESC LIMIT :limit)
+    """
+    )
+    abstract suspend fun cleanup(accountId: Long, limit: Int)
+
+    /**
+     * Cleans the TimelineAccountEntity table from accounts that are no longer referenced in the TimelineStatusEntity table
+     * @param accountId id of the user account for which to clean timeline accounts
+     */
+    @Query(
+        """DELETE FROM TimelineAccountEntity WHERE timelineUserId = :accountId AND serverId NOT IN
+        (SELECT authorServerId FROM TimelineStatusEntity WHERE timelineUserId = :accountId) 
+        AND serverId NOT IN 
+        (SELECT reblogAccountId FROM TimelineStatusEntity WHERE timelineUserId = :accountId AND reblogAccountId IS NOT NULL)"""
+    )
+    abstract suspend fun cleanupAccounts(accountId: Long)
 
     @Query(
         """UPDATE TimelineStatusEntity SET poll = :poll