Periodically optimize the FTS index.

app/src/main/java/org/thoughtcrime/securesms/database/MessageTable.java

@@ -79,6 +79,7 @@ import org.thoughtcrime.securesms.database.model.databaseprotos.SessionSwitchove
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.groups.GroupMigrationMembershipChange;
 import org.thoughtcrime.securesms.insights.InsightsConstants;
+import org.thoughtcrime.securesms.jobs.OptimizeMessageSearchIndexJob;
 import org.thoughtcrime.securesms.jobs.TrimThreadJob;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
@@ -1534,6 +1535,7 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
     String[]       args = SqlUtil.buildArgs(parentStoryId);
 
     db.delete(TABLE_NAME, PARENT_STORY_ID + " = ?", args);
+    OptimizeMessageSearchIndexJob.enqueue();
   }
 
   public int deleteStoriesOlderThan(long timestamp, boolean hasSeenReleaseChannelStories) {
@@ -1578,6 +1580,10 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
         }
       }
 
+      if (deletedStoryCount > 0) {
+        OptimizeMessageSearchIndexJob.enqueue();
+      }
+
       db.setTransactionSuccessful();
       return deletedStoryCount;
     } finally {
@@ -3041,7 +3047,16 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
     return deleteMessage(messageId, threadId);
   }
 
+  public boolean deleteMessage(long messageId, boolean notify) {
+    long threadId = getThreadIdForMessage(messageId);
+    return deleteMessage(messageId, threadId, notify);
+  }
+
   public boolean deleteMessage(long messageId, long threadId) {
+    return deleteMessage(messageId, threadId, true);
+  }
+
+  private boolean deleteMessage(long messageId, long threadId, boolean notify) {
     Log.d(TAG, "deleteMessage(" + messageId + ")");
 
     AttachmentTable attachmentDatabase = SignalDatabase.attachments();
@@ -3058,9 +3073,14 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
 
     SignalDatabase.threads().setLastScrolled(threadId, 0);
     boolean threadDeleted = SignalDatabase.threads().update(threadId, false);
-    notifyConversationListeners(threadId);
-    notifyStickerListeners();
-    notifyStickerPackListeners();
+
+    if (notify) {
+      notifyConversationListeners(threadId);
+      notifyStickerListeners();
+      notifyStickerPackListeners();
+      OptimizeMessageSearchIndexJob.enqueue();
+    }
+
     return threadDeleted;
   }
 
@@ -3269,6 +3289,7 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
       setTransactionSuccessful();
     } finally {
       endTransaction();
+      OptimizeMessageSearchIndexJob.enqueue();
     }
   }
 
@@ -3286,16 +3307,27 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
 
     try (Cursor cursor = db.query(TABLE_NAME, new String[] {ID}, where, null, null, null, null)) {
       while (cursor != null && cursor.moveToNext()) {
-        deleteMessage(cursor.getLong(0));
+        deleteMessage(cursor.getLong(0), false);
       }
     }
+
+    notifyConversationListeners(threadIds);
+    notifyStickerListeners();
+    notifyStickerPackListeners();
+    OptimizeMessageSearchIndexJob.enqueue();
   }
 
   int deleteMessagesInThreadBeforeDate(long threadId, long date) {
     SQLiteDatabase db    = databaseHelper.getSignalWritableDatabase();
     String         where = THREAD_ID + " = ? AND " + DATE_RECEIVED + " < " + date;
 
-    return db.delete(TABLE_NAME, where, SqlUtil.buildArgs(threadId));
+    int count = db.delete(TABLE_NAME, where, SqlUtil.buildArgs(threadId));
+
+    if (count > 0) {
+      OptimizeMessageSearchIndexJob.enqueue();
+    }
+
+    return count;
   }
 
   void deleteAbandonedMessages() {
@@ -3305,6 +3337,7 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
     int deletes = db.delete(TABLE_NAME, where, null);
     if (deletes > 0) {
       Log.i(TAG, "Deleted " + deletes + " abandoned messages");
+      OptimizeMessageSearchIndexJob.enqueue();
     }
   }
 
@@ -3342,6 +3375,7 @@ public class MessageTable extends DatabaseTable implements MessageTypes, Recipie
 
     SQLiteDatabase database = databaseHelper.getSignalWritableDatabase();
     database.delete(TABLE_NAME, null, null);
+    OptimizeMessageSearchIndexJob.enqueue();
   }
 
   public @Nullable ViewOnceExpirationInfo getNearestExpiringViewOnceMessage() {

app/src/main/java/org/thoughtcrime/securesms/database/SearchTable.kt

@@ -6,7 +6,9 @@ import android.database.Cursor
 import android.text.TextUtils
 import org.intellij.lang.annotations.Language
 import org.signal.core.util.SqlUtil
+import org.signal.core.util.ThreadUtil
 import org.signal.core.util.logging.Log
+import org.signal.core.util.withinTransaction
 
 /**
  * Contains all databases necessary for full-text search (FTS).
@@ -148,6 +150,73 @@ class SearchTable(context: Context, databaseHelper: SignalDatabase) : DatabaseTa
     }
   }
 
+  /**
+   * This performs the same thing as the `optimize` command in SQLite, but broken into iterative stages to avoid locking up the database for too long.
+   * If what's going on in this method seems weird, that's because it is, but please read the sqlite docs -- we're following their algorithm:
+   * https://www.sqlite.org/fts5.html#the_optimize_command
+   *
+   * Note that in order for the [SqlUtil.getTotalChanges] call to work, we have to be within a transaction, or else the connection pool screws everything up
+   * (the stats are on a per-connection basis).
+   *
+   * There's this double-batching mechanism happening here to strike a balance between making individual transactions short while also not hammering the
+   * database with a ton of independent transactions.
+   *
+   * To give you some ballpark numbers, on a large database (~400k messages), it takes ~75 iterations to fully optimize everything.
+   */
+  fun optimizeIndex(timeout: Long): Boolean {
+    val pageSize = 64 // chosen through experimentation
+    val batchSize = 10 // chosen through experimentation
+    val noChangeThreshold = 2 // if less changes occurred than this, operation is considered no-op (see sqlite docs ref'd in kdoc)
+
+    val startTime = System.currentTimeMillis()
+    var totalIterations = 0
+    var totalBatches = 0
+    var actualWorkTime = 0L
+    var finished = false
+
+    while (!finished) {
+      var batchIterations = 0
+      val batchStartTime = System.currentTimeMillis()
+
+      writableDatabase.withinTransaction { db ->
+        // Note the negative page size -- see sqlite docs ref'd in kdoc
+        db.execSQL("INSERT INTO $MMS_FTS_TABLE_NAME ($MMS_FTS_TABLE_NAME, rank) values ('merge', -$pageSize)")
+        var previousCount = SqlUtil.getTotalChanges(db)
+
+        val iterativeStatement = db.compileStatement("INSERT INTO $MMS_FTS_TABLE_NAME ($MMS_FTS_TABLE_NAME, rank) values ('merge', $pageSize)")
+        iterativeStatement.execute()
+        var count = SqlUtil.getTotalChanges(db)
+
+        while (batchIterations < batchSize && count - previousCount >= noChangeThreshold) {
+          previousCount = count
+          iterativeStatement.execute()
+
+          count = SqlUtil.getTotalChanges(db)
+          batchIterations++
+        }
+
+        if (count - previousCount < noChangeThreshold) {
+          finished = true
+        }
+      }
+
+      totalIterations += batchIterations
+      totalBatches++
+      actualWorkTime += System.currentTimeMillis() - batchStartTime
+
+      if (actualWorkTime >= timeout) {
+        Log.w(TAG, "Timed out during optimization! We did $totalIterations iterations across $totalBatches batches, taking ${System.currentTimeMillis() - startTime} ms. Bailed out to avoid database lockup.")
+        return false
+      }
+
+      // We want to sleep in between batches to give other db operations a chance to run
+      ThreadUtil.sleep(50)
+    }
+
+    Log.d(TAG, "Took ${System.currentTimeMillis() - startTime} ms and $totalIterations iterations across $totalBatches batches to optimize. Of that time, $actualWorkTime ms were spent actually working (~${actualWorkTime / totalBatches} ms/batch). The rest was spent sleeping.")
+    return true
+  }
+
   private fun createFullTextSearchQuery(query: String): String {
     return query
       .split(" ")