fix: Load multiple olm sessions from the database at once for increased performance

lib/encryption/olm_manager.dart

@@ -358,15 +358,40 @@ class OlmManager {
     return res;
   }
 
-  Future<List<OlmSession>> getOlmSessions(String senderKey) async {
+  Future<void> getOlmSessionsForDevicesFromDatabase(
+      List<String> senderKeys) async {
+    if (client.database == null) {
+      return;
+    }
+    final rows = await client.database
+        .dbGetOlmSessionsForDevices(client.id, senderKeys)
+        .get();
+    final res = <String, List<OlmSession>>{};
+    for (final row in rows) {
+      res[row.identityKey] ??= <OlmSession>[];
+      final sess = OlmSession.fromDb(row, client.userID);
+      if (sess.isValid) {
+        res[row.identityKey].add(sess);
+      }
+    }
+    for (final entry in res.entries) {
+      _olmSessions[entry.key] = entry.value;
+    }
+  }
+
+  Future<List<OlmSession>> getOlmSessions(String senderKey,
+      {bool getFromDb = true}) async {
     var sess = olmSessions[senderKey];
-    if (sess == null || sess.isEmpty) {
+    if ((getFromDb ?? true) && (sess == null || sess.isEmpty)) {
       final sessions = await getOlmSessionsFromDatabase(senderKey);
       if (sessions.isEmpty) {
         return [];
       }
       sess = _olmSessions[senderKey] = sessions;
     }
+    if (sess == null) {
+      return [];
+    }
     sess.sort((a, b) => a.lastReceived == b.lastReceived
         ? a.sessionId.compareTo(b.sessionId)
         : b.lastReceived.compareTo(a.lastReceived));
@@ -475,8 +500,10 @@ class OlmManager {
   }
 
   Future<Map<String, dynamic>> encryptToDeviceMessagePayload(
-      DeviceKeys device, String type, Map<String, dynamic> payload) async {
-    final sess = await getOlmSessions(device.curve25519Key);
+      DeviceKeys device, String type, Map<String, dynamic> payload,
+      {bool getFromDb}) async {
+    final sess =
+        await getOlmSessions(device.curve25519Key, getFromDb: getFromDb);
     if (sess.isEmpty) {
       throw ('No olm session found for ${device.userId}:${device.deviceId}');
     }
@@ -509,9 +536,8 @@ class OlmManager {
     var data = <String, Map<String, Map<String, dynamic>>>{};
     // first check if any of our sessions we want to encrypt for are in the database
     if (client.database != null) {
-      for (final device in deviceKeys) {
-        await getOlmSessions(device.curve25519Key);
-      }
+      await getOlmSessionsForDevicesFromDatabase(
+          deviceKeys.map((d) => d.curve25519Key).toList());
     }
     final deviceKeysWithoutSession = List<DeviceKeys>.from(deviceKeys);
     deviceKeysWithoutSession.removeWhere((DeviceKeys deviceKeys) =>
@@ -526,7 +552,8 @@ class OlmManager {
       }
       try {
         data[device.userId][device.deviceId] =
-            await encryptToDeviceMessagePayload(device, type, payload);
+            await encryptToDeviceMessagePayload(device, type, payload,
+                getFromDb: false);
       } catch (e, s) {
         Logs().w('[LibOlm] Error encrypting to-device event', e, s);
         continue;

lib/src/database/database.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:moor/moor.dart';
-import 'package:olm/olm.dart' as olm;
 
 import '../../famedlysdk.dart' as sdk;
 import '../../matrix_api.dart' as api;
@@ -197,28 +196,6 @@ class Database extends _$Database {
     return res;
   }
 
-  Future<Map<String, List<olm.Session>>> getOlmSessions(
-      int clientId, String userId) async {
-    final raw = await getAllOlmSessions(clientId).get();
-    if (raw.isEmpty) {
-      return {};
-    }
-    final res = <String, List<olm.Session>>{};
-    for (final row in raw) {
-      if (!res.containsKey(row.identityKey)) {
-        res[row.identityKey] = [];
-      }
-      try {
-        var session = olm.Session();
-        session.unpickle(userId, row.pickle);
-        res[row.identityKey].add(session);
-      } catch (e, s) {
-        Logs().e('[LibOlm] Could not unpickle olm session', e, s);
-      }
-    }
-    return res;
-  }
-
   Future<DbOutboundGroupSession> getDbOutboundGroupSession(
       int clientId, String roomId) async {
     final res = await dbGetOutboundGroupSession(clientId, roomId).get();

lib/src/database/database.g.dart

@@ -6281,6 +6281,23 @@ abstract class _$Database extends GeneratedDatabase {
         }).map(olmSessions.mapFromRow);
   }
 
+  Selectable<DbOlmSessions> dbGetOlmSessionsForDevices(
+      int client_id, List<String> identity_keys) {
+    var $arrayStartIndex = 2;
+    final expandedidentity_keys =
+        $expandVar($arrayStartIndex, identity_keys.length);
+    $arrayStartIndex += identity_keys.length;
+    return customSelect(
+        'SELECT * FROM olm_sessions WHERE client_id = :client_id AND identity_key IN ($expandedidentity_keys)',
+        variables: [
+          Variable.withInt(client_id),
+          for (var $ in identity_keys) Variable.withString($)
+        ],
+        readsFrom: {
+          olmSessions
+        }).map(olmSessions.mapFromRow);
+  }
+
   Future<int> storeOlmSession(int client_id, String identitiy_key,
       String session_id, String pickle, int last_received) {
     return customInsert(

lib/src/database/database.moor

@@ -183,6 +183,7 @@ getAllUserDeviceKeysKeys: SELECT * FROM user_device_keys_key WHERE client_id = :
 getAllUserCrossSigningKeys: SELECT * FROM user_cross_signing_keys WHERE client_id = :client_id;
 getAllOlmSessions: SELECT * FROM olm_sessions WHERE client_id = :client_id;
 dbGetOlmSessions: SELECT * FROM olm_sessions WHERE client_id = :client_id AND identity_key = :identity_key;
+dbGetOlmSessionsForDevices: SELECT * FROM olm_sessions WHERE client_id = :client_id AND identity_key IN :identity_keys;
 storeOlmSession: INSERT OR REPLACE INTO olm_sessions (client_id, identity_key, session_id, pickle, last_received) VALUES (:client_id, :identitiy_key, :session_id, :pickle, :last_received);
 getAllOutboundGroupSessions: SELECT * FROM outbound_group_sessions WHERE client_id = :client_id;
 dbGetOutboundGroupSession: SELECT * FROM outbound_group_sessions WHERE client_id = :client_id AND room_id = :room_id;