Added support for bulk downloading to ObjectBox backend

Fixed bugs & reimplemented some removed methods in example app

example/lib/screens/configure_download/configure_download.dart

@@ -67,7 +67,7 @@ class ConfigureDownloadPopup extends StatelessWidget {
                           suffixText: 'max. tps',
                           value: (provider) => provider.rateLimit,
                           min: 1,
-                          max: 500,
+                          max: 50000,
                           maxEligibleTilesPreview: 20,
                           onChanged: (provider, value) =>
                               provider.rateLimit = value,

example/lib/screens/import_store/import_store.dart

@@ -14,7 +14,7 @@ class ImportStorePopup extends StatefulWidget {
 class _ImportStorePopupState extends State<ImportStorePopup> {
   final Map<String, _ImportStore> importStores = {};
 
-// TODO: Implement
+  // TODO: Implement
   @override
   Widget build(BuildContext context) => Scaffold(
         appBar: AppBar(

example/lib/screens/main/pages/recovery/components/recovery_start_button.dart

@@ -1,6 +1,10 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_map/flutter_map.dart';
 import 'package:flutter_map_tile_caching/flutter_map_tile_caching.dart';
+import 'package:provider/provider.dart';
+
+import '../../../../configure_download/configure_download.dart';
+import '../../region_selection/state/region_selection_provider.dart';
 
 class RecoveryStartButton extends StatelessWidget {
   const RecoveryStartButton({
@@ -26,35 +30,32 @@ class RecoveryStartButton extends StatelessWidget {
                 onPressed: !result.isFailed
                     ? null
                     : () async {
-                        //TODO: Implement
-                        /* final DownloaderProvider downloadProvider =
-                        Provider.of<DownloaderProvider>(
-                      context,
-                      listen: false,
-                    )
-                          ..region = region.toRegion(
-                            rectangle: (r) => r,
-                            circle: (c) => c,
-                            line: (l) => l,
-                          )
-                          ..minZoom = region.minZoom
-                          ..maxZoom = region.maxZoom
-                          ..setSelectedStore(
-                            FMTC.instance(region.storeName),
-                          )
-                          ..regionTiles = tiles.data;
-  
-                    await Navigator.of(context).push(
-                      MaterialPageRoute<String>(
-                        builder: (BuildContext context) =>
-                            DownloadRegionPopup(
-                          region: downloadProvider.region!,
-                        ),
-                        fullscreenDialog: true,
-                      ),
-                    );
-  
-                    moveToDownloadPage();*/
+                        final regionSelectionProvider =
+                            Provider.of<RegionSelectionProvider>(
+                          context,
+                          listen: false,
+                        )
+                              ..region = result.region.toRegion()
+                              ..minZoom = result.region.minZoom
+                              ..maxZoom = result.region.maxZoom
+                              ..setSelectedStore(
+                                FMTCStore(result.region.storeName),
+                              );
+                        // TODO: Check
+                        //..regionTiles = tiles.data;
+
+                        await Navigator.of(context).push(
+                          MaterialPageRoute<String>(
+                            builder: (context) => ConfigureDownloadPopup(
+                              region: regionSelectionProvider.region!,
+                              minZoom: result.region.minZoom,
+                              maxZoom: result.region.maxZoom,
+                            ),
+                            fullscreenDialog: true,
+                          ),
+                        );
+
+                        moveToDownloadPage();
                       },
               )
             : const Padding(

lib/src/backend/backend_access.dart

@@ -28,3 +28,22 @@ abstract mixin class FMTCBackendAccess {
     _internal = newInternal;
   }
 }
+
+@meta.internal
+abstract mixin class FMTCBackendAccessThreadSafe {
+  static FMTCBackendInternalThreadSafe? _internal;
+
+  @meta.internal
+  @meta.experimental
+  static FMTCBackendInternalThreadSafe get internal =>
+      _internal ?? (throw RootUnavailable());
+
+  @meta.internal
+  @meta.protected
+  static set internal(FMTCBackendInternalThreadSafe? newInternal) {
+    if (newInternal != null && _internal != null) {
+      throw RootAlreadyInitialised();
+    }
+    _internal = newInternal;
+  }
+}

lib/src/backend/export_external.dart

@@ -1,6 +1,8 @@
 // Copyright © Luka S (JaffaKetchup) under GPL-v3
 // A full license can be found at .\LICENSE
 
-export 'impls/objectbox/backend.dart';
-export 'interfaces/backend.dart';
+export 'impls/objectbox/backend/backend.dart';
+export 'interfaces/backend/backend.dart';
+export 'interfaces/backend/internal.dart';
+export 'interfaces/backend/internal_thread_safe.dart';
 export 'utils/errors.dart';

lib/src/backend/impls/objectbox/backend/backend.dart

@@ -0,0 +1,63 @@
+// Copyright © Luka S (JaffaKetchup) under GPL-v3
+// A full license can be found at .\LICENSE
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'dart:isolate';
+
+import 'package:collection/collection.dart';
+import 'package:flutter/foundation.dart';
+import 'package:path/path.dart' as path;
+import 'package:path_provider/path_provider.dart';
+
+import '../../../../../flutter_map_tile_caching.dart';
+import '../../../export_internal.dart';
+import '../models/generated/objectbox.g.dart';
+import '../models/src/recovery.dart';
+import '../models/src/store.dart';
+import '../models/src/tile.dart';
+
+part 'internal_thread_safe.dart';
+part 'internal.dart';
+part 'internal_worker.dart';
+
+/// Implementation of [FMTCBackend] that uses ObjectBox as the storage database
+final class FMTCObjectBoxBackend implements FMTCBackend {
+  /// {@macro fmtc.backend.initialise}
+  ///
+  /// [maxDatabaseSize] is the maximum size the database file can grow
+  /// to, in KB. Exceeding it throws [DbFullException]. Defaults to 10 GB.
+  ///
+  /// [macosApplicationGroup] should be set when creating a sandboxed macOS app,
+  /// specify the application group (of less than 20 chars). See
+  /// [the ObjectBox docs](https://docs.objectbox.io/getting-started) for
+  /// details.
+  @override
+  Future<void> initialise({
+    String? rootDirectory,
+    int maxDatabaseSize = 10000000,
+    String? macosApplicationGroup,
+  }) =>
+      FMTCObjectBoxBackendInternal._instance.initialise(
+        rootDirectory: rootDirectory,
+        maxDatabaseSize: maxDatabaseSize,
+        macosApplicationGroup: macosApplicationGroup,
+      );
+
+  /// {@macro fmtc.backend.uninitialise}
+  ///
+  /// If [immediate] is `true`, any operations currently underway will be lost,
+  /// as the worker will be killed as quickly as possible (not necessarily
+  /// instantly).
+  /// If `false`, all operations currently underway will be allowed to complete,
+  /// but any operations started after this method call will be lost. A lost
+  /// operation may throw [RootUnavailable].
+  @override
+  Future<void> uninitialise({
+    bool deleteRoot = false,
+    bool immediate = false,
+  }) =>
+      FMTCObjectBoxBackendInternal._instance
+          .uninitialise(deleteRoot: deleteRoot, immediate: immediate);
+}

lib/src/backend/impls/objectbox/backend.dart → lib/src/backend/impls/objectbox/backend/internal.dart

@@ -1,64 +1,7 @@
 // Copyright © Luka S (JaffaKetchup) under GPL-v3
 // A full license can be found at .\LICENSE
 
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
-import 'dart:isolate';
-
-import 'package:collection/collection.dart';
-import 'package:flutter/foundation.dart';
-import 'package:path/path.dart' as path;
-import 'package:path_provider/path_provider.dart';
-
-import '../../../../flutter_map_tile_caching.dart';
-import '../../export_internal.dart';
-import 'models/generated/objectbox.g.dart';
-import 'models/src/recovery.dart';
-import 'models/src/store.dart';
-import 'models/src/tile.dart';
-
-part 'worker.dart';
-
-/// Implementation of [FMTCBackend] that uses ObjectBox as the storage database
-final class FMTCObjectBoxBackend implements FMTCBackend {
-  /// {@macro fmtc.backend.inititialise}
-  ///
-  /// [maxDatabaseSize] is the maximum size the database file can grow
-  /// to, in KB. Exceeding it throws [DbFullException]. Defaults to 10 GB.
-  ///
-  /// [macosApplicationGroup] should be set when creating a sandboxed macOS app,
-  /// specify the application group (of less than 20 chars). See
-  /// [the ObjectBox docs](https://docs.objectbox.io/getting-started) for
-  /// details.
-  @override
-  Future<void> initialise({
-    String? rootDirectory,
-    int maxDatabaseSize = 10000000,
-    String? macosApplicationGroup,
-  }) =>
-      FMTCObjectBoxBackendInternal._instance.initialise(
-        rootDirectory: rootDirectory,
-        maxDatabaseSize: maxDatabaseSize,
-        macosApplicationGroup: macosApplicationGroup,
-      );
-
-  /// {@macro fmtc.backend.uninitialise}
-  ///
-  /// If [immediate] is `true`, any operations currently underway will be lost,
-  /// as the worker will be killed as quickly as possible (not necessarily
-  /// instantly).
-  /// If `false`, all operations currently underway will be allowed to complete,
-  /// but any operations started after this method call will be lost. A lost
-  /// operation may throw [RootUnavailable].
-  @override
-  Future<void> uninitialise({
-    bool deleteRoot = false,
-    bool immediate = false,
-  }) =>
-      FMTCObjectBoxBackendInternal._instance
-          .uninitialise(deleteRoot: deleteRoot, immediate: immediate);
-}
+part of 'backend.dart';
 
 /// Internal implementation of [FMTCBackend] that uses ObjectBox as the storage
 /// database
@@ -164,13 +107,13 @@ class _ObjectBoxBackendImpl implements FMTCObjectBoxBackendInternal {
     ).create(recursive: true);
 
     // Prepare to recieve `SendPort` from worker
+    late final ByteData storeReference;
     _workerResOneShot[0] = Completer();
-    unawaited(
-      _workerResOneShot[0]!.future.then((res) {
-        _sendPort = res!['sendPort'];
-        _workerResOneShot.remove(0);
-      }),
-    );
+    final workerInitialRes = _workerResOneShot[0]!.future.then((res) {
+      storeReference = res!['storeReference'];
+      _sendPort = res['sendPort'];
+      _workerResOneShot.remove(0);
+    });
 
     // Setup worker comms/response handler
     final receivePort = ReceivePort();
@@ -223,7 +166,12 @@ class _ObjectBoxBackendImpl implements FMTCObjectBoxBackendInternal {
       debugName: '[FMTC] ObjectBox Backend Worker',
     );
 
+    await workerInitialRes;
+
     FMTCBackendAccess.internal = this;
+    FMTCBackendAccessThreadSafe.internal = _ObjectBoxBackendThreadSafeImpl._(
+      storeReference: storeReference,
+    );
   }
 
   Future<void> uninitialise({
@@ -267,6 +215,7 @@ class _ObjectBoxBackendImpl implements FMTCObjectBoxBackendInternal {
     //_rotalDebouncer.cancel();
 
     FMTCBackendAccess.internal = null;
+    FMTCBackendAccessThreadSafe.internal = null;
   }
 
   @override
@@ -352,10 +301,11 @@ class _ObjectBoxBackendImpl implements FMTCObjectBoxBackendInternal {
   @override
   Future<ObjectBoxTile?> readTile({
     required String url,
+    String? storeName,
   }) async =>
       (await _sendCmdOneShot(
         type: _WorkerCmdType.readTile,
-        args: {'url': url},
+        args: {'url': url, 'storeName': storeName},
       ))!['tile'];
 
   @override
@@ -378,17 +328,6 @@ class _ObjectBoxBackendImpl implements FMTCObjectBoxBackendInternal {
         args: {'storeName': storeName, 'url': url, 'bytes': bytes},
       );
 
-  @override
-  Future<void> writeTilesDirect({
-    required String storeName,
-    required List<String> urls,
-    required List<Uint8List> bytess,
-  }) =>
-      _sendCmdOneShot(
-        type: _WorkerCmdType.writeTilesDirect,
-        args: {'storeName': storeName, 'urls': urls, 'bytess': bytess},
-      );
-
   @override
   Future<bool?> deleteTile({
     required String storeName,