feat: implement Web Worker support

hive/lib/hive.dart

@@ -8,6 +8,7 @@ import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:crypto/crypto.dart';
+import 'package:hive/src/backend/storage_backend.dart';
 import 'package:hive/src/box/default_compaction_strategy.dart';
 import 'package:hive/src/box/default_key_comparator.dart';
 import 'package:hive/src/crypto/aes_cbc_pkcs7.dart';
@@ -18,9 +19,14 @@ import 'package:hive/src/object/hive_object.dart';
 import 'package:hive/src/util/extensions.dart';
 import 'package:meta/meta.dart';
 
-export 'src/box_collection/box_collection_stub.dart'
-    if (dart.library.html) 'package:hive/src/box_collection/box_collection_indexed_db.dart'
-    if (dart.library.io) 'package:hive/src/box_collection/box_collection.dart';
+import 'src/backend/js/web_worker/web_worker_stub.dart'
+    if (dart.library.html) 'src/backend/js/web_worker/web_worker.dart';
+
+export 'package:hive/src/box_collection/box_collection.dart';
+
+export 'src/backend/js/web_worker/web_worker_stub.dart'
+    if (dart.library.html) 'src/backend/js/web_worker/web_worker.dart';
+export 'src/backend/storage_backend_memory.dart';
 export 'src/object/hive_object.dart' show HiveObject, HiveObjectMixin;
 
 part 'src/annotations/hive_field.dart';

hive/lib/src/backend/js/backend_manager.dart

@@ -1,18 +1,33 @@
 import 'package:hive/hive.dart';
 import 'package:hive/src/backend/storage_backend.dart';
+import 'package:hive/src/backend/stub/backend_manager_memory.dart';
 
 import 'native/backend_manager.dart' as native;
+import 'web_worker/backend_manager.dart' as web_worker;
 
 /// Opens IndexedDB databases
 abstract class BackendManager {
-  BackendManager._();
+  // caching the backend manager as it makes no sense to have different backends
+  // within the same application
+  static BackendManagerInterface? _manager;
+
+  const BackendManager._();
 
-  // dummy implementation as the WebWorker branch is not stable yet
   static BackendManagerInterface select(
       [HiveStorageBackendPreference? backendPreference]) {
-    switch (backendPreference) {
-      default:
-        return native.BackendManager();
+    if (_manager == null) {
+      if (backendPreference is HiveStorageBackendPreferenceWebWorker) {
+        _manager = web_worker.BackendManagerWebWorker(backendPreference);
+      } else if (backendPreference == HiveStorageBackendPreference.native ||
+          backendPreference == null) {
+        _manager = native.BackendManager();
+      } else if (backendPreference == HiveStorageBackendPreference.memory) {
+        _manager = BackendManagerMemory();
+      } else {
+        throw UnimplementedError(
+            '$backendPreference is not a known HiveStorageBackendPreference');
+      }
     }
+    return _manager!;
   }
 }

hive/lib/src/backend/js/native/backend_manager.dart

@@ -30,8 +30,6 @@ class BackendManager implements BackendManagerInterface {
     // in case the objectStore is not contained, re-open the db and
     // update version
     if (!(db.objectStoreNames ?? []).contains(objectStoreName)) {
-      print(
-          'Creating objectStore $objectStoreName in database $databaseName...');
       db = await indexedDB!.open(
         databaseName,
         version: (db.version ?? 1) + 1,
@@ -44,15 +42,49 @@ class BackendManager implements BackendManagerInterface {
       );
     }
 
-    print('Got object store $objectStoreName in database $databaseName.');
-
     return StorageBackendJs(db, cipher, objectStoreName);
   }
 
   @override
-  Future<void> deleteBox(String name, String? path, String? collection) async {
-    print('Delete $name // $collection from disk');
+  Future<Map<String, StorageBackend>> openCollection(
+      Set<String> names,
+      String? path,
+      bool crashRecovery,
+      HiveCipher? cipher,
+      String collection) async {
+    var db =
+        await indexedDB!.open(collection, version: 1, onUpgradeNeeded: (e) {
+      var db = e.target.result as Database;
+      for (var objectStoreName in names) {
+        if (!(db.objectStoreNames ?? []).contains(objectStoreName)) {
+          db.createObjectStore(objectStoreName);
+        }
+      }
+    });
 
+    // in case the objectStore is not contained, re-open the db and
+    // update version
+    if (!(names.every((objectStoreName) =>
+        (db.objectStoreNames ?? []).contains(objectStoreName)))) {
+      db = await indexedDB!.open(
+        collection,
+        version: (db.version ?? 1) + 1,
+        onUpgradeNeeded: (e) {
+          var db = e.target.result as Database;
+          for (var objectStoreName in names) {
+            if (!(db.objectStoreNames ?? []).contains(objectStoreName)) {
+              db.createObjectStore(objectStoreName);
+            }
+          }
+        },
+      );
+    }
+    return Map.fromEntries(
+        names.map((e) => MapEntry(e, StorageBackendJs(db, cipher, e))));
+  }
+
+  @override
+  Future<void> deleteBox(String name, String? path, String? collection) async {
     // compatibility for old store format
     final databaseName = collection ?? name;
     final objectStoreName = collection == null ? 'box' : name;

hive/lib/src/backend/js/native/storage_backend_js.dart

@@ -205,8 +205,6 @@ class StorageBackendJs extends StorageBackend {
         ? window.indexedDB
         : WorkerGlobalScope.instance.indexedDB;
 
-    print('Delete ${_db.name} // $objectStoreName from disk');
-
     // directly deleting the entire DB if a non-collection Box
     if (_db.objectStoreNames?.length == 1) {
       await indexDB!.deleteDatabase(_db.name!);

hive/lib/src/backend/js/web_worker/backend_manager.dart

@@ -0,0 +1,98 @@
+import 'dart:async';
+import 'dart:html';
+import 'dart:indexed_db';
+import 'dart:js' as js;
+import 'package:hive/hive.dart';
+import 'package:hive/src/backend/js/web_worker/web_worker_interface.dart';
+
+import '../../storage_backend.dart';
+import 'storage_backend_web_worker.dart';
+
+/// Opens IndexedDB databases
+class BackendManagerWebWorker implements BackendManagerInterface {
+  final HiveStorageBackendPreferenceWebWorker backendPreference;
+
+  WebWorkerInterface? _interface;
+
+  WebWorkerInterface get interface {
+    _interface ??= WebWorkerInterface(
+        backendPreference.path, backendPreference.onStackTrace);
+    return _interface!;
+  }
+
+  BackendManagerWebWorker(this.backendPreference);
+
+  IdbFactory? get indexedDB => js.context.hasProperty('window')
+      ? window.indexedDB
+      : WorkerGlobalScope.instance.indexedDB;
+
+  @override
+  Future<StorageBackendWebWorker> open(String name, String? path,
+      bool crashRecovery, HiveCipher? cipher, String? collection) async {
+    // compatibility for old store format
+    final databaseName = collection ?? name;
+    final objectStoreName = collection == null ? 'box' : name;
+
+    await interface.query('open', databaseName, objectStoreName);
+    return StorageBackendWebWorker(
+        interface, databaseName, cipher, objectStoreName);
+  }
+
+  @override
+  Future<Map<String, StorageBackend>> openCollection(
+      Set<String> names,
+      String? path,
+      bool crashRecovery,
+      HiveCipher? cipher,
+      String collection) async {
+    // for collections, create an additional interface
+    final interface = WebWorkerInterface(
+        backendPreference.path, backendPreference.onStackTrace);
+    await interface.query('open', collection, null, null, names);
+    return Map.fromEntries(names.map(
+      (e) => MapEntry(
+        e,
+        StorageBackendWebWorker(interface, collection, cipher, e),
+      ),
+    ));
+  }
+
+  @override
+  Future<void> deleteBox(String name, String? path, String? collection) async {
+    // compatibility for old store format
+    final databaseName = collection ?? name;
+    final objectStoreName = collection == null ? 'box' : name;
+
+    // cipher doesn't matter on delete operation
+    await interface.query('delete', databaseName, objectStoreName);
+  }
+
+  @override
+  Future<bool> boxExists(String name, String? path, String? collection) async {
+    // TODO(TheOneWithTheBraid): migrate into web worker
+
+    // compatibility for old store format
+    final databaseName = collection ?? name;
+    final objectStoreName = collection == null ? 'box' : name;
+    // https://stackoverflow.com/a/17473952
+    try {
+      var _exists = true;
+      if (collection == null) {
+        await indexedDB!.open(databaseName, version: 1, onUpgradeNeeded: (e) {
+          e.target.transaction!.abort();
+          _exists = false;
+        });
+      } else {
+        final db =
+            await indexedDB!.open(collection, version: 1, onUpgradeNeeded: (e) {
+          var db = e.target.result as Database;
+          _exists = (db.objectStoreNames ?? []).contains(objectStoreName);
+        });
+        _exists = (db.objectStoreNames ?? []).contains(objectStoreName);
+      }
+      return _exists;
+    } catch (error) {
+      return false;
+    }
+  }
+}