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box_impl.dart
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box_impl.dart
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import 'dart:async';
import 'dart:collection';
import 'package:hive/hive.dart';
import 'package:hive/src/backend/storage_backend.dart';
import 'package:hive/src/binary/frame.dart';
import 'package:hive/src/box/box_base.dart';
import 'package:hive/src/box/box_options.dart';
import 'package:hive/src/box/change_notifier.dart';
import 'package:hive/src/hive_impl.dart';
import 'package:meta/meta.dart';
export 'package:hive/src/backend/storage_backend_stub.dart'
if (dart.library.io) 'package:hive/src/backend/storage_backend_vm.dart'
if (dart.library.html) 'package:hive/src/backend/storage_backend_js.dart';
class BoxEntry {
final dynamic value;
final int offset;
final int length;
const BoxEntry(this.value, this.offset, this.length);
@override
bool operator ==(dynamic other) {
if (other is BoxEntry) {
return other.value == value &&
other.offset == offset &&
other.length == length;
}
return false;
}
}
class BoxImpl extends BoxBase {
static const deletedRatio = 0.15;
static const deletedThreshold = 40;
@override
final String name;
final HiveImpl hive;
final BoxOptions options;
final StorageBackend _backend;
final ChangeNotifier _notifier;
Map<String, BoxEntry> _entries = HashMap();
bool _open = true;
int _deletedEntries = 0;
BoxImpl(this.hive, this.name, this.options, this._backend)
: _notifier = ChangeNotifier(),
super(hive);
@visibleForTesting
BoxImpl.debug(
this.hive, this.name, this.options, this._backend, this._entries,
[ChangeNotifier notifier])
: _notifier = notifier ?? ChangeNotifier(),
super(hive);
@override
bool get isOpen => _open;
@override
String get path => _backend.path;
@override
Iterable<String> get keys {
checkOpen();
return _entries.keys;
}
@protected
void checkOpen() {
if (!_open) {
throw HiveError('Box has already been closed.');
}
}
@override
Stream<BoxEvent> watch({String key}) {
checkOpen();
return _notifier.watch(key: key);
}
Future initialize() async {
_deletedEntries = await _backend.initialize(_entries, options.lazy);
}
@override
Future<T> get<T>(String key, {T defaultValue}) {
checkOpen();
if (!_entries.containsKey(key)) return Future.value(defaultValue);
if (options.lazy) return Future.value(_entries[key]?.value as T);
var entry = _entries[key];
return _backend.readValue(key, entry.offset, entry.length) as Future<T>;
}
@override
dynamic operator [](String key) {
if (!options.lazy) {
throw HiveError('Only lazy boxes can be accessed using [].');
}
return _entries[key]?.value;
}
@override
bool has(String key) {
checkOpen();
return _entries.containsKey(key);
}
@override
Future put(String key, dynamic value) async {
checkOpen();
var frame = Frame(key, value);
if (value != null) {
var entry = await _backend.writeFrame(frame, options.lazy);
if (_entries.containsKey(key)) {
_deletedEntries++;
}
_entries[key] = entry;
} else {
if (!_entries.containsKey(key)) return;
await _backend.writeFrame(frame, options.lazy);
_deletedEntries++;
_entries.remove(key);
}
await performCompactationIfNeeded();
_notifier.notify(key, value);
}
@override
Future delete(String key) {
return put(key, null);
}
@override
Future putAll(Map<String, dynamic> kvPairs) async {
checkOpen();
if (kvPairs.isEmpty) return;
var toBeDeletedEntries = 0;
var frames = <Frame>[];
kvPairs.forEach((key, dynamic val) {
var frame = Frame(key, val);
if (val != null) {
frames.add(frame);
if (_entries.containsKey(key)) {
toBeDeletedEntries++;
}
} else {
if (_entries.containsKey(key)) {
frames.add(frame);
toBeDeletedEntries++;
}
}
});
var newEntries = await _backend.writeFrames(frames, options.lazy);
for (var i = 0; i < frames.length; i++) {
var frame = frames[i];
if (frame.value != null) {
_entries[frame.key] = newEntries[i];
} else {
_entries.remove(frame.key);
}
}
_deletedEntries += toBeDeletedEntries;
await performCompactationIfNeeded();
for (var frame in frames) {
_notifier.notify(frame.key, frame.value);
}
}
@override
Future deleteAll(Iterable<String> keysToDelete) {
var nullValues = List.filled(keysToDelete.length, null);
return putAll(Map<String, void>.fromIterables(keysToDelete, nullValues));
}
@override
Future<Map<String, dynamic>> toMap() {
checkOpen();
if (options.lazy) {
var mappedEntries =
_entries.map<String, dynamic>((k, e) => MapEntry(k, e.value));
return Future.value(mappedEntries);
}
return _backend.readAll(_entries.keys);
}
@override
Future<int> clear() async {
checkOpen();
if (_entries.isEmpty) return 0;
await _backend.clear();
var oldEntries = _entries;
_entries = HashMap();
_deletedEntries = 0;
for (var key in oldEntries.keys) {
_notifier.notify(key, null);
}
return oldEntries.length;
}
@override
Future<void> compact() async {
checkOpen();
if (_deletedEntries == 0) return;
_entries = await _backend.compact(_entries);
_deletedEntries = 0;
}
@visibleForTesting
Future<void> performCompactationIfNeeded() {
if (_deletedEntries > deletedThreshold) {
if (_deletedEntries / _entries.length > deletedRatio) {
return compact();
}
}
return Future.value();
}
@override
Future<void> close() async {
if (!_open) return;
await waitForRunningTransactions();
await _notifier.close();
_open = false;
hive.unregisterBox(name);
await _backend.close();
}
@override
Future<void> deleteFromDisk() async {
await waitForRunningTransactions();
await _notifier.close();
_open = false;
hive.unregisterBox(name);
await _backend.deleteFromDisk();
}
@visibleForTesting
Map<String, BoxEntry> get debugEntries => _entries;
@visibleForTesting
int get debugDeletedEntries => _deletedEntries;
}