120 lines
2.9 KiB
Dart
120 lines
2.9 KiB
Dart
import 'dart:async';
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import 'dart:convert';
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import 'dart:io';
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import 'package:angel_framework/angel_framework.dart';
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import 'package:pool/pool.dart';
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/// Persists in-memory changes to a file on disk.
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class JsonFileService extends Service {
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FileStat _lastStat;
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final Pool _mutex = new Pool(1);
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MapService _store;
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final File file;
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JsonFileService(this.file,
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{bool allowRemoveAll: false, bool allowQuery: true}) {
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_store = new MapService(
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allowRemoveAll: allowRemoveAll == true,
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allowQuery: allowQuery != false);
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}
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_load() async {
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if (!await file.exists()) await file.writeAsString(JSON.encode([]));
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var stat = await file.stat();
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//
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if (_lastStat == null ||
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stat.modified.millisecondsSinceEpoch >
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_lastStat.modified.millisecondsSinceEpoch) {
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_lastStat = stat;
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var contents = await file.readAsString();
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try {
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var list = JSON.decode(contents) as List;
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_store.items.clear(); // Clear exist in-memory copy
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_store.items.addAll(list.map(_revive)); // Insert all new entries
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} catch (e) {
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print('WARNING: Failed to reload contents of ${file.path}.');
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}
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}
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}
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_save() async {
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var r = await _mutex.request();
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await file.writeAsString(JSON.encode(_store.items.map(_jsonify).toList()));
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r.release();
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}
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@override
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Future<List> index([Map params]) async =>
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_load().then((_) => _store.index(params));
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@override
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Future<Map> read(id, [Map params]) =>
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_load().then((_) => _store.read(id, params));
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@override
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Future<Map> create(data, [Map params]) async {
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await _load();
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_store.items.add(data);
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await _save();
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return data;
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}
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@override
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Future<Map> remove(id, [Map params]) async {
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await _load();
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var r = await _store.remove(id, params);
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await _save();
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return r;
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}
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@override
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Future<Map> update(id, data, [Map params]) async {
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await _load();
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var r = await _store.update(id, data, params);
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await _save();
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return r;
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}
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@override
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Future<Map> modify(id, data, [Map params]) async {
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await _load();
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var r = await _store.update(id, data, params);
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await _save();
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return r;
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}
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}
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_safeForJson(x) {
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if (x is DateTime)
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return x.toIso8601String();
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else if (x is Map)
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return _jsonify(x);
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else if (x is num || x is String || x is bool || x == null)
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return x;
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else if (x is Iterable)
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return x.map(_safeForJson).toList();
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else
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return x.toString();
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}
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Map _jsonify(Map map) {
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return map.keys.fold<Map>({}, (out, k) => out..[k] = _safeForJson(map[k]));
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}
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_revive(x) {
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if (x is Map) {
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return x.keys.fold<Map>({}, (out, k) => out..[k] = _revive(x[k]));
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} else if (x is Iterable)
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return x.map(_revive).toList();
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else if (x is String) {
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try {
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return DateTime.parse(x);
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} catch (e) {
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return x;
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}
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} else
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return x;
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}
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