stash_file

A stash file storage extension

Overview

This storage extension for stash provides a file based storage that relies on a highly performing binary serialization of the tems through the use of msgpack serialization format. This storage backend is particularly optimized to support cache features, like expiration and eviction, which are highly dependent on the update of control fields on the cache entries upon user operations. The main advantage is that the update of the control fields does not cause the update of the whole cache entry as some of the other storage implementations like stash_hive or stash_sembast. This storage extension relies on a file system abstraction provided by the file package

Getting Started

Add this to your pubspec.yaml (or create it) replacing x.x.x with the latest version of stash_file:

dependencies:
    stash_file: ^x.x.x

Run the following command to install dependencies:

dart pub get

Finally, to start developing import the followin libraries:

import 'package:stash/stash_api.dart';
import 'package:stash_file/stash_file.dart';

Usage

Vault

The example bellow creates a vault with a file storage backend. In this rather simple example the serialization and deserialization of the object is coded by hand but it's more usual to rely on libraries like json_serializable.

import 'dart:io';

import 'package:stash/stash_api.dart';
import 'package:stash_file/stash_file.dart';

class Task {
  final int id;
  final String title;
  final bool completed;

  Task({required this.id, required this.title, this.completed = false});

  /// Creates a [Task] from json map
  factory Task.fromJson(Map<String, dynamic> json) => Task(
      id: json['id'] as int,
      title: json['title'] as String,
      completed: json['completed'] as bool);

  /// Creates a json map from a [Task]
  Map<String, dynamic> toJson() =>
      <String, dynamic>{'id': id, 'title': title, 'completed': completed};

  @override
  String toString() {
    return 'Task $id, "$title" is ${completed ? "completed" : "not completed"}';
  }
}

void main() async {
  // Temporary directory
  final path = Directory.systemTemp.path;

  // Creates a store
  final store = await newFileLocalVaultStore(path: path);

  // Creates a vault from the previously created store
  final vault = await store.vault<Task>(
      name: 'vault', 
      fromEncodable: (json) => Task.fromJson(json),
      eventListenerMode: EventListenerMode.synchronous)
    ..on<VaultEntryCreatedEvent<Task>>().listen(
        (event) => print('Key "${event.entry.key}" added to the vault'));

  // Adds a task with key 'task1' to the vault
  await vault.put(
      'task1', Task(id: 1, title: 'Run vault store example', completed: true));
  // Retrieves the value from the vault
  print(await vault.get('task1'));
}

Cache

The example bellow creates a cache with a file storage backend. In this rather simple example the serialization and deserialization of the object is coded by hand but it's more usual to rely on libraries like json_serializable.

import 'dart:io';

import 'package:stash/stash_api.dart';
import 'package:stash_file/stash_file.dart';

class Task {
  final int id;
  final String title;
  final bool completed;

  Task({required this.id, required this.title, this.completed = false});

  /// Creates a [Task] from json map
  factory Task.fromJson(Map<String, dynamic> json) => Task(
      id: json['id'] as int,
      title: json['title'] as String,
      completed: json['completed'] as bool);

  /// Creates a json map from a [Task]
  Map<String, dynamic> toJson() =>
      <String, dynamic>{'id': id, 'title': title, 'completed': completed};

  @override
  String toString() {
    return 'Task $id, "$title" is ${completed ? "completed" : "not completed"}';
  }
}

void main() async {
  // Temporary directory
  final path = Directory.systemTemp.path;

  // Creates a store
  final store = await newFileLocalCacheStore(path: path);

  // Creates a cache with a capacity of 10 from the previously created store
  final cache = await store.cache<Task>(
      name: 'cache1',
      fromEncodable: (json) => Task.fromJson(json),
      maxEntries: 10,
      eventListenerMode: EventListenerMode.synchronous)
    ..on<CacheEntryCreatedEvent<Task>>().listen(
        (event) => print('Key "${event.entry.key}" added to the cache'));

  // Adds a task with key 'task1' to the cache
  await cache.put(
      'task1', Task(id: 1, title: 'Run cache store example', completed: true));
  // Retrieves the value from the cache
  print(await cache.get('task1'));
}

Additional Features

Please take a look at the documentation of stash to gather additional information and to explore the full range of capabilities of the stash library

Features and Bugs

Please file feature requests and bugs at the issue tracker.

License

This project is licensed under the MIT License - see the LICENSE file for details