duraq_isar 3.0.0

Isar storage backend for DuraQ, the durable Dart queue

duraq_isar

The Isar storage backend for DuraQ, the durable Dart queue.

It lives outside duraq so that a project using only the SQLite backend does not resolve isar_community and its generated code, and is not held to isar_community's version constraint.

Use

dependencies:
  duraq: ^3.0.0
  duraq_isar: ^3.0.0
  isar_community: ^3.3.2

import 'package:duraq/duraq.dart';
import 'package:duraq_isar/duraq_isar.dart';
import 'package:isar_community/isar.dart';

await Isar.initializeIsarCore(download: true);
final isar = await Isar.open([
  ...IsarStorage.requiredSchemas,
  // your other schemas
], directory: 'path/to/db');

final storage = IsarStorage(isar);
final queue = Queue<String>('emails', storage);

await queue.enqueue('[e-mail]');
await queue.processNext(send);

await storage.close();  // releases locks; the caller still owns the Isar instance
await isar.close();

IsarStorage implements StorageInterface, so everything in the duraq README — retry policies, dead letters, scheduling, maintenance, health checks — works the same way here.

What is specific to this backend

• The caller owns the Isar instance. IsarStorage.close() releases the locks this storage holds and leaves the instance open, because you opened it and may be sharing it with the rest of your application.
• Pass IsarStorage.requiredSchemas rather than listing the collections by hand. The set grows — it gained a schema-version collection in 1.0.0 — and a hand-written list breaks the next time it does.
• removeDuplicateEntries() is a one-off cleanup for databases written by duraq 1.0.1 or earlier, which could store several rows for one entry. Run it once after upgrading.
• Manual transactions throw. An Isar write transaction takes its work as a callback, so beginTransaction/commitTransaction/rollbackTransaction cannot be honoured. Use transaction().

Development

This package is developed in the DuraQ repository. tool/verify.sh at the repository root analyses and tests it alongside duraq. Its suites are the contract suites from duraq, run against this backend.

Test concurrency is capped in dart_test.yaml: Isar holds a native database per open instance, and at higher concurrency the test process is killed rather than failing.