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Support retrying Datastore operations. (dart-archive/gcloud#168)
* Support retrying Datastore operations. * Expose only maxAttempts * add more errors
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‎pkgs/gcloud/CHANGELOG.md

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@@ -1,6 +1,7 @@
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## 0.8.10-wip
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## 0.8.10
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- Widen the SDK constraint to support Dart 3.0
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- Support retrying Datastore operations.
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## 0.8.9
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‎pkgs/gcloud/lib/datastore.dart

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@@ -12,10 +12,12 @@ library;
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import 'dart:async';
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import 'package:http/http.dart' as http;
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import 'package:retry/retry.dart';
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import 'common.dart' show Page;
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import 'service_scope.dart' as ss;
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import 'src/datastore_impl.dart' show DatastoreImpl;
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import 'src/retry_datastore_impl.dart';
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const Symbol _datastoreKey = #gcloud.datastore;
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@@ -391,6 +393,22 @@ abstract class Datastore {
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return DatastoreImpl(client, project);
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}
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/// Retry Datastore operations where the issue seems to be transient.
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///
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/// The [delegate] is the configured [Datastore] implementation that will be
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/// used.
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///
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/// The operations will be retried at maximum of [maxAttempts].
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factory Datastore.withRetry(
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Datastore delegate, {
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int? maxAttempts,
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}) {
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return RetryDatastoreImpl(
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delegate,
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RetryOptions(maxAttempts: maxAttempts ?? 3),
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);
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}
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/// Allocate integer IDs for the partially populated [keys] given as argument.
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///
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/// The returned [Key]s will be fully populated with the allocated IDs.

‎pkgs/gcloud/lib/src/retry_datastore_impl.dart

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@@ -0,0 +1,159 @@
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// Copyright (c) 2023, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'package:retry/retry.dart';
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import '../common.dart';
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import '../datastore.dart' as datastore;
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/// Datastore implementation which retries most operations
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class RetryDatastoreImpl implements datastore.Datastore {
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final datastore.Datastore _delegate;
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final RetryOptions _retryOptions;
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RetryDatastoreImpl(this._delegate, this._retryOptions);
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@override
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Future<List<datastore.Key>> allocateIds(List<datastore.Key> keys) async {
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return await _retryOptions.retry(
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() => _delegate.allocateIds(keys),
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retryIf: _retryIf,
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);
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}
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@override
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Future<datastore.Transaction> beginTransaction({
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bool crossEntityGroup = false,
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}) async {
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return await _retryOptions.retry(
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() => _delegate.beginTransaction(crossEntityGroup: crossEntityGroup),
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retryIf: _retryIf,
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);
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}
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@override
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Future<datastore.CommitResult> commit({
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List<datastore.Entity> inserts = const [],
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List<datastore.Entity> autoIdInserts = const [],
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List<datastore.Key> deletes = const [],
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datastore.Transaction? transaction,
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}) async {
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Future<datastore.CommitResult> fn() async {
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if (transaction == null) {
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return await _delegate.commit(
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inserts: inserts,
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autoIdInserts: autoIdInserts,
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deletes: deletes,
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);
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} else {
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return await _delegate.commit(
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inserts: inserts,
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autoIdInserts: autoIdInserts,
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deletes: deletes,
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transaction: transaction,
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);
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}
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}
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final shouldNotRetry = autoIdInserts.isNotEmpty && transaction == null;
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if (shouldNotRetry) {
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return await fn();
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} else {
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return await _retryOptions.retry(fn, retryIf: _retryIf);
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}
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}
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@override
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Future<List<datastore.Entity?>> lookup(
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List<datastore.Key> keys, {
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datastore.Transaction? transaction,
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}) async {
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return await _retryOptions.retry(
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() async {
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if (transaction == null) {
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return await _delegate.lookup(keys);
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} else {
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return await _delegate.lookup(keys, transaction: transaction);
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}
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},
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retryIf: _retryIf,
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);
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}
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@override
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Future<Page<datastore.Entity>> query(
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datastore.Query query, {
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datastore.Partition? partition,
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datastore.Transaction? transaction,
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}) async {
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Future<Page<datastore.Entity>> fn() async {
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if (partition != null && transaction != null) {
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return await _delegate.query(
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query,
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partition: partition,
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transaction: transaction,
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);
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} else if (partition != null) {
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return await _delegate.query(query, partition: partition);
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} else if (transaction != null) {
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return await _delegate.query(
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query,
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transaction: transaction,
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);
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} else {
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return await _delegate.query(query);
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}
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}
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return await _retryOptions.retry(
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() async => _RetryPage(await fn(), _retryOptions),
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retryIf: _retryIf,
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);
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}
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@override
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Future rollback(datastore.Transaction transaction) async {
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return await _retryOptions.retry(
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() => _delegate.rollback(transaction),
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retryIf: _retryIf,
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);
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}
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}
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class _RetryPage<K> implements Page<K> {
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final Page<K> _delegate;
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final RetryOptions _retryOptions;
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_RetryPage(this._delegate, this._retryOptions);
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@override
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bool get isLast => _delegate.isLast;
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@override
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List<K> get items => _delegate.items;
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@override
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Future<Page<K>> next({int? pageSize}) async {
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return await _retryOptions.retry(
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() async {
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if (pageSize == null) {
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return await _delegate.next();
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} else {
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return await _delegate.next(pageSize: pageSize);
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}
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},
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retryIf: _retryIf,
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);
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}
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}
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bool _retryIf(Exception e) {
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if (e is datastore.TransactionAbortedError ||
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e is datastore.NeedIndexError ||
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e is datastore.QuotaExceededError ||
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e is datastore.PermissionDeniedError) {
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return false;
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}
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return true;
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}

‎pkgs/gcloud/pubspec.yaml

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name: gcloud
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version: 0.8.10-wip
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version: 0.8.10
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description: >-
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High level idiomatic Dart API for Google Cloud Storage, Pub-Sub and Datastore.
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repository: https://github.com/dart-lang/gcloud
@@ -16,6 +16,7 @@ dependencies:
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googleapis: '>=3.0.0 <12.0.0'
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http: '>=0.13.5 <2.0.0'
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meta: ^1.3.0
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retry: ^3.1.1
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dev_dependencies:
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dart_flutter_team_lints: ^1.0.0

‎pkgs/gcloud/test/db_all_e2e_test.dart

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@@ -10,6 +10,7 @@ library gcloud.test.db_all_test;
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import 'dart:async';
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import 'dart:io';
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import 'package:gcloud/datastore.dart';
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import 'package:gcloud/db.dart' as db;
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import 'package:gcloud/src/datastore_impl.dart' as datastore_impl;
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import 'package:http/http.dart';
@@ -25,12 +26,13 @@ Future main() async {
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var now = DateTime.now().millisecondsSinceEpoch;
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var namespace = '${Platform.operatingSystem}$now';
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late datastore_impl.DatastoreImpl datastore;
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late Datastore datastore;
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late db.DatastoreDB datastoreDB;
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Client? client;
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await withAuthClient(scopes, (String project, httpClient) async {
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datastore = datastore_impl.DatastoreImpl(httpClient, project);
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datastore =
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Datastore.withRetry(datastore_impl.DatastoreImpl(httpClient, project));
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datastoreDB = db.DatastoreDB(datastore);
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client = httpClient;
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});

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