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5098b03af4
This change replaces all Ref objects in the code with Key objects. These are
stored in datastore as the same object (raw datastore keys), so this is not
a model change.
Our best practices doc says to use Keys not Refs because:
* The .get() method obscures what's actually going on
- Much harder to visually audit the code for datastore loads
- Hard to distinguish Ref<T> get()'s from Optional get()'s and Supplier get()'s
* Implicit ofy().load() offers much less control
- Antipattern for ultimate goal of making Ofy injectable
- Can't control cache use or batch loading without making ofy() explicit anyway
* Serialization behavior is surprising and could be quite dangerous/incorrect
- Can lead to serialization errors. If it actually worked "as intended",
it would lead to a Ref<> on a serialized object being replaced upon
deserialization with a stale copy of the old value, which could potentially
break all kinds of transactional expectations
* Having both Ref<T> and Key<T> introduces extra boilerplate everywhere
- E.g. helper methods all need to have Ref and Key overloads, or you need to
call .key() to get the Key<T> for every Ref<T> you want to pass in
- Creating a Ref<T> is more cumbersome, since it doesn't have all the create()
overloads that Key<T> has, only create(Key<T>) and create(Entity) - no way to
create directly from kind+ID/name, raw Key, websafe key string, etc.
(Note that Refs are treated specially by Objectify's @Load method and Keys are not;
we don't use that feature, but it is the one advantage Refs have over Keys.)
The direct impetus for this change is that I am trying to audit our use of memcache,
and the implicit .get() calls to datastore were making that very hard.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131965491
75 lines
3.4 KiB
Java
75 lines
3.4 KiB
Java
// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package google.registry.model.translators;
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import static com.google.common.base.MoreObjects.firstNonNull;
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import static google.registry.model.ofy.ObjectifyService.ofy;
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import static google.registry.util.DateTimeUtils.START_OF_TIME;
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import com.google.common.collect.ImmutableSortedMap;
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import com.google.common.collect.Ordering;
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import com.googlecode.objectify.Key;
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import google.registry.config.RegistryEnvironment;
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import google.registry.model.ofy.CommitLogManifest;
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import org.joda.time.DateTime;
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/**
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* Objectify translator for {@code ImmutableSortedMap<DateTime, Key<CommitLogManifest>>} fields.
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*
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* <p>This translator is responsible for doing three things:
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* <ol>
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* <li>Translating the data into two lists of {@code Date} and {@code Key} objects, in a manner
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* similar to {@code @Mapify}.
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* <li>Inserting a key to the transaction's {@link CommitLogManifest} on save.
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* <li>Truncating the map to include only the last key per day for the last 30 days.
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* </ol>
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*
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* <p>This allows you to have a field on your model object that tracks historical revisions of
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* itself, which can be binary searched for point-in-time restoration.
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*
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* <p><b>Warning:</b> Fields of this type must not be {@code null}, or else new entries can't be
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* inserted. You must take care to initialize the field to empty.
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*
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* @see google.registry.model.EppResource
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*/
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public final class CommitLogRevisionsTranslatorFactory
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extends ImmutableSortedMapTranslatorFactory<DateTime, Key<CommitLogManifest>> {
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private static final RegistryEnvironment ENVIRONMENT = RegistryEnvironment.get();
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/**
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* Add a reference to the current commit log to the resource's revisions map.
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*
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* <p>This method also prunes the revisions map. It guarantees to keep enough data so that floor
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* will work going back N days. It does this by making sure one entry exists before that duration,
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* and pruning everything after it. The size of the map is guaranteed to never exceed N+2.
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*
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* <p>We store a maximum of one entry per day. It will be the last transaction that happened on
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* that day.
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*
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* @see google.registry.config.RegistryConfig#getCommitLogDatastoreRetention()
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*/
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@Override
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ImmutableSortedMap<DateTime, Key<CommitLogManifest>> transformBeforeSave(
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ImmutableSortedMap<DateTime, Key<CommitLogManifest>> revisions) {
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DateTime now = ofy().getTransactionTime();
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DateTime threshold = now.minus(ENVIRONMENT.config().getCommitLogDatastoreRetention());
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DateTime preThresholdTime = firstNonNull(revisions.floorKey(threshold), START_OF_TIME);
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return new ImmutableSortedMap.Builder<DateTime, Key<CommitLogManifest>>(Ordering.natural())
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.putAll(revisions.subMap(preThresholdTime, true, now.withTimeAtStartOfDay(), false))
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.put(now, ofy().getCommitLogManifestKey())
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.build();
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}
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}
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