/
AddUuidsTransform.java
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/
AddUuidsTransform.java
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/*
* Copyright 2020 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.cloud.pubsublite.beam;
import com.google.cloud.pubsublite.proto.AttributeValues;
import com.google.cloud.pubsublite.proto.PubSubMessage;
import org.apache.beam.sdk.transforms.MapElements;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.Reshuffle;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.TypeDescriptor;
/** A transform to add UUIDs to each message to be written to Pub/Sub Lite. */
class AddUuidsTransform extends PTransform<PCollection<PubSubMessage>, PCollection<PubSubMessage>> {
private static PubSubMessage addUuid(PubSubMessage message) {
PubSubMessage.Builder builder = message.toBuilder();
builder.putAttributes(
Uuid.DEFAULT_ATTRIBUTE,
AttributeValues.newBuilder().addValues(Uuid.random().value()).build());
return builder.build();
}
@Override
public PCollection<PubSubMessage> expand(PCollection<PubSubMessage> input) {
PCollection<PubSubMessage> withUuids =
input.apply(
"AddUuids",
MapElements.into(new TypeDescriptor<PubSubMessage>() {})
.via(AddUuidsTransform::addUuid));
// Reshuffle into 1000 buckets to avoid having unit-sized bundles under high throughput.
return withUuids.apply(
"ShuffleToPersist", Reshuffle.<PubSubMessage>viaRandomKey().withNumBuckets(1000));
}
}