robinyqiu commented on a change in pull request #12090: URL: https://github.com/apache/beam/pull/12090#discussion_r447150400
########## File path: sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/pubsub/PubsubSchemaCapableIOProvider.java ########## @@ -0,0 +1,264 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.beam.sdk.io.gcp.pubsub; + +import static org.apache.beam.sdk.io.gcp.pubsub.PubsubMessageToRow.ATTRIBUTES_FIELD; +import static org.apache.beam.sdk.io.gcp.pubsub.PubsubMessageToRow.DLQ_TAG; +import static org.apache.beam.sdk.io.gcp.pubsub.PubsubMessageToRow.MAIN_TAG; +import static org.apache.beam.sdk.io.gcp.pubsub.PubsubMessageToRow.PAYLOAD_FIELD; +import static org.apache.beam.sdk.io.gcp.pubsub.PubsubMessageToRow.TIMESTAMP_FIELD; +import static org.apache.beam.sdk.schemas.Schema.TypeName.ROW; +import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument; + +import com.google.auto.service.AutoService; +import java.io.Serializable; +import java.nio.charset.StandardCharsets; +import org.apache.beam.sdk.annotations.Internal; +import org.apache.beam.sdk.schemas.Schema; +import org.apache.beam.sdk.schemas.Schema.FieldType; +import org.apache.beam.sdk.schemas.io.InvalidConfigurationException; +import org.apache.beam.sdk.schemas.io.SchemaCapableIOProvider; +import org.apache.beam.sdk.schemas.io.SchemaIO; +import org.apache.beam.sdk.schemas.transforms.DropFields; +import org.apache.beam.sdk.transforms.MapElements; +import org.apache.beam.sdk.transforms.PTransform; +import org.apache.beam.sdk.transforms.ToJson; +import org.apache.beam.sdk.transforms.WithTimestamps; +import org.apache.beam.sdk.values.PBegin; +import org.apache.beam.sdk.values.PCollection; +import org.apache.beam.sdk.values.PCollectionTuple; +import org.apache.beam.sdk.values.POutput; +import org.apache.beam.sdk.values.Row; +import org.apache.beam.sdk.values.TypeDescriptor; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableMap; + +/** + * {@link org.apache.beam.sdk.schemas.io.SchemaCapableIOProvider} to create {@link PubsubSchemaIO} + * that implements {@link org.apache.beam.sdk.schemas.io.SchemaIO}. + */ +@Internal +@AutoService(SchemaCapableIOProvider.class) +public class PubsubSchemaCapableIOProvider implements SchemaCapableIOProvider { + public static final FieldType VARCHAR = FieldType.STRING; + public static final FieldType TIMESTAMP = FieldType.DATETIME; + + /** Returns an id that uniquely represents this IO. */ + @Override + public String identifier() { + return "pubsub"; + } + + /** + * Returns the expected schema of the configuration object. Note this is distinct from the schema + * of the data source itself. + */ + @Override + public Schema configurationSchema() { + return Schema.builder() + .addNullableField("timestampAttributeKey", FieldType.STRING) + .addNullableField("deadLetterQueue", FieldType.STRING) + .build(); + } + + /** + * Produce a SchemaIO given a String representing the data's location, the schema of the data that + * resides there, and some IO-specific configuration object. + */ + @Override + public PubsubSchemaIO from(String location, Row configuration, Schema dataSchema) { + validateDlq(configuration.getValue("deadLetterQueue")); + validateEventTimestamp(dataSchema); + return PubsubSchemaIO.withConfiguration(location, configuration, dataSchema); + } + + private void validateEventTimestamp(Schema schema) { + if (!PubsubSchemaIO.fieldPresent(schema, TIMESTAMP_FIELD, TIMESTAMP)) { + throw new InvalidConfigurationException( + "Unsupported schema specified for Pubsub source in CREATE TABLE." + + "CREATE TABLE for Pubsub topic must include at least 'event_timestamp' field of " + + "type 'TIMESTAMP'"); + } + } + + private void validateDlq(String deadLetterQueue) { + if (deadLetterQueue != null && deadLetterQueue.isEmpty()) { + throw new InvalidConfigurationException("Dead letter queue topic name is not specified"); + } + } + + /** An abstraction to create schema aware IOs. */ + @Internal + private static class PubsubSchemaIO implements SchemaIO, Serializable { + protected final Row config; + protected final Schema dataSchema; + protected final String location; + protected final Boolean useFlatSchema; + + private PubsubSchemaIO(String location, Row config, Schema dataSchema) { + this.config = config; + this.dataSchema = dataSchema; + this.location = location; + this.useFlatSchema = !definesAttributeAndPayload(dataSchema); + } + + static PubsubSchemaIO withConfiguration(String location, Row config, Schema dataSchema) { + return new PubsubSchemaIO(location, config, dataSchema); + } + + @Override + public Schema schema() { + return dataSchema; + } + + @Override + public PTransform<PBegin, PCollection<Row>> buildReader() { + return new PTransform<PBegin, PCollection<Row>>() { + @Override + public PCollection<Row> expand(PBegin begin) { + PCollectionTuple rowsWithDlq = + begin + .apply("ReadFromPubsub", readMessagesWithAttributes()) + .apply( + "PubsubMessageToRow", + PubsubMessageToRow.builder() + .messageSchema(dataSchema) + .useDlq(useDlqCheck(config)) + .useFlatSchema(useFlatSchema) + .build()); + rowsWithDlq.get(MAIN_TAG).setRowSchema(dataSchema); + + if (useDlqCheck(config)) { + rowsWithDlq.get(DLQ_TAG).apply(writeMessagesToDlq()); + } + + return rowsWithDlq.get(MAIN_TAG); + } + }; + } + + @Override + public PTransform<PCollection<Row>, POutput> buildWriter() { + if (!useFlatSchema) { + throw new UnsupportedOperationException( + "Writing to a Pubsub topic is only supported for flattened schemas"); + } + + return new PTransform<PCollection<Row>, POutput>() { + @Override + public POutput expand(PCollection<Row> input) { + return input + .apply(RowToPubsubMessage.fromTableConfig(config, useFlatSchema)) + .apply(createPubsubMessageWrite()); + } + }; + } + + private PubsubIO.Read<PubsubMessage> readMessagesWithAttributes() { + PubsubIO.Read<PubsubMessage> read = PubsubIO.readMessagesWithAttributes().fromTopic(location); + + return useTimestampAttribute(config) + ? read.withTimestampAttribute(config.getValue("timestampAttributeKey")) + : read; + } + + private PubsubIO.Write<PubsubMessage> createPubsubMessageWrite() { + PubsubIO.Write<PubsubMessage> write = PubsubIO.writeMessages().to(location); + if (useTimestampAttribute(config)) { + write = write.withTimestampAttribute(config.getValue("timestampAttributeKey")); + } + return write; + } + + private PubsubIO.Write<PubsubMessage> writeMessagesToDlq() { + PubsubIO.Write<PubsubMessage> write = + PubsubIO.writeMessages().to(config.getString("deadLetterQueue")); + + return useTimestampAttribute(config) + ? write.withTimestampAttribute(config.getString("timestampAttributeKey")) + : write; + } + + private boolean useDlqCheck(Row config) { + return config.getValue("deadLetterQueue") != null; + } + + private boolean useTimestampAttribute(Row config) { + return config.getValue("timestampAttributeKey") != null; + } + + private boolean definesAttributeAndPayload(Schema schema) { + return fieldPresent( + schema, ATTRIBUTES_FIELD, Schema.FieldType.map(VARCHAR.withNullable(false), VARCHAR)) + && (schema.hasField(PAYLOAD_FIELD) + && ROW.equals(schema.getField(PAYLOAD_FIELD).getType().getTypeName())); + } + + private static boolean fieldPresent( + Schema schema, String field, Schema.FieldType expectedType) { + return schema.hasField(field) + && expectedType.equivalent( + schema.getField(field).getType(), Schema.EquivalenceNullablePolicy.IGNORE); + } + } + + /** + * A {@link PTransform} to convert {@link Row} to {@link PubsubMessage} with JSON payload. + * + * <p>Currently only supports writing a flat schema into a JSON payload. This means that all Row + * field values are written to the {@link PubsubMessage} JSON payload, except for {@code + * event_timestamp}, which is either ignored or written to the message attributes, depending on + * whether config.getValue("timestampAttributeKey") is set. + */ + private static class RowToPubsubMessage Review comment: Make sense. Then maybe moving this class out as package-private? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
