com.spotify.scio.jdbc.JdbcDoFn Maven / Gradle / Ivy
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/*
* Copyright 2023 Spotify AB.
*
* 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.spotify.scio.jdbc;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.SerializableFunction;
/**
* A {@link DoFn} that performs synchronous lookup using JDBC connection.
*
* @param input element type.
* @param JDBC lookup value type.
*/
public abstract class JdbcDoFn extends DoFn {
private final SerializableFunction dataSourceProviderFn;
private transient DataSource dataSource;
private transient Connection connection;
protected JdbcDoFn(SerializableFunction dataSourceProviderFn) {
this.dataSourceProviderFn = dataSourceProviderFn;
}
@Setup
public void setup() {
dataSource = dataSourceProviderFn.apply(null);
}
private void createConnection() throws SQLException {
if (dataSource == null) {
throw new RuntimeException("DataSourceProvider " + dataSourceProviderFn + " returned null");
}
connection = dataSource.getConnection();
}
@Teardown
public void closeConnection() throws SQLException {
if (connection != null) {
try {
connection.close();
} finally {
connection = null;
}
}
}
@StartBundle
public void startBundle() throws SQLException {
// recreate a connection if it is lost
if (connection == null || connection.isClosed()) {
createConnection();
}
}
@ProcessElement
public void processElement(@Element A input, OutputReceiver out) {
B result = lookup(connection, input);
out.output(result);
}
public abstract B lookup(Connection connection, A input);
}