samza-sql-shell/src/main/java/org/apache/samza/sql/client/impl/FileSystemAvroRelSchemaProviderFactory.java

/*
 * 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.samza.sql.client.impl;

import org.apache.avro.Schema;
import org.apache.samza.SamzaException;
import org.apache.samza.config.Config;
import org.apache.samza.sql.avro.AvroRelSchemaProvider;
import org.apache.samza.sql.avro.AvroTypeFactoryImpl;
import org.apache.samza.sql.interfaces.RelSchemaProvider;
import org.apache.samza.sql.interfaces.RelSchemaProviderFactory;
import org.apache.samza.sql.schema.SqlSchema;
import org.apache.samza.system.SystemStream;

import java.io.File;
import java.io.IOException;

/**
 * Relational schemas provider which reads system schema from a given directory
 */
public class FileSystemAvroRelSchemaProviderFactory implements RelSchemaProviderFactory {

  public static final String CFG_SCHEMA_DIR = "schemaDir";

  @Override
  public RelSchemaProvider create(SystemStream systemStream, Config config) {
    return new FileSystemAvroRelSchemaProvider(systemStream, config);
  }

  private class FileSystemAvroRelSchemaProvider implements AvroRelSchemaProvider {
    private final SystemStream systemStream;
    private final String schemaDir;

    public FileSystemAvroRelSchemaProvider(SystemStream systemStream, Config config) {
      this.systemStream = systemStream;
      this.schemaDir = config.get(CFG_SCHEMA_DIR);
    }

    @Override
    public SqlSchema getSqlSchema() {
      String schemaStr = this.getSchema(this.systemStream);
      Schema schema = Schema.parse(schemaStr);
      AvroTypeFactoryImpl avroTypeFactory = new AvroTypeFactoryImpl();
      return avroTypeFactory.createType(schema);
    }

    @Override
    public String getSchema(SystemStream systemStream) {
      String fileName = String.format("%s.avsc", systemStream.getStream());
      File file = new File(schemaDir, fileName);
      try {
        return Schema.parse(file).toString();
      } catch (IOException e) {
        throw new SamzaException(e);
      }
    }
  }
}