samza-sql/src/main/java/org/apache/samza/sql/dsl/SamzaSqlDslConverter.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.dsl;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import org.apache.calcite.rel.RelRoot;
import org.apache.commons.lang3.StringUtils;
import org.apache.samza.SamzaException;
import org.apache.samza.config.Config;
import org.apache.samza.sql.interfaces.DslConverter;
import org.apache.samza.sql.planner.QueryPlanner;
import org.apache.samza.sql.runner.SamzaSqlApplicationConfig;
import org.apache.samza.sql.util.SamzaSqlQueryParser;
import org.apache.samza.sql.util.SqlFileParser;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public class SamzaSqlDslConverter implements DslConverter {

  private static final Logger LOG = LoggerFactory.getLogger(SamzaSqlDslConverter.class);

  private final Config config;

  SamzaSqlDslConverter(Config config) {
    this.config = config;
  }

  @Override
  public Collection<RelRoot> convertDsl(String dsl) {
    // TODO: Introduce an API to parse a dsl string and return one or more sql statements
    List<String> sqlStmts = fetchSqlFromConfig(config);
    List<RelRoot> relRoots = new LinkedList<>();
    for (String sql: sqlStmts) {
      QueryPlanner planner = getQueryPlanner(getSqlConfig(Collections.singletonList(sql), config));
      // we always pass only select query to the planner for samza sql. The reason is that samza sql supports
      // schema evolution where source and destination could up to an extent have independent schema evolution while
      // calcite expects strict comformance of the destination schema with that of the fields in the select query.
      SamzaSqlQueryParser.QueryInfo qinfo = SamzaSqlQueryParser.parseQuery(sql);
      RelRoot relRoot = planner.plan(qinfo.getSelectQuery());
      relRoots.add(relRoot);
    }
    return relRoots;
  }

  /**
   * Get {@link SamzaSqlApplicationConfig} given sql statements and samza config.
   * @param sqlStmts List of sql statements
   * @param config Samza config
   * @return {@link SamzaSqlApplicationConfig}
   */
  public static SamzaSqlApplicationConfig getSqlConfig(List<String> sqlStmts, Config config) {
    List<SamzaSqlQueryParser.QueryInfo> queryInfo = fetchQueryInfo(sqlStmts);
    return new SamzaSqlApplicationConfig(config,
        queryInfo.stream().map(SamzaSqlQueryParser.QueryInfo::getSources).flatMap(Collection::stream)
            .collect(Collectors.toList()),
        queryInfo.stream().map(SamzaSqlQueryParser.QueryInfo::getSink)
            .collect(Collectors.toList()));
  }

  /**
   * Get {@link QueryPlanner} given {@link SamzaSqlApplicationConfig}
   * @param sqlConfig {@link SamzaSqlApplicationConfig}
   * @return {@link QueryPlanner}
   */
  public static QueryPlanner getQueryPlanner(SamzaSqlApplicationConfig sqlConfig) {
    return new QueryPlanner(sqlConfig.getRelSchemaProviders(), sqlConfig.getInputSystemStreamConfigBySource(),
        sqlConfig.getUdfMetadata(), sqlConfig.isQueryPlanOptimizerEnabled());
  }

  /**
   * Get list of {@link org.apache.samza.sql.util.SamzaSqlQueryParser.QueryInfo} given list of sql statements.
   * @param sqlStmts list of sql statements
   * @return list of {@link org.apache.samza.sql.util.SamzaSqlQueryParser.QueryInfo}
   */
  public static List<SamzaSqlQueryParser.QueryInfo> fetchQueryInfo(List<String> sqlStmts) {
    return sqlStmts.stream().map(SamzaSqlQueryParser::parseQuery).collect(Collectors.toList());
  }

  /**
   * Get list of sql statements based on the property set in the config.
   * @param config config
   * @return list of Sql statements
   */
  public static List<String> fetchSqlFromConfig(Map<String, String> config) {
    List<String> sql;
    if (config.containsKey(SamzaSqlApplicationConfig.CFG_SQL_STMT) &&
        StringUtils.isNotBlank(config.get(SamzaSqlApplicationConfig.CFG_SQL_STMT))) {
      String sqlValue = config.get(SamzaSqlApplicationConfig.CFG_SQL_STMT);
      sql = Collections.singletonList(sqlValue);
    } else if (config.containsKey(SamzaSqlApplicationConfig.CFG_SQL_STMTS_JSON) &&
        StringUtils.isNotBlank(config.get(SamzaSqlApplicationConfig.CFG_SQL_STMTS_JSON))) {
      sql = SamzaSqlApplicationConfig.deserializeSqlStmts(config.get(SamzaSqlApplicationConfig.CFG_SQL_STMTS_JSON));
    } else if (config.containsKey(SamzaSqlApplicationConfig.CFG_SQL_FILE)) {
      String sqlFile = config.get(SamzaSqlApplicationConfig.CFG_SQL_FILE);
      sql = SqlFileParser.parseSqlFile(sqlFile);
    } else {
      String msg = "Config doesn't contain the SQL that needs to be executed.";
      LOG.error(msg);
      throw new SamzaException(msg);
    }

    return sql;
  }
}