DbExplorer.java

/*
 *  Copyright 2014 TWO SIGMA OPEN SOURCE, 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.twosigma.beaker.sql.autocomplete.db;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

public abstract class DbExplorer implements DbInfo {

  private DataSource ds;

  public DbExplorer(DataSource ds) {
    super();
    this.ds = ds;
  }

  private List<String> findTableNames(DbCache dbCache, final Connection conn,
                                      String schemaName, final String key)
    throws SQLException
  {

    List<String> ret = dbCache.getTableNames(conn, schemaName, key);

    if (ret != null){
      return ret;
    }

    ret = queryTableNames(conn, schemaName, key);

    if (ret != null) {

      dbCache.putTableNames(conn, schemaName, key, ret);

      return ret;
    }

    return null;
  }


  @Override
  public List<String> getTableNames(DbCache dbCache, String schemaName, final String key) {
    try (Connection conn = ds.getConnection();) {

        if (schemaName == null) {
          schemaName = conn.getSchema();

          if (schemaName == null) {
            schemaName = conn.getCatalog();
          }
        }

        return findTableNames(dbCache, conn, schemaName, key);
      } catch (SQLException e) {
      // Do nothing
    }
    return null;
  }

  private List<String> findTableFieldNames(DbCache dbCache, final Connection conn,
                                           String schemaName, final String tableName,
                                           final String key)
    throws SQLException
  {
    List<String> ret = dbCache.getTableFieldNames(conn, schemaName, tableName, key);

    if (ret != null){
      return ret;
    }

    ret = queryFieldNames(conn, schemaName, tableName, key);

    if (ret != null) {

      dbCache.putTableFieldNames(conn, schemaName, tableName, key, ret);

      return ret;
    }

    return null;
  }


  @Override
  public List<String> getTableFieldNames(DbCache dbCache, String schemaName, final String tableName, final String key) {
    try (Connection conn = ds.getConnection();) {

        if (schemaName == null) {
          schemaName = conn.getSchema();

          if (schemaName == null) {
            schemaName = conn.getCatalog();
          }
        }

        return findTableFieldNames(dbCache, conn, schemaName, tableName, key);

      } catch (SQLException e) {
      e.printStackTrace();
    }
    return null;
  }

  public abstract List<String> queryTableNames(final Connection conn, final String shemaName,
                                               final String key)
    throws SQLException;

  public abstract List<String> queryFieldNames(final Connection conn, final String shemaName,
                                               final String tableName, final String key)
    throws SQLException;
}