core/src/main/java/org/apache/calcite/avatica/Handler.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.calcite.avatica;

import java.sql.SQLException;

/**
 * Called at various points in the JDBC lifecycle.
 *
 * <p>Most drivers will use {@link HandlerImpl}, which provides no-op
 * implementations of all methods. You only need to override methods if you
 * need to achieve special effects.</p>
 */
public interface Handler {
  /** Called by container when a connection is being created.
   *
   * <p>If the implementation of this method throws, the connection
   * will not be created.</p>
   *
   * @param connection Connection
   * @throws SQLException on error
   */
  void onConnectionInit(AvaticaConnection connection) throws SQLException;

  /** Called by container when a connection is being closed.
   *
   * <p>If the implementation of this method throws, the call to
   * {@link java.sql.Connection#close} that triggered this method will throw an
   * exception, but the connection will still be marked closed.</p>
   *
   * @param connection Connection
   */
  void onConnectionClose(AvaticaConnection connection);

  /** Called by container when a statement is being executed.
   *
   * <p>If the session would like the statement results stored in a temporary
   * table, {@code resultSink} is not null.
   * The provider must call its {@link ResultSink#toBeCompleted}
   * method at some point during execution (not necessarily before the call to
   * this method returns).</p>
   *
   * @param statement Statement
   * @param resultSink Place to put result of query. Null if container does not
   *                   want results stored to a temporary table
   * @throws RuntimeException on error
   */
  void onStatementExecute(
      AvaticaStatement statement,
      ResultSink resultSink);

  /** Called by container when a statement is being closed.
   *
   * <p>This method is called after marking the statement closed, and after
   * closing any open {@link java.sql.ResultSet} objects.</p>
   *
   * <p>If the implementation of this method throws, the call to
   * {@link java.sql.Statement#close} that triggered this method will throw an
   * exception, but the statement will still be marked closed.
   *
   * @param statement Statement
   * @throws RuntimeException on error
   */
  void onStatementClose(AvaticaStatement statement);

  /** Handler for temporary tables. */
  interface ResultSink {
    /** Registers a temporary table. */
    void toBeCompleted();
  }
}

// End Handler.java