cppcache/include/geode/CqListener.hpp

/*
 * 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.
 */

#pragma once

#ifndef GEODE_CQLISTENER_H_
#define GEODE_CQLISTENER_H_

#include "CqEvent.hpp"
#include "internal/geode_globals.hpp"

namespace apache {
namespace geode {
namespace client {

class CacheListener;

/**
 * @class CqListener CqListener.hpp
 *
 * Application plug-in interface for handling continuous query events after
 * they occur. The listener has two methods, one that is called when there
 * is an event satisfied by the CQ and the other called when there is an
 * error during CQ processing.
 */
class APACHE_GEODE_EXPORT CqListener {
 public:
  virtual ~CqListener() noexcept = default;

  CqListener();
  CqListener(const CacheListener& other) = delete;

  void operator=(const CqListener& other) = delete;

  /**
   * This method is invoked when an event is occurred on the region
   * that satisfied the query condition of this CQ.
   * This event does not contain an error.
   */
  virtual void onEvent(const CqEvent& aCqEvent);

  /**
   * This method is invoked when there is an error during CQ processing.
   * The error can appear while applying query condition on the event.
   * e.g if the event doesn't has attributes as specified in the CQ query.
   * This event does contain an error. The newValue may or may not be
   * available, and will be nullptr if not available.
   */
  virtual void onError(const CqEvent& aCqEvent);

  /** Called when the region containing this callback is closed or destroyed,
   * when
   * the cache is closed, or when a callback is removed from a region
   * using an <code>AttributesMutator</code>.
   *
   * <p>Implementations should cleanup any external
   * resources such as database connections. Any runtime exceptions this method
   * throws will be logged.
   *
   * <p>It is possible for this method to be called multiple times on a single
   * callback instance, so implementations must be tolerant of this.
   *
   * @see Cache#close()
   * @see Region#close
   * @see Region#localDestroyRegion()
   * @see Region#destroyRegion()
   * @see AttributesMutator
   */
  virtual void close();
};
}  // namespace client
}  // namespace geode
}  // namespace apache

#endif  // GEODE_CQLISTENER_H_