/*
 *
 * 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 org.apache.hadoop.hbase;

import java.io.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * Coprocess interface.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface Coprocessor {
  static final int VERSION = 1;

  /** Highest installation priority */
  static final int PRIORITY_HIGHEST = 0;
  /** High (system) installation priority */
  static final int PRIORITY_SYSTEM = Integer.MAX_VALUE / 4;
  /** Default installation priority for user coprocessors */
  static final int PRIORITY_USER = Integer.MAX_VALUE / 2;
  /** Lowest installation priority */
  static final int PRIORITY_LOWEST = Integer.MAX_VALUE;

  /**
   * Lifecycle state of a given coprocessor instance.
   */
  public enum State {
    UNINSTALLED,
    INSTALLED,
    STARTING,
    ACTIVE,
    STOPPING,
    STOPPED
  }

  // Interface
  void start(CoprocessorEnvironment env) throws IOException;

  void stop(CoprocessorEnvironment env) throws IOException;
}