content: /*
   * 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.bookkeeper.metastore;
  
  import java.util.Collections;
  import java.util.Set;
  import org.apache.bookkeeper.versioning.Version;
  import org.apache.bookkeeper.versioning.Versioned;
  
  /**
   * Metastore Table interface.
   */
  public interface MetastoreTable {
  
      // select all fields when reading or scanning entries
      Set<String> ALL_FIELDS = null;
      // select non fields to return when reading/scanning entries
      Set<String> NON_FIELDS = Collections.emptySet();
  
      /**
       * Get table name.
       *
       * @return table name
       */
      String getName();
  
      /**
       * Get all fields of a key.
       *
       * <p>
       * Return Code:<ul>
       * <li>{@link MSException.Code.OK}: success returning the key</li>
       * <li>{@link MSException.Code.NoKey}: no key found</li>
       * <li>{@link MSException.Code.IllegalOp}/{@link MSException.Code.ServiceDown}: other issues</li>
       * </ul></p>
       *
       * @param key
       *          Key Name
       * @param cb
       *          Callback to return all fields of the key
       * @param ctx
       *          Callback context
       */
      void get(String key, MetastoreCallback<Versioned<Value>> cb, Object ctx);
  
      /**
       * Get all fields of a key.
       *
       * <p>
       * Return Code:<ul>
       * <li>{@link MSException.Code.OK}: success returning the key</li>
       * <li>{@link MSException.Code.NoKey}: no key found</li>
       * <li>{@link MSException.Code.IllegalOp}/{@link MSException.Code.ServiceDown}: other issues</li>
       * </ul></p>
       *
       * @param key
       *          Key Name
       * @param watcher
       *          Watcher object to receive notifications
       * @param cb
       *          Callback to return all fields of the key
       * @param ctx
       *          Callback context
       */
      void get(String key, MetastoreWatcher watcher, MetastoreCallback<Versioned<Value>> cb, Object ctx);
  
      /**
       * Get specified fields of a key.
       *
       * <p>
       * Return Code:<ul>
       * <li>{@link MSException.Code.OK}: success returning the key</li>
       * <li>{@link MSException.Code.NoKey}: no key found</li>
       * <li>{@link MSException.Code.IllegalOp}/{@link MSException.Code.ServiceDown}: other issues</li>
       * </ul></p>
       *
       * @param key
       *          Key Name
       * @param fields
       *          Fields to return
       * @param cb
       *          Callback to return specified fields of the key
       * @param ctx
       *          Callback context
       */
      void get(String key, Set<String> fields, MetastoreCallback<Versioned<Value>> cb, Object ctx);
  
      /**
       * Update a key according to its version.
       *
       * <p>
       * Return Code:<ul>
       * <li>{@link MSException.Code.OK}: success updating the key</li>
       * <li>{@link MSException.Code.BadVersion}: failed to update the key due to bad version</li>
       * <li>{@link MSException.Code.NoKey}: no key found to update data, if not provided {@link Version.NEW}</li>
       * <li>{@link MSException.Code.KeyExists}: entry exists providing {@link Version.NEW}</li>
       * <li>{@link MSException.Code.IllegalOp}/{@link MSException.Code.ServiceDown}: other issues</li>
       * </ul></p>
       *
       * <p>The key is updated only when the version matches its current version.
       * In particular, if the provided version is:<ul>
       * <li>{@link Version.ANY}: update the data without comparing its version.
       *      <b>Note this usage is not encouraged since it may mess up data consistency.</b></li>
       * <li>{@link Version.NEW}: create the entry if it doesn't exist before;
       *      Otherwise return {@link MSException.Code.KeyExists}.</li>
       * </ul>
       *
       * @param key
       *          Key Name
       * @param value
       *          Value to update.
       * @param version
       *          Version specified to update.
       * @param cb
       *          Callback to return new version after updated.
       * @param ctx
       *          Callback context
       */
      void put(String key, Value value, Version version, MetastoreCallback<Version> cb, Object ctx);
  
      /**
       * Remove a key by its version.
       *
       * <p>The key is removed only when the version matches its current version.
       * If <code>version</code> is {@link Version.ANY}, the key would be removed directly.
       *
       * <p>
       * Return Code:<ul>
       * <li>{@link MSException.Code.OK}: success updating the key</li>
       * <li>{@link MSException.Code.NoKey}: if the key doesn't exist.</li>
       * <li>{@link MSException.Code.BadVersion}: failed to delete the key due to bad version</li>
       * <li>{@link MSException.Code.IllegalOp}/{@link MSException.Code.ServiceDown}: other issues</li>
       * </ul></p>
       *
       * @param key
       *          Key Name.
       * @param version
       *          Version specified to remove.
       * @param cb
       *          Callback to return all fields of the key
       * @param ctx
       *          Callback context
       */
      void remove(String key, Version version, MetastoreCallback<Void> cb, Object ctx);
  
      /**
       * Open a cursor to loop over all the entries of the table,
       * which returns all fields for each entry.
       * The returned cursor doesn't need to guarantee any order,
       * since the underlying might be a hash table or an order table.
       *
       * @param cb
       *          Callback to return an opened cursor
       * @param ctx
       *          Callback context
       */
      void openCursor(MetastoreCallback<MetastoreCursor> cb, Object ctx);
  
      /**
       * Open a cursor to loop over all the entries of the table,
       * which returns the specified <code>fields</code> for each entry.
       * The returned cursor doesn't need to guarantee any order,
       * since the underlying might be a hash table or an order table.
       *
       * @param fields
       *          Fields to select
       * @param cb
       *          Callback to return an opened cursor
       * @param ctx
       *          Callback context
       */
      void openCursor(Set<String> fields, MetastoreCallback<MetastoreCursor> cb, Object ctx);
  
      /**
       * Close the table.
       */
      void close();
  }
  