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.api.kv;
  
  
  import java.util.concurrent.CompletableFuture;
  import org.apache.bookkeeper.api.kv.op.CompareOp;
  import org.apache.bookkeeper.api.kv.op.Op;
  import org.apache.bookkeeper.api.kv.result.TxnResult;
  
  /**
   * Txn is the interface that wraps mini-transactions.
   *
   * <h3>Usage examples</h3>
   *
   * <pre>{@code
   * txn.If(
   *    new Cmp(KEY, Cmp.Op.GREATER, CmpTarget.value(VALUE)),
   *    new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(2))
   * ).Then(
   *    Op.put(KEY2, VALUE2, PutOption.DEFAULT),
   *    Op.put(KEY3, VALUE3, PutOption.DEFAULT)
   * ).Else(
   *    Op.put(KEY4, VALUE4, PutOption.DEFAULT),
   *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
   * ).commit();
   * }</pre>
   *
   * <p>Txn also supports If, Then, and Else chaining. e.g.
   * <pre>{@code
   * txn.If(
   *    new Cmp(KEY, Cmp.Op.GREATER, CmpTarget.value(VALUE))
   * ).If(
   *    new Cmp(KEY, cmp.Op.EQUAL, CmpTarget.version(VERSION))
   * ).Then(
   *    Op.put(KEY2, VALUE2, PutOption.DEFAULT)
   * ).Then(
   *    Op.put(KEY3, VALUE3, PutOption.DEFAULT)
   * ).Else(
   *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
   * ).Else(
   *    Op.put(KEY4, VALUE4, PutOption.DEFAULT)
   * ).commit();
   * }</pre>
   */
  public interface Txn<K, V> {
  
      /**
       * takes a list of comparison. If all comparisons passed in succeed,
       * the operations passed into Then() will be executed. Or the operations
       * passed into Else() will be executed.
       */
      // CHECKSTYLE.OFF: MethodName
      Txn<K, V> If(CompareOp... cmps);
      // CHECKSTYLE.ON: MethodName
  
      /**
       * takes a list of operations. The Ops list will be executed, if the
       * comparisons passed in If() succeed.
       */
      // CHECKSTYLE.OFF: MethodName
      Txn<K, V> Then(Op... ops);
      // CHECKSTYLE.ON: MethodName
  
      /**
       * takes a list of operations. The Ops list will be executed, if the
       * comparisons passed in If() fail.
       */
      // CHECKSTYLE.OFF: MethodName
      Txn<K, V> Else(Op... ops);
      // CHECKSTYLE.OFF: MethodName
  
      /**
       * tries to commit the transaction.
       *
       * @return a TxnResponse wrapped in CompletableFuture
       */
      CompletableFuture<TxnResult<K, V>> commit();
  
  }
  