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A driver for Apache Cassandra 1.2+ that works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's binary protocol.

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/*
 * Copyright DataStax, Inc.
 *
 * 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 com.datastax.driver.core;

import com.datastax.driver.core.exceptions.DriverInternalError;

public enum ConsistencyLevel {
  ANY(0),
  ONE(1),
  TWO(2),
  THREE(3),
  QUORUM(4),
  ALL(5),
  LOCAL_QUORUM(6),
  EACH_QUORUM(7),
  SERIAL(8),
  LOCAL_SERIAL(9),
  LOCAL_ONE(10);

  // Used by the native protocol
  final int code;
  private static final ConsistencyLevel[] codeIdx;

  static {
    int maxCode = -1;
    for (ConsistencyLevel cl : ConsistencyLevel.values()) maxCode = Math.max(maxCode, cl.code);
    codeIdx = new ConsistencyLevel[maxCode + 1];
    for (ConsistencyLevel cl : ConsistencyLevel.values()) {
      if (codeIdx[cl.code] != null) throw new IllegalStateException("Duplicate code");
      codeIdx[cl.code] = cl;
    }
  }

  private ConsistencyLevel(int code) {
    this.code = code;
  }

  static ConsistencyLevel fromCode(int code) {
    if (code < 0 || code >= codeIdx.length)
      throw new DriverInternalError(String.format("Unknown code %d for a consistency level", code));
    return codeIdx[code];
  }

  /**
   * Whether or not this consistency level applies to the local data-center only.
   *
   * @return whether this consistency level is {@code LOCAL_ONE}, {@code LOCAL_QUORUM}, or {@code
   *     LOCAL_SERIAL}.
   */
  public boolean isDCLocal() {
    return this == LOCAL_ONE || this == LOCAL_QUORUM || this == LOCAL_SERIAL;
  }

  /**
   * Whether or not this consistency level is serial, that is, applies only to the "paxos" phase of
   * a Lightweight
   * transaction.
   *
   * Serial consistency levels are only meaningful when executing conditional updates ({@code
   * INSERT}, {@code UPDATE} or {@code DELETE} statements with an {@code IF} condition).
   *
   * Two consistency levels belong to this category: {@link #SERIAL} and {@link #LOCAL_SERIAL}.
   *
   * @return whether this consistency level is {@link #SERIAL} or {@link #LOCAL_SERIAL}.
   * @see Statement#setSerialConsistencyLevel(ConsistencyLevel)
   * @see Lightweight
   *     transactions
   */
  public boolean isSerial() {
    return this == SERIAL || this == LOCAL_SERIAL;
  }
}