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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.exceptions;

import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.core.EndPoint;
import java.net.InetAddress;
import java.util.Collections;
import java.util.Map;

/**
 * A non-timeout error during a read query.
 *
 * This happens when some of the replicas that were contacted by the coordinator replied with an
 * error.
 */
@SuppressWarnings("serial")
public class ReadFailureException extends QueryConsistencyException {

  private final int failed;
  private final boolean dataPresent;
  private final Map failuresMap;

  /**
   * This constructor should only be used internally by the driver when decoding error responses.
   */
  public ReadFailureException(
      ConsistencyLevel consistency,
      int received,
      int required,
      int failed,
      Map failuresMap,
      boolean dataPresent) {
    this(null, consistency, received, required, failed, failuresMap, dataPresent);
  }

  /** @deprecated Legacy constructor for backward compatibility. */
  @Deprecated
  public ReadFailureException(
      ConsistencyLevel consistency, int received, int required, int failed, boolean dataPresent) {
    this(
        null,
        consistency,
        received,
        required,
        failed,
        Collections.emptyMap(),
        dataPresent);
  }

  public ReadFailureException(
      EndPoint endPoint,
      ConsistencyLevel consistency,
      int received,
      int required,
      int failed,
      Map failuresMap,
      boolean dataPresent) {
    super(
        endPoint,
        String.format(
            "Cassandra failure during read query at consistency %s "
                + "(%d responses were required but only %d replica responded, %d failed)",
            consistency, required, received, failed),
        consistency,
        received,
        required);
    this.failed = failed;
    this.failuresMap = failuresMap;
    this.dataPresent = dataPresent;
  }

  /** @deprecated Legacy constructor for backward compatibility. */
  @Deprecated
  public ReadFailureException(
      EndPoint endPoint,
      ConsistencyLevel consistency,
      int received,
      int required,
      int failed,
      boolean dataPresent) {
    this(
        endPoint,
        consistency,
        received,
        required,
        failed,
        Collections.emptyMap(),
        dataPresent);
  }

  private ReadFailureException(
      EndPoint endPoint,
      String msg,
      Throwable cause,
      ConsistencyLevel consistency,
      int received,
      int required,
      int failed,
      Map failuresMap,
      boolean dataPresent) {
    super(endPoint, msg, cause, consistency, received, required);
    this.failed = failed;
    this.failuresMap = failuresMap;
    this.dataPresent = dataPresent;
  }

  /**
   * Returns the number of replicas that experienced a failure while executing the request.
   *
   * @return the number of failures.
   */
  public int getFailures() {
    return failed;
  }

  /**
   * Returns the a failure reason code for each node that failed.
   *
   * 
At the time of writing, the existing reason codes are:
   *
   * 

   *   {@code 0x0000}: the error does not have a specific code assigned yet, or the cause is
   *       unknown.
   *   
{@code 0x0001}: The read operation scanned too many tombstones (as defined by {@code
   *       tombstone_failure_threshold} in {@code cassandra.yaml}, causing a {@code
   *       TombstoneOverwhelmingException}.
   * 
   *
   * (please refer to the Cassandra documentation for your version for the most up-to-date list of
   * errors)
   *
   * This feature is available for protocol v5 or above only. With lower protocol versions, the
   * map will always be empty.
   *
   * @return a map of IP addresses to failure codes.
   */
  public Map getFailuresMap() {
    return failuresMap;
  }

  /**
   * Whether the actual data was amongst the received replica responses.
   *
   * During reads, Cassandra doesn't request data from every replica to minimize internal network
   * traffic. Instead, some replicas are only asked for a checksum of the data. A read timeout may
   * occurred even if enough replicas have responded to fulfill the consistency level if only
   * checksum responses have been received. This method allows to detect that case.
   *
   * @return whether the data was amongst the received replica responses.
   */
  public boolean wasDataRetrieved() {
    return dataPresent;
  }

  @Override
  public ReadFailureException copy() {
    return new ReadFailureException(
        getEndPoint(),
        getMessage(),
        this,
        getConsistencyLevel(),
        getReceivedAcknowledgements(),
        getRequiredAcknowledgements(),
        getFailures(),
        getFailuresMap(),
        wasDataRetrieved());
  }

  public ReadFailureException copy(EndPoint endPoint) {
    return new ReadFailureException(
        endPoint,
        getMessage(),
        this,
        getConsistencyLevel(),
        getReceivedAcknowledgements(),
        getRequiredAcknowledgements(),
        failed,
        getFailuresMap(),
        dataPresent);
  }
}