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/*
 * Copyright DataStax, Inc.
 *
 * This software can be used solely with DataStax Enterprise. Please consult the license at
 * http://www.datastax.com/terms/datastax-dse-driver-license-terms
 */
package com.datastax.driver.core.exceptions;

import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.core.EndPoint;

/** A Cassandra timeout during a read query. */
public class ReadTimeoutException extends QueryConsistencyException {

  private static final long serialVersionUID = 0;

  private final boolean dataPresent;

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

  public ReadTimeoutException(
      EndPoint endPoint,
      ConsistencyLevel consistency,
      int received,
      int required,
      boolean dataPresent) {
    super(
        endPoint,
        String.format(
            "Cassandra timeout during read query at consistency %s (%s)",
            consistency, formatDetails(received, required, dataPresent)),
        consistency,
        received,
        required);
    this.dataPresent = dataPresent;
  }

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

  private static String formatDetails(int received, int required, boolean dataPresent) {
    if (received < required)
      return String.format(
          "%d responses were required but only %d replica responded", required, received);
    else if (!dataPresent) return "the replica queried for data didn't respond";
    else return "timeout while waiting for repair of inconsistent replica";
  }

  /**
   * 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
   * have 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 ReadTimeoutException copy() {
    return new ReadTimeoutException(
        getEndPoint(),
        getMessage(),
        this,
        getConsistencyLevel(),
        getReceivedAcknowledgements(),
        getRequiredAcknowledgements(),
        wasDataRetrieved());
  }

  /**
   * Create a copy of this exception with a nicer stack trace, and including the coordinator address
   * that caused this exception to be raised.
   *
   * 
This method is mainly intended for internal use by the driver and exists mainly because:
   *
   * 

   *   the original exception was decoded from a response frame and at that time, the
   *       coordinator address was not available; and
   *   
the newly-created exception will refer to the current thread in its stack trace, which
   *       generally yields a more user-friendly stack trace that the original one.
   * 
   *
   * @param endPoint The full address of the host that caused this exception to be thrown.
   * @return a copy/clone of this exception, but with the given host address instead of the original
   *     one.
   */
  public ReadTimeoutException copy(EndPoint endPoint) {
    return new ReadTimeoutException(
        endPoint,
        getMessage(),
        this,
        getConsistencyLevel(),
        getReceivedAcknowledgements(),
        getRequiredAcknowledgements(),
        wasDataRetrieved());
  }
}