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A driver for DataStax Enterprise (DSE) and Apache Cassandra 1.2+ clusters that works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's binary protocol, supporting DSE-specific features such as geospatial types, DSE Graph and DSE authentication.

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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;

import com.google.common.util.concurrent.ListenableFuture;

/**
 * The result of an {@link ContinuousPagingSession#executeContinuouslyAsync(Statement,
 * ContinuousPagingOptions) asynchronous continuous paging query}.
 *
 * DSE replies to a continuous query with a stream of response frames. There is one instance of
 * this class for each frame.
 */
public interface AsyncContinuousPagingResult {
  /**
   * Returns an iterable of the rows in the current page.
   *
   * 
More results might be available via {@link #nextPage()}.
   */
  Iterable currentPage();

  /** Indicates if this is the last page in the stream of results. */
  boolean isLast();

  /**
   * Returns a future wrapping the next page in the stream of results.
   *
   * 
This will return a failed future for the last page; you should always check {@link
   * #isLast()} before calling this method.
   */
  ListenableFuture nextPage();

  /** Returns the definition of the columns returned in this result set. */
  ColumnDefinitions getColumnDefinitions();

  /** Returns the page number. */
  int pageNumber();

  /**
   * Cancels the continuous query.
   *
   * 
The driver will send an additional request to ask DSE to stop sending results. Because that
   * request is asynchronous (and because the driver caches pages locally), there will probably be
   * more pages available (via {@link #nextPage()}) after a call to this method. However, note that
   * the server does not set {@link #isLast()} after a cancellation, so there is no reliable way to
   * detect how many of these remaining pages are left.
   */
  void cancel();

  /**
   * Returns information on the execution of the query, and on the response frame used to build this
   * result.
   *
   * 
In particular, it contains the paging state for the current page.
   *
   * The driver does not support query traces for continuous queries, the corresponding field
   * will always be {@code null}.
   */
  ExecutionInfo getExecutionInfo();
}