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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;

/**
 * The result of a {@link ContinuousPagingSession#executeContinuously(Statement,
 * ContinuousPagingOptions) synchronous continuous paging query}.
 *
 * A synchronous query uses asynchronous calls internally; this object handles the details of
 * performing those calls, and assembling the results in an {@code Iterable}.
 *
 * 
Note that {@link #iterator()} will always return the same iterator instance; in other word,
 * this object is only iterable once, it is not possible to restart the iteration from the
 * beginning.
 *
 * 
This object is not thread safe, it should only be accessed from the thread that executed the
 * query.
 */
public interface ContinuousPagingResult extends Iterable {

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

  /**
   * Cancels the continuous query.
   *
   * 
The iteration will stop at the current page in the stream of results; if the server sends
   * more pages after the cancellation (or if more pages were available in the driver's local
   * cache), they will be discarded. Note however that there might still be rows available in the
   * current page.
   *
   * 
Therefore, if you plan to resume the iteration later, the correct procedure is:
   *
   * 

   *   invoke this method;
   *   
keep iterating on this object until it doesn't return any more rows;
   *   
retrieve the paging state with {@code getExecutionInfo().getPagingState()}, and reinject
   *       it in the statement to resume the iteration.
   * 
   */
  void cancel();

  /**
   * Returns information on the execution of the query, and on the response frame corresponding to
   * the current state of the iteration.
   *
   * The driver does not support query traces for continuous queries, the corresponding field
   * will always be {@code null}.
   */
  ExecutionInfo getExecutionInfo();
}