com.datastax.dse.driver.api.core.cql.continuous

Interface ContinuousAsyncResultSet

All Superinterfaces:

AsyncPagingIterable<Row,ContinuousAsyncResultSet>

public interface ContinuousAsyncResultSet
extends AsyncPagingIterable<Row,ContinuousAsyncResultSet>

The result of an 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.

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancels the continuous query.
ExecutionInfo	getExecutionInfo() Returns information about the execution of this page of results.
int	pageNumber() Returns the current page's number.

Methods inherited from interface com.datastax.oss.driver.api.core.AsyncPagingIterable

currentPage, fetchNextPage, getColumnDefinitions, hasMorePages, map, one, remaining, wasApplied

Method Detail

pageNumber

int pageNumber()

Returns the current page's number. Pages are numbered starting from 1.

cancel

void cancel()

Cancels the continuous query.

There might still be rows available in the current page after the cancellation; these rows can be retrieved normally.

Also, there might be more pages available in the driver's local page cache after the cancellation; these extra pages will be discarded.

Therefore, if you plan to resume the iteration later, the correct procedure is as follows:

1. Cancel the operation by invoking this method, or by cancelling the next page's future;
2. Keep iterating on the current page until it doesn't return any more rows;
3. Retrieve the paging state with getExecutionInfo().getPagingState();
4. Re-inject the paging state in the statement;
5. Resume the operation by invoking executeContinuouslyAsync again.

After a cancellation, futures returned by AsyncPagingIterable.fetchNextPage() that are not yet complete will always complete exceptionally by throwing a CancellationException, even if they were obtained before the cancellation.

getExecutionInfo

@NonNull
ExecutionInfo getExecutionInfo()

Returns information about the execution of this page of results.

Note: because the driver does not support query traces for continuous queries, ExecutionInfo.getTracingId() will always be null.

Specified by:

getExecutionInfo in interface AsyncPagingIterable<Row,ContinuousAsyncResultSet>