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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.
/*
* 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.datastax.driver.core.exceptions.NoHostAvailableException;
import com.datastax.driver.core.exceptions.QueryExecutionException;
import com.datastax.driver.core.exceptions.QueryValidationException;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* A future on a {@link ResultSet}.
*
* Note that this class implements Guava's {@code
* ListenableFuture} and can so be used with Guava's future utilities.
*/
public interface ResultSetFuture extends ListenableFuture {
/**
* Waits for the query to return and return its result.
*
* This method is usually more convenient than {@link #get} because it:
*
* - Waits for the result uninterruptibly, and so doesn't throw
* {@link InterruptedException}.
* - Returns meaningful exceptions, instead of having to deal
* with ExecutionException.
*
* As such, it is the preferred way to get the future result.
*
* @return the query result set.
* @throws NoHostAvailableException if no host in the cluster can be
* contacted successfully to execute this query.
* @throws QueryExecutionException if the query triggered an execution
* exception, that is an exception thrown by Cassandra when it cannot execute
* the query with the requested consistency level successfully.
* @throws QueryValidationException if the query is invalid (syntax error,
* unauthorized or any other validation problem).
*/
public ResultSet getUninterruptibly();
/**
* Waits for the provided time for the query to return and return its
* result if available.
*
* This method is usually more convenient than {@link #get} because it:
*
* - Waits for the result uninterruptibly, and so doesn't throw
* {@link InterruptedException}.
* - Returns meaningful exceptions, instead of having to deal
* with ExecutionException.
*
* As such, it is the preferred way to get the future result.
*
* @param timeout the time to wait for the query to return.
* @param unit the unit for {@code timeout}.
* @return the query result set.
* @throws NoHostAvailableException if no host in the cluster can be
* contacted successfully to execute this query.
* @throws QueryExecutionException if the query triggered an execution
* exception, that is an exception thrown by Cassandra when it cannot execute
* the query with the requested consistency level successfully.
* @throws QueryValidationException if the query if invalid (syntax error,
* unauthorized or any other validation problem).
* @throws TimeoutException if the wait timed out (Note that this is
* different from a Cassandra timeout, which is a {@code
* QueryExecutionException}).
*/
public ResultSet getUninterruptibly(long timeout, TimeUnit unit) throws TimeoutException;
/**
* Attempts to cancel the execution of the request corresponding to this
* future. This attempt will fail if the request has already returned.
*
* Please note that this only cancel the request driver side, but nothing
* is done to interrupt the execution of the request Cassandra side (and that even
* if {@code mayInterruptIfRunning} is true) since Cassandra does not
* support such interruption.
*
* This method can be used to ensure no more work is performed driver side
* (which, while it doesn't include stopping a request already submitted
* to a Cassandra node, may include not retrying another Cassandra host on
* failure/timeout) if the ResultSet is not going to be retried. Typically,
* the code to wait for a request result for a maximum of 1 second could
* look like:
*
* ResultSetFuture future = session.executeAsync(...some query...);
* try {
* ResultSet result = future.get(1, TimeUnit.SECONDS);
* ... process result ...
* } catch (TimeoutException e) {
* future.cancel(true); // Ensure any resource used by this query driver
* // side is released immediately
* ... handle timeout ...
* }
*
*
* @param mayInterruptIfRunning the value of this parameter is currently
* ignored.
* @return {@code false} if the future could not be cancelled (it has already
* completed normally); {@code true} otherwise.
*/
@Override
public boolean cancel(boolean mayInterruptIfRunning);
}