com.datastax.dse.driver.api.core.graph.AsyncGraphResultSet Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.datastax.dse.driver.api.core.graph;
import com.datastax.dse.driver.internal.core.graph.GraphExecutionInfoConverter;
import com.datastax.oss.driver.api.core.cql.ExecutionInfo;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.util.Iterator;
import java.util.concurrent.CompletionStage;
/**
* The result of an asynchronous graph query.
*
* The default implementation returned by the driver is not thread-safe: the iterable
* returned by {@link #currentPage()} should only be iterated by a single thread. However, if
* subsequent pages are requested via {@link #fetchNextPage()}, it's safe to process those new
* instances in other threads (as long as each individual page of results is not accessed
* concurrently).
*
* @see GraphResultSet
*/
public interface AsyncGraphResultSet {
/** The execution information for this page of results. */
@NonNull
default ExecutionInfo getRequestExecutionInfo() {
return GraphExecutionInfoConverter.convert(getExecutionInfo());
}
/**
* The execution information for this page of results.
*
* @deprecated Use {@link #getRequestExecutionInfo()} instead.
*/
@Deprecated
@NonNull
com.datastax.dse.driver.api.core.graph.GraphExecutionInfo getExecutionInfo();
/** How many rows are left before the current page is exhausted. */
int remaining();
/**
* The nodes in the current page. To keep iterating beyond that, use {@link #hasMorePages()} and
* {@link #fetchNextPage()}.
*
*
Note that this method always returns the same object, and that that object can only be
* iterated once: nodes are "consumed" as they are read.
*/
@NonNull
Iterable currentPage();
/**
* Returns the next node, or {@code null} if the result set is exhausted.
*
* This is convenient for queries that are known to return exactly one node.
*/
@Nullable
default GraphNode one() {
Iterator iterator = currentPage().iterator();
return iterator.hasNext() ? iterator.next() : null;
}
/**
* Whether there are more pages of results. If so, call {@link #fetchNextPage()} to fetch the next
* one asynchronously.
*/
boolean hasMorePages();
/**
* Fetch the next page of results asynchronously.
*
* @throws IllegalStateException if there are no more pages. Use {@link #hasMorePages()} to check
* if you can call this method.
*/
@NonNull
CompletionStage fetchNextPage() throws IllegalStateException;
/**
* Cancels the query and asks the server to stop sending results.
*
* At this time, graph queries are not paginated and the server sends all the results at once;
* therefore this method has no effect.
*/
void cancel();
}