| /* |
| * 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 org.apache.cassandra.service.pager; |
| |
| import java.nio.ByteBuffer; |
| |
| import org.apache.cassandra.db.*; |
| import org.apache.cassandra.db.rows.*; |
| import org.apache.cassandra.db.filter.*; |
| import org.apache.cassandra.transport.ProtocolVersion; |
| |
| /** |
| * Common interface to single partition queries (by slice and by name). |
| * |
| * For use by MultiPartitionPager. |
| */ |
| public class SinglePartitionPager extends AbstractQueryPager |
| { |
| private final SinglePartitionReadCommand command; |
| |
| private volatile PagingState.RowMark lastReturned; |
| |
| public SinglePartitionPager(SinglePartitionReadCommand command, PagingState state, ProtocolVersion protocolVersion) |
| { |
| super(command, protocolVersion); |
| this.command = command; |
| |
| if (state != null) |
| { |
| lastReturned = state.rowMark; |
| restoreState(command.partitionKey(), state.remaining, state.remainingInPartition); |
| } |
| } |
| |
| private SinglePartitionPager(SinglePartitionReadCommand command, |
| ProtocolVersion protocolVersion, |
| PagingState.RowMark rowMark, |
| int remaining, |
| int remainingInPartition) |
| { |
| super(command, protocolVersion); |
| this.command = command; |
| this.lastReturned = rowMark; |
| restoreState(command.partitionKey(), remaining, remainingInPartition); |
| } |
| |
| @Override |
| public SinglePartitionPager withUpdatedLimit(DataLimits newLimits) |
| { |
| return new SinglePartitionPager(command.withUpdatedLimit(newLimits), |
| protocolVersion, |
| lastReturned, |
| maxRemaining(), |
| remainingInPartition()); |
| } |
| |
| public ByteBuffer key() |
| { |
| return command.partitionKey().getKey(); |
| } |
| |
| public DataLimits limits() |
| { |
| return command.limits(); |
| } |
| |
| public PagingState state() |
| { |
| return lastReturned == null |
| ? null |
| : new PagingState(null, lastReturned, maxRemaining(), remainingInPartition()); |
| } |
| |
| protected ReadCommand nextPageReadCommand(int pageSize) |
| { |
| Clustering clustering = lastReturned == null ? null : lastReturned.clustering(command.metadata()); |
| DataLimits limits = (lastReturned == null || command.isForThrift()) ? limits().forPaging(pageSize) |
| : limits().forPaging(pageSize, key(), remainingInPartition()); |
| |
| return command.forPaging(clustering, limits); |
| } |
| |
| protected void recordLast(DecoratedKey key, Row last) |
| { |
| if (last != null && last.clustering() != Clustering.STATIC_CLUSTERING) |
| lastReturned = PagingState.RowMark.create(command.metadata(), last, protocolVersion); |
| } |
| |
| protected boolean isPreviouslyReturnedPartition(DecoratedKey key) |
| { |
| return lastReturned != null; |
| } |
| } |