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The AWS Java SDK for Amazon DynamoDB module holds the client classes that are used for communicating with Amazon DynamoDB Service

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/*
 * Copyright 2011-2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed 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://aws.amazon.com/apache2.0
 *
 * This file 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.amazonaws.services.dynamodbv2.datamodeling;

import java.util.LinkedList;
import java.util.List;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperConfig.PaginationLoadingStrategy;
import com.amazonaws.services.dynamodbv2.model.ScanResult;

/**
 * Implementation of the List interface that represents the results from a parallel scan
 * in AWS DynamoDB. Paginated results are loaded on demand when the user
 * executes an operation that requires them. Some operations, such as size(),
 * must fetch the entire list, but results are lazily fetched page by page when
 * possible.
 * 

* This is an unmodifiable list, so callers should not invoke any operations * that modify this list, otherwise they will throw an * UnsupportedOperationException. * * @param * The type of objects held in this list. * @see PaginatedList */ public class PaginatedParallelScanList extends PaginatedList { /** The current parallel scan task which contains all the information about the scan request */ private final ParallelScanTask parallelScanTask; private final DynamoDBMapperConfig config; public PaginatedParallelScanList( DynamoDBMapper mapper, Class clazz, AmazonDynamoDB dynamo, ParallelScanTask parallelScanTask, PaginationLoadingStrategy paginationLoadingStrategy, DynamoDBMapperConfig config) { super(mapper, clazz, dynamo, paginationLoadingStrategy); this.parallelScanTask = parallelScanTask; this.config = config; // Marshal the first batch of results in allResults allResults.addAll(marshalParallelScanResultsIntoObjects(parallelScanTask.getNextBatchOfScanResults())); // If the results should be eagerly loaded at once if (paginationLoadingStrategy == PaginationLoadingStrategy.EAGER_LOADING) { loadAllResults(); } } @Override protected boolean atEndOfResults() { return parallelScanTask.isAllSegmentScanFinished(); } @Override protected List fetchNextPage() { return marshalParallelScanResultsIntoObjects(parallelScanTask.getNextBatchOfScanResults()); } private List marshalParallelScanResultsIntoObjects(List scanResults) { List allItems = new LinkedList(); for (ScanResult scanResult : scanResults) { if (null != scanResult) { allItems.addAll(mapper.marshallIntoObjects( mapper.toParameters( scanResult.getItems(), clazz, parallelScanTask.getTableName(), config))); } } return allItems; } }





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