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/* * Copyright 2013 the original author or authors. * * 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://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.socialsignin.spring.data.dynamodb.repository.query; import java.io.Serializable; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.socialsignin.spring.data.dynamodb.core.DynamoDBOperations; import org.socialsignin.spring.data.dynamodb.query.Query; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageImpl; import org.springframework.data.domain.Pageable; import org.springframework.data.domain.Slice; import org.springframework.data.domain.SliceImpl; import org.springframework.data.repository.query.ParameterAccessor; import org.springframework.data.repository.query.Parameters; import org.springframework.data.repository.query.ParametersParameterAccessor; import org.springframework.data.repository.query.RepositoryQuery; /** * @author Michael Lavelle */ public abstract class AbstractDynamoDBQuery<T, ID extends Serializable> implements RepositoryQuery { protected final DynamoDBOperations dynamoDBOperations; private final DynamoDBQueryMethod<T, ID> method; public AbstractDynamoDBQuery(DynamoDBOperations dynamoDBOperations, DynamoDBQueryMethod<T, ID> method) { this.dynamoDBOperations = dynamoDBOperations; this.method = method; } protected QueryExecution<T, ID> getExecution() { if (method.isCollectionQuery() && !isSingleEntityResultsRestriction()) { return new CollectionExecution(); } else if (method.isSliceQuery() && !isSingleEntityResultsRestriction()) { return new SlicedExecution(method.getParameters()); } else if (method.isPageQuery() && !isSingleEntityResultsRestriction()) { return new PagedExecution(method.getParameters()); } else if (method.isModifyingQuery()) { throw new UnsupportedOperationException("Modifying queries not yet supported"); } else if (isSingleEntityResultsRestriction()) { return new SingleEntityLimitedExecution(); } else { return new SingleEntityExecution(); } } protected abstract Query<T> doCreateQuery(Object[] values); protected abstract Query<Long> doCreateCountQuery(Object[] values, boolean pageQuery); protected abstract boolean isCountQuery(); protected abstract Integer getResultsRestrictionIfApplicable(); protected abstract boolean isSingleEntityResultsRestriction(); protected Query<T> doCreateQueryWithPermissions(Object values[]) { Query<T> query = doCreateQuery(values); query.setScanEnabled(method.isScanEnabled()); return query; } protected Query<Long> doCreateCountQueryWithPermissions(Object values[], boolean pageQuery) { Query<Long> query = doCreateCountQuery(values, pageQuery); query.setScanCountEnabled(method.isScanCountEnabled()); return query; } private interface QueryExecution<T, ID extends Serializable> { public Object execute(AbstractDynamoDBQuery<T, ID> query, Object[] values); } class CollectionExecution implements QueryExecution<T, ID> { @Override public Object execute(AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { Query<T> query = dynamoDBQuery.doCreateQueryWithPermissions(values); if (getResultsRestrictionIfApplicable() != null) { return restrictMaxResultsIfNecessary(query.getResultList().iterator()); } else return query.getResultList(); } private List<T> restrictMaxResultsIfNecessary(Iterator<T> iterator) { int processed = 0; List<T> resultsPage = new ArrayList<T>(); while (iterator.hasNext() && processed < getResultsRestrictionIfApplicable()) { resultsPage.add(iterator.next()); processed++; } return resultsPage; } } /** * Executes the {@link AbstractStringBasedJpaQuery} to return a * {@link org.springframework.data.domain.Page} of entities. */ class PagedExecution implements QueryExecution<T, ID> { private final Parameters<?, ?> parameters; public PagedExecution(Parameters<?, ?> parameters) { this.parameters = parameters; } private int scanThroughResults(Iterator<T> iterator, int resultsToScan) { int processed = 0; while (iterator.hasNext() && processed < resultsToScan) { iterator.next(); processed++; } return processed; } private List<T> readPageOfResultsRestrictMaxResultsIfNecessary(Iterator<T> iterator, int pageSize) { int processed = 0; int toProcess = getResultsRestrictionIfApplicable() != null ? Math.min(pageSize, getResultsRestrictionIfApplicable()) : pageSize; List<T> resultsPage = new ArrayList<T>(); while (iterator.hasNext() && processed < toProcess) { resultsPage.add(iterator.next()); processed++; } return resultsPage; } @Override public Object execute(AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { ParameterAccessor accessor = new ParametersParameterAccessor(parameters, values); Pageable pageable = accessor.getPageable(); Query<T> query = dynamoDBQuery.doCreateQueryWithPermissions(values); List<T> results = query.getResultList(); return createPage(results, pageable, dynamoDBQuery, values); } private Page<T> createPage(List<T> allResults, Pageable pageable, AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { Iterator<T> iterator = allResults.iterator(); int processedCount = 0; if (pageable.getOffset() > 0) { processedCount = scanThroughResults(iterator, pageable.getOffset()); if (processedCount < pageable.getOffset()) return new PageImpl<T>(new ArrayList<T>()); } List<T> results = readPageOfResultsRestrictMaxResultsIfNecessary(iterator, pageable.getPageSize()); Query<Long> countQuery = dynamoDBQuery.doCreateCountQueryWithPermissions(values, true); long count = countQuery.getSingleResult(); if (getResultsRestrictionIfApplicable() != null) { count = Math.min(count, getResultsRestrictionIfApplicable()); } return new PageImpl<T>(results, pageable, count); } } class SlicedExecution implements QueryExecution<T, ID> { private final Parameters<?, ?> parameters; public SlicedExecution(Parameters<?, ?> parameters) { this.parameters = parameters; } private int scanThroughResults(Iterator<T> iterator, int resultsToScan) { int processed = 0; while (iterator.hasNext() && processed < resultsToScan) { iterator.next(); processed++; } return processed; } private List<T> readPageOfResultsRestrictMaxResultsIfNecessary(Iterator<T> iterator, int pageSize) { int processed = 0; int toProcess = getResultsRestrictionIfApplicable() != null ? Math.min(pageSize, getResultsRestrictionIfApplicable()) : pageSize; List<T> resultsPage = new ArrayList<T>(); while (iterator.hasNext() && processed < toProcess) { resultsPage.add(iterator.next()); processed++; } return resultsPage; } @Override public Object execute(AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { ParameterAccessor accessor = new ParametersParameterAccessor(parameters, values); Pageable pageable = accessor.getPageable(); Query<T> query = dynamoDBQuery.doCreateQueryWithPermissions(values); List<T> results = query.getResultList(); return createSlice(results, pageable); } private Slice<T> createSlice(List<T> allResults, Pageable pageable) { Iterator<T> iterator = allResults.iterator(); int processedCount = 0; if (pageable.getOffset() > 0) { processedCount = scanThroughResults(iterator, pageable.getOffset()); if (processedCount < pageable.getOffset()) return new SliceImpl<T>(new ArrayList<T>()); } List<T> results = readPageOfResultsRestrictMaxResultsIfNecessary(iterator, pageable.getPageSize()); // Scan ahead to retrieve the next page count boolean hasMoreResults = scanThroughResults(iterator, 1) > 0; if (getResultsRestrictionIfApplicable() != null && getResultsRestrictionIfApplicable().intValue() <= results.size()) hasMoreResults = false; return new SliceImpl<T>(results, pageable, hasMoreResults); } } class SingleEntityExecution implements QueryExecution<T, ID> { @Override public Object execute(AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { if (isCountQuery()) { return dynamoDBQuery.doCreateCountQueryWithPermissions(values, false).getSingleResult(); } else { return dynamoDBQuery.doCreateQueryWithPermissions(values).getSingleResult(); } } } class SingleEntityLimitedExecution implements QueryExecution<T, ID> { @Override public Object execute(AbstractDynamoDBQuery<T, ID> dynamoDBQuery, Object[] values) { if (isCountQuery()) { return dynamoDBQuery.doCreateCountQueryWithPermissions(values, false).getSingleResult(); } else { List<T> resultList = dynamoDBQuery.doCreateQueryWithPermissions(values).getResultList(); return resultList.size() == 0 ? null : resultList.get(0); } } } /* * (non-Javadoc) * * @see * org.springframework.data.repository.query.RepositoryQuery#execute(java * .lang.Object[]) */ public Object execute(Object[] parameters) { return getExecution().execute(this, parameters); } @Override public DynamoDBQueryMethod<T, ID> getQueryMethod() { return this.method; } }