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/*
* Copyright 2016-2020 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
*
* https://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.springframework.data.gemfire.search.lucene.support;
import static org.springframework.data.gemfire.domain.ListablePage.newListablePage;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Function;
import java.util.stream.Collectors;
import org.apache.geode.cache.lucene.LuceneResultStruct;
import org.apache.geode.cache.lucene.PageableLuceneQueryResults;
import org.springframework.data.domain.Page;
import org.springframework.data.gemfire.domain.support.AbstractPageSupport;
import org.springframework.data.gemfire.search.lucene.ProjectingLuceneAccessor;
import org.springframework.util.Assert;
/**
* The {@link LucenePage} class is a Spring Data {@link Page} implementation supporting Spring Data style paging
* of {@link PageableLuceneQueryResults} complete with Spring Data projections.
*
* @author John Blum
* @see java.util.List
* @see org.apache.geode.cache.lucene.LuceneResultStruct
* @see org.apache.geode.cache.lucene.PageableLuceneQueryResults
* @see org.springframework.data.domain.Page
* @see org.springframework.data.gemfire.domain.support.AbstractPageSupport
* @see org.springframework.data.gemfire.search.lucene.ProjectingLuceneAccessor
* @since 1.1.0
*/
public class LucenePage extends AbstractPageSupport {
/**
* Factory method used to construct a new instance of {@link LucenePage} initialized with
* the given {@link PageableLuceneQueryResults Lucene query results}, {@link Integer page size},
* and {@link Class projection type}.
*
* The {@link LucenePage previous page} is set to {@literal null}.
*
* @param template {@link ProjectingLuceneAccessor} used to perform Lucene queries and data access operations
* along with projections.
* @param queryResults {@link PageableLuceneQueryResults} wrapped by this {@link LucenePage}.
* @param pageSize number of elements on a {@link LucenePage}.
* @param projectionType {@link Class} type of the projection used to view an individual {@link LuceneResultStruct}
* in the {@link PageableLuceneQueryResults Lucene query results}.
* @throws IllegalArgumentException if {@link ProjectingLuceneAccessor} or the {@link PageableLuceneQueryResults}
* are {@literal null}, or the {@link PageableLuceneQueryResults} do not have
* a {@link PageableLuceneQueryResults#hasNext() next page}.
* @see #LucenePage(ProjectingLuceneAccessor, PageableLuceneQueryResults, int, Class)
*/
public static LucenePage newLucenePage(ProjectingLuceneAccessor template,
PageableLuceneQueryResults queryResults, int pageSize, Class projectionType) {
return new LucenePage<>(template, queryResults, pageSize, projectionType);
}
/**
* Factory method used to construct a new instance of {@link LucenePage} initialized with
* the given {@link PageableLuceneQueryResults Lucene query results}, {@link Integer page size},
* {@link Class projection type} and {@link LucenePage previous page}, if one exists.
*
* @param template {@link ProjectingLuceneAccessor} used to perform Lucene queries and data access operations
* along with projections.
* @param queryResults {@link PageableLuceneQueryResults} wrapped by this {@link LucenePage}.
* @param pageSize number of elements on a {@link LucenePage}.
* @param projectionType {@link Class} type of the projection used to view an individual {@link LuceneResultStruct}
* in the {@link PageableLuceneQueryResults Lucene query results}.
* @param previousPage {@link LucenePage previous page} in the chain of {@link LucenePage pages},
* if this {@link LucenePage} is not the first {@link LucenePage}. Can be {@literal null}.
* @throws IllegalArgumentException if {@link ProjectingLuceneAccessor} or the {@link PageableLuceneQueryResults}
* are {@literal null}, or the {@link PageableLuceneQueryResults} do not have
* a {@link PageableLuceneQueryResults#hasNext() next page}.
* @see #LucenePage(ProjectingLuceneAccessor, PageableLuceneQueryResults, int, Class, LucenePage)
*/
public static LucenePage newLucenePage(ProjectingLuceneAccessor template,
PageableLuceneQueryResults queryResults, int pageSize, Class projectionType,
LucenePage previousPage) {
return new LucenePage<>(template, queryResults, pageSize, projectionType, previousPage);
}
private LucenePage next;
private LucenePage previous;
private final int pageSize;
private final Class projectionType;
private final List content;
private final PageableLuceneQueryResults queryResults;
private final ProjectingLuceneAccessor template;
/**
* Constructs a new instance of {@link LucenePage} initialized with
* the given {@link PageableLuceneQueryResults Lucene query results}, {@link Integer page size}
* and {@link Class projection type}.
*
* The {@link LucenePage previous page} is set to {@literal null}.
*
* @param template {@link ProjectingLuceneAccessor} used to perform Lucene queries and data access operations
* along with projections.
* @param queryResults {@link PageableLuceneQueryResults} wrapped by this {@link LucenePage}.
* @param pageSize number of elements on a {@link LucenePage}.
* @param projectionType {@link Class} type of the projection used to view an individual {@link LuceneResultStruct}
* in the {@link PageableLuceneQueryResults Lucene query results}.
* @throws IllegalArgumentException if {@link ProjectingLuceneAccessor} or the {@link PageableLuceneQueryResults}
* are {@literal null}, or the {@link PageableLuceneQueryResults} do not have
* a {@link PageableLuceneQueryResults#hasNext() next page}.
* @see #LucenePage(ProjectingLuceneAccessor, PageableLuceneQueryResults, int, Class, LucenePage)
*/
public LucenePage(ProjectingLuceneAccessor template, PageableLuceneQueryResults queryResults,
int pageSize, Class projectionType) {
this(template, queryResults, pageSize, projectionType, null);
}
/**
* Constructs a new instance of {@link LucenePage} initialized with
* the given {@link PageableLuceneQueryResults Lucene query results}, {@link Integer page size},
* {@link Class projection type} and {@link LucenePage previous page}, if one exists.
*
* @param template {@link ProjectingLuceneAccessor} used to perform Lucene queries and data access operations
* along with projections.
* @param queryResults {@link PageableLuceneQueryResults} wrapped by this {@link LucenePage}.
* @param pageSize number of elements on a {@link LucenePage}.
* @param projectionType {@link Class} type of the projection used to view an individual {@link LuceneResultStruct}
* in the {@link PageableLuceneQueryResults Lucene query results}.
* @param previous {@link LucenePage previous page} in the chain of {@link LucenePage pages},
* if this {@link LucenePage} is not the first {@link LucenePage}. Can be {@literal null}.
* @throws IllegalArgumentException if {@link ProjectingLuceneAccessor} or the {@link PageableLuceneQueryResults}
* are {@literal null}, or the {@link PageableLuceneQueryResults} do not have
* a {@link PageableLuceneQueryResults#hasNext() next page}.
* @see #materialize(ProjectingLuceneAccessor, List, Class)
*/
public LucenePage(ProjectingLuceneAccessor template, PageableLuceneQueryResults queryResults,
int pageSize, Class projectionType, LucenePage previous) {
Assert.notNull(template, "ProjectingLuceneAccessor must not be null");
Assert.notNull(queryResults, "PageableLuceneQueryResults must not be null");
Assert.isTrue(queryResults.hasNext(), "PageableLuceneQueryResults must have content");
this.template = template;
this.queryResults = queryResults;
this.pageSize = pageSize;
this.projectionType = projectionType;
this.previous = previous;
this.content = materialize(template, queryResults.next(), projectionType);
}
/**
* Renders the {@link List} of {@link LuceneResultStruct} objects into projected values based on
* the {@link Class projection type}.
*
* @param template {@link ProjectingLuceneAccessor} used to project the desired values
* from the {@link List} of {@link LuceneResultStruct} objects.
* @param pageOfQueryResults Lucene query results captured in the {@link List}
* of {@link LuceneResultStruct} objects.
* @param projectionType {@link Class} type to project the {@link LuceneResultStruct} objects as.
* @return a {@link List} of projected values of the given {@link Class projection type}.
* @see org.apache.geode.cache.lucene.LuceneResultStruct
*/
protected List materialize(ProjectingLuceneAccessor template, List> pageOfQueryResults,
Class projectionType) {
return template.project(pageOfQueryResults, projectionType);
}
/**
* Returns the number of elements per {@link LucenePage page}.
*
* @return an integer value indicating the number of elements on a {@link LucenePage page}.
*/
protected int getPageSize() {
return this.pageSize;
}
/**
* Returns the {@link Class} type of the projection.
*
* @return a {@link Class} specifying the projection type.
*/
protected Class getProjectionType() {
return this.projectionType;
}
/**
* Returns the {@link PageableLuceneQueryResults Lucene query results} backing this {@link LucenePage}.
*
* @return a reference to the {@link PageableLuceneQueryResults} backing this {@link LucenePage}.
* @see org.springframework.data.gemfire.search.lucene.support.LucenePage
* @see org.apache.geode.cache.lucene.PageableLuceneQueryResults
*/
protected PageableLuceneQueryResults getQueryResults() {
return this.queryResults;
}
/**
* Returns the {@link ProjectingLuceneAccessor} used by this {@link LucenePage} to perform
* Lucene data access operations and projections.
*
* @return the {@link ProjectingLuceneAccessor} used by this {@link LucenePage} to perform
* Lucene data access operations and projections.
* @see org.springframework.data.gemfire.search.lucene.ProjectingLuceneAccessor
*/
protected ProjectingLuceneAccessor getTemplate() {
return this.template;
}
/**
* @inheritDoc
*/
@Override
public boolean hasNext() {
return getQueryResults().hasNext();
}
/**
* @inheritDoc
*/
@Override
public boolean hasPrevious() {
return (getPrevious() != null);
}
/**
* @inheritDoc
*/
@Override
public List getContent() {
return Collections.unmodifiableList(this.content);
}
/**
* Null-safe method to return the next {@link LucenePage page} in the collection of {@link Page pages}.
*
* @return the next {@link LucenePage page} in the collection of {@link Page pages}.
* @throws IllegalStateException if no more {@link Page pages} exist beyond this {@link LucenePage page}.
* @see org.springframework.data.gemfire.search.lucene.support.LucenePage
* @see #getPrevious()
*/
public LucenePage getNext() {
return Optional.ofNullable(this.next).orElseGet(() -> {
Assert.state(hasNext(), "No more pages");
this.next = newLucenePage(getTemplate(), getQueryResults(), getPageSize(), getProjectionType(), this);
return this.next;
});
}
/**
* @inheritDoc
*/
@Override
public int getNumber() {
AtomicInteger number = new AtomicInteger(1);
Optional.ofNullable(getPrevious()).ifPresent(previous -> {
while (previous != null) {
previous = previous.getPrevious();
number.incrementAndGet();
}
});
return number.get();
}
/**
* Returns the previous {@link LucenePage page} in the collection of {@link Page pages}.
*
* @return the previous {@link LucenePage page} in the collection of {@link Page pages}
* or {@literal null} if no {@link LucenePage} proceeds this {@link LucenePage page}.
* @see org.springframework.data.gemfire.search.lucene.support.LucenePage
* @see #getNext()
*/
public LucenePage getPrevious() {
return this.previous;
}
/**
* @inheritDoc
*/
@Override
public int getSize() {
return getPageSize();
}
/**
* @inheritDoc
*/
@Override
public long getTotalElements() {
return getQueryResults().size();
}
/**
* @inheritDoc
*/
@Override
public int getTotalPages() {
long totalElements = getTotalElements();
int pageSize = getPageSize();
int totalPages = Double.valueOf(Math.floor(totalElements / pageSize)).intValue();
totalPages += (totalElements % pageSize != 0 ? 1 : 0);
return totalPages;
}
/**
* @inheritDoc
*/
@Override
public Page map(Function converter) {
return newListablePage(getContent().stream().map(converter::apply).collect(Collectors.toList()));
}
}
