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Commit 4718c45

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Introduce public ReactivePageableExecutionUtils variant of pageable utils.
Closes #3209 
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/*
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* Copyright 2021-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.data.support;
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import reactor.core.publisher.Mono;
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import java.util.List;
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import org.springframework.data.domain.Page;
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import org.springframework.data.domain.PageImpl;
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import org.springframework.data.domain.Pageable;
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import org.springframework.util.Assert;
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/**
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* Support for query execution using {@link Pageable}. Using {@link ReactivePageableExecutionUtils} assumes that data
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* queries are cheaper than {@code COUNT} queries and so some cases can take advantage of optimizations.
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*
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* @author Mark Paluch
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* @since 3.5
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*/
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public abstract class ReactivePageableExecutionUtils {
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private ReactivePageableExecutionUtils() {}
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/**
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* Constructs a {@link Page} based on the given {@code content}, {@link Pageable} and {@link Mono} applying
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* optimizations. The construction of {@link Page} omits a count query if the total can be determined based on the
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* result size and {@link Pageable}.
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*
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* @param content must not be {@literal null}.
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* @param pageable must not be {@literal null}.
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* @param totalSupplier must not be {@literal null}.
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* @return the {@link Page}.
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*/
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public static <T> Mono<Page<T>> getPage(List<T> content, Pageable pageable, Mono<Long> totalSupplier) {
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Assert.notNull(content, "Content must not be null");
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Assert.notNull(pageable, "Pageable must not be null");
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Assert.notNull(totalSupplier, "TotalSupplier must not be null");
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if (pageable.isUnpaged() || pageable.getOffset() == 0) {
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if (pageable.isUnpaged() || pageable.getPageSize() > content.size()) {
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return Mono.just(new PageImpl<>(content, pageable, content.size()));
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}
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return totalSupplier.map(total -> new PageImpl<>(content, pageable, total));
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}
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if (!content.isEmpty() && pageable.getPageSize() > content.size()) {
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return Mono.just(new PageImpl<>(content, pageable, pageable.getOffset() + content.size()));
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}
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return totalSupplier.map(total -> new PageImpl<>(content, pageable, total));
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}
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}
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/*
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* Copyright 2020-2024 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.data.support;
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import static java.util.Collections.*;
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import static org.assertj.core.api.Assertions.*;
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import static org.mockito.Mockito.*;
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import reactor.core.publisher.Mono;
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import java.util.Arrays;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.api.extension.ExtendWith;
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import org.mockito.junit.jupiter.MockitoExtension;
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import org.springframework.data.domain.PageRequest;
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import org.springframework.data.domain.Pageable;
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/**
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* Unit tests for {@link ReactivePageableExecutionUtils}.
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*
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* @author Mark Paluch
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*/
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@SuppressWarnings("unchecked")
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@ExtendWith(MockitoExtension.class)
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class ReactivePageableExecutionUtilsUnitTests {
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@Test // DATAMCNS-884, GH-3209
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void firstPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
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Mono<Long> totalSupplierMock = mock(Mono.class);
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var page = ReactivePageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 10), totalSupplierMock)
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.block();
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assertThat(page).contains(1, 2, 3);
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assertThat(page.getTotalElements()).isEqualTo(3L);
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verifyNoInteractions(totalSupplierMock);
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}
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@Test // DATAMCNS-884, GH-3209
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void noPageableRequestDoesNotRequireTotal() {
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Mono<Long> totalSupplierMock = mock(Mono.class);
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var page = ReactivePageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), Pageable.unpaged(), totalSupplierMock)
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.block();
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assertThat(page).contains(1, 2, 3);
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assertThat(page.getTotalElements()).isEqualTo(3L);
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verifyNoInteractions(totalSupplierMock);
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}
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@Test // DATAMCNS-884, GH-3209
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void subsequentPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
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Mono<Long> totalSupplierMock = mock(Mono.class);
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var page = ReactivePageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(5, 10), totalSupplierMock)
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.block();
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assertThat(page).contains(1, 2, 3);
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assertThat(page.getTotalElements()).isEqualTo(53L);
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verifyNoInteractions(totalSupplierMock);
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}
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@Test // DATAMCNS-884, GH-3209
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void firstPageRequestHitsUpperBoundRequiresTotal() {
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Mono<Long> totalSupplierMock = Mono.just(4L);
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var page = ReactivePageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 3), totalSupplierMock)
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.block();
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assertThat(page).contains(1, 2, 3);
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assertThat(page.getTotalElements()).isEqualTo(4L);
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}
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@Test // DATAMCNS-884, GH-3209
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void subsequentPageRequestHitsUpperBoundRequiresTotal() {
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Mono<Long> totalSupplierMock = Mono.just(7L);
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var page = ReactivePageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(1, 3), totalSupplierMock)
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.block();
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assertThat(page).contains(1, 2, 3);
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assertThat(page.getTotalElements()).isEqualTo(7L);
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}
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@Test // DATAMCNS-884, GH-3209
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void subsequentPageRequestWithoutResultRequiresRequireTotal() {
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Mono<Long> totalSupplierMock = Mono.just(7L);
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var page = ReactivePageableExecutionUtils.getPage(emptyList(), PageRequest.of(5, 10), totalSupplierMock).block();
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assertThat(page.getTotalElements()).isEqualTo(7L);
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}
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}

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