DATACMNS-1820 - Moves PageabeExecutionUtils to o.s.data.support.

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-commons</artifactId>
-	<version>2.4.0-SNAPSHOT</version>
+	<version>2.4.0-DATACMNS-1820-SNAPSHOT</version>
 
 	<name>Spring Data Core</name>
 

src/main/java/org/springframework/data/repository/support/PageableExecutionUtils.java

@@ -19,9 +19,7 @@
 import java.util.function.LongSupplier;
 
 import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageImpl;
 import org.springframework.data.domain.Pageable;
-import org.springframework.util.Assert;
 
 /**
  * Support for query execution using {@link Pageable}. Using {@link PageableExecutionUtils} assumes that data queries
@@ -30,8 +28,11 @@
  * @author Mark Paluch
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Jens Schauder
  * @since 1.13
+ * @deprecated since 2.4. Use {@link org.springframework.data.support.PageableExecutionUtils} instead
  */
+@Deprecated
 public abstract class PageableExecutionUtils {
 
 	private PageableExecutionUtils() {}
@@ -47,24 +48,6 @@ private PageableExecutionUtils() {}
 	 * @return the {@link Page}.
 	 */
 	public static <T> Page<T> getPage(List<T> content, Pageable pageable, LongSupplier totalSupplier) {
-
-		Assert.notNull(content, "Content must not be null!");
-		Assert.notNull(pageable, "Pageable must not be null!");
-		Assert.notNull(totalSupplier, "TotalSupplier must not be null!");
-
-		if (pageable.isUnpaged() || pageable.getOffset() == 0) {
-
-			if (pageable.isUnpaged() || pageable.getPageSize() > content.size()) {
-				return new PageImpl<>(content, pageable, content.size());
-			}
-
-			return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
-		}
-
-		if (content.size() != 0 && pageable.getPageSize() > content.size()) {
-			return new PageImpl<>(content, pageable, pageable.getOffset() + content.size());
-		}
-
-		return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
+		return org.springframework.data.support.PageableExecutionUtils.getPage(content, pageable, totalSupplier);
 	}
 }

src/main/java/org/springframework/data/support/PageableExecutionUtils.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 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.support;
+
+import java.util.List;
+import java.util.function.LongSupplier;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageImpl;
+import org.springframework.data.domain.Pageable;
+import org.springframework.util.Assert;
+
+/**
+ * Support for query execution using {@link Pageable}. Using {@link PageableExecutionUtils} assumes that data queries
+ * are cheaper than {@code COUNT} queries and so some cases can take advantage of optimizations.
+ *
+ * @author Mark Paluch
+ * @author Oliver Gierke
+ * @author Christoph Strobl
+ * @author Jens Schauder
+ * @since 2.4
+ */
+public abstract class PageableExecutionUtils {
+
+	private PageableExecutionUtils() {}
+
+	/**
+	 * Constructs a {@link Page} based on the given {@code content}, {@link Pageable} and {@link Supplier} applying
+	 * optimizations. The construction of {@link Page} omits a count query if the total can be determined based on the
+	 * result size and {@link Pageable}.
+	 *
+	 * @param content must not be {@literal null}.
+	 * @param pageable must not be {@literal null}.
+	 * @param totalSupplier must not be {@literal null}.
+	 * @return the {@link Page}.
+	 */
+	public static <T> Page<T> getPage(List<T> content, Pageable pageable, LongSupplier totalSupplier) {
+
+		Assert.notNull(content, "Content must not be null!");
+		Assert.notNull(pageable, "Pageable must not be null!");
+		Assert.notNull(totalSupplier, "TotalSupplier must not be null!");
+
+		if (pageable.isUnpaged() || pageable.getOffset() == 0) {
+
+			if (pageable.isUnpaged() || pageable.getPageSize() > content.size()) {
+				return new PageImpl<>(content, pageable, content.size());
+			}
+
+			return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
+		}
+
+		if (content.size() != 0 && pageable.getPageSize() > content.size()) {
+			return new PageImpl<>(content, pageable, pageable.getOffset() + content.size());
+		}
+
+		return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
+	}
+}

src/test/java/org/springframework/data/support/PageableExecutionUtilsUnitTests.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 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.support;
+
+import static java.util.Collections.*;
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.util.Arrays;
+import java.util.function.LongSupplier;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+
+/**
+ * Unit tests for {@link PageableExecutionUtils}.
+ *
+ * @author Mark Paluch
+ * @author Oliver Gierke
+ * @author Jens Schauder
+ */
+@ExtendWith(MockitoExtension.class)
+class PageableExecutionUtilsUnitTests {
+
+	@Mock LongSupplier totalSupplierMock;
+
+	@Test // DATAMCNS-884
+	void firstPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 10),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(3L);
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void noPageableRequestDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), Pageable.unpaged(), totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(3L);
+
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(5, 10),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(53L);
+
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void firstPageRequestHitsUpperBoundRequiresTotal() {
+
+		doReturn(4L).when(totalSupplierMock).getAsLong();
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 3),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(4L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestHitsUpperBoundRequiresTotal() {
+
+		doReturn(7L).when(totalSupplierMock).getAsLong();
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(1, 3),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(7L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestWithoutResultRequiresRequireTotal() {
+
+		doReturn(7L).when(totalSupplierMock).getAsLong();
+		Page<Integer> page = PageableExecutionUtils.getPage(emptyList(), PageRequest.of(5, 10), totalSupplierMock);
+
+		assertThat(page.getTotalElements()).isEqualTo(7L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+}