Add blocking queue item reader and writer

Resolves #2350
Resolves #2044

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/queue/BlockingQueueItemReader.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2024 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.batch.item.queue;
+
+import org.springframework.batch.item.ItemReader;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * This is an {@link ItemReader} that reads items from a {@link BlockingQueue}. It stops
+ * reading (ie returns {@code null}) if no items are available in the queue after a
+ * configurable timeout.
+ *
+ * @param <T> type of items to read.
+ * @author Mahmoud Ben Hassine
+ * @since 5.2.0
+ */
+public class BlockingQueueItemReader<T> implements ItemReader<T> {
+
+	private final BlockingQueue<T> queue;
+
+	private long timeout = 1L;
+
+	private TimeUnit timeUnit = TimeUnit.SECONDS;
+
+	/**
+	 * Create a new {@link BlockingQueueItemReader}.
+	 * @param queue the queue to read items from
+	 */
+	public BlockingQueueItemReader(BlockingQueue<T> queue) {
+		this.queue = queue;
+	}
+
+	/**
+	 * Set the reading timeout and time unit. Defaults to 1 second.
+	 * @param timeout the timeout after which the reader stops reading
+	 * @param timeUnit the unit of the timeout
+	 */
+	public void setTimeout(long timeout, TimeUnit timeUnit) {
+		this.timeout = timeout;
+		this.timeUnit = timeUnit;
+	}
+
+	@Override
+	public T read() throws Exception {
+		return this.queue.poll(this.timeout, this.timeUnit);
+	}
+
+}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/queue/BlockingQueueItemWriter.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024 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.batch.item.queue;
+
+import org.springframework.batch.item.Chunk;
+import org.springframework.batch.item.ItemWriter;
+
+import java.util.concurrent.BlockingQueue;
+
+/**
+ * This is an {@link ItemWriter} that writes items to a {@link BlockingQueue}.
+ *
+ * @param <T> type of items to write
+ * @since 5.2.0
+ * @author Mahmoud Ben Hassine
+ */
+public class BlockingQueueItemWriter<T> implements ItemWriter<T> {
+
+	private final BlockingQueue<T> queue;
+
+	/**
+	 * Create a new {@link BlockingQueueItemWriter}.
+	 * @param queue the queue to write items to
+	 */
+	public BlockingQueueItemWriter(BlockingQueue<T> queue) {
+		this.queue = queue;
+	}
+
+	@Override
+	public void write(Chunk<? extends T> items) throws Exception {
+		for (T item : items) {
+			this.queue.put(item);
+		}
+	}
+
+}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/queue/builder/BlockingQueueItemReaderBuilder.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2024 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.batch.item.queue.builder;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.batch.item.queue.BlockingQueueItemReader;
+import org.springframework.util.Assert;
+
+/**
+ * Builder for {@link BlockingQueueItemReader}.
+ *
+ * @param <T> type of items to read
+ * @since 5.2.0
+ * @author Mahmoud Ben Hassine
+ */
+public class BlockingQueueItemReaderBuilder<T> {
+
+	private BlockingQueue<T> queue;
+
+	private long timeout = 1L;
+
+	private TimeUnit timeUnit = TimeUnit.SECONDS;
+
+	/**
+	 * Set the queue to read items from.
+	 * @param queue the queue to read items from.
+	 * @return this instance of the builder
+	 */
+	public BlockingQueueItemReaderBuilder<T> queue(BlockingQueue<T> queue) {
+		this.queue = queue;
+		return this;
+	}
+
+	/**
+	 * Set the reading timeout. Defaults to 1 second.
+	 * @param timeout the reading timeout.
+	 * @return this instance of the builder
+	 */
+	public BlockingQueueItemReaderBuilder<T> timeout(long timeout, TimeUnit timeUnit) {
+		this.timeout = timeout;
+		this.timeUnit = timeUnit;
+		return this;
+	}
+
+	/**
+	 * Create a configured {@link BlockingQueueItemReader}.
+	 * @return a configured {@link BlockingQueueItemReader}.
+	 */
+	public BlockingQueueItemReader<T> build() {
+		Assert.state(this.queue != null, "The blocking queue is required.");
+		BlockingQueueItemReader<T> blockingQueueItemReader = new BlockingQueueItemReader<>(this.queue);
+		blockingQueueItemReader.setTimeout(this.timeout, this.timeUnit);
+		return blockingQueueItemReader;
+	}
+
+}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/queue/builder/BlockingQueueItemWriterBuilder.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2024 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.batch.item.queue.builder;
+
+import java.util.concurrent.BlockingQueue;
+
+import org.springframework.batch.item.queue.BlockingQueueItemWriter;
+import org.springframework.util.Assert;
+
+/**
+ * Builder for a {@link BlockingQueueItemWriter}.
+ *
+ * @param <T> type of items to write
+ * @since 5.2.0
+ * @author Mahmoud Ben Hassine
+ */
+public class BlockingQueueItemWriterBuilder<T> {
+
+	private BlockingQueue<T> queue;
+
+	/**
+	 * Create a new {@link BlockingQueueItemWriterBuilder}
+	 * @param queue the queue to write items to
+	 * @return this instance of the builder
+	 */
+	public BlockingQueueItemWriterBuilder<T> queue(BlockingQueue<T> queue) {
+		this.queue = queue;
+		return this;
+	}
+
+	/**
+	 * Create a configured {@link BlockingQueueItemWriter}.
+	 * @return a configured {@link BlockingQueueItemWriter}.
+	 */
+	public BlockingQueueItemWriter<T> build() {
+		Assert.state(this.queue != null, "The blocking queue is required.");
+		return new BlockingQueueItemWriter<>(this.queue);
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/queue/BlockingQueueItemReaderTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2024 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.batch.item.queue;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.batch.item.queue.builder.BlockingQueueItemReaderBuilder;
+
+/**
+ * Test class for {@link BlockingQueueItemReader}.
+ *
+ * @author Mahmoud Ben Hassine
+ */
+class BlockingQueueItemReaderTests {
+
+	@Test
+	void testRead() throws Exception {
+		// given
+		BlockingQueue<String> queue = new ArrayBlockingQueue<>(10);
+		queue.put("foo");
+		BlockingQueueItemReader<String> reader = new BlockingQueueItemReaderBuilder<String>().queue(queue)
+			.timeout(10, TimeUnit.MILLISECONDS)
+			.build();
+
+		// when & then
+		Assertions.assertEquals("foo", reader.read());
+		Assertions.assertNull(reader.read());
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/queue/BlockingQueueItemWriterTests.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024 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.batch.item.queue;
+
+import java.util.List;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.batch.item.Chunk;
+import org.springframework.batch.item.queue.builder.BlockingQueueItemWriterBuilder;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Test class for {@link BlockingQueueItemWriter}.
+ *
+ * @author Mahmoud Ben Hassine
+ */
+class BlockingQueueItemWriterTests {
+
+	@Test
+	void testWrite() throws Exception {
+		// given
+		BlockingQueue<String> queue = new ArrayBlockingQueue<>(10);
+		BlockingQueueItemWriter<String> writer = new BlockingQueueItemWriterBuilder<String>().queue(queue).build();
+
+		// when
+		writer.write(Chunk.of("foo", "bar"));
+
+		// then
+		assertTrue(queue.containsAll(List.of("foo", "bar")));
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/queue/builder/BlockingQueueItemReaderBuilderTests.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2024 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.batch.item.queue.builder;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.batch.item.queue.BlockingQueueItemReader;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+/**
+ * Test class for {@link BlockingQueueItemReaderBuilder}.
+ *
+ * @author Mahmoud Ben Hassine
+ */
+class BlockingQueueItemReaderBuilderTests {
+
+	@Test
+	void testMandatoryQueue() {
+		assertThrows(IllegalStateException.class, () -> new BlockingQueueItemReaderBuilder<String>().build());
+	}
+
+	@Test
+	void testBuildReader() {
+		// given
+		BlockingQueue<String> queue = new ArrayBlockingQueue<>(5);
+
+		// when
+		BlockingQueueItemReader<String> reader = new BlockingQueueItemReaderBuilder<String>().queue(queue).build();
+
+		// then
+		assertNotNull(reader);
+		assertEquals(queue, ReflectionTestUtils.getField(reader, "queue"));
+	}
+
+}