garydgregory commented on a change in pull request #215: URL: https://github.com/apache/commons-io/pull/215#discussion_r646560785
########## File path: src/main/java/org/apache/commons/io/ByteBufferCleaner.java ########## @@ -0,0 +1,144 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io; + +import java.lang.reflect.Field; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.nio.ByteBuffer; + +/** + * Utility to manually clean a direct {@link ByteBuffer}. Without manual Review comment: Move this class to the input package and make it package private to reduce the public API surface, we can make it public later. ########## File path: src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java ########## @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io.input; + +import static org.apache.commons.io.IOUtils.EOF; + +import java.io.BufferedInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileChannel.MapMode; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.ByteBufferCleaner; + +/** + * An {@link InputStream} that utilizes memory mapped files to improve + * performance. A sliding window of the file is mapped to memory to avoid + * mapping the entire file to memory at one time. The size of the sliding buffer + * is user configurable. + * + * For most operating systems, mapping a file into memory is more expensive than + * reading or writing a few tens of kilobytes of data. From the standpoint of + * performance it is generally only worth mapping relatively large files into + * memory. Use of this class can provide approximately a 25% increase in + * throughput when reading large files. <br> + * Note: Use of this class does not necessarily obviate the need to use a + * {@link BufferedInputStream}. Depending on the use case, the use of buffering + * may still further improve performance. For example: + * + * <pre> + * new BufferedInputStream(new GzipInputStream(new MemoryMappedFileInputStream(path)))) + * </pre> + * + * will greatly outperform: + * + * <pre> + * new GzipInputStream(new MemoryMappedFileInputStream(path)) Review comment: This comparison does not make sense. You should compare using this class with a code fragment that does not use it. ########## File path: src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java ########## @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io.input; + +import static org.apache.commons.io.IOUtils.EOF; + +import java.io.BufferedInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileChannel.MapMode; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.ByteBufferCleaner; + +/** + * An {@link InputStream} that utilizes memory mapped files to improve + * performance. A sliding window of the file is mapped to memory to avoid + * mapping the entire file to memory at one time. The size of the sliding buffer + * is user configurable. + * + * For most operating systems, mapping a file into memory is more expensive than + * reading or writing a few tens of kilobytes of data. From the standpoint of + * performance it is generally only worth mapping relatively large files into + * memory. Use of this class can provide approximately a 25% increase in + * throughput when reading large files. <br> Review comment: I would not make any performance claims without backing it up with evidwnce like a test anyone can run on their combination of OS/JRE/file. IOW, provide a test where the user can specify the file size in a sys prop or command line for example. ########## File path: src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java ########## @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io.input; + +import static org.apache.commons.io.IOUtils.EOF; + +import java.io.BufferedInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileChannel.MapMode; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.ByteBufferCleaner; + +/** + * An {@link InputStream} that utilizes memory mapped files to improve + * performance. A sliding window of the file is mapped to memory to avoid + * mapping the entire file to memory at one time. The size of the sliding buffer + * is user configurable. + * + * For most operating systems, mapping a file into memory is more expensive than + * reading or writing a few tens of kilobytes of data. From the standpoint of + * performance it is generally only worth mapping relatively large files into + * memory. Use of this class can provide approximately a 25% increase in + * throughput when reading large files. <br> + * Note: Use of this class does not necessarily obviate the need to use a + * {@link BufferedInputStream}. Depending on the use case, the use of buffering + * may still further improve performance. For example: + * + * <pre> + * new BufferedInputStream(new GzipInputStream(new MemoryMappedFileInputStream(path)))) + * </pre> + * + * will greatly outperform: + * + * <pre> + * new GzipInputStream(new MemoryMappedFileInputStream(path)) + * </pre> + * + * @since 2.9.0 + */ Review comment: We are up to 2.10.0 now 😉 ########## File path: src/test/java/org/apache/commons/io/ByteBufferCleanerTest.java ########## @@ -0,0 +1,49 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io; + +import static org.junit.jupiter.api.Assertions.*; + +import java.nio.ByteBuffer; + +import org.apache.commons.lang3.RandomUtils; +import org.junit.jupiter.api.Test; + +class ByteBufferCleanerTest { Review comment: The style of this component is to make test classes and methods public. ########## File path: src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java ########## @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io.input; + +import static org.apache.commons.io.IOUtils.EOF; + +import java.io.BufferedInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileChannel.MapMode; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.ByteBufferCleaner; + +/** + * An {@link InputStream} that utilizes memory mapped files to improve + * performance. A sliding window of the file is mapped to memory to avoid + * mapping the entire file to memory at one time. The size of the sliding buffer + * is user configurable. + * + * For most operating systems, mapping a file into memory is more expensive than + * reading or writing a few tens of kilobytes of data. From the standpoint of + * performance it is generally only worth mapping relatively large files into + * memory. Use of this class can provide approximately a 25% increase in + * throughput when reading large files. <br> Review comment: Close all HTML tags. You might as well use a paragraph here. ########## File path: src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java ########## @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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.apache.commons.io.input; + +import static org.apache.commons.io.IOUtils.EOF; + +import java.io.BufferedInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.FileChannel.MapMode; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; + +import org.apache.commons.io.ByteBufferCleaner; + +/** + * An {@link InputStream} that utilizes memory mapped files to improve + * performance. A sliding window of the file is mapped to memory to avoid + * mapping the entire file to memory at one time. The size of the sliding buffer + * is user configurable. + * + * For most operating systems, mapping a file into memory is more expensive than + * reading or writing a few tens of kilobytes of data. From the standpoint of + * performance it is generally only worth mapping relatively large files into + * memory. Use of this class can provide approximately a 25% increase in + * throughput when reading large files. <br> + * Note: Use of this class does not necessarily obviate the need to use a + * {@link BufferedInputStream}. Depending on the use case, the use of buffering + * may still further improve performance. For example: + * + * <pre> + * new BufferedInputStream(new GzipInputStream(new MemoryMappedFileInputStream(path)))) + * </pre> + * + * will greatly outperform: + * + * <pre> + * new GzipInputStream(new MemoryMappedFileInputStream(path)) + * </pre> + * + * @since 2.9.0 + */ +public class MemoryMappedFileInputStream extends InputStream { + /** + * Default size of the sliding memory mapped buffer. We use 256K, equal to 65536 + * pages (given a 4K page size). Increasing the value beyond the default size + * will generally not provide any increase in throughput. + */ + private static final int DEFAULT_BUFFER_SIZE = 256 * 1024; + private static final ByteBuffer EMPTY_BUFFER = ByteBuffer.wrap(new byte[0]).asReadOnlyBuffer(); + private static final boolean IS_CLEANING_SUPPORTED = ByteBufferCleaner.isSupported(); + private final int bufferSize; + private final FileChannel channel; + private ByteBuffer buffer = EMPTY_BUFFER; + private boolean closed = false; + /** + * The starting position (within the file) of the next sliding buffer. + */ + private long nextBufferPosition = 0; + + public MemoryMappedFileInputStream(final Path file) throws IOException { + this(file, DEFAULT_BUFFER_SIZE); + } + + public MemoryMappedFileInputStream(final Path file, final int bufferSize) throws IOException { + this.bufferSize = bufferSize; + this.channel = FileChannel.open(file, StandardOpenOption.READ); + } + + @Override + public int read() throws IOException { + ensureOpen(); + if (!buffer.hasRemaining()) { + nextBuffer(); + if (!buffer.hasRemaining()) { + return EOF; + } + } + return Short.toUnsignedInt(buffer.get()); + } + + @Override + public int read(byte[] b, int off, int len) throws IOException { Review comment: Use final where you can. -- This is an automated message from the Apache Git Service. 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