DeferredFileOutputStream.java
/*
* 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.output;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Objects;
import java.util.function.Supplier;
import org.apache.commons.io.build.AbstractStreamBuilder;
import org.apache.commons.io.file.PathUtils;
/**
* An output stream which will retain data in memory until a specified threshold is reached, and only then commit it to disk. If the stream is closed before the
* threshold is reached, the data will not be written to disk at all.
* <p>
* To build an instance, use {@link Builder}.
* </p>
* <p>
* The caller is responsible for deleting the output file ({@link #getFile()}, {@link #getPath()}) created by a DeferredFileOutputStream when the caller only
* configured a prefix.
* </p>
* <p>
* The caller is responsible for deleting the output file passed to a constructor or builder through {@link Builder#setOutputFile(File)} or
* {@link Builder#setOutputFile(Path)}.
* </p>
* <p>
* This class originated in FileUpload processing. In this use case, you do not know in advance the size of the file being uploaded. If the file is small you
* want to store it in memory (for speed), but if the file is large you want to store it to file (to avoid memory issues).
* </p>
*
* @see Builder
*/
public class DeferredFileOutputStream extends ThresholdingOutputStream {
// @formatter:off
/**
* Builds a new {@link DeferredFileOutputStream}.
* <p>
* For example:
* </p>
* <pre>{@code
* DeferredFileOutputStream s = DeferredFileOutputStream.builder()
* .setBufferSize(4096)
* .setDirectory(dir)
* .setOutputFile(outputFile)
* .setPrefix(prefix)
* .setSuffix(suffix)
* .setThreshold(threshold)
* .get();}
* </pre>
* <p>
* The only super's aspect used us buffer size.
* </p>
*
* @see #get()
* @since 2.12.0
*/
// @formatter:on
public static class Builder extends AbstractStreamBuilder<DeferredFileOutputStream, Builder> {
private int threshold;
private Path outputFile;
private String prefix;
private String suffix;
private Path directory;
/**
* Constructs a new builder.
*/
public Builder() {
setBufferSizeDefault(AbstractByteArrayOutputStream.DEFAULT_SIZE);
setBufferSize(AbstractByteArrayOutputStream.DEFAULT_SIZE);
}
/**
* Builds a new {@link DeferredFileOutputStream}.
* <p>
* This builder use the following aspects:
* </p>
* <ul>
* <li>{@link #getBufferSize()}</li>
* <li>threshold</li>
* <li>outputFile</li>
* <li>prefix</li>
* <li>suffix</li>
* <li>directory</li>
* </ul>
*
* @return a new instance.
*/
@Override
public DeferredFileOutputStream get() {
return new DeferredFileOutputStream(threshold, outputFile, prefix, suffix, directory, getBufferSize());
}
/**
* Sets the temporary file directory.
*
* @param directory Temporary file directory.
* @return this
*/
public Builder setDirectory(final File directory) {
this.directory = toPath(directory, null);
return this;
}
/**
* Sets the temporary file directory.
*
* @param directory Temporary file directory.
* @return this
* @since 2.14.0
*/
public Builder setDirectory(final Path directory) {
this.directory = toPath(directory, null);
return this;
}
/**
* Sets the file to which data is saved beyond the threshold.
*
* @param outputFile The file to which data is saved beyond the threshold.
* @return this
*/
public Builder setOutputFile(final File outputFile) {
this.outputFile = toPath(outputFile, null);
return this;
}
/**
* Sets the file to which data is saved beyond the threshold.
*
* @param outputFile The file to which data is saved beyond the threshold.
* @return this
* @since 2.14.0
*/
public Builder setOutputFile(final Path outputFile) {
this.outputFile = toPath(outputFile, null);
return this;
}
/**
* Sets the prefix to use for the temporary file.
*
* @param prefix Prefix to use for the temporary file.
* @return this
*/
public Builder setPrefix(final String prefix) {
this.prefix = prefix;
return this;
}
/**
* Sets the suffix to use for the temporary file.
*
* @param suffix Suffix to use for the temporary file.
* @return this
*/
public Builder setSuffix(final String suffix) {
this.suffix = suffix;
return this;
}
/**
* Sets the number of bytes at which to trigger an event.
*
* @param threshold The number of bytes at which to trigger an event.
* @return this
*/
public Builder setThreshold(final int threshold) {
this.threshold = threshold;
return this;
}
}
/**
* Constructs a new {@link Builder}.
*
* @return a new {@link Builder}.
* @since 2.12.0
*/
public static Builder builder() {
return new Builder();
}
private static int checkBufferSize(final int initialBufferSize) {
if (initialBufferSize < 0) {
throw new IllegalArgumentException("Initial buffer size must be at least 0.");
}
return initialBufferSize;
}
private static Path toPath(final File file, final Supplier<Path> defaultPathSupplier) {
return file != null ? file.toPath() : defaultPathSupplier == null ? null : defaultPathSupplier.get();
}
private static Path toPath(final Path file, final Supplier<Path> defaultPathSupplier) {
return file != null ? file : defaultPathSupplier == null ? null : defaultPathSupplier.get();
}
/**
* The output stream to which data will be written prior to the threshold being reached.
*/
private ByteArrayOutputStream memoryOutputStream;
/**
* The output stream to which data will be written at any given time. This will always be one of {@code memoryOutputStream} or {@code diskOutputStream}.
*/
private OutputStream currentOutputStream;
/**
* The file to which output will be directed if the threshold is exceeded.
*/
private Path outputPath;
/**
* The temporary file prefix.
*/
private final String prefix;
/**
* The temporary file suffix.
*/
private final String suffix;
/**
* The directory to use for temporary files.
*/
private final Path directory;
/**
* True when close() has been called successfully.
*/
private boolean closed;
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point. The initial
* buffer size will default to {@value AbstractByteArrayOutputStream#DEFAULT_SIZE} bytes which is ByteArrayOutputStream's default buffer size.
*
* @param threshold The number of bytes at which to trigger an event.
* @param outputFile The file to which data is saved beyond the threshold.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public DeferredFileOutputStream(final int threshold, final File outputFile) {
this(threshold, outputFile, null, null, null, AbstractByteArrayOutputStream.DEFAULT_SIZE);
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data either to a file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param outputFile The file to which data is saved beyond the threshold.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
* @param initialBufferSize The initial size of the in memory buffer.
* @throws IllegalArgumentException if initialBufferSize < 0.
*/
private DeferredFileOutputStream(final int threshold, final File outputFile, final String prefix, final String suffix, final File directory,
final int initialBufferSize) {
super(threshold);
this.outputPath = toPath(outputFile, null);
this.prefix = prefix;
this.suffix = suffix;
this.directory = toPath(directory, PathUtils::getTempDirectory);
this.memoryOutputStream = new ByteArrayOutputStream(checkBufferSize(initialBufferSize));
this.currentOutputStream = memoryOutputStream;
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param initialBufferSize The initial size of the in memory buffer.
* @param outputFile The file to which data is saved beyond the threshold.
* @since 2.5
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final File outputFile) {
this(threshold, outputFile, null, null, null, initialBufferSize);
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param initialBufferSize The initial size of the in memory buffer.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
* @since 2.5
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final String prefix, final String suffix, final File directory) {
this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, initialBufferSize);
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data either to a file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param outputFile The file to which data is saved beyond the threshold.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
* @param initialBufferSize The initial size of the in memory buffer.
* @throws IllegalArgumentException if initialBufferSize < 0.
*/
private DeferredFileOutputStream(final int threshold, final Path outputFile, final String prefix, final String suffix, final Path directory,
final int initialBufferSize) {
super(threshold);
this.outputPath = toPath(outputFile, null);
this.prefix = prefix;
this.suffix = suffix;
this.directory = toPath(directory, PathUtils::getTempDirectory);
this.memoryOutputStream = new ByteArrayOutputStream(checkBufferSize(initialBufferSize));
this.currentOutputStream = memoryOutputStream;
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point. The
* initial buffer size will default to 32 bytes which is ByteArrayOutputStream's default buffer size.
*
* @param threshold The number of bytes at which to trigger an event.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
* @since 1.4
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
*/
@Deprecated
public DeferredFileOutputStream(final int threshold, final String prefix, final String suffix, final File directory) {
this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, AbstractByteArrayOutputStream.DEFAULT_SIZE);
}
/**
* Closes underlying output stream, and mark this as closed
*
* @throws IOException if an error occurs.
*/
@Override
public void close() throws IOException {
super.close();
closed = true;
}
/**
* Gets the data for this output stream as an array of bytes, assuming that the data has been retained in memory. If the data was written to disk, this
* method returns {@code null}.
*
* @return The data for this output stream, or {@code null} if no such data is available.
*/
public byte[] getData() {
return memoryOutputStream != null ? memoryOutputStream.toByteArray() : null;
}
/**
* Gets either the output File specified in the constructor or the temporary File created or null.
* <p>
* If the constructor specifying the File is used then it returns that same output File, even when threshold has not been reached.
* </p>
* <p>
* If constructor specifying a temporary File prefix/suffix is used then the temporary File created once the threshold is reached is returned if the
* threshold was not reached then {@code null} is returned.
* </p>
*
* @return The File for this output stream, or {@code null} if no such File exists.
*/
public File getFile() {
return outputPath != null ? outputPath.toFile() : null;
}
/**
* Gets either the output Path specified in the constructor or the temporary Path created or null.
* <p>
* If the constructor specifying the file is used then it returns that same output Path, even when threshold has not been reached.
* </p>
* <p>
* If constructor specifying a temporary Path prefix/suffix is used then the temporary Path created once the threshold is reached is returned if the
* threshold was not reached then {@code null} is returned.
* </p>
*
* @return The Path for this output stream, or {@code null} if no such Path exists.
* @since 2.14.0
*/
public Path getPath() {
return outputPath;
}
/**
* Gets the current output stream. This may be memory based or disk based, depending on the current state with respect to the threshold.
*
* @return The underlying output stream.
* @throws IOException if an error occurs.
*/
@Override
protected OutputStream getStream() throws IOException {
return currentOutputStream;
}
/**
* Tests whether or not the data for this output stream has been retained in memory.
*
* @return {@code true} if the data is available in memory; {@code false} otherwise.
*/
public boolean isInMemory() {
return !isThresholdExceeded();
}
/**
* Switches the underlying output stream from a memory based stream to one that is backed by disk. This is the point at which we realize that too much data
* is being written to keep in memory, so we elect to switch to disk-based storage.
*
* @throws IOException if an error occurs.
*/
@Override
protected void thresholdReached() throws IOException {
if (prefix != null) {
outputPath = Files.createTempFile(directory, prefix, suffix);
}
PathUtils.createParentDirectories(outputPath, null, PathUtils.EMPTY_FILE_ATTRIBUTE_ARRAY);
final OutputStream fos = Files.newOutputStream(outputPath);
try {
memoryOutputStream.writeTo(fos);
} catch (final IOException e) {
fos.close();
throw e;
}
currentOutputStream = fos;
memoryOutputStream = null;
}
/**
* Converts the current contents of this byte stream to an {@link InputStream}. If the data for this output stream has been retained in memory, the returned
* stream is backed by buffers of {@code this} stream, avoiding memory allocation and copy, thus saving space and time.<br>
* Otherwise, the returned stream will be one that is created from the data that has been committed to disk.
*
* @return the current contents of this output stream.
* @throws IOException if this stream is not yet closed or an error occurs.
* @see org.apache.commons.io.output.ByteArrayOutputStream#toInputStream()
*
* @since 2.9.0
*/
public InputStream toInputStream() throws IOException {
// we may only need to check if this is closed if we are working with a file
// but we should force the habit of closing whether we are working with
// a file or memory.
if (!closed) {
throw new IOException("Stream not closed");
}
if (isInMemory()) {
return memoryOutputStream.toInputStream();
}
return Files.newInputStream(outputPath);
}
/**
* Writes the data from this output stream to the specified output stream, after it has been closed.
*
* @param outputStream output stream to write to.
* @throws NullPointerException if the OutputStream is {@code null}.
* @throws IOException if this stream is not yet closed or an error occurs.
*/
public void writeTo(final OutputStream outputStream) throws IOException {
// we may only need to check if this is closed if we are working with a file
// but we should force the habit of closing whether we are working with
// a file or memory.
if (!closed) {
throw new IOException("Stream not closed");
}
if (isInMemory()) {
memoryOutputStream.writeTo(outputStream);
} else {
Files.copy(outputPath, outputStream);
}
}
}