    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.io.output;
    018
    019import java.io.File;
    020import java.io.IOException;
    021import java.io.InputStream;
    022import java.io.OutputStream;
    023import java.nio.file.Files;
    024import java.nio.file.Path;
    025import java.util.Objects;
    026import java.util.function.Supplier;
    027
    028import org.apache.commons.io.build.AbstractStreamBuilder;
    029import org.apache.commons.io.file.PathUtils;
    030
    031/**
    032 * 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
    033 * threshold is reached, the data will not be written to disk at all.
    034 * <p>
    035 * 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
    036 * 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).
    037 * </p>
    038 */
    039public class DeferredFileOutputStream extends ThresholdingOutputStream {
    040
    041    /**
    042     * Builds a new {@link DeferredFileOutputStream} instance.
    043     * <p>
    044     * For example:
    045     * </p>
    046     * <pre>{@code
    047     * DeferredFileOutputStream s = DeferredFileOutputStream.builder()
    048     *   .setPath(path)
    049     *   .setBufferSize(4096)
    050     *   .setDirectory(dir)
    051     *   .setOutputFile(outputFile)
    052     *   .setPrefix(prefix)
    053     *   .setSuffix(suffix)
    054     *   .setThreshold(threshold)
    055     *   .get()}
    056     * </pre>
    057     * @since 2.12.0
    058     */
    059    public static class Builder extends AbstractStreamBuilder<DeferredFileOutputStream, Builder> {
    060
    061        private int threshold;
    062        private File outputFile;
    063        private String prefix;
    064        private String suffix;
    065        private File directory;
    066
    067        public Builder() {
    068            setBufferSizeDefault(AbstractByteArrayOutputStream.DEFAULT_SIZE);
    069            setBufferSize(AbstractByteArrayOutputStream.DEFAULT_SIZE);
    070        }
    071
    072        @Override
    073        public DeferredFileOutputStream get() {
    074            return new DeferredFileOutputStream(threshold, outputFile, prefix, suffix, directory, getBufferSize());
    075        }
    076
    077        /**
    078         * Sets the temporary file directory.
    079         *
    080         * @param directory Temporary file directory.
    081         * @return this
    082         */
    083        public Builder setDirectory(final File directory) {
    084            this.directory = directory;
    085            return this;
    086        }
    087
    088        /**
    089         * Sets the file to which data is saved beyond the threshold.
    090         *
    091         * @param outputFile The file to which data is saved beyond the threshold.
    092         * @return this
    093         */
    094        public Builder setOutputFile(final File outputFile) {
    095            this.outputFile = outputFile;
    096            return this;
    097        }
    098
    099        /**
    100         * Sets the prefix to use for the temporary file.
    101         *
    102         * @param prefix Prefix to use for the temporary file.
    103         * @return this
    104         */
    105        public Builder setPrefix(final String prefix) {
    106            this.prefix = prefix;
    107            return this;
    108        }
    109
    110        /**
    111         * Sets the suffix to use for the temporary file.
    112         *
    113         * @param suffix Suffix to use for the temporary file.
    114         * @return this
    115         */
    116        public Builder setSuffix(final String suffix) {
    117            this.suffix = suffix;
    118            return this;
    119        }
    120
    121        /**
    122         * Sets the number of bytes at which to trigger an event.
    123         *
    124         * @param threshold The number of bytes at which to trigger an event.
    125         * @return this
    126         */
    127        public Builder setThreshold(final int threshold) {
    128            this.threshold = threshold;
    129            return this;
    130        }
    131
    132    }
    133
    134    /**
    135     * Constructs a new {@link Builder}.
    136     *
    137     * @return a new {@link Builder}.
    138     * @since 2.12.0
    139     */
    140    public static Builder builder() {
    141        return new Builder();
    142    }
    143
    144    private static int checkBufferSize(final int initialBufferSize) {
    145        if (initialBufferSize < 0) {
    146            throw new IllegalArgumentException("Initial buffer size must be at least 0.");
    147        }
    148        return initialBufferSize;
    149    }
    150
    151    /**
    152     * The output stream to which data will be written prior to the threshold being reached.
    153     */
    154    private ByteArrayOutputStream memoryOutputStream;
    155
    156    /**
    157     * The output stream to which data will be written at any given time. This will always be one of {@code memoryOutputStream} or {@code diskOutputStream}.
    158     */
    159    private OutputStream currentOutputStream;
    160
    161    /**
    162     * The file to which output will be directed if the threshold is exceeded.
    163     */
    164    private Path outputPath;
    165
    166    /**
    167     * The temporary file prefix.
    168     */
    169    private final String prefix;
    170
    171    /**
    172     * The temporary file suffix.
    173     */
    174    private final String suffix;
    175
    176    /**
    177     * The directory to use for temporary files.
    178     */
    179    private final Path directory;
    180
    181    /**
    182     * True when close() has been called successfully.
    183     */
    184    private boolean closed;
    185
    186    /**
    187     * 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
    188     * buffer size will default to {@value AbstractByteArrayOutputStream#DEFAULT_SIZE} bytes which is ByteArrayOutputStream's default buffer size.
    189     *
    190     * @param threshold  The number of bytes at which to trigger an event.
    191     * @param outputFile The file to which data is saved beyond the threshold.
    192     * @deprecated Use {@link #builder()}
    193     */
    194    @Deprecated
    195    public DeferredFileOutputStream(final int threshold, final File outputFile) {
    196        this(threshold, outputFile, null, null, null, AbstractByteArrayOutputStream.DEFAULT_SIZE);
    197    }
    198
    199    /**
    200     * 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.
    201     *
    202     * @param threshold         The number of bytes at which to trigger an event.
    203     * @param outputFile        The file to which data is saved beyond the threshold.
    204     * @param prefix            Prefix to use for the temporary file.
    205     * @param suffix            Suffix to use for the temporary file.
    206     * @param directory         Temporary file directory.
    207     * @param initialBufferSize The initial size of the in memory buffer.
    208     */
    209    private DeferredFileOutputStream(final int threshold, final File outputFile, final String prefix, final String suffix, final File directory,
    210            final int initialBufferSize) {
    211        super(threshold);
    212        this.outputPath = toPath(outputFile, null);
    213        this.prefix = prefix;
    214        this.suffix = suffix;
    215        this.directory = toPath(directory, PathUtils::getTempDirectory);
    216        memoryOutputStream = new ByteArrayOutputStream(checkBufferSize(initialBufferSize));
    217        currentOutputStream = memoryOutputStream;
    218    }
    219
    220    /**
    221     * Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.
    222     *
    223     * @param threshold         The number of bytes at which to trigger an event.
    224     * @param initialBufferSize The initial size of the in memory buffer.
    225     * @param outputFile        The file to which data is saved beyond the threshold.
    226     * @since 2.5
    227     * @deprecated Use {@link #builder()}
    228     */
    229    @Deprecated
    230    public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final File outputFile) {
    231        this(threshold, outputFile, null, null, null, initialBufferSize);
    232    }
    233
    234    /**
    235     * 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.
    236     *
    237     * @param threshold         The number of bytes at which to trigger an event.
    238     * @param initialBufferSize The initial size of the in memory buffer.
    239     * @param prefix            Prefix to use for the temporary file.
    240     * @param suffix            Suffix to use for the temporary file.
    241     * @param directory         Temporary file directory.
    242     * @since 2.5
    243     * @deprecated Use {@link #builder()}
    244     */
    245    @Deprecated
    246    public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final String prefix, final String suffix, final File directory) {
    247        this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, initialBufferSize);
    248    }
    249
    250    /**
    251     * 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
    252     * initial buffer size will default to 32 bytes which is ByteArrayOutputStream's default buffer size.
    253     *
    254     * @param threshold The number of bytes at which to trigger an event.
    255     * @param prefix    Prefix to use for the temporary file.
    256     * @param suffix    Suffix to use for the temporary file.
    257     * @param directory Temporary file directory.
    258     * @since 1.4
    259     * @deprecated Use {@link #builder()}
    260     */
    261    @Deprecated
    262    public DeferredFileOutputStream(final int threshold, final String prefix, final String suffix, final File directory) {
    263        this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, AbstractByteArrayOutputStream.DEFAULT_SIZE);
    264    }
    265
    266    /**
    267     * Closes underlying output stream, and mark this as closed
    268     *
    269     * @throws IOException if an error occurs.
    270     */
    271    @Override
    272    public void close() throws IOException {
    273        super.close();
    274        closed = true;
    275    }
    276
    277    /**
    278     * 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
    279     * method returns {@code null}.
    280     *
    281     * @return The data for this output stream, or {@code null} if no such data is available.
    282     */
    283    public byte[] getData() {
    284        return memoryOutputStream != null ? memoryOutputStream.toByteArray() : null;
    285    }
    286
    287    /**
    288     * Gets either the output file specified in the constructor or the temporary file created or null.
    289     * <p>
    290     * If the constructor specifying the file is used then it returns that same output file, even when threshold has not been reached.
    291     * <p>
    292     * If constructor specifying a temporary file prefix/suffix is used then the temporary file created once the threshold is reached is returned If the
    293     * threshold was not reached then {@code null} is returned.
    294     *
    295     * @return The file for this output stream, or {@code null} if no such file exists.
    296     */
    297    public File getFile() {
    298        return outputPath != null ? outputPath.toFile() : null;
    299    }
    300
    301    /**
    302     * Gets the current output stream. This may be memory based or disk based, depending on the current state with respect to the threshold.
    303     *
    304     * @return The underlying output stream.
    305     *
    306     * @throws IOException if an error occurs.
    307     */
    308    @Override
    309    protected OutputStream getStream() throws IOException {
    310        return currentOutputStream;
    311    }
    312
    313    /**
    314     * Tests whether or not the data for this output stream has been retained in memory.
    315     *
    316     * @return {@code true} if the data is available in memory; {@code false} otherwise.
    317     */
    318    public boolean isInMemory() {
    319        return !isThresholdExceeded();
    320    }
    321
    322    /**
    323     * 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
    324     * is being written to keep in memory, so we elect to switch to disk-based storage.
    325     *
    326     * @throws IOException if an error occurs.
    327     */
    328    @Override
    329    protected void thresholdReached() throws IOException {
    330        if (prefix != null) {
    331            outputPath = Files.createTempFile(directory, prefix, suffix);
    332        }
    333        PathUtils.createParentDirectories(outputPath);
    334        final OutputStream fos = Files.newOutputStream(outputPath);
    335        try {
    336            memoryOutputStream.writeTo(fos);
    337        } catch (final IOException e) {
    338            fos.close();
    339            throw e;
    340        }
    341        currentOutputStream = fos;
    342        memoryOutputStream = null;
    343    }
    344
    345    /**
    346     * 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
    347     * stream is backed by buffers of {@code this} stream, avoiding memory allocation and copy, thus saving space and time.<br>
    348     * Otherwise, the returned stream will be one that is created from the data that has been committed to disk.
    349     *
    350     * @return the current contents of this output stream.
    351     * @throws IOException if this stream is not yet closed or an error occurs.
    352     * @see org.apache.commons.io.output.ByteArrayOutputStream#toInputStream()
    353     *
    354     * @since 2.9.0
    355     */
    356    public InputStream toInputStream() throws IOException {
    357        // we may only need to check if this is closed if we are working with a file
    358        // but we should force the habit of closing whether we are working with
    359        // a file or memory.
    360        if (!closed) {
    361            throw new IOException("Stream not closed");
    362        }
    363
    364        if (isInMemory()) {
    365            return memoryOutputStream.toInputStream();
    366        }
    367        return Files.newInputStream(outputPath);
    368    }
    369
    370    private Path toPath(final File file, final Supplier<Path> defaultPathSupplier) {
    371        return file != null ? file.toPath() : defaultPathSupplier == null ? null : defaultPathSupplier.get();
    372    }
    373
    374    /**
    375     * Writes the data from this output stream to the specified output stream, after it has been closed.
    376     *
    377     * @param outputStream output stream to write to.
    378     * @throws NullPointerException if the OutputStream is {@code null}.
    379     * @throws IOException          if this stream is not yet closed or an error occurs.
    380     */
    381    public void writeTo(final OutputStream outputStream) throws IOException {
    382        // we may only need to check if this is closed if we are working with a file
    383        // but we should force the habit of closing whether we are working with
    384        // a file or memory.
    385        if (!closed) {
    386            throw new IOException("Stream not closed");
    387        }
    388
    389        if (isInMemory()) {
    390            memoryOutputStream.writeTo(outputStream);
    391        } else {
    392            Files.copy(outputPath, outputStream);
    393        }
    394    }
    395}