    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 *      https://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 * To build an instance, use {@link Builder}.
    036 * </p>
    037 * <p>
    038 * The caller is responsible for deleting the output file ({@link #getFile()}, {@link #getPath()}) created by a DeferredFileOutputStream when the caller only
    039 * configured a prefix.
    040 * </p>
    041 * <p>
    042 * The caller is responsible for deleting the output file passed to a constructor or builder through {@link Builder#setOutputFile(File)} or
    043 * {@link Builder#setOutputFile(Path)}.
    044 * </p>
    045 * <p>
    046 * 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
    047 * 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).
    048 * </p>
    049 *
    050 * @see Builder
    051 */
    052public class DeferredFileOutputStream extends ThresholdingOutputStream {
    053
    054    // @formatter:off
    055    /**
    056     * Builds a new {@link DeferredFileOutputStream}.
    057     * <p>
    058     * For example:
    059     * </p>
    060     * <pre>{@code
    061     * DeferredFileOutputStream s = DeferredFileOutputStream.builder()
    062     *   .setBufferSize(4096)
    063     *   .setDirectory(dir)
    064     *   .setOutputFile(outputFile)
    065     *   .setPrefix(prefix)
    066     *   .setSuffix(suffix)
    067     *   .setThreshold(threshold)
    068     *   .get();}
    069     * </pre>
    070     * <p>
    071     * The only super's aspect used is buffer size.
    072     * </p>
    073     *
    074     * @see #get()
    075     * @since 2.12.0
    076     */
    077    // @formatter:on
    078    public static class Builder extends AbstractStreamBuilder<DeferredFileOutputStream, Builder> {
    079
    080        private int threshold;
    081        private Path outputFile;
    082        private String prefix;
    083        private String suffix;
    084        private Path directory;
    085
    086        /**
    087         * Constructs a new builder of {@link DeferredFileOutputStream}.
    088         */
    089        public Builder() {
    090            setBufferSizeDefault(AbstractByteArrayOutputStream.DEFAULT_SIZE);
    091            setBufferSize(AbstractByteArrayOutputStream.DEFAULT_SIZE);
    092        }
    093
    094        /**
    095         * Builds a new {@link DeferredFileOutputStream}.
    096         * <p>
    097         * This builder uses the following aspects:
    098         * </p>
    099         * <ul>
    100         * <li>{@link #getBufferSize()}</li>
    101         * <li>threshold</li>
    102         * <li>outputFile</li>
    103         * <li>prefix</li>
    104         * <li>suffix</li>
    105         * <li>directory</li>
    106         * </ul>
    107         *
    108         * @return a new instance.
    109         * @see #getUnchecked()
    110         */
    111        @Override
    112        public DeferredFileOutputStream get() {
    113            return new DeferredFileOutputStream(this);
    114        }
    115
    116        /**
    117         * Sets the temporary file directory.
    118         *
    119         * @param directory Temporary file directory.
    120         * @return {@code this} instance.
    121         */
    122        public Builder setDirectory(final File directory) {
    123            this.directory = toPath(directory, null);
    124            return this;
    125        }
    126
    127        /**
    128         * Sets the temporary file directory.
    129         *
    130         * @param directory Temporary file directory.
    131         * @return {@code this} instance.
    132         * @since 2.14.0
    133         */
    134        public Builder setDirectory(final Path directory) {
    135            this.directory = toPath(directory, null);
    136            return this;
    137        }
    138
    139        /**
    140         * Sets the file to which data is saved beyond the threshold.
    141         *
    142         * @param outputFile The file to which data is saved beyond the threshold.
    143         * @return {@code this} instance.
    144         */
    145        public Builder setOutputFile(final File outputFile) {
    146            this.outputFile = toPath(outputFile, null);
    147            return this;
    148        }
    149
    150        /**
    151         * Sets the file to which data is saved beyond the threshold.
    152         *
    153         * @param outputFile The file to which data is saved beyond the threshold.
    154         * @return {@code this} instance.
    155         * @since 2.14.0
    156         */
    157        public Builder setOutputFile(final Path outputFile) {
    158            this.outputFile = toPath(outputFile, null);
    159            return this;
    160        }
    161
    162        /**
    163         * Sets the prefix to use for the temporary file.
    164         *
    165         * @param prefix Prefix to use for the temporary file.
    166         * @return {@code this} instance.
    167         */
    168        public Builder setPrefix(final String prefix) {
    169            this.prefix = prefix;
    170            return this;
    171        }
    172
    173        /**
    174         * Sets the suffix to use for the temporary file.
    175         *
    176         * @param suffix Suffix to use for the temporary file.
    177         * @return {@code this} instance.
    178         */
    179        public Builder setSuffix(final String suffix) {
    180            this.suffix = suffix;
    181            return this;
    182        }
    183
    184        /**
    185         * Sets the number of bytes at which to trigger an event.
    186         *
    187         * @param threshold The number of bytes at which to trigger an event.
    188         * @return {@code this} instance.
    189         */
    190        public Builder setThreshold(final int threshold) {
    191            this.threshold = threshold;
    192            return this;
    193        }
    194
    195    }
    196
    197    /**
    198     * Constructs a new {@link Builder}.
    199     *
    200     * @return a new {@link Builder}.
    201     * @since 2.12.0
    202     */
    203    public static Builder builder() {
    204        return new Builder();
    205    }
    206
    207    private static int checkBufferSize(final int initialBufferSize) {
    208        if (initialBufferSize < 0) {
    209            throw new IllegalArgumentException("Initial buffer size must be at least 0.");
    210        }
    211        return initialBufferSize;
    212    }
    213
    214    private static Path toPath(final File file, final Supplier<Path> defaultPathSupplier) {
    215        return file != null ? file.toPath() : defaultPathSupplier == null ? null : defaultPathSupplier.get();
    216    }
    217
    218    private static Path toPath(final Path file, final Supplier<Path> defaultPathSupplier) {
    219        return file != null ? file : defaultPathSupplier == null ? null : defaultPathSupplier.get();
    220    }
    221
    222    /**
    223     * The output stream to which data will be written prior to the threshold being reached.
    224     */
    225    private ByteArrayOutputStream memoryOutputStream;
    226
    227    /**
    228     * The output stream to which data will be written at any given time. This will always be one of {@code memoryOutputStream} or {@code diskOutputStream}.
    229     */
    230    private OutputStream currentOutputStream;
    231
    232    /**
    233     * The file to which output will be directed if the threshold is exceeded.
    234     */
    235    private Path outputPath;
    236
    237    /**
    238     * The temporary file prefix.
    239     */
    240    private final String prefix;
    241
    242    /**
    243     * The temporary file suffix.
    244     */
    245    private final String suffix;
    246
    247    /**
    248     * The directory to use for temporary files.
    249     */
    250    private final Path directory;
    251
    252    /**
    253     * True when close() has been called successfully.
    254     */
    255    private boolean closed;
    256
    257    /**
    258     * 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.
    259     *
    260     * @param builder         The construction data source.
    261     */
    262    private DeferredFileOutputStream(final Builder builder) {
    263        super(builder.threshold);
    264        this.outputPath = toPath(builder.outputFile, null);
    265        this.prefix = builder.prefix;
    266        this.suffix = builder.suffix;
    267        this.directory = toPath(builder.directory, PathUtils::getTempDirectory);
    268        this.memoryOutputStream = new ByteArrayOutputStream(checkBufferSize(builder.getBufferSize()));
    269        this.currentOutputStream = memoryOutputStream;
    270    }
    271
    272    /**
    273     * 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
    274     * buffer size will default to {@value AbstractByteArrayOutputStream#DEFAULT_SIZE} bytes which is ByteArrayOutputStream's default buffer size.
    275     *
    276     * @param threshold  The number of bytes at which to trigger an event.
    277     * @param outputFile The file to which data is saved beyond the threshold.
    278     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    279     */
    280    @Deprecated
    281    public DeferredFileOutputStream(final int threshold, final File outputFile) {
    282        this(threshold, outputFile, null, null, null, AbstractByteArrayOutputStream.DEFAULT_SIZE);
    283    }
    284
    285    /**
    286     * 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.
    287     *
    288     * @param threshold         The number of bytes at which to trigger an event.
    289     * @param outputFile        The file to which data is saved beyond the threshold.
    290     * @param prefix            Prefix to use for the temporary file.
    291     * @param suffix            Suffix to use for the temporary file.
    292     * @param directory         Temporary file directory.
    293     * @param initialBufferSize The initial size of the in memory buffer.
    294     * @throws IllegalArgumentException if initialBufferSize &lt; 0.
    295     */
    296    private DeferredFileOutputStream(final int threshold, final File outputFile, final String prefix, final String suffix, final File directory,
    297            final int initialBufferSize) {
    298        super(threshold);
    299        this.outputPath = toPath(outputFile, null);
    300        this.prefix = prefix;
    301        this.suffix = suffix;
    302        this.directory = toPath(directory, PathUtils::getTempDirectory);
    303        this.memoryOutputStream = new ByteArrayOutputStream(checkBufferSize(initialBufferSize));
    304        this.currentOutputStream = memoryOutputStream;
    305    }
    306
    307    /**
    308     * Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.
    309     *
    310     * @param threshold         The number of bytes at which to trigger an event.
    311     * @param initialBufferSize The initial size of the in memory buffer.
    312     * @param outputFile        The file to which data is saved beyond the threshold.
    313     * @since 2.5
    314     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    315     */
    316    @Deprecated
    317    public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final File outputFile) {
    318        this(threshold, outputFile, null, null, null, initialBufferSize);
    319    }
    320
    321    /**
    322     * 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.
    323     *
    324     * @param threshold         The number of bytes at which to trigger an event.
    325     * @param initialBufferSize The initial size of the in memory buffer.
    326     * @param prefix            Prefix to use for the temporary file.
    327     * @param suffix            Suffix to use for the temporary file.
    328     * @param directory         Temporary file directory.
    329     * @since 2.5
    330     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    331     */
    332    @Deprecated
    333    public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final String prefix, final String suffix, final File directory) {
    334        this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, initialBufferSize);
    335    }
    336
    337    /**
    338     * 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
    339     * initial buffer size will default to 32 bytes which is ByteArrayOutputStream's default buffer size.
    340     *
    341     * @param threshold The number of bytes at which to trigger an event.
    342     * @param prefix    Prefix to use for the temporary file.
    343     * @param suffix    Suffix to use for the temporary file.
    344     * @param directory Temporary file directory.
    345     * @since 1.4
    346     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    347     */
    348    @Deprecated
    349    public DeferredFileOutputStream(final int threshold, final String prefix, final String suffix, final File directory) {
    350        this(threshold, null, Objects.requireNonNull(prefix, "prefix"), suffix, directory, AbstractByteArrayOutputStream.DEFAULT_SIZE);
    351    }
    352
    353    /**
    354     * Closes underlying output stream, and mark this as closed
    355     *
    356     * @throws IOException if an error occurs.
    357     */
    358    @Override
    359    public void close() throws IOException {
    360        super.close();
    361        closed = true;
    362    }
    363
    364    /**
    365     * 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
    366     * method returns {@code null}.
    367     *
    368     * @return The data for this output stream, or {@code null} if no such data is available.
    369     */
    370    public byte[] getData() {
    371        return memoryOutputStream != null ? memoryOutputStream.toByteArray() : null;
    372    }
    373
    374    /**
    375     * Gets either the output File specified in the constructor or the temporary File created or null.
    376     * <p>
    377     * If the constructor specifying the File is used then it returns that same output File, even when threshold has not been reached.
    378     * </p>
    379     * <p>
    380     * If constructor specifying a temporary File prefix/suffix is used then the temporary File created once the threshold is reached is returned if the
    381     * threshold was not reached then {@code null} is returned.
    382     * </p>
    383     *
    384     * @return The File for this output stream, or {@code null} if no such File exists.
    385     */
    386    public File getFile() {
    387        return outputPath != null ? outputPath.toFile() : null;
    388    }
    389
    390    /**
    391     * Gets either the output Path specified in the constructor or the temporary Path created or null.
    392     * <p>
    393     * If the constructor specifying the file is used then it returns that same output Path, even when threshold has not been reached.
    394     * </p>
    395     * <p>
    396     * If constructor specifying a temporary Path prefix/suffix is used then the temporary Path created once the threshold is reached is returned if the
    397     * threshold was not reached then {@code null} is returned.
    398     * </p>
    399     *
    400     * @return The Path for this output stream, or {@code null} if no such Path exists.
    401     * @since 2.14.0
    402     */
    403    public Path getPath() {
    404        return outputPath;
    405    }
    406
    407    /**
    408     * Gets the current output stream. This may be memory based or disk based, depending on the current state with respect to the threshold.
    409     *
    410     * @return The underlying output stream.
    411     * @throws IOException if an error occurs.
    412     * @deprecated Use {@link #getOutputStream()}.
    413     */
    414    @Deprecated
    415    @Override
    416    protected OutputStream getStream() throws IOException {
    417        return currentOutputStream;
    418    }
    419
    420    /**
    421     * Tests whether or not the data for this output stream has been retained in memory.
    422     *
    423     * @return {@code true} if the data is available in memory; {@code false} otherwise.
    424     */
    425    public boolean isInMemory() {
    426        return !isThresholdExceeded();
    427    }
    428
    429    /**
    430     * 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
    431     * is being written to keep in memory, so we elect to switch to disk-based storage.
    432     *
    433     * @throws IOException if an error occurs.
    434     */
    435    @Override
    436    protected void thresholdReached() throws IOException {
    437        if (prefix != null) {
    438            outputPath = Files.createTempFile(directory, prefix, suffix);
    439        }
    440        PathUtils.createParentDirectories(outputPath, null, PathUtils.EMPTY_FILE_ATTRIBUTE_ARRAY);
    441        final OutputStream fos = Files.newOutputStream(outputPath);
    442        try {
    443            memoryOutputStream.writeTo(fos);
    444        } catch (final IOException e) {
    445            fos.close();
    446            throw e;
    447        }
    448        currentOutputStream = fos;
    449        memoryOutputStream = null;
    450    }
    451
    452    /**
    453     * 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
    454     * stream is backed by buffers of {@code this} stream, avoiding memory allocation and copy, thus saving space and time.
    455     * <p>
    456     * Otherwise, the returned stream will be one that is created from the data that has been committed to disk.
    457     * </p>
    458     *
    459     * @return the current contents of this output stream.
    460     * @throws IOException if this stream is not yet closed or an error occurs.
    461     * @see org.apache.commons.io.output.ByteArrayOutputStream#toInputStream()
    462     * @since 2.9.0
    463     */
    464    public InputStream toInputStream() throws IOException {
    465        // we may only need to check if this is closed if we are working with a file
    466        // but we should force the habit of closing whether we are working with
    467        // a file or memory.
    468        if (!closed) {
    469            throw new IOException("Stream not closed");
    470        }
    471        if (isInMemory()) {
    472            return memoryOutputStream.toInputStream();
    473        }
    474        return Files.newInputStream(outputPath);
    475    }
    476
    477    /**
    478     * Writes the data from this output stream to the specified output stream, after it has been closed.
    479     *
    480     * @param outputStream output stream to write to.
    481     * @throws NullPointerException if the OutputStream is {@code null}.
    482     * @throws IOException          if this stream is not yet closed or an error occurs.
    483     */
    484    public void writeTo(final OutputStream outputStream) throws IOException {
    485        // we may only need to check if this is closed if we are working with a file
    486        // but we should force the habit of closing whether we are working with
    487        // a file or memory.
    488        if (!closed) {
    489            throw new IOException("Stream not closed");
    490        }
    491        if (isInMemory()) {
    492            memoryOutputStream.writeTo(outputStream);
    493        } else {
    494            Files.copy(outputPath, outputStream);
    495        }
    496    }
    497}