1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io.output;
18
19 import java.io.File;
20 import java.io.IOException;
21 import java.io.InputStream;
22 import java.io.OutputStream;
23 import java.nio.file.Files;
24 import java.nio.file.Path;
25 import java.util.Objects;
26 import java.util.function.Supplier;
27
28 import org.apache.commons.io.build.AbstractStreamBuilder;
29 import org.apache.commons.io.file.PathUtils;
30
31 /**
32 * 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
33 * threshold is reached, the data will not be written to disk at all.
34 * <p>
35 * To build an instance, use {@link Builder}.
36 * </p>
37 * <p>
38 * The caller is responsible for deleting the output file ({@link #getFile()}, {@link #getPath()}) created by a DeferredFileOutputStream when the caller only
39 * configured a prefix.
40 * </p>
41 * <p>
42 * The caller is responsible for deleting the output file passed to a constructor or builder through {@link Builder#setOutputFile(File)} or
43 * {@link Builder#setOutputFile(Path)}.
44 * </p>
45 * <p>
46 * 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
47 * 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).
48 * </p>
49 *
50 * @see Builder
51 */
52 public class DeferredFileOutputStream extends ThresholdingOutputStream {
53
54 // @formatter:off
55 /**
56 * Builds a new {@link DeferredFileOutputStream}.
57 * <p>
58 * For example:
59 * </p>
60 * <pre>{@code
61 * DeferredFileOutputStream s = DeferredFileOutputStream.builder()
62 * .setBufferSize(4096)
63 * .setDirectory(dir)
64 * .setOutputFile(outputFile)
65 * .setPrefix(prefix)
66 * .setSuffix(suffix)
67 * .setThreshold(threshold)
68 * .get();}
69 * </pre>
70 * <p>
71 * The only super's aspect used is buffer size.
72 * </p>
73 *
74 * @see #get()
75 * @since 2.12.0
76 */
77 // @formatter:on
78 public static class Builder extends AbstractStreamBuilder<DeferredFileOutputStream, Builder> {
79
80 private int threshold;
81 private Path outputFile;
82 private String prefix;
83 private String suffix;
84 private Path directory;
85
86 /**
87 * Constructs a new builder of {@link DeferredFileOutputStream}.
88 */
89 public Builder() {
90 setBufferSizeDefault(AbstractByteArrayOutputStream.DEFAULT_SIZE);
91 setBufferSize(AbstractByteArrayOutputStream.DEFAULT_SIZE);
92 }
93
94 /**
95 * Builds a new {@link DeferredFileOutputStream}.
96 * <p>
97 * This builder uses the following aspects:
98 * </p>
99 * <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 < 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.<br>
455 * Otherwise, the returned stream will be one that is created from the data that has been committed to disk.
456 *
457 * @return the current contents of this output stream.
458 * @throws IOException if this stream is not yet closed or an error occurs.
459 * @see org.apache.commons.io.output.ByteArrayOutputStream#toInputStream()
460 * @since 2.9.0
461 */
462 public InputStream toInputStream() throws IOException {
463 // we may only need to check if this is closed if we are working with a file
464 // but we should force the habit of closing whether we are working with
465 // a file or memory.
466 if (!closed) {
467 throw new IOException("Stream not closed");
468 }
469 if (isInMemory()) {
470 return memoryOutputStream.toInputStream();
471 }
472 return Files.newInputStream(outputPath);
473 }
474
475 /**
476 * Writes the data from this output stream to the specified output stream, after it has been closed.
477 *
478 * @param outputStream output stream to write to.
479 * @throws NullPointerException if the OutputStream is {@code null}.
480 * @throws IOException if this stream is not yet closed or an error occurs.
481 */
482 public void writeTo(final OutputStream outputStream) throws IOException {
483 // we may only need to check if this is closed if we are working with a file
484 // but we should force the habit of closing whether we are working with
485 // a file or memory.
486 if (!closed) {
487 throw new IOException("Stream not closed");
488 }
489 if (isInMemory()) {
490 memoryOutputStream.writeTo(outputStream);
491 } else {
492 Files.copy(outputPath, outputStream);
493 }
494 }
495 }