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1   /*
2    * Copyright (C) 2008-2010, Google Inc.
3    * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
4    * and other copyright owners as documented in the project's IP log.
5    *
6    * This program and the accompanying materials are made available
7    * under the terms of the Eclipse Distribution License v1.0 which
8    * accompanies this distribution, is reproduced below, and is
9    * available at http://www.eclipse.org/org/documents/edl-v10.php
10   *
11   * All rights reserved.
12   *
13   * Redistribution and use in source and binary forms, with or
14   * without modification, are permitted provided that the following
15   * conditions are met:
16   *
17   * - Redistributions of source code must retain the above copyright
18   *   notice, this list of conditions and the following disclaimer.
19   *
20   * - Redistributions in binary form must reproduce the above
21   *   copyright notice, this list of conditions and the following
22   *   disclaimer in the documentation and/or other materials provided
23   *   with the distribution.
24   *
25   * - Neither the name of the Eclipse Foundation, Inc. nor the
26   *   names of its contributors may be used to endorse or promote
27   *   products derived from this software without specific prior
28   *   written permission.
29   *
30   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
31   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
32   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
35   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
36   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
38   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
39   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
41   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
42   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43   */
44  
45  package org.eclipse.jgit.storage.pack;
46  
47  import java.util.concurrent.Executor;
48  import java.util.zip.Deflater;
49  
50  import org.eclipse.jgit.internal.storage.file.PackIndexWriter;
51  import org.eclipse.jgit.lib.Config;
52  import org.eclipse.jgit.lib.Repository;
53  
54  /**
55   * Configuration used by a pack writer when constructing the stream.
56   *
57   * A configuration may be modified once created, but should not be modified
58   * while it is being used by a PackWriter. If a configuration is not modified it
59   * is safe to share the same configuration instance between multiple concurrent
60   * threads executing different PackWriters.
61   */
62  public class PackConfig {
63  	/**
64  	 * Default value of deltas reuse option: {@value}
65  	 *
66  	 * @see #setReuseDeltas(boolean)
67  	 */
68  	public static final boolean DEFAULT_REUSE_DELTAS = true;
69  
70  	/**
71  	 * Default value of objects reuse option: {@value}
72  	 *
73  	 * @see #setReuseObjects(boolean)
74  	 */
75  	public static final boolean DEFAULT_REUSE_OBJECTS = true;
76  
77  	/**
78  	 * Default value of keep old packs option: {@value}
79  	 * @see #setPreserveOldPacks(boolean)
80  	 * @since 4.7
81  	 */
82  	public static final boolean DEFAULT_PRESERVE_OLD_PACKS = false;
83  
84  	/**
85  	 * Default value of prune old packs option: {@value}
86  	 * @see #setPrunePreserved(boolean)
87  	 * @since 4.7
88  	 */
89  	public static final boolean DEFAULT_PRUNE_PRESERVED = false;
90  
91  	/**
92  	 * Default value of delta compress option: {@value}
93  	 *
94  	 * @see #setDeltaCompress(boolean)
95  	 */
96  	public static final boolean DEFAULT_DELTA_COMPRESS = true;
97  
98  	/**
99  	 * Default value of delta base as offset option: {@value}
100 	 *
101 	 * @see #setDeltaBaseAsOffset(boolean)
102 	 */
103 	public static final boolean DEFAULT_DELTA_BASE_AS_OFFSET = false;
104 
105 	/**
106 	 * Default value of maximum delta chain depth: {@value}
107 	 *
108 	 * @see #setMaxDeltaDepth(int)
109 	 */
110 	public static final int DEFAULT_MAX_DELTA_DEPTH = 50;
111 
112 	/**
113 	 * Default window size during packing: {@value}
114 	 *
115 	 * @see #setDeltaSearchWindowSize(int)
116 	 */
117 	public static final int DEFAULT_DELTA_SEARCH_WINDOW_SIZE = 10;
118 
119 	/**
120 	 * Default big file threshold: {@value}
121 	 *
122 	 * @see #setBigFileThreshold(int)
123 	 */
124 	public static final int DEFAULT_BIG_FILE_THRESHOLD = 50 * 1024 * 1024;
125 
126 	/**
127 	 * Default delta cache size: {@value}
128 	 *
129 	 * @see #setDeltaCacheSize(long)
130 	 */
131 	public static final long DEFAULT_DELTA_CACHE_SIZE = 50 * 1024 * 1024;
132 
133 	/**
134 	 * Default delta cache limit: {@value}
135 	 *
136 	 * @see #setDeltaCacheLimit(int)
137 	 */
138 	public static final int DEFAULT_DELTA_CACHE_LIMIT = 100;
139 
140 	/**
141 	 * Default index version: {@value}
142 	 *
143 	 * @see #setIndexVersion(int)
144 	 */
145 	public static final int DEFAULT_INDEX_VERSION = 2;
146 
147 	/**
148 	 * Default value of the build bitmaps option: {@value}
149 	 *
150 	 * @see #setBuildBitmaps(boolean)
151 	 * @since 3.0
152 	 */
153 	public static final boolean DEFAULT_BUILD_BITMAPS = true;
154 
155 	/**
156 	 * Default count of most recent commits to select for bitmaps. Only applies
157 	 * when bitmaps are enabled: {@value}
158 	 *
159 	 * @see #setBitmapContiguousCommitCount(int)
160 	 * @since 4.2
161 	 */
162 	public static final int DEFAULT_BITMAP_CONTIGUOUS_COMMIT_COUNT = 100;
163 
164 	/**
165 	 * Count at which the span between selected commits changes from
166 	 * "bitmapRecentCommitSpan" to "bitmapDistantCommitSpan". Only applies when
167 	 * bitmaps are enabled: {@value}
168 	 *
169 	 * @see #setBitmapRecentCommitCount(int)
170 	 * @since 4.2
171 	 */
172 	public static final int DEFAULT_BITMAP_RECENT_COMMIT_COUNT = 20000;
173 
174 	/**
175 	 * Default spacing between commits in recent history when selecting commits
176 	 * for bitmaps. Only applies when bitmaps are enabled: {@value}
177 	 *
178 	 * @see #setBitmapRecentCommitSpan(int)
179 	 * @since 4.2
180 	 */
181 	public static final int DEFAULT_BITMAP_RECENT_COMMIT_SPAN = 100;
182 
183 	/**
184 	 * Default spacing between commits in distant history when selecting commits
185 	 * for bitmaps. Only applies when bitmaps are enabled: {@value}
186 	 *
187 	 * @see #setBitmapDistantCommitSpan(int)
188 	 * @since 4.2
189 	 */
190 	public static final int DEFAULT_BITMAP_DISTANT_COMMIT_SPAN = 5000;
191 
192 	/**
193 	 * Default count of branches required to activate inactive branch commit
194 	 * selection. If the number of branches is less than this then bitmaps for
195 	 * the entire commit history of all branches will be created, otherwise
196 	 * branches marked as "inactive" will have coverage for only partial
197 	 * history: {@value}
198 	 *
199 	 * @see #setBitmapExcessiveBranchCount(int)
200 	 * @since 4.2
201 	 */
202 	public static final int DEFAULT_BITMAP_EXCESSIVE_BRANCH_COUNT = 100;
203 
204 	/**
205 	 * Default age at which a branch is considered inactive. Age is taken as the
206 	 * number of days ago that the most recent commit was made to a branch. Only
207 	 * affects bitmap processing if bitmaps are enabled and the
208 	 * "excessive branch count" has been exceeded: {@value}
209 	 *
210 	 * @see #setBitmapInactiveBranchAgeInDays(int)
211 	 * @since 4.2
212 	 */
213 	public static final int DEFAULT_BITMAP_INACTIVE_BRANCH_AGE_IN_DAYS = 90;
214 
215 	private int compressionLevel = Deflater.DEFAULT_COMPRESSION;
216 
217 	private boolean reuseDeltas = DEFAULT_REUSE_DELTAS;
218 
219 	private boolean reuseObjects = DEFAULT_REUSE_OBJECTS;
220 
221 	private boolean preserveOldPacks = DEFAULT_PRESERVE_OLD_PACKS;
222 
223 	private boolean prunePreserved = DEFAULT_PRUNE_PRESERVED;
224 
225 	private boolean deltaBaseAsOffset = DEFAULT_DELTA_BASE_AS_OFFSET;
226 
227 	private boolean deltaCompress = DEFAULT_DELTA_COMPRESS;
228 
229 	private int maxDeltaDepth = DEFAULT_MAX_DELTA_DEPTH;
230 
231 	private int deltaSearchWindowSize = DEFAULT_DELTA_SEARCH_WINDOW_SIZE;
232 
233 	private long deltaSearchMemoryLimit;
234 
235 	private long deltaCacheSize = DEFAULT_DELTA_CACHE_SIZE;
236 
237 	private int deltaCacheLimit = DEFAULT_DELTA_CACHE_LIMIT;
238 
239 	private int bigFileThreshold = DEFAULT_BIG_FILE_THRESHOLD;
240 
241 	private int threads;
242 
243 	private Executor executor;
244 
245 	private int indexVersion = DEFAULT_INDEX_VERSION;
246 
247 	private boolean buildBitmaps = DEFAULT_BUILD_BITMAPS;
248 
249 	private int bitmapContiguousCommitCount = DEFAULT_BITMAP_CONTIGUOUS_COMMIT_COUNT;
250 
251 	private int bitmapRecentCommitCount = DEFAULT_BITMAP_RECENT_COMMIT_COUNT;
252 
253 	private int bitmapRecentCommitSpan = DEFAULT_BITMAP_RECENT_COMMIT_SPAN;
254 
255 	private int bitmapDistantCommitSpan = DEFAULT_BITMAP_DISTANT_COMMIT_SPAN;
256 
257 	private int bitmapExcessiveBranchCount = DEFAULT_BITMAP_EXCESSIVE_BRANCH_COUNT;
258 
259 	private int bitmapInactiveBranchAgeInDays = DEFAULT_BITMAP_INACTIVE_BRANCH_AGE_IN_DAYS;
260 
261 	private boolean cutDeltaChains;
262 
263 	private boolean singlePack;
264 
265 	/** Create a default configuration. */
266 	public PackConfig() {
267 		// Fields are initialized to defaults.
268 	}
269 
270 	/**
271 	 * Create a configuration honoring the repository's settings.
272 	 *
273 	 * @param db
274 	 *            the repository to read settings from. The repository is not
275 	 *            retained by the new configuration, instead its settings are
276 	 *            copied during the constructor.
277 	 */
278 	public PackConfig(Repository db) {
279 		fromConfig(db.getConfig());
280 	}
281 
282 	/**
283 	 * Create a configuration honoring settings in a {@link Config}.
284 	 *
285 	 * @param cfg
286 	 *            the source to read settings from. The source is not retained
287 	 *            by the new configuration, instead its settings are copied
288 	 *            during the constructor.
289 	 */
290 	public PackConfig(Config cfg) {
291 		fromConfig(cfg);
292 	}
293 
294 	/**
295 	 * Copy an existing configuration to a new instance.
296 	 *
297 	 * @param cfg
298 	 *            the source configuration to copy from.
299 	 */
300 	public PackConfig(PackConfig cfg) {
301 		this.compressionLevel = cfg.compressionLevel;
302 		this.reuseDeltas = cfg.reuseDeltas;
303 		this.reuseObjects = cfg.reuseObjects;
304 		this.preserveOldPacks = cfg.preserveOldPacks;
305 		this.prunePreserved = cfg.prunePreserved;
306 		this.deltaBaseAsOffset = cfg.deltaBaseAsOffset;
307 		this.deltaCompress = cfg.deltaCompress;
308 		this.maxDeltaDepth = cfg.maxDeltaDepth;
309 		this.deltaSearchWindowSize = cfg.deltaSearchWindowSize;
310 		this.deltaSearchMemoryLimit = cfg.deltaSearchMemoryLimit;
311 		this.deltaCacheSize = cfg.deltaCacheSize;
312 		this.deltaCacheLimit = cfg.deltaCacheLimit;
313 		this.bigFileThreshold = cfg.bigFileThreshold;
314 		this.threads = cfg.threads;
315 		this.executor = cfg.executor;
316 		this.indexVersion = cfg.indexVersion;
317 		this.buildBitmaps = cfg.buildBitmaps;
318 		this.bitmapContiguousCommitCount = cfg.bitmapContiguousCommitCount;
319 		this.bitmapRecentCommitCount = cfg.bitmapRecentCommitCount;
320 		this.bitmapRecentCommitSpan = cfg.bitmapRecentCommitSpan;
321 		this.bitmapDistantCommitSpan = cfg.bitmapDistantCommitSpan;
322 		this.bitmapExcessiveBranchCount = cfg.bitmapExcessiveBranchCount;
323 		this.bitmapInactiveBranchAgeInDays = cfg.bitmapInactiveBranchAgeInDays;
324 		this.cutDeltaChains = cfg.cutDeltaChains;
325 		this.singlePack = cfg.singlePack;
326 	}
327 
328 	/**
329 	 * Check whether to reuse deltas existing in repository.
330 	 *
331 	 * Default setting: {@value #DEFAULT_REUSE_DELTAS}
332 	 *
333 	 * @return true if object is configured to reuse deltas; false otherwise.
334 	 */
335 	public boolean isReuseDeltas() {
336 		return reuseDeltas;
337 	}
338 
339 	/**
340 	 * Set reuse deltas configuration option for the writer.
341 	 *
342 	 * When enabled, writer will search for delta representation of object in
343 	 * repository and use it if possible. Normally, only deltas with base to
344 	 * another object existing in set of objects to pack will be used. The
345 	 * exception however is thin-packs where the base object may exist on the
346 	 * other side.
347 	 *
348 	 * When raw delta data is directly copied from a pack file, its checksum is
349 	 * computed to verify the data is not corrupt.
350 	 *
351 	 * Default setting: {@value #DEFAULT_REUSE_DELTAS}
352 	 *
353 	 * @param reuseDeltas
354 	 *            boolean indicating whether or not try to reuse deltas.
355 	 */
356 	public void setReuseDeltas(boolean reuseDeltas) {
357 		this.reuseDeltas = reuseDeltas;
358 	}
359 
360 	/**
361 	 * Checks whether to reuse existing objects representation in repository.
362 	 *
363 	 * Default setting: {@value #DEFAULT_REUSE_OBJECTS}
364 	 *
365 	 * @return true if writer is configured to reuse objects representation from
366 	 *         pack; false otherwise.
367 	 */
368 	public boolean isReuseObjects() {
369 		return reuseObjects;
370 	}
371 
372 	/**
373 	 * Set reuse objects configuration option for the writer.
374 	 *
375 	 * If enabled, writer searches for compressed representation in a pack file.
376 	 * If possible, compressed data is directly copied from such a pack file.
377 	 * Data checksum is verified.
378 	 *
379 	 * Default setting: {@value #DEFAULT_REUSE_OBJECTS}
380 	 *
381 	 * @param reuseObjects
382 	 *            boolean indicating whether or not writer should reuse existing
383 	 *            objects representation.
384 	 */
385 	public void setReuseObjects(boolean reuseObjects) {
386 		this.reuseObjects = reuseObjects;
387 	}
388 
389 	/**
390 	 * Checks whether to preserve old packs in a preserved directory
391 	 *
392 	 * Default setting: {@value #DEFAULT_PRESERVE_OLD_PACKS}
393 	 *
394 	 * @return true if repacking will preserve old pack files.
395 	 * @since 4.7
396 	 */
397 	public boolean isPreserveOldPacks() {
398 		return preserveOldPacks;
399 	}
400 
401 	/**
402 	 * Set preserve old packs configuration option for repacking.
403 	 *
404 	 * If enabled, old pack files are moved into a preserved subdirectory instead
405 	 * of being deleted
406 	 *
407 	 * Default setting: {@value #DEFAULT_PRESERVE_OLD_PACKS}
408 	 *
409 	 * @param preserveOldPacks
410 	 *            boolean indicating whether or not preserve old pack files
411 	 * @since 4.7
412 	 */
413 	public void setPreserveOldPacks(boolean preserveOldPacks) {
414 		this.preserveOldPacks = preserveOldPacks;
415 	}
416 
417 	/**
418 	 * Checks whether to remove preserved pack files in a preserved directory
419 	 *
420 	 * Default setting: {@value #DEFAULT_PRUNE_PRESERVED}
421 	 *
422 	 * @return true if repacking will remove preserved pack files.
423 	 * @since 4.7
424 	 */
425 	public boolean isPrunePreserved() {
426 		return prunePreserved;
427 	}
428 
429 	/**
430 	 * Set prune preserved configuration option for repacking.
431 	 *
432 	 * If enabled, preserved pack files are removed from a preserved subdirectory
433 	 *
434 	 * Default setting: {@value #DEFAULT_PRESERVE_OLD_PACKS}
435 	 *
436 	 * @param prunePreserved
437 	 *            boolean indicating whether or not preserve old pack files
438 	 * @since 4.7
439 	 */
440 	public void setPrunePreserved(boolean prunePreserved) {
441 		this.prunePreserved = prunePreserved;
442 	}
443 
444 	/**
445 	 * True if writer can use offsets to point to a delta base.
446 	 *
447 	 * If true the writer may choose to use an offset to point to a delta base
448 	 * in the same pack, this is a newer style of reference that saves space.
449 	 * False if the writer has to use the older (and more compatible style) of
450 	 * storing the full ObjectId of the delta base.
451 	 *
452 	 * Default setting: {@value #DEFAULT_DELTA_BASE_AS_OFFSET}
453 	 *
454 	 * @return true if delta base is stored as an offset; false if it is stored
455 	 *         as an ObjectId.
456 	 */
457 	public boolean isDeltaBaseAsOffset() {
458 		return deltaBaseAsOffset;
459 	}
460 
461 	/**
462 	 * Set writer delta base format.
463 	 *
464 	 * Delta base can be written as an offset in a pack file (new approach
465 	 * reducing file size) or as an object id (legacy approach, compatible with
466 	 * old readers).
467 	 *
468 	 * Default setting: {@value #DEFAULT_DELTA_BASE_AS_OFFSET}
469 	 *
470 	 * @param deltaBaseAsOffset
471 	 *            boolean indicating whether delta base can be stored as an
472 	 *            offset.
473 	 */
474 	public void setDeltaBaseAsOffset(boolean deltaBaseAsOffset) {
475 		this.deltaBaseAsOffset = deltaBaseAsOffset;
476 	}
477 
478 	/**
479 	 * Check whether the writer will create new deltas on the fly.
480 	 *
481 	 * Default setting: {@value #DEFAULT_DELTA_COMPRESS}
482 	 *
483 	 * @return true if the writer will create a new delta when either
484 	 *         {@link #isReuseDeltas()} is false, or no suitable delta is
485 	 *         available for reuse.
486 	 */
487 	public boolean isDeltaCompress() {
488 		return deltaCompress;
489 	}
490 
491 	/**
492 	 * Set whether or not the writer will create new deltas on the fly.
493 	 *
494 	 * Default setting: {@value #DEFAULT_DELTA_COMPRESS}
495 	 *
496 	 * @param deltaCompress
497 	 *            true to create deltas when {@link #isReuseDeltas()} is false,
498 	 *            or when a suitable delta isn't available for reuse. Set to
499 	 *            false to write whole objects instead.
500 	 */
501 	public void setDeltaCompress(boolean deltaCompress) {
502 		this.deltaCompress = deltaCompress;
503 	}
504 
505 	/**
506 	 * Get maximum depth of delta chain set up for the writer.
507 	 *
508 	 * Generated chains are not longer than this value.
509 	 *
510 	 * Default setting: {@value #DEFAULT_MAX_DELTA_DEPTH}
511 	 *
512 	 * @return maximum delta chain depth.
513 	 */
514 	public int getMaxDeltaDepth() {
515 		return maxDeltaDepth;
516 	}
517 
518 	/**
519 	 * Set up maximum depth of delta chain for the writer.
520 	 *
521 	 * Generated chains are not longer than this value. Too low value causes low
522 	 * compression level, while too big makes unpacking (reading) longer.
523 	 *
524 	 * Default setting: {@value #DEFAULT_MAX_DELTA_DEPTH}
525 	 *
526 	 * @param maxDeltaDepth
527 	 *            maximum delta chain depth.
528 	 */
529 	public void setMaxDeltaDepth(int maxDeltaDepth) {
530 		this.maxDeltaDepth = maxDeltaDepth;
531 	}
532 
533 	/**
534 	 * @return true if existing delta chains should be cut at
535 	 *         {@link #getMaxDeltaDepth()}. Default is false, allowing existing
536 	 *         chains to be of any length.
537 	 * @since 3.0
538 	 */
539 	public boolean getCutDeltaChains() {
540 		return cutDeltaChains;
541 	}
542 
543 	/**
544 	 * Enable cutting existing delta chains at {@link #getMaxDeltaDepth()}.
545 	 *
546 	 * By default this is disabled and existing chains are kept at whatever
547 	 * length a prior packer was configured to create. This allows objects to be
548 	 * packed one with a large depth (for example 250), and later to quickly
549 	 * repack the repository with a shorter depth (such as 50), but reusing the
550 	 * complete delta chains created by the earlier 250 depth.
551 	 *
552 	 * @param cut
553 	 *            true to cut existing chains.
554 	 * @since 3.0
555 	 */
556 	public void setCutDeltaChains(boolean cut) {
557 		cutDeltaChains = cut;
558 	}
559 
560 	/**
561 	 * @return true if all of refs/* should be packed in a single pack. Default
562 	 *        is false, packing a separate GC_REST pack for references outside
563 	 *        of refs/heads/* and refs/tags/*.
564 	 * @since 4.9
565 	 */
566 	public boolean getSinglePack() {
567 		return singlePack;
568 	}
569 
570 	/**
571 	 * If {@code true}, packs a single GC pack for all objects reachable from
572 	 * refs/*. Otherwise packs the GC pack with objects reachable from
573 	 * refs/heads/* and refs/tags/*, and a GC_REST pack with the remaining
574 	 * reachable objects. Disabled by default, packing GC and GC_REST.
575 	 *
576 	 * @param single
577 	 *            true to pack a single GC pack rather than GC and GC_REST packs
578 	 * @since 4.9
579 	 */
580 	public void setSinglePack(boolean single) {
581 		singlePack = single;
582 	}
583 
584 	/**
585 	 * Get the number of objects to try when looking for a delta base.
586 	 *
587 	 * This limit is per thread, if 4 threads are used the actual memory used
588 	 * will be 4 times this value.
589 	 *
590 	 * Default setting: {@value #DEFAULT_DELTA_SEARCH_WINDOW_SIZE}
591 	 *
592 	 * @return the object count to be searched.
593 	 */
594 	public int getDeltaSearchWindowSize() {
595 		return deltaSearchWindowSize;
596 	}
597 
598 	/**
599 	 * Set the number of objects considered when searching for a delta base.
600 	 *
601 	 * Default setting: {@value #DEFAULT_DELTA_SEARCH_WINDOW_SIZE}
602 	 *
603 	 * @param objectCount
604 	 *            number of objects to search at once. Must be at least 2.
605 	 */
606 	public void setDeltaSearchWindowSize(int objectCount) {
607 		if (objectCount <= 2)
608 			setDeltaCompress(false);
609 		else
610 			deltaSearchWindowSize = objectCount;
611 	}
612 
613 	/**
614 	 * Get maximum number of bytes to put into the delta search window.
615 	 *
616 	 * Default setting is 0, for an unlimited amount of memory usage. Actual
617 	 * memory used is the lower limit of either this setting, or the sum of
618 	 * space used by at most {@link #getDeltaSearchWindowSize()} objects.
619 	 *
620 	 * This limit is per thread, if 4 threads are used the actual memory limit
621 	 * will be 4 times this value.
622 	 *
623 	 * @return the memory limit.
624 	 */
625 	public long getDeltaSearchMemoryLimit() {
626 		return deltaSearchMemoryLimit;
627 	}
628 
629 	/**
630 	 * Set the maximum number of bytes to put into the delta search window.
631 	 *
632 	 * Default setting is 0, for an unlimited amount of memory usage. If the
633 	 * memory limit is reached before {@link #getDeltaSearchWindowSize()} the
634 	 * window size is temporarily lowered.
635 	 *
636 	 * @param memoryLimit
637 	 *            Maximum number of bytes to load at once, 0 for unlimited.
638 	 */
639 	public void setDeltaSearchMemoryLimit(long memoryLimit) {
640 		deltaSearchMemoryLimit = memoryLimit;
641 	}
642 
643 	/**
644 	 * Get the size of the in-memory delta cache.
645 	 *
646 	 * This limit is for the entire writer, even if multiple threads are used.
647 	 *
648 	 * Default setting: {@value #DEFAULT_DELTA_CACHE_SIZE}
649 	 *
650 	 * @return maximum number of bytes worth of delta data to cache in memory.
651 	 *         If 0 the cache is infinite in size (up to the JVM heap limit
652 	 *         anyway). A very tiny size such as 1 indicates the cache is
653 	 *         effectively disabled.
654 	 */
655 	public long getDeltaCacheSize() {
656 		return deltaCacheSize;
657 	}
658 
659 	/**
660 	 * Set the maximum number of bytes of delta data to cache.
661 	 *
662 	 * During delta search, up to this many bytes worth of small or hard to
663 	 * compute deltas will be stored in memory. This cache speeds up writing by
664 	 * allowing the cached entry to simply be dumped to the output stream.
665 	 *
666 	 * Default setting: {@value #DEFAULT_DELTA_CACHE_SIZE}
667 	 *
668 	 * @param size
669 	 *            number of bytes to cache. Set to 0 to enable an infinite
670 	 *            cache, set to 1 (an impossible size for any delta) to disable
671 	 *            the cache.
672 	 */
673 	public void setDeltaCacheSize(long size) {
674 		deltaCacheSize = size;
675 	}
676 
677 	/**
678 	 * Maximum size in bytes of a delta to cache.
679 	 *
680 	 * Default setting: {@value #DEFAULT_DELTA_CACHE_LIMIT}
681 	 *
682 	 * @return maximum size (in bytes) of a delta that should be cached.
683 	 */
684 	public int getDeltaCacheLimit() {
685 		return deltaCacheLimit;
686 	}
687 
688 	/**
689 	 * Set the maximum size of a delta that should be cached.
690 	 *
691 	 * During delta search, any delta smaller than this size will be cached, up
692 	 * to the {@link #getDeltaCacheSize()} maximum limit. This speeds up writing
693 	 * by allowing these cached deltas to be output as-is.
694 	 *
695 	 * Default setting: {@value #DEFAULT_DELTA_CACHE_LIMIT}
696 	 *
697 	 * @param size
698 	 *            maximum size (in bytes) of a delta to be cached.
699 	 */
700 	public void setDeltaCacheLimit(int size) {
701 		deltaCacheLimit = size;
702 	}
703 
704 	/**
705 	 * Get the maximum file size that will be delta compressed.
706 	 *
707 	 * Files bigger than this setting will not be delta compressed, as they are
708 	 * more than likely already highly compressed binary data files that do not
709 	 * delta compress well, such as MPEG videos.
710 	 *
711 	 * Default setting: {@value #DEFAULT_BIG_FILE_THRESHOLD}
712 	 *
713 	 * @return the configured big file threshold.
714 	 */
715 	public int getBigFileThreshold() {
716 		return bigFileThreshold;
717 	}
718 
719 	/**
720 	 * Set the maximum file size that should be considered for deltas.
721 	 *
722 	 * Default setting: {@value #DEFAULT_BIG_FILE_THRESHOLD}
723 	 *
724 	 * @param bigFileThreshold
725 	 *            the limit, in bytes.
726 	 */
727 	public void setBigFileThreshold(int bigFileThreshold) {
728 		this.bigFileThreshold = bigFileThreshold;
729 	}
730 
731 	/**
732 	 * Get the compression level applied to objects in the pack.
733 	 *
734 	 * Default setting: {@value java.util.zip.Deflater#DEFAULT_COMPRESSION}
735 	 *
736 	 * @return current compression level, see {@link java.util.zip.Deflater}.
737 	 */
738 	public int getCompressionLevel() {
739 		return compressionLevel;
740 	}
741 
742 	/**
743 	 * Set the compression level applied to objects in the pack.
744 	 *
745 	 * Default setting: {@value java.util.zip.Deflater#DEFAULT_COMPRESSION}
746 	 *
747 	 * @param level
748 	 *            compression level, must be a valid level recognized by the
749 	 *            {@link java.util.zip.Deflater} class.
750 	 */
751 	public void setCompressionLevel(int level) {
752 		compressionLevel = level;
753 	}
754 
755 	/**
756 	 * Get the number of threads used during delta compression.
757 	 *
758 	 * Default setting: 0 (auto-detect processors)
759 	 *
760 	 * @return number of threads used for delta compression. 0 will auto-detect
761 	 *         the threads to the number of available processors.
762 	 */
763 	public int getThreads() {
764 		return threads;
765 	}
766 
767 	/**
768 	 * Set the number of threads to use for delta compression.
769 	 *
770 	 * During delta compression, if there are enough objects to be considered
771 	 * the writer will start up concurrent threads and allow them to compress
772 	 * different sections of the repository concurrently.
773 	 *
774 	 * An application thread pool can be set by {@link #setExecutor(Executor)}.
775 	 * If not set a temporary pool will be created by the writer, and torn down
776 	 * automatically when compression is over.
777 	 *
778 	 * Default setting: 0 (auto-detect processors)
779 	 *
780 	 * @param threads
781 	 *            number of threads to use. If &lt;= 0 the number of available
782 	 *            processors for this JVM is used.
783 	 */
784 	public void setThreads(int threads) {
785 		this.threads = threads;
786 	}
787 
788 	/** @return the preferred thread pool to execute delta search on. */
789 	public Executor getExecutor() {
790 		return executor;
791 	}
792 
793 	/**
794 	 * Set the executor to use when using threads.
795 	 *
796 	 * During delta compression if the executor is non-null jobs will be queued
797 	 * up on it to perform delta compression in parallel. Aside from setting the
798 	 * executor, the caller must set {@link #setThreads(int)} to enable threaded
799 	 * delta search.
800 	 *
801 	 * @param executor
802 	 *            executor to use for threads. Set to null to create a temporary
803 	 *            executor just for the writer.
804 	 */
805 	public void setExecutor(Executor executor) {
806 		this.executor = executor;
807 	}
808 
809 	/**
810 	 * Get the pack index file format version this instance creates.
811 	 *
812 	 * Default setting: {@value #DEFAULT_INDEX_VERSION}
813 	 *
814 	 * @return the index version, the special version 0 designates the oldest
815 	 *         (most compatible) format available for the objects.
816 	 * @see PackIndexWriter
817 	 */
818 	public int getIndexVersion() {
819 		return indexVersion;
820 	}
821 
822 	/**
823 	 * Set the pack index file format version this instance will create.
824 	 *
825 	 * Default setting: {@value #DEFAULT_INDEX_VERSION}
826 	 *
827 	 * @param version
828 	 *            the version to write. The special version 0 designates the
829 	 *            oldest (most compatible) format available for the objects.
830 	 * @see PackIndexWriter
831 	 */
832 	public void setIndexVersion(int version) {
833 		indexVersion = version;
834 	}
835 
836 	/**
837 	 * True if writer is allowed to build bitmaps for indexes.
838 	 *
839 	 * Default setting: {@value #DEFAULT_BUILD_BITMAPS}
840 	 *
841 	 * @return true if delta base is the writer can choose to output an index
842 	 *         with bitmaps.
843 	 * @since 3.0
844 	 */
845 	public boolean isBuildBitmaps() {
846 		return buildBitmaps;
847 	}
848 
849 	/**
850 	 * Set writer to allow building bitmaps for supported pack files.
851 	 *
852 	 * Index files can include bitmaps to speed up future ObjectWalks.
853 	 *
854 	 * Default setting: {@value #DEFAULT_BUILD_BITMAPS}
855 	 *
856 	 * @param buildBitmaps
857 	 *            boolean indicating whether bitmaps may be included in the
858 	 *            index.
859 	 * @since 3.0
860 	 */
861 	public void setBuildBitmaps(boolean buildBitmaps) {
862 		this.buildBitmaps = buildBitmaps;
863 	}
864 
865 	/**
866 	 * Get the count of most recent commits for which to build bitmaps.
867 	 *
868 	 * Default setting: {@value #DEFAULT_BITMAP_CONTIGUOUS_COMMIT_COUNT}
869 	 *
870 	 * @return the count of most recent commits for which to build bitmaps
871 	 * @since 4.2
872 	 */
873 	public int getBitmapContiguousCommitCount() {
874 		return bitmapContiguousCommitCount;
875 	}
876 
877 	/**
878 	 * Set the count of most recent commits for which to build bitmaps.
879 	 *
880 	 * Default setting: {@value #DEFAULT_BITMAP_CONTIGUOUS_COMMIT_COUNT}
881 	 *
882 	 * @param count
883 	 *            the count of most recent commits for which to build bitmaps
884 	 * @since 4.2
885 	 */
886 	public void setBitmapContiguousCommitCount(int count) {
887 		bitmapContiguousCommitCount = count;
888 	}
889 
890 	/**
891 	 * Get the count at which to switch from "bitmapRecentCommitSpan" to
892 	 * "bitmapDistantCommitSpan".
893 	 *
894 	 * Default setting: {@value #DEFAULT_BITMAP_RECENT_COMMIT_COUNT}
895 	 *
896 	 * @return the count for switching between recent and distant spans
897 	 * @since 4.2
898 	 */
899 	public int getBitmapRecentCommitCount() {
900 		return bitmapRecentCommitCount;
901 	}
902 
903 	/**
904 	 * Set the count at which to switch from "bitmapRecentCommitSpan" to
905 	 * "bitmapDistantCommitSpan".
906 	 *
907 	 * Default setting: {@value #DEFAULT_BITMAP_RECENT_COMMIT_COUNT}
908 	 *
909 	 * @param count
910 	 *            the count for switching between recent and distant spans
911 	 * @since 4.2
912 	 */
913 	public void setBitmapRecentCommitCount(int count) {
914 		bitmapRecentCommitCount = count;
915 	}
916 
917 	/**
918 	 * Get the span of commits when building bitmaps for recent history.
919 	 *
920 	 * Default setting: {@value #DEFAULT_BITMAP_RECENT_COMMIT_SPAN}
921 	 *
922 	 * @return the span of commits when building bitmaps for recent history
923 	 * @since 4.2
924 	 */
925 	public int getBitmapRecentCommitSpan() {
926 		return bitmapRecentCommitSpan;
927 	}
928 
929 	/**
930 	 * Set the span of commits when building bitmaps for recent history.
931 	 *
932 	 * Default setting: {@value #DEFAULT_BITMAP_RECENT_COMMIT_SPAN}
933 	 *
934 	 * @param span
935 	 *            the span of commits when building bitmaps for recent history
936 	 * @since 4.2
937 	 */
938 	public void setBitmapRecentCommitSpan(int span) {
939 		bitmapRecentCommitSpan = span;
940 	}
941 
942 	/**
943 	 * Get the span of commits when building bitmaps for distant history.
944 	 *
945 	 * Default setting: {@value #DEFAULT_BITMAP_DISTANT_COMMIT_SPAN}
946 	 *
947 	 * @return the span of commits when building bitmaps for distant history
948 	 * @since 4.2
949 	 */
950 	public int getBitmapDistantCommitSpan() {
951 		return bitmapDistantCommitSpan;
952 	}
953 
954 	/**
955 	 * Set the span of commits when building bitmaps for distant history.
956 	 *
957 	 * Default setting: {@value #DEFAULT_BITMAP_DISTANT_COMMIT_SPAN}
958 	 *
959 	 * @param span
960 	 *            the span of commits when building bitmaps for distant history
961 	 * @since 4.2
962 	 */
963 	public void setBitmapDistantCommitSpan(int span) {
964 		bitmapDistantCommitSpan = span;
965 	}
966 
967 	/**
968 	 * Get the count of branches deemed "excessive". If the count of branches in
969 	 * a repository exceeds this number and bitmaps are enabled, "inactive"
970 	 * branches will have fewer bitmaps than "active" branches.
971 	 *
972 	 * Default setting: {@value #DEFAULT_BITMAP_EXCESSIVE_BRANCH_COUNT}
973 	 *
974 	 * @return the count of branches deemed "excessive"
975 	 * @since 4.2
976 	 */
977 	public int getBitmapExcessiveBranchCount() {
978 		return bitmapExcessiveBranchCount;
979 	}
980 
981 	/**
982 	 * Set the count of branches deemed "excessive". If the count of branches in
983 	 * a repository exceeds this number and bitmaps are enabled, "inactive"
984 	 * branches will have fewer bitmaps than "active" branches.
985 	 *
986 	 * Default setting: {@value #DEFAULT_BITMAP_EXCESSIVE_BRANCH_COUNT}
987 	 *
988 	 * @param count
989 	 *            the count of branches deemed "excessive"
990 	 * @since 4.2
991 	 */
992 	public void setBitmapExcessiveBranchCount(int count) {
993 		bitmapExcessiveBranchCount = count;
994 	}
995 
996 	/**
997 	 * Get the the age in days that marks a branch as "inactive".
998 	 *
999 	 * Default setting: {@value #DEFAULT_BITMAP_INACTIVE_BRANCH_AGE_IN_DAYS}
1000 	 *
1001 	 * @return the age in days that marks a branch as "inactive"
1002 	 * @since 4.2
1003 	 */
1004 	public int getBitmapInactiveBranchAgeInDays() {
1005 		return bitmapInactiveBranchAgeInDays;
1006 	}
1007 
1008 	/**
1009 	 * Set the the age in days that marks a branch as "inactive".
1010 	 *
1011 	 * Default setting: {@value #DEFAULT_BITMAP_INACTIVE_BRANCH_AGE_IN_DAYS}
1012 	 *
1013 	 * @param ageInDays
1014 	 *            the age in days that marks a branch as "inactive"
1015 	 * @since 4.2
1016 	 */
1017 	public void setBitmapInactiveBranchAgeInDays(int ageInDays) {
1018 		bitmapInactiveBranchAgeInDays = ageInDays;
1019 	}
1020 
1021 	/**
1022 	 * Update properties by setting fields from the configuration.
1023 	 *
1024 	 * If a property's corresponding variable is not defined in the supplied
1025 	 * configuration, then it is left unmodified.
1026 	 *
1027 	 * @param rc
1028 	 *            configuration to read properties from.
1029 	 */
1030 	public void fromConfig(final Config rc) {
1031 		setMaxDeltaDepth(rc.getInt("pack", "depth", getMaxDeltaDepth())); //$NON-NLS-1$ //$NON-NLS-2$
1032 		setDeltaSearchWindowSize(rc.getInt(
1033 				"pack", "window", getDeltaSearchWindowSize())); //$NON-NLS-1$ //$NON-NLS-2$
1034 		setDeltaSearchMemoryLimit(rc.getLong(
1035 				"pack", "windowmemory", getDeltaSearchMemoryLimit())); //$NON-NLS-1$ //$NON-NLS-2$
1036 		setDeltaCacheSize(rc.getLong(
1037 				"pack", "deltacachesize", getDeltaCacheSize())); //$NON-NLS-1$ //$NON-NLS-2$
1038 		setDeltaCacheLimit(rc.getInt(
1039 				"pack", "deltacachelimit", getDeltaCacheLimit())); //$NON-NLS-1$ //$NON-NLS-2$
1040 		setCompressionLevel(rc.getInt("pack", "compression", //$NON-NLS-1$ //$NON-NLS-2$
1041 				rc.getInt("core", "compression", getCompressionLevel()))); //$NON-NLS-1$ //$NON-NLS-2$
1042 		setIndexVersion(rc.getInt("pack", "indexversion", getIndexVersion())); //$NON-NLS-1$ //$NON-NLS-2$
1043 		setBigFileThreshold(rc.getInt(
1044 				"core", "bigfilethreshold", getBigFileThreshold())); //$NON-NLS-1$ //$NON-NLS-2$
1045 		setThreads(rc.getInt("pack", "threads", getThreads())); //$NON-NLS-1$ //$NON-NLS-2$
1046 
1047 		// These variables aren't standardized
1048 		//
1049 		setReuseDeltas(rc.getBoolean("pack", "reusedeltas", isReuseDeltas())); //$NON-NLS-1$ //$NON-NLS-2$
1050 		setReuseObjects(
1051 				rc.getBoolean("pack", "reuseobjects", isReuseObjects())); //$NON-NLS-1$ //$NON-NLS-2$
1052 		setDeltaCompress(
1053 				rc.getBoolean("pack", "deltacompression", isDeltaCompress())); //$NON-NLS-1$ //$NON-NLS-2$
1054 		setCutDeltaChains(
1055 				rc.getBoolean("pack", "cutdeltachains", getCutDeltaChains())); //$NON-NLS-1$ //$NON-NLS-2$
1056 		setSinglePack(
1057 				rc.getBoolean("pack", "singlepack", getSinglePack())); //$NON-NLS-1$ //$NON-NLS-2$
1058 		setBuildBitmaps(
1059 				rc.getBoolean("pack", "buildbitmaps", isBuildBitmaps())); //$NON-NLS-1$ //$NON-NLS-2$
1060 		setBitmapContiguousCommitCount(
1061 				rc.getInt("pack", "bitmapcontiguouscommitcount", //$NON-NLS-1$ //$NON-NLS-2$
1062 						getBitmapContiguousCommitCount()));
1063 		setBitmapRecentCommitCount(rc.getInt("pack", "bitmaprecentcommitcount", //$NON-NLS-1$ //$NON-NLS-2$
1064 				getBitmapRecentCommitCount()));
1065 		setBitmapRecentCommitSpan(rc.getInt("pack", "bitmaprecentcommitspan", //$NON-NLS-1$ //$NON-NLS-2$
1066 				getBitmapRecentCommitSpan()));
1067 		setBitmapDistantCommitSpan(rc.getInt("pack", "bitmapdistantcommitspan", //$NON-NLS-1$ //$NON-NLS-2$
1068 				getBitmapDistantCommitSpan()));
1069 		setBitmapExcessiveBranchCount(rc.getInt("pack", //$NON-NLS-1$
1070 				"bitmapexcessivebranchcount", getBitmapExcessiveBranchCount())); //$NON-NLS-1$
1071 		setBitmapInactiveBranchAgeInDays(
1072 				rc.getInt("pack", "bitmapinactivebranchageindays", //$NON-NLS-1$ //$NON-NLS-2$
1073 						getBitmapInactiveBranchAgeInDays()));
1074 	}
1075 
1076 	@Override
1077 	public String toString() {
1078 		final StringBuilder b = new StringBuilder();
1079 		b.append("maxDeltaDepth=").append(getMaxDeltaDepth()); //$NON-NLS-1$
1080 		b.append(", deltaSearchWindowSize=").append(getDeltaSearchWindowSize()); //$NON-NLS-1$
1081 		b.append(", deltaSearchMemoryLimit=") //$NON-NLS-1$
1082 				.append(getDeltaSearchMemoryLimit());
1083 		b.append(", deltaCacheSize=").append(getDeltaCacheSize()); //$NON-NLS-1$
1084 		b.append(", deltaCacheLimit=").append(getDeltaCacheLimit()); //$NON-NLS-1$
1085 		b.append(", compressionLevel=").append(getCompressionLevel()); //$NON-NLS-1$
1086 		b.append(", indexVersion=").append(getIndexVersion()); //$NON-NLS-1$
1087 		b.append(", bigFileThreshold=").append(getBigFileThreshold()); //$NON-NLS-1$
1088 		b.append(", threads=").append(getThreads()); //$NON-NLS-1$
1089 		b.append(", reuseDeltas=").append(isReuseDeltas()); //$NON-NLS-1$
1090 		b.append(", reuseObjects=").append(isReuseObjects()); //$NON-NLS-1$
1091 		b.append(", deltaCompress=").append(isDeltaCompress()); //$NON-NLS-1$
1092 		b.append(", buildBitmaps=").append(isBuildBitmaps()); //$NON-NLS-1$
1093 		b.append(", bitmapContiguousCommitCount=") //$NON-NLS-1$
1094 				.append(getBitmapContiguousCommitCount());
1095 		b.append(", bitmapRecentCommitCount=") //$NON-NLS-1$
1096 				.append(getBitmapRecentCommitCount());
1097 		b.append(", bitmapRecentCommitSpan=") //$NON-NLS-1$
1098 				.append(getBitmapRecentCommitSpan());
1099 		b.append(", bitmapDistantCommitSpan=") //$NON-NLS-1$
1100 				.append(getBitmapDistantCommitSpan());
1101 		b.append(", bitmapExcessiveBranchCount=") //$NON-NLS-1$
1102 				.append(getBitmapExcessiveBranchCount());
1103 		b.append(", bitmapInactiveBranchAge=") //$NON-NLS-1$
1104 				.append(getBitmapInactiveBranchAgeInDays());
1105 		b.append(", singlePack=").append(getSinglePack()); //$NON-NLS-1$
1106 		return b.toString();
1107 	}
1108 }