2 * Copyright (c) Meta Platforms, Inc. and affiliates.
5 * This source code is licensed under both the BSD-style license (found in the
6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
7 * in the COPYING file in the root directory of this source tree).
8 * You may select, at your option, one of the above-listed licenses.
11 #ifndef ZDICT_STATIC_LINKING_ONLY
12 # define ZDICT_STATIC_LINKING_ONLY
15 #include "../common/threading.h" /* ZSTD_pthread_mutex_t */
16 #include "../common/mem.h" /* U32, BYTE */
20 * COVER_best_t is used for two purposes:
21 * 1. Synchronizing threads.
22 * 2. Saving the best parameters and dictionary.
24 * All of the methods except COVER_best_init() are thread safe if zstd is
25 * compiled with multithreaded support.
27 typedef struct COVER_best_s {
28 ZSTD_pthread_mutex_t mutex;
29 ZSTD_pthread_cond_t cond;
33 ZDICT_cover_params_t parameters;
34 size_t compressedSize;
38 * A segment is a range in the source as well as the score of the segment.
47 *Number of epochs and size of each epoch.
55 * Struct used for the dictionary selection function.
57 typedef struct COVER_dictSelection {
60 size_t totalCompressedSize;
61 } COVER_dictSelection_t;
64 * Computes the number of epochs and the size of each epoch.
65 * We will make sure that each epoch gets at least 10 * k bytes.
67 * The COVER algorithms divide the data up into epochs of equal size and
68 * select one segment from each epoch.
70 * @param maxDictSize The maximum allowed dictionary size.
71 * @param nbDmers The number of dmers we are training on.
72 * @param k The parameter k (segment size).
73 * @param passes The target number of passes over the dmer corpus.
74 * More passes means a better dictionary.
76 COVER_epoch_info_t COVER_computeEpochs(U32 maxDictSize, U32 nbDmers,
80 * Warns the user when their corpus is too small.
82 void COVER_warnOnSmallCorpus(size_t maxDictSize, size_t nbDmers, int displayLevel);
85 * Checks total compressed size of a dictionary
87 size_t COVER_checkTotalCompressedSize(const ZDICT_cover_params_t parameters,
88 const size_t *samplesSizes, const BYTE *samples,
90 size_t nbTrainSamples, size_t nbSamples,
91 BYTE *const dict, size_t dictBufferCapacity);
94 * Returns the sum of the sample sizes.
96 size_t COVER_sum(const size_t *samplesSizes, unsigned nbSamples) ;
99 * Initialize the `COVER_best_t`.
101 void COVER_best_init(COVER_best_t *best);
104 * Wait until liveJobs == 0.
106 void COVER_best_wait(COVER_best_t *best);
109 * Call COVER_best_wait() and then destroy the COVER_best_t.
111 void COVER_best_destroy(COVER_best_t *best);
114 * Called when a thread is about to be launched.
115 * Increments liveJobs.
117 void COVER_best_start(COVER_best_t *best);
120 * Called when a thread finishes executing, both on error or success.
121 * Decrements liveJobs and signals any waiting threads if liveJobs == 0.
122 * If this dictionary is the best so far save it and its parameters.
124 void COVER_best_finish(COVER_best_t *best, ZDICT_cover_params_t parameters,
125 COVER_dictSelection_t selection);
127 * Error function for COVER_selectDict function. Checks if the return
130 unsigned COVER_dictSelectionIsError(COVER_dictSelection_t selection);
133 * Error function for COVER_selectDict function. Returns a struct where
134 * return.totalCompressedSize is a ZSTD error.
136 COVER_dictSelection_t COVER_dictSelectionError(size_t error);
139 * Always call after selectDict is called to free up used memory from
140 * newly created dictionary.
142 void COVER_dictSelectionFree(COVER_dictSelection_t selection);
145 * Called to finalize the dictionary and select one based on whether or not
146 * the shrink-dict flag was enabled. If enabled the dictionary used is the
147 * smallest dictionary within a specified regression of the compressed size
148 * from the largest dictionary.
150 COVER_dictSelection_t COVER_selectDict(BYTE* customDictContent, size_t dictBufferCapacity,
151 size_t dictContentSize, const BYTE* samplesBuffer, const size_t* samplesSizes, unsigned nbFinalizeSamples,
152 size_t nbCheckSamples, size_t nbSamples, ZDICT_cover_params_t params, size_t* offsets, size_t totalCompressedSize);