facebook
/
zstd
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #1225 from jennifermliu/dev 

Split samples when building dictionary for COVER
dev
Nick Terrell 2018-07-13 13:26:15 -07:00 committed by GitHub
parent aa2415402d 612b346ed5
commit 45821fac0c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 76 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
lib/dictBuilder/cover.c
View File

@ -39,6 +39,7 @@
* Constants
***************************************/
#define COVER_MAX_SAMPLES_SIZE (sizeof(size_t) == 8 ? ((U32)-1) : ((U32)1 GB))
#define DEFAULT_SPLITPOINT 1.0
/*-*************************************
* Console display
@ -203,6 +204,8 @@ typedef struct {
size_t *offsets;
const size_t *samplesSizes;
size_t nbSamples;
size_t nbTrainSamples;
size_t nbTestSamples;
U32 *suffix;
size_t suffixSize;
U32 *freqs;
@ -222,7 +225,7 @@ static COVER_ctx_t *g_ctx = NULL;
*/
static size_t COVER_sum(const size_t *samplesSizes, unsigned nbSamples) {
size_t sum = 0;
size_t i;
unsigned i;
for (i = 0; i < nbSamples; ++i) {
sum += samplesSizes[i];
}
@ -494,6 +497,10 @@ static int COVER_checkParameters(ZDICT_cover_params_t parameters,
if (parameters.d > parameters.k) {
return 0;
}
/* 0 < splitPoint <= 1 */
if (parameters.splitPoint <= 0 || parameters.splitPoint > 1){
return 0;
}
return 1;
}
@ -531,9 +538,14 @@ static void COVER_ctx_destroy(COVER_ctx_t *ctx) {
*/
static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
const size_t *samplesSizes, unsigned nbSamples,
unsigned d) {
unsigned d, double splitPoint) {
const BYTE *const samples = (const BYTE *)samplesBuffer;
const size_t totalSamplesSize = COVER_sum(samplesSizes, nbSamples);
/* Split samples into testing and training sets */
const unsigned nbTrainSamples = splitPoint < 1.0 ? (unsigned)((double)nbSamples * splitPoint) : nbSamples;
const unsigned nbTestSamples = splitPoint < 1.0 ? nbSamples - nbTrainSamples : nbSamples;
const size_t trainingSamplesSize = splitPoint < 1.0 ? COVER_sum(samplesSizes, nbTrainSamples) : totalSamplesSize;
const size_t testSamplesSize = splitPoint < 1.0 ? COVER_sum(samplesSizes + nbTrainSamples, nbTestSamples) : totalSamplesSize;
/* Checks */
if (totalSamplesSize < MAX(d, sizeof(U64)) ||
totalSamplesSize >= (size_t)COVER_MAX_SAMPLES_SIZE) {
@ -541,15 +553,29 @@ static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
(U32)(totalSamplesSize>>20), (COVER_MAX_SAMPLES_SIZE >> 20));
return 0;
}
/* Check if there are at least 5 training samples */
if (nbTrainSamples < 5) {
DISPLAYLEVEL(1, "Total number of training samples is %u and is invalid.", nbTrainSamples);
return 0;
}
/* Check if there's testing sample */
if (nbTestSamples < 1) {
DISPLAYLEVEL(1, "Total number of testing samples is %u and is invalid.", nbTestSamples);
return 0;
}
/* Zero the context */
memset(ctx, 0, sizeof(*ctx));
DISPLAYLEVEL(2, "Training on %u samples of total size %u\n", nbSamples,
(U32)totalSamplesSize);
DISPLAYLEVEL(2, "Training on %u samples of total size %u\n", nbTrainSamples,
(U32)trainingSamplesSize);
DISPLAYLEVEL(2, "Testing on %u samples of total size %u\n", nbTestSamples,
(U32)testSamplesSize);
ctx->samples = samples;
ctx->samplesSizes = samplesSizes;
ctx->nbSamples = nbSamples;
ctx->nbTrainSamples = nbTrainSamples;
ctx->nbTestSamples = nbTestSamples;
/* Partial suffix array */
ctx->suffixSize = totalSamplesSize - MAX(d, sizeof(U64)) + 1;
ctx->suffixSize = trainingSamplesSize - MAX(d, sizeof(U64)) + 1;
ctx->suffix = (U32 *)malloc(ctx->suffixSize * sizeof(U32));
/* Maps index to the dmerID */
ctx->dmerAt = (U32 *)malloc(ctx->suffixSize * sizeof(U32));
@ -563,7 +589,7 @@ static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
ctx->freqs = NULL;
ctx->d = d;
/* Fill offsets from the samlesSizes */
/* Fill offsets from the samplesSizes */
{
U32 i;
ctx->offsets[0] = 0;
@ -665,7 +691,7 @@ ZDICTLIB_API size_t ZDICT_trainFromBuffer_cover(
BYTE* const dict = (BYTE*)dictBuffer;
COVER_ctx_t ctx;
COVER_map_t activeDmers;
parameters.splitPoint = 1.0;
/* Initialize global data */
g_displayLevel = parameters.zParams.notificationLevel;
/* Checks */
@ -684,7 +710,7 @@ ZDICTLIB_API size_t ZDICT_trainFromBuffer_cover(
}
/* Initialize context and activeDmers */
if (!COVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples,
parameters.d)) {
parameters.d, parameters.splitPoint)) {
return ERROR(GENERIC);
}
if (!COVER_map_init(&activeDmers, parameters.k - parameters.d + 1)) {
@ -839,7 +865,7 @@ typedef struct COVER_tryParameters_data_s {
} COVER_tryParameters_data_t;
/**
* Tries a set of parameters and upates the COVER_best_t with the results.
* Tries a set of parameters and updates the COVER_best_t with the results.
* This function is thread safe if zstd is compiled with multithreaded support.
* It takes its parameters as an *OWNING* opaque pointer to support threading.
*/
@ -870,7 +896,7 @@ static void COVER_tryParameters(void *opaque) {
dictBufferCapacity, parameters);
dictBufferCapacity = ZDICT_finalizeDictionary(
dict, dictBufferCapacity, dict + tail, dictBufferCapacity - tail,
ctx->samples, ctx->samplesSizes, (unsigned)ctx->nbSamples,
ctx->samples, ctx->samplesSizes, (unsigned)ctx->nbTrainSamples,
parameters.zParams);
if (ZDICT_isError(dictBufferCapacity)) {
DISPLAYLEVEL(1, "Failed to finalize dictionary\n");
@ -889,7 +915,8 @@ static void COVER_tryParameters(void *opaque) {
/* Allocate dst with enough space to compress the maximum sized sample */
{
size_t maxSampleSize = 0;
for (i = 0; i < ctx->nbSamples; ++i) {
i = parameters.splitPoint < 1.0 ? ctx->nbTrainSamples : 0;
for (; i < ctx->nbSamples; ++i) {
maxSampleSize = MAX(ctx->samplesSizes[i], maxSampleSize);
}
dstCapacity = ZSTD_compressBound(maxSampleSize);
@ -904,7 +931,8 @@ static void COVER_tryParameters(void *opaque) {
}
/* Compress each sample and sum their sizes (or error) */
totalCompressedSize = dictBufferCapacity;
for (i = 0; i < ctx->nbSamples; ++i) {
i = parameters.splitPoint < 1.0 ? ctx->nbTrainSamples : 0;
for (; i < ctx->nbSamples; ++i) {
const size_t size = ZSTD_compress_usingCDict(
cctx, dst, dstCapacity, ctx->samples + ctx->offsets[i],
ctx->samplesSizes[i], cdict);
@ -941,6 +969,8 @@ ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
ZDICT_cover_params_t *parameters) {
/* constants */
const unsigned nbThreads = parameters->nbThreads;
const double splitPoint =
parameters->splitPoint <= 0.0 ? DEFAULT_SPLITPOINT : parameters->splitPoint;
const unsigned kMinD = parameters->d == 0 ? 6 : parameters->d;
const unsigned kMaxD = parameters->d == 0 ? 8 : parameters->d;
const unsigned kMinK = parameters->k == 0 ? 50 : parameters->k;
@ -958,6 +988,10 @@ ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
POOL_ctx *pool = NULL;
/* Checks */
if (splitPoint <= 0 || splitPoint > 1) {
LOCALDISPLAYLEVEL(displayLevel, 1, "Incorrect parameters\n");
return ERROR(GENERIC);
}
if (kMinK < kMaxD || kMaxK < kMinK) {
LOCALDISPLAYLEVEL(displayLevel, 1, "Incorrect parameters\n");
return ERROR(GENERIC);
@ -988,7 +1022,7 @@ ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
/* Initialize the context for this value of d */
COVER_ctx_t ctx;
LOCALDISPLAYLEVEL(displayLevel, 3, "d=%u\n", d);
if (!COVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples, d)) {
if (!COVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples, d, splitPoint)) {
LOCALDISPLAYLEVEL(displayLevel, 1, "Failed to initialize context\n");
COVER_best_destroy(&best);
POOL_free(pool);
@ -1013,6 +1047,7 @@ ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(
data->parameters = *parameters;
data->parameters.k = k;
data->parameters.d = d;
data->parameters.splitPoint = splitPoint;
data->parameters.steps = kSteps;
data->parameters.zParams.notificationLevel = g_displayLevel;
/* Check the parameters */

1
lib/dictBuilder/zdict.h
View File

@ -86,6 +86,7 @@ typedef struct {
unsigned d; /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */
unsigned steps; /* Number of steps : Only used for optimization : 0 means default (32) : Higher means more parameters checked */
unsigned nbThreads; /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */
double splitPoint; /* Percentage of samples used for training: the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (1.0), 1.0 when all samples are used for both training and testing */
ZDICT_params_t zParams;
} ZDICT_cover_params_t;

2
programs/README.md
View File

@ -150,7 +150,7 @@ Advanced arguments :
Dictionary builder :
--train ## : create a dictionary from a training set of files
--train-cover[=k=#,d=#,steps=#] : use the cover algorithm with optional args
--train-cover[=k=#,d=#,steps=#,split=#] : use the cover algorithm with optional args
--train-legacy[=s=#] : use the legacy algorithm with selectivity (default: 9)
-o file : `file` is dictionary name (default: dictionary)
--maxdict=# : limit dictionary to specified size (default: 112640)

3
programs/dibio.c
View File

@ -323,7 +323,8 @@ int DiB_trainFromFiles(const char* dictFileName, unsigned maxDictSize,
srcBuffer, sampleSizes, fs.nbSamples,
coverParams);
if (!ZDICT_isError(dictSize)) {
DISPLAYLEVEL(2, "k=%u\nd=%u\nsteps=%u\n", coverParams->k, coverParams->d, coverParams->steps);
unsigned splitPercentage = (unsigned)(coverParams->splitPoint * 100);
DISPLAYLEVEL(2, "k=%u\nd=%u\nsteps=%u\nsplit=%u\n", coverParams->k, coverParams->d, coverParams->steps, splitPercentage);
}
} else {
dictSize = ZDICT_trainFromBuffer_cover(dictBuffer, maxDictSize, srcBuffer,

5
programs/zstd.1
View File

@ -217,8 +217,9 @@ Split input files in blocks of size # (default: no split)
A dictionary ID is a locally unique ID that a decoder can use to verify it is using the right dictionary\. By default, zstd will create a 4\-bytes random number ID\. It\'s possible to give a precise number instead\. Short numbers have an advantage : an ID < 256 will only need 1 byte in the compressed frame header, and an ID < 65536 will only need 2 bytes\. This compares favorably to 4 bytes default\. However, it\'s up to the dictionary manager to not assign twice the same ID to 2 different dictionaries\.
.
.TP
\fB\-\-train\-cover[=k#,d=#,steps=#]\fR
Select parameters for the default dictionary builder algorithm named cover\. If \fId\fR is not specified, then it tries \fId\fR = 6 and \fId\fR = 8\. If \fIk\fR is not specified, then it tries \fIsteps\fR values in the range [50, 2000]\. If \fIsteps\fR is not specified, then the default value of 40 is used\. Requires that \fId\fR <= \fIk\fR\.
\fB\-\-train\-cover[=k#,d=#,steps=#,split=#]\fR
Select parameters for the default dictionary builder algorithm named cover\. If \fId\fR is not specified, then it tries \fId\fR = 6 and \fId\fR = 8\. If \fIk\fR is not specified, then it tries \fIsteps\fR values in the range [50, 2000]\. If \fIsteps\fR is not specified, then the default value of 40 is used\. If \fIsplit\fR is not specified or \fIsplit\fR <= 0, then the default value of 100 is used\. If \fIsplit\fR is 100, all input samples are used for both training and testing
to find optimal _d_ and _k_ to build dictionary.Requires that \fId\fR <= \fIk\fR\.
.
.IP
Selects segments of size \fIk\fR with highest score to put in the dictionary\. The score of a segment is computed by the sum of the frequencies of all the subsegments of size \fId\fR\. Generally \fId\fR should be in the range [6, 8], occasionally up to 16, but the algorithm will run faster with d <= \fI8\fR\. Good values for \fIk\fR vary widely based on the input data, but a safe range is [2 * \fId\fR, 2000]\. Supports multithreading if \fBzstd\fR is compiled with threading support\.

7
programs/zstd.1.md
View File

@ -223,11 +223,12 @@ Compression of small files similar to the sample set will be greatly improved.
This compares favorably to 4 bytes default.
However, it's up to the dictionary manager to not assign twice the same ID to
2 different dictionaries.
* `--train-cover[=k#,d=#,steps=#]`:
* `--train-cover[=k#,d=#,steps=#,split=#]`:
Select parameters for the default dictionary builder algorithm named cover.
If _d_ is not specified, then it tries _d_ = 6 and _d_ = 8.
If _k_ is not specified, then it tries _steps_ values in the range [50, 2000].
If _steps_ is not specified, then the default value of 40 is used.
If _split_ is not specified or split <= 0, then the default value of 100 is used.
Requires that _d_ <= _k_.
Selects segments of size _k_ with highest score to put in the dictionary.
@ -237,6 +238,8 @@ Compression of small files similar to the sample set will be greatly improved.
algorithm will run faster with d <= _8_.
Good values for _k_ vary widely based on the input data, but a safe range is
[2 * _d_, 2000].
If _split_ is 100, all input samples are used for both training and testing
to find optimal _d_ and _k_ to build dictionary.
Supports multithreading if `zstd` is compiled with threading support.
Examples:
@ -249,6 +252,8 @@ Compression of small files similar to the sample set will be greatly improved.
`zstd --train-cover=k=50 FILEs`
`zstd --train-cover=k=50,split=60 FILEs`
* `--train-legacy[=selectivity=#]`:
Use legacy dictionary builder algorithm with the given dictionary
_selectivity_ (default: 9).

11
programs/zstdcli.c
View File

@ -84,6 +84,7 @@ static U32 g_ldmMinMatch = 0;
static U32 g_ldmHashEveryLog = LDM_PARAM_DEFAULT;
static U32 g_ldmBucketSizeLog = LDM_PARAM_DEFAULT;
#define DEFAULT_SPLITPOINT 1.0
/*-************************************
* Display Macros
@ -170,7 +171,7 @@ static int usage_advanced(const char* programName)
DISPLAY( "\n");
DISPLAY( "Dictionary builder : \n");
DISPLAY( "--train ## : create a dictionary from a training set of files \n");
DISPLAY( "--train-cover[=k=#,d=#,steps=#] : use the cover algorithm with optional args\n");
DISPLAY( "--train-cover[=k=#,d=#,steps=#,split=#] : use the cover algorithm with optional args\n");
DISPLAY( "--train-legacy[=s=#] : use the legacy algorithm with selectivity (default: %u)\n", g_defaultSelectivityLevel);
DISPLAY( " -o file : `file` is dictionary name (default: %s) \n", g_defaultDictName);
DISPLAY( "--maxdict=# : limit dictionary to specified size (default: %u) \n", g_defaultMaxDictSize);
@ -282,10 +283,15 @@ static unsigned parseCoverParameters(const char* stringPtr, ZDICT_cover_params_t
if (longCommandWArg(&stringPtr, "k=")) { params->k = readU32FromChar(&stringPtr); if (stringPtr[0]==',') { stringPtr++; continue; } else break; }
if (longCommandWArg(&stringPtr, "d=")) { params->d = readU32FromChar(&stringPtr); if (stringPtr[0]==',') { stringPtr++; continue; } else break; }
if (longCommandWArg(&stringPtr, "steps=")) { params->steps = readU32FromChar(&stringPtr); if (stringPtr[0]==',') { stringPtr++; continue; } else break; }
if (longCommandWArg(&stringPtr, "split=")) {
unsigned splitPercentage = readU32FromChar(&stringPtr);
params->splitPoint = (double)splitPercentage / 100.0;
if (stringPtr[0]==',') { stringPtr++; continue; } else break;
}
return 0;
}
if (stringPtr[0] != 0) return 0;
DISPLAYLEVEL(4, "cover: k=%u\nd=%u\nsteps=%u\n", params->k, params->d, params->steps);
DISPLAYLEVEL(4, "cover: k=%u\nd=%u\nsteps=%u\nsplit=%u\n", params->k, params->d, params->steps, (unsigned)(params->splitPoint * 100));
return 1;
}
@ -310,6 +316,7 @@ static ZDICT_cover_params_t defaultCoverParams(void)
memset(&params, 0, sizeof(params));
params.d = 8;
params.steps = 4;
params.splitPoint = DEFAULT_SPLITPOINT;
return params;
}
#endif

7
tests/playTests.sh
View File

@ -412,7 +412,7 @@ $ECHO "\n===> cover dictionary builder : advanced options "
TESTFILE=../programs/zstdcli.c
./datagen > tmpDict
$ECHO "- Create first dictionary"
$ZSTD --train-cover=k=46,d=8 *.c ../programs/*.c -o tmpDict
$ZSTD --train-cover=k=46,d=8,split=80 *.c ../programs/*.c -o tmpDict
cp $TESTFILE tmp
$ZSTD -f tmp -D tmpDict
$ZSTD -d tmp.zst -D tmpDict -fo result
@ -426,6 +426,11 @@ cmp tmpDict tmpDict1 && die "dictionaries should have different ID !"
$ECHO "- Create dictionary with size limit"
$ZSTD --train-cover=steps=8 *.c ../programs/*.c -o tmpDict2 --maxdict=4K
rm tmp*
$ECHO "- Compare size of dictionary from 90% training samples with 80% training samples"
$ZSTD --train-cover=split=90 -r *.c ../programs/*.c
$ZSTD --train-cover=split=80 -r *.c ../programs/*.c
$ECHO "- Create dictionary using all samples for both training and testing"
$ZSTD --train-cover=split=100 -r *.c ../programs/*.c
$ECHO "\n===> legacy dictionary builder "