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Move hash table access for own functions

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This commit is contained in:
Stella Lau 2017-07-14 14:27:55 -07:00
parent 2d8e6c6608
commit 6e443b4960
6 changed files with 189 additions and 64 deletions
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77
contrib/long_distance_matching/ldm.c
View File

@ -23,17 +23,23 @@ struct LDM_hashEntry {
offset_t offset;
};
typedef struct LDM_hashTable {
U32 numEntries;
U32 minimumTagMask; // TODO: what if tag == offset?
// Maximum number of elements in the table.
U32 limit;
// TODO: move to its own file.
struct LDM_hashTable {
U32 size;
LDM_hashEntry *entries;
} LDM_hashTable;
};
LDM_hashEntry *HASH_getHash(
const LDM_hashTable *table, const hash_t hash) {
return &(table->entries[hash]);
}
void HASH_insert(LDM_hashTable *table,
const hash_t hash, const LDM_hashEntry entry) {
*HASH_getHash(table, hash) = entry;
}
// TODO: Add offset histogram by powers of two
// TODO: Scanning speed
// TODO: Memory usage
struct LDM_compressStats {
@ -74,7 +80,9 @@ struct LDM_CCtx {
LDM_compressStats stats; /* Compression statistics */
LDM_hashEntry *hashTable;
LDM_hashTable hashTable;
// LDM_hashEntry *hashTable;
// LDM_hashEntry hashTable[LDM_HASHTABLESIZE_U32];
@ -93,18 +101,19 @@ struct LDM_CCtx {
const BYTE *DEBUG_setNextHash;
};
void LDM_outputHashTableOccupancy(
const LDM_hashEntry *hashTable, U32 hashTableSize) {
void LDM_outputHashTableOccupancy(const LDM_hashTable *hashTable) {
U32 i = 0;
U32 ctr = 0;
for (; i < hashTableSize; i++) {
if (hashTable[i].offset == 0) {
for (; i < hashTable->size; i++) {
if (HASH_getHash(hashTable, i)->offset == 0) {
ctr++;
}
}
printf("Hash table size, empty slots, %% empty: %u, %u, %.3f\n",
hashTableSize, ctr,
100.0 * (double)(ctr) / (double)hashTableSize);
hashTable->size, ctr,
100.0 * (double)(ctr) / (double)hashTable->size);
}
// TODO: This can be done more efficiently (but it is not that important as it
@ -120,13 +129,14 @@ static int intLog2(U32 x) {
// TODO: Maybe we would eventually prefer to have linear rather than
// exponential buckets.
void LDM_outputHashTableOffsetHistogram(const LDM_CCtx *cctx) {
int i = 0;
U32 i = 0;
int buckets[32] = { 0 };
printf("\n");
printf("Hash table histogram\n");
for (; i < LDM_HASHTABLESIZE_U32; i++) {
int offset = (cctx->ip - cctx->ibase) - cctx->hashTable[i].offset;
for (; i < cctx->hashTable.size; i++) {
int offset = (cctx->ip - cctx->ibase) -
HASH_getHash(&cctx->hashTable, i)->offset;
buckets[intLog2(offset)]++;
}
@ -135,7 +145,7 @@ void LDM_outputHashTableOffsetHistogram(const LDM_CCtx *cctx) {
printf("2^%*d: %10u %6.3f%%\n", 2, i,
buckets[i],
100.0 * (double) buckets[i] /
(double) LDM_HASHTABLESIZE_U32);
(double) cctx->hashTable.size);
}
printf("\n");
}
@ -305,7 +315,7 @@ static void putHashOfCurrentPositionFromHash(
LDM_CCtx *cctx, hash_t hash, U32 sum) {
#ifdef COMPUTE_STATS
if (cctx->stats.numHashInserts < LDM_HASHTABLESIZE_U32) {
offset_t offset = cctx->hashTable[hash].offset;
offset_t offset = HASH_getHash(&cctx->hashTable, hash)->offset;
cctx->stats.numHashInserts++;
if (offset != 0 && !LDM_isValidMatch(cctx->ip, offset + cctx->ibase)) {
cctx->stats.numCollisions++;
@ -317,7 +327,7 @@ static void putHashOfCurrentPositionFromHash(
// Note: this works only when cctx->step is 1.
if (((cctx->ip - cctx->ibase) & HASH_ONLY_EVERY) == HASH_ONLY_EVERY) {
const LDM_hashEntry entry = { cctx->ip - cctx->ibase };
cctx->hashTable[hash] = entry;
HASH_insert(&cctx->hashTable, hash, entry);
}
cctx->lastPosHashed = cctx->ip;
@ -362,7 +372,7 @@ static void LDM_putHashOfCurrentPosition(LDM_CCtx *cctx) {
* Returns the position of the entry at hashTable[hash].
*/
static const BYTE *getPositionOnHash(LDM_CCtx *cctx, hash_t hash) {
return cctx->hashTable[hash].offset + cctx->ibase;
return HASH_getHash(&cctx->hashTable, hash)->offset + cctx->ibase;
}
U32 LDM_countMatchLength(const BYTE *pIn, const BYTE *pMatch,
@ -389,6 +399,11 @@ void LDM_readHeader(const void *src, U64 *compressedSize,
// ip += sizeof(U64);
}
static void LDM_initializeHashTable(LDM_hashTable *table) {
table->size = LDM_HASHTABLESIZE_U32;
table->entries = calloc(LDM_HASHTABLESIZE_U32, sizeof(LDM_hashEntry));
}
void LDM_initializeCCtx(LDM_CCtx *cctx,
const void *src, size_t srcSize,
void *dst, size_t maxDstSize) {
@ -408,7 +423,9 @@ void LDM_initializeCCtx(LDM_CCtx *cctx,
cctx->anchor = cctx->ibase;
memset(&(cctx->stats), 0, sizeof(cctx->stats));
cctx->hashTable = calloc(LDM_HASHTABLESIZE_U32, sizeof(LDM_hashEntry));
LDM_initializeHashTable(&cctx->hashTable);
// calloc(LDM_HASHTABLESIZE_U32, sizeof(LDM_hashEntry));
// memset(cctx->hashTable, 0, sizeof(cctx->hashTable));
cctx->stats.minOffset = UINT_MAX;
cctx->stats.windowSizeLog = LDM_WINDOW_SIZE_LOG;
@ -424,6 +441,10 @@ void LDM_initializeCCtx(LDM_CCtx *cctx,
cctx->DEBUG_setNextHash = 0;
}
void LDM_destroyCCtx(LDM_CCtx *cctx) {
free((cctx->hashTable).entries);
}
/**
* Finds the "best" match.
*
@ -594,10 +615,14 @@ size_t LDM_compress(const void *src, size_t srcSize,
#ifdef COMPUTE_STATS
LDM_printCompressStats(&cctx.stats);
LDM_outputHashTableOccupancy(cctx.hashTable, LDM_HASHTABLESIZE_U32);
LDM_outputHashTableOccupancy(&cctx.hashTable);
#endif
return cctx.op - cctx.obase;
{
const size_t ret = cctx.op - cctx.obase;
LDM_destroyCCtx(&cctx);
return ret;
}
}
struct LDM_DCtx {

11
contrib/long_distance_matching/ldm.h
View File

@ -26,6 +26,7 @@
typedef U32 offset_t;
typedef U32 hash_t;
typedef struct LDM_hashEntry LDM_hashEntry;
typedef struct LDM_hashTable LDM_hashTable;
typedef struct LDM_compressStats LDM_compressStats;
typedef struct LDM_CCtx LDM_CCtx;
typedef struct LDM_DCtx LDM_DCtx;
@ -62,17 +63,23 @@ size_t LDM_compress(const void *src, size_t srcSize,
/**
* Initialize the compression context.
*
* Allocates memory for the hash table.
*/
void LDM_initializeCCtx(LDM_CCtx *cctx,
const void *src, size_t srcSize,
void *dst, size_t maxDstSize);
/**
* Frees up memory allocating in initializeCCtx
*/
void LDM_destroyCCtx(LDM_CCtx *cctx);
/**
* Prints the percentage of the hash table occupied (where occupied is defined
* as the entry being non-zero).
*/
void LDM_outputHashTableOccupancy(const LDM_hashEntry *hashTable,
U32 hashTableSize);
void LDM_outputHashTableOccupancy(const LDM_hashTable *hashTable);
/**
* Prints the distribution of offsets in the hash table.

4
contrib/long_distance_matching/versions/v0.5/Makefile
View File

@ -9,7 +9,7 @@
# This Makefile presumes libzstd is installed, using `sudo make install`
CPPFLAGS+= -I../../../../lib/common
CPPFLAGS+= -I../../lib/common
CFLAGS ?= -O3
DEBUGFLAGS = -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
-Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement \
@ -27,7 +27,7 @@ default: all
all: main-ldm
main-ldm : ldm.c main-ldm.c
main-ldm : ldm.h ldm.c main-ldm.c
$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
clean:

133
contrib/long_distance_matching/versions/v0.5/ldm.c
View File

@ -15,7 +15,7 @@
#define RUN_MASK ((1U<<RUN_BITS)-1)
#define COMPUTE_STATS
#define CHECKSUM_CHAR_OFFSET 0
#define CHECKSUM_CHAR_OFFSET 10
//#define RUN_CHECKS
//#define LDM_DEBUG
@ -23,10 +23,21 @@ struct LDM_hashEntry {
offset_t offset;
};
typedef struct LDM_hashTable {
U32 numEntries;
U32 minimumTagMask; // TODO: what if tag == offset?
// Maximum number of elements in the table.
U32 limit;
LDM_hashEntry *entries;
} LDM_hashTable;
// TODO: Add offset histogram by powers of two
// TODO: Scanning speed
// TODO: Memory usage
struct LDM_compressStats {
U32 windowSizeLog, hashTableSizeLog;
U32 numMatches;
U64 totalMatchLength;
U64 totalLiteralLength;
@ -36,6 +47,8 @@ struct LDM_compressStats {
U32 numCollisions;
U32 numHashInserts;
U32 offsetHistogram[32];
};
struct LDM_CCtx {
@ -61,7 +74,9 @@ struct LDM_CCtx {
LDM_compressStats stats; /* Compression statistics */
LDM_hashEntry hashTable[LDM_HASHTABLESIZE_U32];
LDM_hashEntry *hashTable;
// LDM_hashEntry hashTable[LDM_HASHTABLESIZE_U32];
const BYTE *lastPosHashed; /* Last position hashed */
hash_t lastHash; /* Hash corresponding to lastPosHashed */
@ -78,7 +93,7 @@ struct LDM_CCtx {
const BYTE *DEBUG_setNextHash;
};
void LDM_outputHashtableOccupancy(
void LDM_outputHashTableOccupancy(
const LDM_hashEntry *hashTable, U32 hashTableSize) {
U32 i = 0;
U32 ctr = 0;
@ -92,26 +107,78 @@ void LDM_outputHashtableOccupancy(
100.0 * (double)(ctr) / (double)hashTableSize);
}
// TODO: This can be done more efficiently (but it is not that important as it
// is only used for computing stats).
static int intLog2(U32 x) {
int ret = 0;
while (x >>= 1) {
ret++;
}
return ret;
}
// TODO: Maybe we would eventually prefer to have linear rather than
// exponential buckets.
void LDM_outputHashTableOffsetHistogram(const LDM_CCtx *cctx) {
int i = 0;
int buckets[32] = { 0 };
printf("\n");
printf("Hash table histogram\n");
for (; i < LDM_HASHTABLESIZE_U32; i++) {
int offset = (cctx->ip - cctx->ibase) - cctx->hashTable[i].offset;
buckets[intLog2(offset)]++;
}
i = 0;
for (; i < 32; i++) {
printf("2^%*d: %10u %6.3f%%\n", 2, i,
buckets[i],
100.0 * (double) buckets[i] /
(double) LDM_HASHTABLESIZE_U32);
}
printf("\n");
}
void LDM_printCompressStats(const LDM_compressStats *stats) {
int i = 0;
printf("=====================\n");
printf("Compression statistics\n");
//TODO: compute percentage matched?
printf("Window size, hash table size (bytes): 2^%u, 2^%u\n",
stats->windowSizeLog, stats->hashTableSizeLog);
printf("num matches, total match length: %u, %llu\n",
stats->numMatches,
stats->totalMatchLength);
printf("avg match length: %.1f\n", ((double)stats->totalMatchLength) /
(double)stats->numMatches);
printf("avg literal length: %.1f\n",
((double)stats->totalLiteralLength) / (double)stats->numMatches);
printf("avg literal length, total literalLength: %.1f, %llu\n",
((double)stats->totalLiteralLength) / (double)stats->numMatches,
stats->totalLiteralLength);
printf("avg offset length: %.1f\n",
((double)stats->totalOffset) / (double)stats->numMatches);
printf("min offset, max offset: %u %u\n",
printf("min offset, max offset: %u, %u\n",
stats->minOffset, stats->maxOffset);
printf("\n");
printf("offset histogram: offset, num matches, %% of matches\n");
for (; i <= intLog2(stats->maxOffset); i++) {
printf("2^%*d: %10u %6.3f%%\n", 2, i,
stats->offsetHistogram[i],
100.0 * (double) stats->offsetHistogram[i] /
(double) stats->numMatches);
}
printf("\n");
printf("num collisions, num hash inserts, %% collisions: %u, %u, %.3f\n",
stats->numCollisions, stats->numHashInserts,
stats->numHashInserts == 0 ?
1.0 : (100.0 * (double)stats->numCollisions) /
(double)stats->numHashInserts);
printf("=====================\n");
}
int LDM_isValidMatch(const BYTE *pIn, const BYTE *pMatch) {
@ -145,7 +212,7 @@ int LDM_isValidMatch(const BYTE *pIn, const BYTE *pMatch) {
* of the hash table.
*/
static hash_t checksumToHash(U32 sum) {
return ((sum * 2654435761U) >> ((32)-LDM_HASHLOG));
return ((sum * 2654435761U) >> (32 - LDM_HASHLOG));
}
/**
@ -341,8 +408,12 @@ void LDM_initializeCCtx(LDM_CCtx *cctx,
cctx->anchor = cctx->ibase;
memset(&(cctx->stats), 0, sizeof(cctx->stats));
memset(cctx->hashTable, 0, sizeof(cctx->hashTable));
cctx->hashTable = calloc(LDM_HASHTABLESIZE_U32, sizeof(LDM_hashEntry));
// memset(cctx->hashTable, 0, sizeof(cctx->hashTable));
cctx->stats.minOffset = UINT_MAX;
cctx->stats.windowSizeLog = LDM_WINDOW_SIZE_LOG;
cctx->stats.hashTableSizeLog = LDM_MEMORY_USAGE;
cctx->lastPosHashed = NULL;
@ -353,6 +424,10 @@ void LDM_initializeCCtx(LDM_CCtx *cctx,
cctx->DEBUG_setNextHash = 0;
}
void LDM_destroyCCtx(LDM_CCtx *cctx) {
free(cctx->hashTable);
}
/**
* Finds the "best" match.
*
@ -379,7 +454,7 @@ static int LDM_findBestMatch(LDM_CCtx *cctx, const BYTE **match) {
*match = getPositionOnHash(cctx, h);
putHashOfCurrentPositionFromHash(cctx, h, sum);
} while (cctx->ip - *match > WINDOW_SIZE ||
} while (cctx->ip - *match > LDM_WINDOW_SIZE ||
!LDM_isValidMatch(cctx->ip, *match));
setNextHash(cctx);
return 0;
@ -443,24 +518,19 @@ void LDM_outputBlock(LDM_CCtx *cctx,
size_t LDM_compress(const void *src, size_t srcSize,
void *dst, size_t maxDstSize) {
LDM_CCtx cctx;
const BYTE *match;
LDM_initializeCCtx(&cctx, src, srcSize, dst, maxDstSize);
/* Hash the first position and put it into the hash table. */
LDM_putHashOfCurrentPosition(&cctx);
// TODO: loop condition is not accurate.
while (1) {
const BYTE *match;
/**
* Find a match.
* If no more matches can be found (i.e. the length of the remaining input
* is less than the minimum match length), then stop searching for matches
* and encode the final literals.
*/
if (LDM_findBestMatch(&cctx, &match) != 0) {
goto _last_literals;
}
/**
* Find a match.
* If no more matches can be found (i.e. the length of the remaining input
* is less than the minimum match length), then stop searching for matches
* and encode the final literals.
*/
while (LDM_findBestMatch(&cctx, &match) == 0) {
#ifdef COMPUTE_STATS
cctx.stats.numMatches++;
#endif
@ -485,6 +555,8 @@ size_t LDM_compress(const void *src, size_t srcSize,
cctx.ip + LDM_MIN_MATCH_LENGTH, match + LDM_MIN_MATCH_LENGTH,
cctx.ihashLimit);
LDM_outputBlock(&cctx, literalLength, offset, matchLength);
#ifdef COMPUTE_STATS
cctx.stats.totalLiteralLength += literalLength;
cctx.stats.totalOffset += offset;
@ -493,8 +565,8 @@ size_t LDM_compress(const void *src, size_t srcSize,
offset < cctx.stats.minOffset ? offset : cctx.stats.minOffset;
cctx.stats.maxOffset =
offset > cctx.stats.maxOffset ? offset : cctx.stats.maxOffset;
cctx.stats.offsetHistogram[(U32)intLog2(offset)]++;
#endif
LDM_outputBlock(&cctx, literalLength, offset, matchLength);
// Move ip to end of block, inserting hashes at each position.
cctx.nextIp = cctx.ip + cctx.step;
@ -514,20 +586,26 @@ size_t LDM_compress(const void *src, size_t srcSize,
cctx.anchor = cctx.ip;
LDM_updateLastHashFromNextHash(&cctx);
}
_last_literals:
// LDM_outputHashTableOffsetHistogram(&cctx);
/* Encode the last literals (no more matches). */
{
const size_t lastRun = (size_t)(cctx.iend - cctx.anchor);
const size_t lastRun = cctx.iend - cctx.anchor;
BYTE *pToken = cctx.op++;
LDM_encodeLiteralLengthAndLiterals(&cctx, pToken, lastRun);
}
#ifdef COMPUTE_STATS
LDM_printCompressStats(&cctx.stats);
LDM_outputHashtableOccupancy(cctx.hashTable, LDM_HASHTABLESIZE_U32);
LDM_outputHashTableOccupancy(cctx.hashTable, LDM_HASHTABLESIZE_U32);
#endif
return (cctx.op - (const BYTE *)cctx.obase);
{
const size_t ret = cctx.op - cctx.obase;
LDM_destroyCCtx(&cctx);
return ret;
}
}
struct LDM_DCtx {
@ -611,7 +689,6 @@ size_t LDM_decompress(const void *src, size_t compressedSize,
// TODO: implement and test hash function
void LDM_test(void) {
}
/*

26
contrib/long_distance_matching/versions/v0.5/ldm.h
View File

@ -11,16 +11,17 @@
#define LDM_OFFSET_SIZE 4
// Defines the size of the hash table.
#define LDM_MEMORY_USAGE 22
#define LDM_MEMORY_USAGE 16
#define LDM_HASHLOG (LDM_MEMORY_USAGE-2)
#define LDM_HASHTABLESIZE (1 << (LDM_MEMORY_USAGE))
#define LDM_HASHTABLESIZE_U32 ((LDM_HASHTABLESIZE) >> 2)
#define WINDOW_SIZE (1 << 25)
#define LDM_WINDOW_SIZE_LOG 25
#define LDM_WINDOW_SIZE (1 << (LDM_WINDOW_SIZE_LOG))
//These should be multiples of four.
#define LDM_MIN_MATCH_LENGTH 8
#define LDM_HASH_LENGTH 8
#define LDM_MIN_MATCH_LENGTH 4
#define LDM_HASH_LENGTH 4
typedef U32 offset_t;
typedef U32 hash_t;
@ -61,18 +62,33 @@ size_t LDM_compress(const void *src, size_t srcSize,
/**
* Initialize the compression context.
*
* Allocates memory for the hash table.
*/
void LDM_initializeCCtx(LDM_CCtx *cctx,
const void *src, size_t srcSize,
void *dst, size_t maxDstSize);
/**
* Frees up memory allocating in initializeCCtx
*/
void LDM_destroyCCtx(LDM_CCtx *cctx);
/**
* Prints the percentage of the hash table occupied (where occupied is defined
* as the entry being non-zero).
*/
void LDM_outputHashtableOccupancy(const LDM_hashEntry *hashTable,
void LDM_outputHashTableOccupancy(const LDM_hashEntry *hashTable,
U32 hashTableSize);
/**
* Prints the distribution of offsets in the hash table.
*
* The offsets are defined as the distance of the hash table entry from the
* current input position of the cctx.
*/
void LDM_outputHashTableOffsetHistogram(const LDM_CCtx *cctx);
/**
* Outputs compression statistics to stdout.
*/

2
contrib/long_distance_matching/versions/v0.5/main-ldm.c
View File

@ -13,7 +13,7 @@
#include "zstd.h"
#define DEBUG
//#define TEST
#define TEST
/* Compress file given by fname and output to oname.
* Returns 0 if successful, error code otherwise.