krak/zstd
krak/zstd
1
0
Fork 0
mirror of https://github.com/facebook/zstd.git synced 2025-03-06 16:56:49 +02:00
Code Issues Releases 1 Activity

[lib] Add rsyncable mode

Browse Source 
- Add rsyncable mode to multithreaded mode
- Factor out LDM's hash function for reuse
This commit is contained in:
Nick Terrell 2018-11-14 12:15:20 -08:00
parent c584e84e68
commit b9693d3a49
7 changed files with 218 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/compress/zstd_compress.c
View File

@ -254,6 +254,7 @@ static int ZSTD_isUpdateAuthorized(ZSTD_cParameter param)
case ZSTD_p_nbWorkers:
case ZSTD_p_jobSize:
case ZSTD_p_overlapSizeLog:
case ZSTD_p_rsyncable:
case ZSTD_p_enableLongDistanceMatching:
case ZSTD_p_ldmHashLog:
case ZSTD_p_ldmMinMatch:
@ -315,6 +316,7 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned v
case ZSTD_p_jobSize:
case ZSTD_p_overlapSizeLog:
case ZSTD_p_rsyncable:
return ZSTD_CCtxParam_setParameter(&cctx->requestedParams, param, value);
case ZSTD_p_enableLongDistanceMatching:
@ -441,6 +443,13 @@ size_t ZSTD_CCtxParam_setParameter(
return ZSTDMT_CCtxParam_setMTCtxParameter(CCtxParams, ZSTDMT_p_overlapSectionLog, value);
#endif
case ZSTD_p_rsyncable :
#ifndef ZSTD_MULTITHREAD
return ERROR(parameter_unsupported);
#else
return ZSTDMT_CCtxParam_setMTCtxParameter(CCtxParams, ZSTDMT_p_rsyncable, value);
#endif
case ZSTD_p_enableLongDistanceMatching :
CCtxParams->ldmParams.enableLdm = (value>0);
return CCtxParams->ldmParams.enableLdm;
@ -544,6 +553,13 @@ size_t ZSTD_CCtxParam_getParameter(
#else
*value = CCtxParams->overlapSizeLog;
break;
#endif
case ZSTD_p_rsyncable :
#ifndef ZSTD_MULTITHREAD
return ERROR(parameter_unsupported);
#else
*value = CCtxParams->rsyncable;
break;
#endif
case ZSTD_p_enableLongDistanceMatching :
*value = CCtxParams->ldmParams.enableLdm;
@ -1160,7 +1176,7 @@ static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc,
ZSTD_ldm_adjustParameters(&params.ldmParams, &params.cParams);
assert(params.ldmParams.hashLog >= params.ldmParams.bucketSizeLog);
assert(params.ldmParams.hashEveryLog < 32);
zc->ldmState.hashPower = ZSTD_ldm_getHashPower(params.ldmParams.minMatchLength);
zc->ldmState.hashPower = ZSTD_rollingHash_primePower(params.ldmParams.minMatchLength);
}
{ size_t const windowSize = MAX(1, (size_t)MIN(((U64)1 << params.cParams.windowLog), pledgedSrcSize));

59
lib/compress/zstd_compress_internal.h
View File

@ -193,6 +193,7 @@ struct ZSTD_CCtx_params_s {
unsigned nbWorkers;
unsigned jobSize;
unsigned overlapSizeLog;
unsigned rsyncable;
/* Long distance matching parameters */
ldmParams_t ldmParams;
@ -492,6 +493,64 @@ MEM_STATIC size_t ZSTD_hashPtr(const void* p, U32 hBits, U32 mls)
}
}
/** ZSTD_ipow() :
* Return base^exponent.
*/
static U64 ZSTD_ipow(U64 base, U64 exponent)
{
U64 power = 1;
while (exponent) {
if (exponent & 1) power *= base;
exponent >>= 1;
base *= base;
}
return power;
}
#define ZSTD_ROLL_HASH_CHAR_OFFSET 10
/** ZSTD_rollingHash_append() :
* Add the buffer to the hash value.
*/
static U64 ZSTD_rollingHash_append(U64 hash, void const* buf, size_t size)
{
BYTE const* istart = (BYTE const*)buf;
size_t pos;
for (pos = 0; pos < size; ++pos) {
hash *= prime8bytes;
hash += istart[pos] + ZSTD_ROLL_HASH_CHAR_OFFSET;
}
return hash;
}
/** ZSTD_rollingHash_compute() :
* Compute the rolling hash value of the buffer.
*/
MEM_STATIC U64 ZSTD_rollingHash_compute(void const* buf, size_t size)
{
return ZSTD_rollingHash_append(0, buf, size);
}
/** ZSTD_rollingHash_primePower() :
* Compute the primePower to be passed to ZSTD_rollingHash_rotate() for a hash
* over a window of length bytes.
*/
MEM_STATIC U64 ZSTD_rollingHash_primePower(U32 length)
{
return ZSTD_ipow(prime8bytes, length - 1);
}
/** ZSTD_rollingHash_rotate() :
* Rotate the rolling hash by one byte.
*/
MEM_STATIC U64 ZSTD_rollingHash_rotate(U64 hash, BYTE toRemove, BYTE toAdd, U64 primePower)
{
hash -= (toRemove + ZSTD_ROLL_HASH_CHAR_OFFSET) * primePower;
hash *= prime8bytes;
hash += toAdd + ZSTD_ROLL_HASH_CHAR_OFFSET;
return hash;
}
/*-*************************************
* Round buffer management
***************************************/

64
lib/compress/zstd_ldm.c
View File

@ -143,56 +143,6 @@ static void ZSTD_ldm_makeEntryAndInsertByTag(ldmState_t* ldmState,
}
}
/** ZSTD_ldm_getRollingHash() :
* Get a 64-bit hash using the first len bytes from buf.
*
* Giving bytes s = s_1, s_2, ... s_k, the hash is defined to be
* H(s) = s_1*(a^(k-1)) + s_2*(a^(k-2)) + ... + s_k*(a^0)
*
* where the constant a is defined to be prime8bytes.
*
* The implementation adds an offset to each byte, so
* H(s) = (s_1 + HASH_CHAR_OFFSET)*(a^(k-1)) + ... */
static U64 ZSTD_ldm_getRollingHash(const BYTE* buf, U32 len)
{
U64 ret = 0;
U32 i;
for (i = 0; i < len; i++) {
ret *= prime8bytes;
ret += buf[i] + LDM_HASH_CHAR_OFFSET;
}
return ret;
}
/** ZSTD_ldm_ipow() :
* Return base^exp. */
static U64 ZSTD_ldm_ipow(U64 base, U64 exp)
{
U64 ret = 1;
while (exp) {
if (exp & 1) { ret *= base; }
exp >>= 1;
base *= base;
}
return ret;
}
U64 ZSTD_ldm_getHashPower(U32 minMatchLength) {
DEBUGLOG(4, "ZSTD_ldm_getHashPower: mml=%u", minMatchLength);
assert(minMatchLength >= ZSTD_LDM_MINMATCH_MIN);
return ZSTD_ldm_ipow(prime8bytes, minMatchLength - 1);
}
/** ZSTD_ldm_updateHash() :
* Updates hash by removing toRemove and adding toAdd. */
static U64 ZSTD_ldm_updateHash(U64 hash, BYTE toRemove, BYTE toAdd, U64 hashPower)
{
hash -= ((toRemove + LDM_HASH_CHAR_OFFSET) * hashPower);
hash *= prime8bytes;
hash += toAdd + LDM_HASH_CHAR_OFFSET;
return hash;
}
/** ZSTD_ldm_countBackwardsMatch() :
* Returns the number of bytes that match backwards before pIn and pMatch.
*
@ -261,9 +211,9 @@ static U64 ZSTD_ldm_fillLdmHashTable(ldmState_t* state,
const BYTE* cur = lastHashed + 1;
while (cur < iend) {
rollingHash = ZSTD_ldm_updateHash(rollingHash, cur[-1],
cur[ldmParams.minMatchLength-1],
state->hashPower);
rollingHash = ZSTD_rollingHash_rotate(rollingHash, cur[-1],
cur[ldmParams.minMatchLength-1],
state->hashPower);
ZSTD_ldm_makeEntryAndInsertByTag(state,
rollingHash, hBits,
(U32)(cur - base), ldmParams);
@ -324,11 +274,11 @@ static size_t ZSTD_ldm_generateSequences_internal(
size_t forwardMatchLength = 0, backwardMatchLength = 0;
ldmEntry_t* bestEntry = NULL;
if (ip != istart) {
rollingHash = ZSTD_ldm_updateHash(rollingHash, lastHashed[0],
lastHashed[minMatchLength],
hashPower);
rollingHash = ZSTD_rollingHash_rotate(rollingHash, lastHashed[0],
lastHashed[minMatchLength],
hashPower);
} else {
rollingHash = ZSTD_ldm_getRollingHash(ip, minMatchLength);
rollingHash = ZSTD_rollingHash_compute(ip, minMatchLength);
}
lastHashed = ip;

4
lib/compress/zstd_ldm.h
View File

@ -86,10 +86,6 @@ size_t ZSTD_ldm_getTableSize(ldmParams_t params);
*/
size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize);
/** ZSTD_ldm_getTableSize() :
* Return prime8bytes^(minMatchLength-1) */
U64 ZSTD_ldm_getHashPower(U32 minMatchLength);
/** ZSTD_ldm_adjustParameters() :
* If the params->hashEveryLog is not set, set it to its default value based on
* windowLog and params->hashLog.

129
lib/compress/zstdmt_compress.c
View File

@ -471,7 +471,7 @@ static int ZSTDMT_serialState_reset(serialState_t* serialState, ZSTDMT_seqPool*
assert(params.ldmParams.hashLog >= params.ldmParams.bucketSizeLog);
assert(params.ldmParams.hashEveryLog < 32);
serialState->ldmState.hashPower =
ZSTD_ldm_getHashPower(params.ldmParams.minMatchLength);
ZSTD_rollingHash_primePower(params.ldmParams.minMatchLength);
} else {
memset(&params.ldmParams, 0, sizeof(params.ldmParams));
}
@ -777,6 +777,14 @@ typedef struct {
static const roundBuff_t kNullRoundBuff = {NULL, 0, 0};
#define RSYNC_LENGTH 32
typedef struct {
U64 hash;
U64 hitMask;
U64 primePower;
} rsyncState_t;
struct ZSTDMT_CCtx_s {
POOL_ctx* factory;
ZSTDMT_jobDescription* jobs;
@ -790,6 +798,7 @@ struct ZSTDMT_CCtx_s {
inBuff_t inBuff;
roundBuff_t roundBuff;
serialState_t serial;
rsyncState_t rsync;
unsigned singleBlockingThread;
unsigned jobIDMask;
unsigned doneJobID;
@ -988,6 +997,9 @@ size_t ZSTDMT_CCtxParam_setMTCtxParameter(ZSTD_CCtx_params* params,
DEBUGLOG(4, "ZSTDMT_p_overlapSectionLog : %u", value);
params->overlapSizeLog = (value >= 9) ? 9 : value;
return value;
case ZSTDMT_p_rsyncable :
params->rsyncable = (value == 0 ? 0 : 1);
return value;
default :
return ERROR(parameter_unsupported);
}
@ -996,15 +1008,7 @@ size_t ZSTDMT_CCtxParam_setMTCtxParameter(ZSTD_CCtx_params* params,
size_t ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, unsigned value)
{
DEBUGLOG(4, "ZSTDMT_setMTCtxParameter");
switch(parameter)
{
case ZSTDMT_p_jobSize :
return ZSTDMT_CCtxParam_setMTCtxParameter(&mtctx->params, parameter, value);
case ZSTDMT_p_overlapSectionLog :
return ZSTDMT_CCtxParam_setMTCtxParameter(&mtctx->params, parameter, value);
default :
return ERROR(parameter_unsupported);
}
return ZSTDMT_CCtxParam_setMTCtxParameter(&mtctx->params, parameter, value);
}
size_t ZSTDMT_getMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, unsigned* value)
@ -1016,6 +1020,9 @@ size_t ZSTDMT_getMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter,
case ZSTDMT_p_overlapSectionLog:
*value = mtctx->params.overlapSizeLog;
break;
case ZSTDMT_p_rsyncable:
*value = mtctx->params.rsyncable;
break;
default:
return ERROR(parameter_unsupported);
}
@ -1381,6 +1388,16 @@ size_t ZSTDMT_initCStream_internal(
if (mtctx->targetSectionSize == 0) {
mtctx->targetSectionSize = 1ULL << ZSTDMT_computeTargetJobLog(params);
}
if (params.rsyncable) {
/* Aim for the targetsectionSize as the average job size. */
U32 const jobSizeMB = (U32)(mtctx->targetSectionSize >> 20);
U32 const rsyncBits = ZSTD_highbit32(jobSizeMB) + 20;
assert(jobSizeMB >= 1);
DEBUGLOG(4, "rsyncLog = %u", rsyncBits);
mtctx->rsync.hash = 0;
mtctx->rsync.hitMask = (1ULL << rsyncBits) - 1;
mtctx->rsync.primePower = ZSTD_rollingHash_primePower(RSYNC_LENGTH);
}
if (mtctx->targetSectionSize < mtctx->targetPrefixSize) mtctx->targetSectionSize = mtctx->targetPrefixSize; /* job size must be >= overlap size */
DEBUGLOG(4, "Job Size : %u KB (note : set to %u)", (U32)(mtctx->targetSectionSize>>10), params.jobSize);
DEBUGLOG(4, "inBuff Size : %u KB", (U32)(mtctx->targetSectionSize>>10));
@ -1818,6 +1835,80 @@ static int ZSTDMT_tryGetInputRange(ZSTDMT_CCtx* mtctx)
return 1;
}
typedef struct {
size_t toLoad; /* The number of bytes to load from the input. */
int flush; /* Boolean declaring if we must flush because we found a synchronization point. */
} syncPoint_t;
/**
* Searches through the input for a synchronization point. If one is found, we
* will instruct the caller to flush, and return the number of bytes to load.
* Otherwise, we will load as many bytes as possible and instruct the caller
* to continue as normal.
*/
static syncPoint_t findSynchronizationPoint(ZSTDMT_CCtx const* mtctx, ZSTD_inBuffer const input) {
BYTE const* const istart = (BYTE const*)input.src + input.pos;
U64 const primePower = mtctx->rsync.primePower;
U64 const hitMask = mtctx->rsync.hitMask;
syncPoint_t syncPoint;
U64 hash;
BYTE const* prev;
size_t pos;
syncPoint.toLoad = MIN(input.size - input.pos, mtctx->targetSectionSize - mtctx->inBuff.filled);
syncPoint.flush = 0;
if (!mtctx->params.rsyncable)
/* Rsync is disabled. */
return syncPoint;
if (mtctx->inBuff.filled + syncPoint.toLoad < RSYNC_LENGTH)
/* Not enough to compute the hash.
* We will miss any synchronization points in this RSYNC_LENGTH byte
* window. However, since it depends only in the internal buffers, if the
* state is already synchronized, we will remain synchronized.
* Additionally, the probability that we miss a synchronization point is
* low: RSYNC_LENGTH / targetSectionSize.
*/
return syncPoint;
/* Initialize the loop variables. */
if (mtctx->inBuff.filled >= RSYNC_LENGTH) {
/* We have enough bytes buffered to initialize the hash.
* Start scanning at the beginning of the input.
*/
pos = 0;
prev = (BYTE const*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled - RSYNC_LENGTH;
hash = ZSTD_rollingHash_compute(prev, RSYNC_LENGTH);
} else {
/* We don't have enough bytes buffered to initialize the hash, but
* we know we have at least RSYNC_LENGTH bytes total.
* Start scanning after the first RSYNC_LENGTH bytes less the bytes
* already buffered.
*/
pos = RSYNC_LENGTH - mtctx->inBuff.filled;
prev = (BYTE const*)mtctx->inBuff.buffer.start - pos;
hash = ZSTD_rollingHash_compute(mtctx->inBuff.buffer.start, mtctx->inBuff.filled);
hash = ZSTD_rollingHash_append(hash, istart, pos);
}
/* Starting with the hash of the previous RSYNC_LENGTH bytes, roll
* through the input. If we hit a synchronization point, then cut the
* job off, and tell the compressor to flush the job. Otherwise, load
* all the bytes and continue as normal.
* If we go too long without a synchronization point (targetSectionSize)
* then a block will be emitted anyways, but this is okay, since if we
* are already synchronized we will remain synchronized.
*/
for (; pos < syncPoint.toLoad; ++pos) {
BYTE const toRemove = pos < RSYNC_LENGTH ? prev[pos] : istart[pos - RSYNC_LENGTH];
/* if (pos >= RSYNC_LENGTH) assert(ZSTD_rollingHash_compute(istart + pos - RSYNC_LENGTH, RSYNC_LENGTH) == hash); */
hash = ZSTD_rollingHash_rotate(hash, toRemove, istart[pos], primePower);
if ((hash & hitMask) == hitMask) {
syncPoint.toLoad = pos + 1;
syncPoint.flush = 1;
break;
}
}
return syncPoint;
}
/** ZSTDMT_compressStream_generic() :
* internal use only - exposed to be invoked from zstd_compress.c
@ -1844,7 +1935,8 @@ size_t ZSTDMT_compressStream_generic(ZSTDMT_CCtx* mtctx,
}
/* single-pass shortcut (note : synchronous-mode) */
if ( (mtctx->nextJobID == 0) /* just started */
if ( (!mtctx->params.rsyncable) /* rsyncable mode is disabled */
&& (mtctx->nextJobID == 0) /* just started */
&& (mtctx->inBuff.filled == 0) /* nothing buffered */
&& (!mtctx->jobReady) /* no job already created */
&& (endOp == ZSTD_e_end) /* end order */
@ -1876,14 +1968,17 @@ size_t ZSTDMT_compressStream_generic(ZSTDMT_CCtx* mtctx,
DEBUGLOG(5, "ZSTDMT_tryGetInputRange completed successfully : mtctx->inBuff.buffer.start = %p", mtctx->inBuff.buffer.start);
}
if (mtctx->inBuff.buffer.start != NULL) {
size_t const toLoad = MIN(input->size - input->pos, mtctx->targetSectionSize - mtctx->inBuff.filled);
syncPoint_t const syncPoint = findSynchronizationPoint(mtctx, *input);
if (syncPoint.flush && endOp == ZSTD_e_continue) {
endOp = ZSTD_e_flush;
}
assert(mtctx->inBuff.buffer.capacity >= mtctx->targetSectionSize);
DEBUGLOG(5, "ZSTDMT_compressStream_generic: adding %u bytes on top of %u to buffer of size %u",
(U32)toLoad, (U32)mtctx->inBuff.filled, (U32)mtctx->targetSectionSize);
memcpy((char*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled, (const char*)input->src + input->pos, toLoad);
input->pos += toLoad;
mtctx->inBuff.filled += toLoad;
forwardInputProgress = toLoad>0;
(U32)syncPoint.toLoad, (U32)mtctx->inBuff.filled, (U32)mtctx->targetSectionSize);
memcpy((char*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled, (const char*)input->src + input->pos, syncPoint.toLoad);
input->pos += syncPoint.toLoad;
mtctx->inBuff.filled += syncPoint.toLoad;
forwardInputProgress = syncPoint.toLoad>0;
}
if ((input->pos < input->size) && (endOp == ZSTD_e_end))
endOp = ZSTD_e_flush; /* can't end now : not all input consumed */

3
lib/compress/zstdmt_compress.h
View File

@ -85,7 +85,8 @@ ZSTDLIB_API size_t ZSTDMT_initCStream_usingCDict(ZSTDMT_CCtx* mtctx,
* List of parameters that can be set using ZSTDMT_setMTCtxParameter() */
typedef enum {
ZSTDMT_p_jobSize, /* Each job is compressed in parallel. By default, this value is dynamically determined depending on compression parameters. Can be set explicitly here. */
ZSTDMT_p_overlapSectionLog /* Each job may reload a part of previous job to enhance compressionr ratio; 0 == no overlap, 6(default) == use 1/8th of window, >=9 == use full window. This is a "sticky" parameter : its value will be re-used on next compression job */
ZSTDMT_p_overlapSectionLog, /* Each job may reload a part of previous job to enhance compressionr ratio; 0 == no overlap, 6(default) == use 1/8th of window, >=9 == use full window. This is a "sticky" parameter : its value will be re-used on next compression job */
ZSTDMT_p_rsyncable /* Enables rsyncable mode. */
} ZSTDMT_parameter;
/* ZSTDMT_setMTCtxParameter() :

21
lib/zstd.h
View File

@ -1149,6 +1149,27 @@ typedef enum {
* enum. See the comments on that enum for an
* explanation of the feature.
*/
ZSTD_p_rsyncable, /* Enables rsyncable mode, which makes compressed
* files more rsync friendly by adding periodic
* synchronization points to the compressed data.
* The target average block size is
* ZSTD_p_jobSize / 2. You can modify the job size
* to increase or decrease the granularity of the
* synchronization point. Once the jobSize is
* smaller than the window size, you will start to
* see degraded compression ratio.
* NOTE: This only works when multithreading is
* enabled.
* NOTE: You probably don't want to use this with
* long range mode, since that will decrease the
* effectiveness of the synchronization points,
* but your milage may vary.
* NOTE: Rsyncable mode will limit the maximum
* compression speed to approximately 400 MB/s.
* If your compression level is already running
* significantly slower than that (< 200 MB/s),
* the speed won't be significantly impacted.
*/
} ZSTD_cParameter;