AuroraMiddleware/zstd
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improved ZSTDMT_compress()

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Use a bit more threads by default.
Uses overlap segments to boost compression ratio (like the streaming variant)
This commit is contained in:
Yann Collet 2017-03-30 15:51:58 -07:00
parent 6476c51b86
commit 458e955c23
1 changed files with 9 additions and 4 deletions
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13
lib/compress/zstdmt_compress.c
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@ -228,7 +228,8 @@ void ZSTDMT_compressChunk(void* jobDescription)
ZSTDMT_jobDescription* const job = (ZSTDMT_jobDescription*)jobDescription;
const void* const src = (const char*)job->srcStart + job->dictSize;
buffer_t const dstBuff = job->dstBuff;
DEBUGLOG(3, "job (first:%u) (last:%u) : dictSize %u, srcSize %u", job->firstChunk, job->lastChunk, (U32)job->dictSize, (U32)job->srcSize);
DEBUGLOG(3, "job (first:%u) (last:%u) : dictSize %u, srcSize %u",
job->firstChunk, job->lastChunk, (U32)job->dictSize, (U32)job->srcSize);
if (job->cdict) { /* should only happen for first segment */
size_t const initError = ZSTD_compressBegin_usingCDict(job->cctx, job->cdict, job->fullFrameSize);
if (job->cdict) DEBUGLOG(3, "using CDict ");
@ -250,7 +251,8 @@ void ZSTDMT_compressChunk(void* jobDescription)
job->cSize = (job->lastChunk) ?
ZSTD_compressEnd (job->cctx, dstBuff.start, dstBuff.size, src, job->srcSize) :
ZSTD_compressContinue(job->cctx, dstBuff.start, dstBuff.size, src, job->srcSize);
DEBUGLOG(3, "compressed %u bytes into %u bytes (first:%u) (last:%u)", (unsigned)job->srcSize, (unsigned)job->cSize, job->firstChunk, job->lastChunk);
DEBUGLOG(3, "compressed %u bytes into %u bytes (first:%u) (last:%u)",
(unsigned)job->srcSize, (unsigned)job->cSize, job->firstChunk, job->lastChunk);
_endJob:
PTHREAD_MUTEX_LOCK(job->jobCompleted_mutex);
@ -388,8 +390,9 @@ size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
int compressionLevel)
{
ZSTD_parameters params = ZSTD_getParams(compressionLevel, srcSize, 0);
size_t const overlapSize = (size_t)1 << (params.cParams.windowLog - 3);
size_t const chunkTargetSize = (size_t)1 << (params.cParams.windowLog + 2);
unsigned const nbChunksMax = (unsigned)(srcSize / chunkTargetSize) + (srcSize < chunkTargetSize) /* min 1 */;
unsigned const nbChunksMax = (unsigned)(srcSize / chunkTargetSize) + 1;
unsigned nbChunks = MIN(nbChunksMax, mtctx->nbThreads);
size_t const proposedChunkSize = (srcSize + (nbChunks-1)) / nbChunks;
size_t const avgChunkSize = ((proposedChunkSize & 0x1FFFF) < 0xFFFF) ? proposedChunkSize + 0xFFFF : proposedChunkSize; /* avoid too small last block */
@ -413,6 +416,7 @@ size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
buffer_t const dstAsBuffer = { dst, dstCapacity };
buffer_t const dstBuffer = u ? ZSTDMT_getBuffer(mtctx->buffPool, dstBufferCapacity) : dstAsBuffer;
ZSTD_CCtx* const cctx = ZSTDMT_getCCtx(mtctx->cctxPool);
size_t dictSize = u ? overlapSize : 0;
if ((cctx==NULL) || (dstBuffer.start==NULL)) {
mtctx->jobs[u].cSize = ERROR(memory_allocation); /* job result */
@ -421,7 +425,8 @@ size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
break; /* let's wait for previous jobs to complete, but don't start new ones */
}
mtctx->jobs[u].srcStart = srcStart + frameStartPos;
mtctx->jobs[u].srcStart = srcStart + frameStartPos - dictSize;
mtctx->jobs[u].dictSize = dictSize;
mtctx->jobs[u].srcSize = chunkSize;
mtctx->jobs[u].fullFrameSize = srcSize;
mtctx->jobs[u].params = params;