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ZSTD_estimateCCtx_advanced()

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ZSTD_estimateCCtx() is now a "simple" function,
taking int compressionLevel as single argument.

ZSTD_estimateCCtx_advanced() takes a CParams argument,
which is both more complete and more complex to generate.
This commit is contained in:
Yann Collet 2017-06-26 15:52:39 -07:00
parent 379f9d874d
commit 31af8290d1
4 changed files with 31 additions and 13 deletions
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15
doc/zstd_manual.html
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@ -389,6 +389,12 @@ unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
however it does mean that all frame data must be present and valid.
</p></pre><BR>
<pre><b>size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a ZSTD frame
`srcSize` must be >= ZSTD_frameHeaderSize_prefix.
@return : size of the Frame Header
</p></pre><BR>
<a name="Chapter13"></a><h2>Context memory usage</h2><pre></pre>
<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
@ -401,12 +407,15 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
Object memory usage can evolve if it's re-used multiple times.
</p></pre><BR>
<pre><b>size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams);
<pre><b>size_t ZSTD_estimateCCtxSize(int compressionLevel);
size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams);
size_t ZSTD_estimateDCtxSize(void);
</b><p> These functions make it possible to estimate memory usage
of a future target object, before its allocation,
given a set of parameters, which vary depending on target object.
of a future {D,C}Ctx, before its creation.
The objective is to guide decision before allocation.
ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large".
If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation.
ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
Note : CCtx estimation is only correct for single-threaded compression
</p></pre><BR>

16
lib/compress/zstd_compress.c
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@ -532,7 +532,7 @@ ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, u
}
size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams)
size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams)
{
size_t const blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog);
U32 const divider = (cParams.searchLength==3) ? 3 : 4;
@ -558,9 +558,15 @@ size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams)
return sizeof(ZSTD_CCtx) + neededSpace;
}
size_t ZSTD_estimateCCtxSize(int compressionLevel)
{
ZSTD_compressionParameters const cParams = ZSTD_getCParams(compressionLevel, 0, 0);
return ZSTD_estimateCCtxSize_advanced(cParams);
}
size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams)
{
size_t const CCtxSize = ZSTD_estimateCCtxSize(cParams);
size_t const CCtxSize = ZSTD_estimateCCtxSize_advanced(cParams);
size_t const blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog);
size_t const inBuffSize = ((size_t)1 << cParams.windowLog) + blockSize;
size_t const outBuffSize = ZSTD_compressBound(blockSize) + 1;
@ -3355,8 +3361,8 @@ size_t ZSTD_compress(void* dst, size_t dstCapacity, const void* src, size_t srcS
size_t ZSTD_estimateCDictSize(ZSTD_compressionParameters cParams, size_t dictSize, unsigned byReference)
{
DEBUGLOG(5, "sizeof(ZSTD_CDict) : %u", (U32)sizeof(ZSTD_CDict));
DEBUGLOG(5, "CCtx estimate : %u", (U32)ZSTD_estimateCCtxSize(cParams));
return sizeof(ZSTD_CDict) + ZSTD_estimateCCtxSize(cParams)
DEBUGLOG(5, "CCtx estimate : %u", (U32)ZSTD_estimateCCtxSize_advanced(cParams));
return sizeof(ZSTD_CDict) + ZSTD_estimateCCtxSize_advanced(cParams)
+ (byReference ? 0 : dictSize);
}
@ -3482,7 +3488,7 @@ ZSTD_CDict* ZSTD_initStaticCDict(void* workspace, size_t workspaceSize,
unsigned byReference, ZSTD_dictMode_e dictMode,
ZSTD_compressionParameters cParams)
{
size_t const cctxSize = ZSTD_estimateCCtxSize(cParams);
size_t const cctxSize = ZSTD_estimateCCtxSize_advanced(cParams);
size_t const neededSize = sizeof(ZSTD_CDict) + (byReference ? 0 : dictSize)
+ cctxSize;
ZSTD_CDict* const cdict = (ZSTD_CDict*) workspace;

9
lib/zstd.h
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@ -495,11 +495,14 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
/*! ZSTD_estimate*() :
* These functions make it possible to estimate memory usage
* of a future target object, before its allocation,
* given a set of parameters, which vary depending on target object.
* of a future {D,C}Ctx, before its creation.
* The objective is to guide decision before allocation.
* ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large".
* If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation.
* ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
* Note : CCtx estimation is only correct for single-threaded compression */
ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams);
ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel);
ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams);
ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
/*! ZSTD_estimate?StreamSize() :

4
tests/paramgrill.c
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@ -390,8 +390,8 @@ static int BMK_seed(winnerInfo_t* winners, const ZSTD_compressionParameters para
double W_DMemUsed_note = W_ratioNote * ( 40 + 9*cLevel) - log((double)W_DMemUsed);
double O_DMemUsed_note = O_ratioNote * ( 40 + 9*cLevel) - log((double)O_DMemUsed);
size_t W_CMemUsed = (1 << params.windowLog) + ZSTD_estimateCCtxSize(params);
size_t O_CMemUsed = (1 << winners[cLevel].params.windowLog) + ZSTD_estimateCCtxSize(winners[cLevel].params);
size_t W_CMemUsed = (1 << params.windowLog) + ZSTD_estimateCCtxSize_advanced(params);
size_t O_CMemUsed = (1 << winners[cLevel].params.windowLog) + ZSTD_estimateCCtxSize_advanced(winners[cLevel].params);
double W_CMemUsed_note = W_ratioNote * ( 50 + 13*cLevel) - log((double)W_CMemUsed);
double O_CMemUsed_note = O_ratioNote * ( 50 + 13*cLevel) - log((double)O_CMemUsed);