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added function to control monotonic memory budget increase of ZSTD_defaultCParameters[0]

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It's a runtime test, based on assert(),
played once, on first ZSTD_getCParams() usage,
when ZSTD_DEBUG is enabled.
This commit is contained in:
Yann Collet
2017-06-28 15:34:56 -07:00
parent adbe74a8ac
commit 813535105b
3 changed files with 58 additions and 10 deletions
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lib/compress/zstd_compress.c
+46
View File
@@ -4098,6 +4098,43 @@ static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEV
},
};
/* This function just controls
* the monotonic memory budget increase of ZSTD_defaultCParameters[0].
* Run only once, on first ZSTD_getCParams() usage, when ZSTD_DEBUG is enabled
*/
MEM_STATIC void ZSTD_check_compressionLevel_monotonicIncrease_memoryBudget(void)
{
# define ZSTD_TABLECOST(h,c) ((1<<(h)) + (1<<(c)))
# define ZDCP_FIELD(l,field) (ZSTD_defaultCParameters[0][l].field)
# define ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(l) { \
assert(ZDCP_FIELD(l,windowLog) <= ZDCP_FIELD(l+1,windowLog) ); \
assert(ZSTD_TABLECOST(ZDCP_FIELD(l,hashLog), ZDCP_FIELD(l,chainLog)) <= ZSTD_TABLECOST(ZDCP_FIELD(l+1,hashLog), ZDCP_FIELD(l+1,chainLog)) ); \
}
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(1);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(2);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(3);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(4);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(5);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(6);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(7);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(8);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(9);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(10);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(11);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(12);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(13);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(14);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(15);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(16);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(17);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(18);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(19);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(20);
ZSTD_CHECK_MONOTONIC_INCREASE_LEVEL(21);
assert(ZSTD_maxCLevel()==22);
}
/*! ZSTD_getCParams() :
* @return ZSTD_compressionParameters structure for a selected compression level, `srcSize` and `dictSize`.
* Size values are optional, provide 0 if not known or unused */
@@ -4108,6 +4145,15 @@ ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long l
U32 const tableID = (rSize <= 256 KB) + (rSize <= 128 KB) + (rSize <= 16 KB); /* intentional underflow for srcSizeHint == 0 */
if (compressionLevel <= 0) compressionLevel = ZSTD_CLEVEL_DEFAULT; /* 0 == default; no negative compressionLevel yet */
if (compressionLevel > ZSTD_MAX_CLEVEL) compressionLevel = ZSTD_MAX_CLEVEL;
#if defined(ZSTD_DEBUG) && (ZSTD_DEBUG>=1)
static int g_monotonicTest = 1;
if (g_monotonicTest) {
ZSTD_check_compressionLevel_monotonicIncrease_memoryBudget();
g_monotonicTest=0;
}
#endif
{ ZSTD_compressionParameters const cp = ZSTD_defaultCParameters[tableID][compressionLevel];
return ZSTD_adjustCParams_internal(cp, srcSizeHint, dictSize); }
}
lib/zstd.h
+6 -5
View File
@@ -496,9 +496,9 @@ 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 {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() can provide a tighter estimation.
* ZSTD_estimateCCtxSize() will provide a budget large enough for any compression level up to selected one.
* It will also consider src size to be arbitrarily "large", which is worst case.
* If srcSize is known to always be small, ZSTD_estimateCCtxSize_advanced() can provide a tighter 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(int compressionLevel);
@@ -506,8 +506,9 @@ ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cPa
ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
/*! ZSTD_estimate?StreamSize() :
* ZSTD_estimateCStreamSize() will consider src size to be arbitrarily "large".
* If srcSize is known to be small, ZSTD_estimateCStreamSize_advanced() can provide a tighter estimation.
* ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one.
* It will also consider src size to be arbitrarily "large", which is worst case.
* If srcSize is known to always be small, ZSTD_estimateCStreamSize_advanced() can provide a tighter estimation.
* ZSTD_estimateCStreamSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
* Note : CStream estimation is only correct for single-threaded compression.
* ZSTD_DStream memory budget depends on window Size.