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Only Re-Alloc / Reset When Needed When Switching Between Regular and High Compression Modes

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This commit is contained in:
W. Felix Handte 2018-02-12 14:44:53 -05:00
parent b3628cb0c5
commit 7060bcabf0
1 changed files with 27 additions and 13 deletions
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40
lib/lz4frame.c
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@ -188,7 +188,15 @@ typedef struct LZ4F_cctx_s
U64 totalInSize;
XXH32_state_t xxh;
void* lz4CtxPtr;
U32 lz4CtxLevel; /* 0: unallocated; 1: LZ4_stream_t; 3: LZ4_streamHC_t */
/* lz4CtxLevel records both what size of memory has been allocated into the
* ctx pointer field and what it's being used as.
* - The low bit (& 1) value indicates whether the ctx is being used for
* hc (1) or not (0).
* - The next bit (& 2) indicates whether the allocated memory is big
* enough for a non-hc context.
* - The next bit (& 4) indicates whether the allocated memory is big
* enough for an hc context. */
U32 lz4CtxLevel;
} LZ4F_cctx_t;
@ -356,7 +364,7 @@ size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
LZ4_resetStream(&lz4ctx);
cctxI.lz4CtxPtr = &lz4ctx;
cctxI.lz4CtxLevel = 1;
cctxI.lz4CtxLevel = 2;
} /* fast compression context pre-created on stack */
memset(&options, 0, sizeof(options));
@ -513,21 +521,27 @@ size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
cctxPtr->prefs = *preferencesPtr;
/* Ctx Management */
{ U32 const ctxTypeID = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 1 : 2; /* 0:nothing ; 1:LZ4 table ; 2:HC tables */
if (cctxPtr->lz4CtxLevel < ctxTypeID) {
{ U32 const ctxSufficientAllocBits = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 2 : 6;
U32 const ctxTypeBit = cctxPtr->prefs.compressionLevel >= LZ4HC_CLEVEL_MIN;
if ((cctxPtr->lz4CtxLevel & ctxSufficientAllocBits) != ctxSufficientAllocBits) {
FREEMEM(cctxPtr->lz4CtxPtr);
if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
cctxPtr->lz4CtxPtr = (void*)LZ4_createStream();
else
} else {
cctxPtr->lz4CtxPtr = (void*)LZ4_createStreamHC();
}
if (cctxPtr->lz4CtxPtr == NULL) return err0r(LZ4F_ERROR_allocation_failed);
cctxPtr->lz4CtxLevel = ctxTypeID;
} else if (cctxPtr->lz4CtxLevel != ctxTypeID) {
/* otherwise, we must be transitioning from HC -> LZ4.
* In that case, avoid reallocating, since a LZ4 ctx
* fits in an HC ctx. Just reset. */
LZ4_resetStream((LZ4_stream_t *) cctxPtr->lz4CtxPtr);
cctxPtr->lz4CtxLevel = ctxTypeID;
cctxPtr->lz4CtxLevel = ctxSufficientAllocBits | ctxTypeBit;
} else if ((cctxPtr->lz4CtxLevel & 1) != ctxTypeBit) {
/* otherwise, a sufficient buffer is allocated, but we need to
* reset it to the correct context type */
if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
LZ4_resetStream((LZ4_stream_t *) cctxPtr->lz4CtxPtr);
cctxPtr->lz4CtxLevel &= ~1;
} else {
LZ4_resetStreamHC((LZ4_streamHC_t *) cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
cctxPtr->lz4CtxLevel |= 1;
}
}
}