From 473ade269628d1fb6cbc7b96a91e1c0aec1b8e59 Mon Sep 17 00:00:00 2001 From: Henri Beauchamp Date: Tue, 31 Jan 2023 17:42:51 +0100 Subject: SL-19110 Fast hashing classes for use in place of the slow LLMD5, where speed matters. (#64) This commit adds the HBXX64 and HBXX128 classes for use as a drop-in replacement for the slow LLMD5 hashing class, where speed matters and backward compatibility (with standard hashing algorithms) and/or cryptographic hashing qualities are not required. It also replaces LLMD5 with HBXX* in a few existing hot (well, ok, just "warm" for some) paths meeting the above requirements, while paving the way for future use cases, such as in the DRTVWR-559 and sibling branches where the slow LLMD5 is used (e.g. to hash materials and vertex buffer cache entries), and could be use such a (way) faster algorithm with very significant benefits and no negative impact. Here is the comment I added in indra/llcommon/hbxx.h: // HBXXH* classes are to be used where speed matters and cryptographic quality // is not required (no "one-way" guarantee, though they are likely not worst in // this respect than MD5 which got busted and is now considered too weak). The // xxHash code they are built upon is vectorized and about 50 times faster than // MD5. A 64 bits hash class is also provided for when 128 bits of entropy are // not needed. The hashes collision rate is similar to MD5's. // See https://github.com/Cyan4973/xxHash#readme for details. --- indra/llprimitive/llmodel.cpp | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) (limited to 'indra/llprimitive') diff --git a/indra/llprimitive/llmodel.cpp b/indra/llprimitive/llmodel.cpp index 206142fdd5..52fb8e3802 100644 --- a/indra/llprimitive/llmodel.cpp +++ b/indra/llprimitive/llmodel.cpp @@ -31,7 +31,7 @@ #include "llconvexdecomposition.h" #include "llsdserialize.h" #include "llvector4a.h" -#include "llmd5.h" +#include "hbxxh.h" #ifdef LL_USESYSTEMLIBS # include @@ -1564,7 +1564,7 @@ LLSD LLMeshSkinInfo::asLLSD(bool include_joints, bool lock_scale_if_joint_positi void LLMeshSkinInfo::updateHash() { // get hash of data relevant to render batches - LLMD5 hash; + HBXXH64 hash; //mJointNames for (auto& name : mJointNames) @@ -1573,24 +1573,19 @@ void LLMeshSkinInfo::updateHash() } //mJointNums - hash.update((U8*)&(mJointNums[0]), sizeof(S32) * mJointNums.size()); + hash.update((const void*)mJointNums.data(), sizeof(S32) * mJointNums.size()); //mInvBindMatrix F32* src = mInvBindMatrix[0].getF32ptr(); - for (int i = 0; i < mInvBindMatrix.size() * 16; ++i) + for (size_t i = 0, count = mInvBindMatrix.size() * 16; i < count; ++i) { S32 t = llround(src[i] * 10000.f); - hash.update((U8*)&t, sizeof(S32)); + hash.update((const void*)&t, sizeof(S32)); } - //hash.update((U8*)&(mInvBindMatrix[0]), sizeof(LLMatrix4a) * mInvBindMatrix.size()); + //hash.update((const void*)mInvBindMatrix.data(), sizeof(LLMatrix4a) * mInvBindMatrix.size()); - hash.finalize(); - - U64 digest[2]; - hash.raw_digest((U8*) digest); - - mHash = digest[0]; + mHash = hash.digest(); } U32 LLMeshSkinInfo::sizeBytes() const -- cgit v1.2.3