From 9438ef5f79fdac11080c3fa10c518e335fd7d8d6 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/llcommon/lluuid.cpp | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) (limited to 'indra/llcommon/lluuid.cpp') diff --git a/indra/llcommon/lluuid.cpp b/indra/llcommon/lluuid.cpp index acce8366ea..8ff6c45760 100644 --- a/indra/llcommon/lluuid.cpp +++ b/indra/llcommon/lluuid.cpp @@ -40,11 +40,11 @@ #include "lluuid.h" #include "llerror.h" #include "llrand.h" -#include "llmd5.h" #include "llstring.h" #include "lltimer.h" #include "llthread.h" #include "llmutex.h" +#include "hbxxh.h" const LLUUID LLUUID::null; const LLTransactionID LLTransactionID::tnull; @@ -402,11 +402,9 @@ LLUUID LLUUID::operator^(const LLUUID& rhs) const void LLUUID::combine(const LLUUID& other, LLUUID& result) const { - LLMD5 md5_uuid; - md5_uuid.update((unsigned char*)mData, 16); - md5_uuid.update((unsigned char*)other.mData, 16); - md5_uuid.finalize(); - md5_uuid.raw_digest(result.mData); + HBXXH128 hash((const void*)mData, 16, false); // false = do not finalize + hash.update((const void*)other.mData, 16); + hash.digest(result); } LLUUID LLUUID::combine(const LLUUID &other) const @@ -857,17 +855,12 @@ void LLUUID::generate() tmp >>= 8; mData[8] = (unsigned char) tmp; - LLMD5 md5_uuid; - - md5_uuid.update(mData,16); - md5_uuid.finalize(); - md5_uuid.raw_digest(mData); + HBXXH128::digest(*this, (const void*)mData, 16); } void LLUUID::generate(const std::string& hash_string) { - LLMD5 md5_uuid((U8*)hash_string.c_str()); - md5_uuid.raw_digest(mData); + HBXXH128::digest(*this, hash_string); } U32 LLUUID::getRandomSeed() @@ -885,13 +878,8 @@ U32 LLUUID::getRandomSeed() seed[7]=(unsigned char)(pid); getSystemTime((uuid_time_t *)(&seed[8])); - LLMD5 md5_seed; - - md5_seed.update(seed,16); - md5_seed.finalize(); - md5_seed.raw_digest(seed); - - return(*(U32 *)seed); + U64 seed64 = HBXXH64((const void*)seed, 16).digest(); + return U32(seed64) ^ U32(seed64 >> 32); } BOOL LLUUID::parseUUID(const std::string& buf, LLUUID* value) -- cgit v1.2.3