diff options
Diffstat (limited to 'indra/llcommon/llrand.cpp')
| -rw-r--r-- | indra/llcommon/llrand.cpp | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/indra/llcommon/llrand.cpp b/indra/llcommon/llrand.cpp index 33afc50cf7..0192111574 100644 --- a/indra/llcommon/llrand.cpp +++ b/indra/llcommon/llrand.cpp @@ -58,7 +58,9 @@ * to restore uniform distribution. */ -static LLRandLagFib2281 gRandomGenerator(LLUUID::getRandomSeed()); +// gRandomGenerator is a stateful static object, which is therefore not +// inherently thread-safe. +static thread_local LLRandLagFib2281 gRandomGenerator(LLUUID::getRandomSeed()); // no default implementation, only specific F64 and F32 specializations template <typename REAL> @@ -71,7 +73,7 @@ inline F64 ll_internal_random<F64>() // CPUs (or at least multi-threaded processes) seem to // occasionally give an obviously incorrect random number -- like // 5^15 or something. Sooooo, clamp it as described above. - F64 rv = gRandomGenerator(); + F64 rv{ gRandomGenerator() }; if(!((rv >= 0.0) && (rv < 1.0))) return fmod(rv, 1.0); return rv; } @@ -79,7 +81,13 @@ inline F64 ll_internal_random<F64>() template <> inline F32 ll_internal_random<F32>() { - return F32(ll_internal_random<F64>()); + // *HACK: clamp the result as described above. + // Per Monty, it's important to clamp using the correct fmodf() rather + // than expanding to F64 for fmod() and then truncating back to F32. Prior + // to this change, we were getting sporadic ll_frand() == 1.0 results. + F32 rv{ narrow<F32>(gRandomGenerator()) }; + if(!((rv >= 0.0f) && (rv < 1.0f))) return fmodf(rv, 1.0f); + return rv; } /*------------------------------ F64 aliases -------------------------------*/ |