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Replace random(), pg_erand48(), etc with a better PRNG API and algorithm.

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Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code.  In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.

xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy.  It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random().  It is not cryptographically strong, but neither
are the functions it replaces.

Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself

Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
This commit is contained in:
Tom Lane
2021-11-28 21:32:36 -05:00
parent f44ceb46ec
commit 3804539e48
50 changed files with 543 additions and 480 deletions
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26
configure vendored
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@ -16463,32 +16463,6 @@ esac
fi
ac_fn_c_check_func "$LINENO" "random" "ac_cv_func_random"
if test "x$ac_cv_func_random" = xyes; then :
$as_echo "#define HAVE_RANDOM 1" >>confdefs.h
else
case " $LIBOBJS " in
*" random.$ac_objext "* ) ;;
*) LIBOBJS="$LIBOBJS random.$ac_objext"
;;
esac
fi
ac_fn_c_check_func "$LINENO" "srandom" "ac_cv_func_srandom"
if test "x$ac_cv_func_srandom" = xyes; then :
$as_echo "#define HAVE_SRANDOM 1" >>confdefs.h
else
case " $LIBOBJS " in
*" srandom.$ac_objext "* ) ;;
*) LIBOBJS="$LIBOBJS srandom.$ac_objext"
;;
esac
fi
ac_fn_c_check_func "$LINENO" "strlcat" "ac_cv_func_strlcat"
if test "x$ac_cv_func_strlcat" = xyes; then :
$as_echo "#define HAVE_STRLCAT 1" >>confdefs.h