Add a way to reset multiple global random seeds

src/utils/rand.jl

@@ -1,4 +1,4 @@
-# global seed value for oscar to allow creating deterministic random number
+# global seed value for OSCAR to allow creating deterministic random number
 # generators
 # we initialize this here with a random value as well to allow use during
 # precompilation
@@ -33,3 +33,35 @@ be set to a fixed value with `Oscar.set_seed!` as it is done in `runtests.jl`.
 """
 get_seeded_rng() = return MersenneTwister([get_seed()])
 
+
+"""
+    seed_global!(s::Integer)
+
+Reset the random seed for many global RNGs used by OSCAR. Currently that includes:
+- the default Julia random source, `Random.default_rng()`
+- the default GAP random source `GlobalMersenneTwister`
+- the legacy GAP random source `GlobalRandomSource`
+
+In the future this should also reset the random seeds for Singular, Polymake
+and possibly other components used in OSCAR.
+
+```jldoctest
+julia> Oscar.seed_global!(1234)
+
+julia> rand(1:1000)
+326
+
+julia> GAP.Globals.Random(1,1000)
+749
+```
+"""
+seed_global!(s::Integer) = seed_global!(UInt32(s))
+
+function seed_global!(s::UInt32)
+  Random.seed!(s)
+
+  GAP.Globals.Reset(GAP.Globals.GlobalRandomSource, GAP.Obj(s))
+  GAP.Globals.Reset(GAP.Globals.GlobalMersenneTwister, GAP.Obj(s))
+
+  return nothing
+end