module ThreadSafe::Util::XorShiftRandom
A xorshift random number (positive +Fixnum+s) generator, provides reasonably cheap way to generate thread local random numbers without contending for the global Kernel.rand
.
Usage:
x = XorShiftRandom.get # uses Kernel.rand to generate an initial seed while true if (x = XorShiftRandom.xorshift).odd? # thread-localy generate a next random number do_something_at_random end end
Constants
- MAX_XOR_SHIFTABLE_INT
Public Instance Methods
get()
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Generates an initial non-zero positive Fixnum
via Kernel.rand
.
# File lib/thread_safe/util/xor_shift_random.rb, line 19 def get Kernel.rand(MAX_XOR_SHIFTABLE_INT) + 1 # 0 can't be xorshifted end
xorshift(x)
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using the “yˆ=y>>a; yˆ=y<<b; yˆ=y>>c;” transform with the (a,b,c) tuple with values (3,1,14) to minimise Bignum overflows
# File lib/thread_safe/util/xor_shift_random.rb, line 26 def xorshift(x) x ^= x >> 3 x ^= (x << 1) & MAX_INT # cut-off Bignum overflow x ^= x >> 14 end