Random key/token generation that is much faster than UUID (at a higher risk, obviously)

fast_random_key_gen.rb

# From:
# https://stackoverflow.com/questions/88311/how-best-to-generate-a-random-string-in-ruby

#Generates a random URL-safe key/token much faster than UUID
#Comes with additional risk for high integrity keys, but for many cases it's good enough. 
#I'm using it to generate unique file names without the overhead of UUID.

#Occasionally returns a key of length-1
length = 5
p rand(36**length).to_s(36)
  
#Always returns specified length
length = 5
p (36**(length-1) + rand(36**length - 36**(length-1))).to_s(36)