Add uuid_v7 support

UUIDv7, currently RFC is a new version that allows for time
ordering thanks to a unix timestamp component.

@see https://datatracker.ietf.org/doc/draft-peabody-dispatch-new-uuid-format/04/

lib/random/formatter.rb

@@ -148,6 +148,28 @@ def uuid
     "%08x-%04x-%04x-%04x-%04x%08x" % ary
   end
 
+  # Random::Formatter#uuid generates a random v7 UUID (Universally Unique IDentifier).
+  #
+  #   require 'random/formatter'
+  #
+  #   prng.uuid_v7 #=> "67fd173a-8401-7654-b51a-7654b702351a"
+  #   prng.uuid_v7 #=> "67fd173a-8401-7bb0-9f7e-0bb063b7df7e"
+  #   prng.uuid_v7 #=> "6bfd173a-8401-7eb0-bb89-4eb0e36a7b89"
+  #
+  # The version 7 UUID is random, but contains a time-based part for order (except the version).
+  #
+  # The result contains 122 random bits (15.25 random bytes).
+  #
+  # See RFC 4122 for details of UUID.
+  #
+  def uuid_v7
+    ts = [Process.clock_gettime(Process::CLOCK_REALTIME, :millisecond)].pack('Q').unpack('Nn')
+    ary = random_bytes(10).unpack("nnnN")
+    ary[0] = (ary[2] & 0x0fff) | 0x7000
+    ary[1] = (ary[3] & 0x3fff) | 0x8000
+    "%08x-%04x-%04x-%04x-%04x%08x" % (ts + ary)
+  end
+
   private def gen_random(n)
     self.bytes(n)
   end

test/ruby/test_random_formatter.rb

@@ -75,6 +75,17 @@ def test_uuid
       assert_match(/\A\h{8}-\h{4}-\h{4}-\h{4}-\h{12}\z/, uuid)
     end
 
+    def test_uuid_v7
+      uuid = @it.uuid_v7
+      assert_equal(36, uuid.size)
+
+      # Check time_hi_and_version and clock_seq_hi_res bits (RFC 4122 4.4)
+      assert_equal('7', uuid[14])
+      assert_include(%w'8 9 a b', uuid[19])
+
+      assert_match(/\A\h{8}-\h{4}-\h{4}-\h{4}-\h{12}\z/, uuid)
+    end
+
     def test_alphanumeric
       65.times do |n|
         an = @it.alphanumeric(n)