redis_cas_bench.rb

require 'redis'

class RedisBench
  def initialize(count)
    @count = count
    @r = Redis.new
  end

  def bench(prepare_items, label, &blk)
    @r.flushall
    if prepare_items
      @count.times do |i|
        @r.set(sprintf('k%07d', i), sprintf('va%07d', i))
      end
    end

    s = Time.now
    blk.call
    puts "#{label}: #{Time.now - s} sec"
  end
  private :bench

  def run
    [true, false].each do |prepare_items|
      if prepare_items
        puts "=========== with prepared items ==========="
      else
        puts "=========== with no items ==========="
      end
      puts

      bench(prepare_items, 'set') do
        @count.times do |i|
          @r.set(sprintf('k%07d', i), sprintf('va%07d', i))
        end
      end

      bench(prepare_items, 'getset') do
        @count.times do |i|
          @r.getset(sprintf('k%07d', i), sprintf('vb%07d', i))
        end
      end

      bench(prepare_items, 'eval(cas)') do
        lua_script = <<-EOF
local old_v = redis.call('get', KEYS[1])
if (old_v == false) then
  redis.call('set', KEYS[1], ARGV[1])
end
return old_v
        EOF
        @count.times do |i|
          @r.eval(lua_script, [sprintf('k%07d', i)], [sprintf('vc%07d', i)])
        end
      end

      bench(prepare_items, 'eval(multi-cas)') do
        xs = []
        @count.times do |i|
          xs << [sprintf('k%07d', i), sprintf('vd%07d', i)]
          if xs.size == 20
            lua_script = <<-EOF
local old_vs = redis.call('mget', #{xs.size.times.map{|i| "KEYS[#{i + 1}]"}.join(',')})
local len = #{xs.size}
local i = 1
while i <= len do
  if (old_vs[i] == false) then
    redis.call('set', KEYS[i], ARGV[i])
  end
  i = i + 1
end
return old_vs
EOF
            @r.eval(lua_script, xs.map{|kv| kv[0]}, xs.map{|kv| kv[1]})
            xs.clear
          end
        end
      end
      puts
    end
  end
end

RedisBench.new(10000).run

=========== with prepared items ===========

set: 0.873195 sec
getset: 0.907826 sec
eval(cas): 1.095413 sec
eval(multi-cas): 0.198834 sec

=========== with no items ===========

set: 0.935378 sec
getset: 0.882512 sec
eval(cas): 1.101836 sec
eval(multi-cas): 0.201168 sec