current_user performance :)

gistfile1.rb

Hey guys, since current_user is a method used in every request I decided to give it a few benchmarks

I'm gisting this so if anyone may find good literature

here was my start point question:
which is best?
(yes this approach doesn't validate an auth token)

  def current_user
    if session[:user_id]
      @current_user ||= User.find(session[:user_id])
    end
    @current_user
  end

  def current_user
    @current_user ||= User.find(session[:user_id]) rescue nil
  end

benchmarks:

require 'benchmark'

TIMES = 100
Benchmark.bmbm do |x|
  x.report("where first number") do
    TIMES.times { |i| User.where(:id=>i+100).first rescue nil }
  end
  x.report("where first nil") do
    TIMES.times { |i| User.where(:id=>nil).first rescue nil }
  end
  x.report("exception number") do
    TIMES.times { |i| User.find(i+100) rescue nil}
  end
  x.report("exception nil") do
    TIMES.times { User.find(nil) rescue nil }
  end
  x.report("if nil") do
    TIMES.times { User.find(nil) rescue nil if nil }
  end
end

                        user     system      total        real
where first number  0.070000   0.000000   0.070000 (  0.084907)
where first nil     0.080000   0.000000   0.080000 (  0.083039)
exception number    0.070000   0.000000   0.070000 (  0.076446)
exception nil       0.010000   0.000000   0.010000 (  0.007718)
if nil              0.010000   0.000000   0.010000 (  0.000077)


where first number
User Load (2.1ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 100 LIMIT 1
where first nil
User Load (1.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" IS NULL LIMIT 1
exception number
User Load (0.3ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 100]]



TIMES = 100_000
Benchmark.bmbm do |x|
  x.report("exception nil") do
    TIMES.times { User.find(nil) rescue nil }
  end
  x.report("if nil") do
    TIMES.times { User.find(nil) rescue nil if nil }
  end
  x.report("if nil present?") do
    TIMES.times { User.find(nil) rescue nil if nil.present? }
  end
  x.report("if nil nil?") do
    TIMES.times { User.find(nil) rescue nil if nil.present? }
  end
  x.report("unless nil nil?") do
    TIMES.times { User.find(nil) rescue nil unless nil.nil? }
  end
  x.report("unless nil blank?") do
    TIMES.times { User.find(nil) rescue nil unless nil.blank? }
  end
end

                        user     system      total        real
exception nil      11.070000   0.070000  11.140000 ( 11.160613)
if nil              0.020000   0.000000   0.020000 (  0.014595)
if nil present?     0.040000   0.000000   0.040000 (  0.042207)
if nil nil?         0.040000   0.000000   0.040000 (  0.041937)
unless nil nil?     0.030000   0.000000   0.030000 (  0.024599)
unless nil blank?   0.030000   0.000000   0.030000 (  0.027269)
if not nil nil?     0.030000   0.000000   0.030000 (  0.027878)
if not nil blank?   0.030000   0.000000   0.030000 (  0.028738)
if ! nil nil?       0.030000   0.000000   0.030000 (  0.027755)
if ! nil blank?     0.030000   0.000000   0.030000 (  0.028921)



conclusion: 

1. where :id sucks
2. find(nil) runs faster than find(number)
3. unless, if, if not, if ! => are the same
4. nil.checkmethod? looks nicer but runs slower
5. if value => most fastest

so this method is the ultimate bestest

  def current_user
    @current_user ||= User.find(session[:user_id]) rescue nil if session[:user_id]
  end