Refactors on Date#<=> and DateTime#<=>

Yes, no problem, will come with the results :)

Ok, I executed 10000 times with Ruby 1.8.7 the tests, each with 3 asserts, that compares:

Time with Time
Time with DateTime
Time with TimeWithZone
DateTime with Time
DateTime with DateTime
DateTime with TimeWithZone

and found that the call that is really expensive is Time#to_datetime .

As the first patch called #to_datetime in both self and the argument in Time#<=>, the performance of comparing a Time with another Time got really bad, as two expensive unnecessary operations were being called. In the second attached patch I changed Time#<=> to only execute self#to_datetime if the argument is a datetime. With this change, the performance was improved in all cases but just a little bit, in a normal request it may be insignificant.

Time#<=> DateTime

before:

47.57% 0.68% 28.62 0.41 0.00 28.21 30000 Time#<=> 285

     26.58   0.92    0.00    25.66   30000/30000    Time#to_datetime    290
     1.27    0.35    0.00    0.92    30000/30000    Date#compare_without_coercion   290
     0.31    0.21    0.00    0.10    30000/30000    Object#acts_like?   288
     0.05    0.05    0.00    0.00    30000/60000    Kernel#respond_to?  287

after:

47.22% 0.27% 28.49 0.17 0.00 28.33 30000 Time#<=> 280

     26.81   0.92    0.00    25.89   30000/30000    Time#to_datetime    281
     1.52    0.17    0.00    1.36    30000/30000    DateTime#<=>    281

Time#<=> Time

before:

13.67% 6.31% 0.72 0.33 0.00 0.39 30000 Time#<=> 285

     0.30    0.21    0.00    0.10    30000/30000    Object#acts_like?   288
     0.04    0.04    0.00    0.00    30000/60000    Kernel#respond_to?  287
     0.04    0.04    0.00    0.00    30000/30000    Time#compare_without_coercion   292

after:

7.66% 4.70% 0.39 0.24 0.00 0.15 30000 Time#<=> 282

     0.07    0.07    0.00    0.00    30000/30000    Time#to_time    283
     0.04    0.04    0.00    0.00    30000/30000    Kernel#is_a?    283
     0.04    0.04    0.00    0.00    30000/30000    Time#compare_without_coercion   283

Time#<=> TimeWithZone

before:

17.05% 5.52% 1.17 0.38 0.00 0.79 30000 Time#<=> 285

     0.39    0.26    0.00    0.13    30000/30000    ActiveSupport::TimeWithZone#respond_to? 287
     0.29    0.20    0.00    0.09    30000/30000    Object#acts_like?   288
     0.08    0.08    0.00    0.00    30000/30000    ActiveSupport::TimeWithZone#comparable_time 287
     0.04    0.04    0.00    0.00    30000/30000    Time#compare_without_coercion   292

after:

9.72% 3.77% 0.63 0.24 0.00 0.38 30000 Time#<=> 282

     0.19    0.11    0.00    0.08    30000/30000    ActiveSupport::TimeWithZone#to_time 283
     0.16    0.12    0.00    0.04    30000/30000    ActiveSupport::TimeWithZone#is_a?   283
     0.04    0.04    0.00    0.00    30000/30000    Time#compare_without_coercion   283