String#rindex has poor performance for pathological cases #1140
Description
When calling rindex on a long string that does not ever match and has a non-single-byte character, the behavior seems to be O(N^2). MRI's behavior appears to be O(N).
MRI 1.9.3-p448
length user system total real
10 0.000000 0.000000 0.000000 ( 0.000004)
100 0.000000 0.000000 0.000000 ( 0.000005)
1000 0.000000 0.000000 0.000000 ( 0.000014)
10000 0.000000 0.000000 0.000000 ( 0.000097)
100000 0.000000 0.000000 0.000000 ( 0.000942)
JRuby 1.7.5
length user system total real
10 0.000000 0.000000 0.000000 ( 0.000000)
100 0.000000 0.000000 0.000000 ( 0.001000)
1000 0.000000 0.000000 0.000000 ( 0.000000)
10000 0.040000 0.000000 0.040000 ( 0.026000)
100000 2.620000 0.000000 2.620000 ( 2.625000)