Advanced Rails - Building Industrial-Strength Web Apps in Record Time

Other Systems | 183

def factorial(n)

result = 1

n.downto(2) { |x| result *= x }

result

end

# Reimplemented in C (compiled on the fly)

inline do |builder|

builder.c <<-EOINLINE

long factorial_c(int max) {

int i = max,

result = 1;

while (i >= 2) { result *= i--; }

return result;

}

EOINLINE

end

end

We can then set up a benchmark to compare the two implementations:

t = Test.new

Benchmark.bmbm do |b|

b.report("Ruby factorial") do

200_000.times { t.factorial(20) }

end

b.report("C factorial") do

200_000.times { t.factorial_c(20) }

end

end

On my machine, the C implementation is extremely fast—more than 25 times the
speed of the standard Ruby implementation!

user system total real

Ruby factorial 2.760000 0.010000 2.770000 ( 2.753621)

C factorial 0.110000 0.000000 0.110000 ( 0.104440)

The best part of RubyInline is that it keeps your code clean. Ruby and C code
addressing the same area can be intermingled, rather than being spread across multi-
ple files. And RubyInline handles the type conversion for you—you can deal with
ints,longs, andchar *s, and they will automatically be converted to and from Ruby
types.

ActionMailer

Email delivery can be a difficult and aggravating aspect of a deployed application.
The SMT Pprotocol was not designed to withstand the types of attacks that are being
directed at the mail system today, and so delivering mail can be a more complicated
process than it may seem.