Timeout Idiom

ruby-talk
1

This idiom has been a decent shortcut for my work:

require 'timeout'

def timeout?(sec)
begin
freq = [0.01, sec / 1000].max
timeout(sec) {
while true
return false if yield
sleep(freq)
end
}
rescue Timeout::Error
return true
end
end

Code police may even approve, since 'timeout.rb' kinda uses
exception-throwing as flow control.

2

Some little style improvements. Note that you automatically have a codeblock in
a function, so you can spare the extra begin - end. Also there is a loop
function that makes while(true) explicit.

A personal style thing is, that I like to use { } for blocks whose return value
is of interest, and do end blocks for blocks whose side-effects are of
interest.

require 'timeout'

def timeout?(sec)
  freq = [0.01, sec / 1000].max
  timeout(sec) do
    loop do
      return false if yield
      sleep(freq)
    end
  end
rescue Timeout::Error
  return true
end

[0.5, 0.9, 1.0, 2.0, 3.0].each do | sleep_time |
  result = timeout?(1) do sleep sleep_time end
  puts "While sleeping #{sleep_time}s #{result ? 'a' : 'no'} timeout occured."
end

Best regards,

Brian

PS: Unindented code is really hard to read. I only understood your code after
using xemacs autoindentation.

···

On Fri, 10 Dec 2004 00:52:27 +0900 "Chuckl" <Killian2422@yahoo.com> wrote:

This idiom has been a decent shortcut for my work:

require 'timeout'

def timeout?(sec)
begin
freq = [0.01, sec / 1000].max
timeout(sec) {
while true
return false if yield
sleep(freq)
end
}
rescue Timeout::Error
return true
end
end

Code police may even approve, since 'timeout.rb' kinda uses
exception-throwing as flow control.

--
Brian Schröder
http://www.brian-schroeder.de/

3

Chuckl wrote:

This idiom has been a decent shortcut for my work:

require 'timeout'

def timeout?(sec)
begin
freq = [0.01, sec / 1000].max
timeout(sec) {
while true
return false if yield
sleep(freq)
end
}
rescue Timeout::Error
return true
end

Code police may even approve, since 'timeout.rb' kinda uses
exception-throwing as flow control.

Here's a class I've found useful (I use a C version, as well). It avoids the drift problem of just calling sleep(constant) for a constant value each time--it measures the error and corrects for it, if possible, so that even it will always try to get back on track. No threads, exceptions, or throw. Both external and internal iterator forms. Tests and docs included.

http://redshift.sourceforge.net/timer/

4

Sorry about the (lack of) indentation. That's what I get for using
Google groups and skipping "preview." And thanks for the style advice
-- obviously I'm new to Ruby.