Ruby: Run loop if variable set

Question

I'm executing a command with in ruby using open3, and Im setting a timeout using the safe_timeout gem (because of known issues with timeout reported here)

The code I have is very simple:

SafeTimeout.timeout(t) do
  stdout, stdeerr, status = Open3.capture3(cmd)
  @output = stdout
  @result = status.exitstatus
  @pid = status.pid
  @timeout = t
end

The caveat here is that I only want to run this within the timeout block if t is defined.

Obviously I can use an if statement but then I'd have duplicate stuff and it doesn't feel very "ruby-like" to me.

Is there a nice way to do something like:

if t
  timeout.do
    command
  end
else
  command_without_timeout
end

?

Mark Reed · Accepted Answer · 2016-01-25 21:30:59Z

4

You can use a Proc - the reified version of a Ruby code block. Put your command in the proc, and then either pass the proc to the timeout method (using the & operator to pass it as a block instead of a normal parameter) or else just call it directly. Example:

block = proc do
  # this is the code I want to run
  # with or without the timeout 
  stdout, stdeerr, status = Open3.capture3(cmd)
  @output = stdout
  @result = status.exitstatus
  @pid = status.pid
  @timeout = t
end

if t then
  SafeTimeout.timeout(t, &block)
else
  block.call
end

edited Jan 25, 2016 at 21:30

answered Jan 25, 2016 at 21:05

Mark Reed

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4 Comments

jaxxstorm Over a year ago

Awesome! This is what I ended up with. Thanks for the quick reply!

jaxxstorm Over a year ago

Quick question actually. I also want to get the duration of the block to determine how long it took to execute. When running block.call I can just do the following: startTime = Time.now block.call @duration = Time.now - startTime However doesn't seem clear to me how to do this with &block - is there a way?

Mark Reed Over a year ago

Why can't you do it with the timeout version, too? startTime = Time.now; if t then SafeTimeout.timeout(t,&block) else block.call end; @duration = Time.now - startTime

jaxxstorm Over a year ago

Ignore me, it was a stupid question anyway. I know how long it took because I set a timeout for it to end. D'oh

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