Add IO#timeout attribute and use it for blocking IO operations.

[ioquatix]

https://bugs.ruby-lang.org/issues/18630

[nobu]

Consider the backward compatibility of ruby/openssl.

[ko1]

I recommend to denote examples like "socket read/write".

[ko1]

ah, it's not a description for the method.

[ioquatix]

Sorry, I don't fully understand your feedback, but I'm happy to improve the documentation.

[ioquatix]

I have a follow up PR to improve the usage for backwards compatible extensions: #6507

[ioquatix]

Update to openssl gem: ruby/openssl#547

[eregon]

Should have been ..."3.2", fixed in ruby/spec@c3677cf

[ioquatix]

Thanks!

[paddor]

Sorry for asking here, but I'm reluctant to post a bug on Ruby Redmine. Should this feature work on all IO, like File and IO.fd_for(some_readiness_fd)? Because for me it doesn't.

require 'io/wait'
require 'socket'
require 'async'

begin
  STDIN.timeout = 1
  STDIN.read
rescue IO::TimeoutError
  puts "IO#timeout= worked on STDIN"
end


begin
  r, w = UNIXSocket.pair
  r.timeout = 1
  r.read
rescue IO::TimeoutError
  puts "IO#timeout= worked on UNIXSocket"
else
  puts "IO#timeout= did NOT work on UNIXSocket"
end


begin
  file = File.open '/dev/null'
  file.timeout = 1
  file.read
rescue IO::TimeoutError
  puts "IO#timeout= worked on File"
else
  puts "IO#timeout= did NOT work on File"
end


Async do
  file.read
rescue IO::TimeoutError
  puts "IO#timeout= worked on File in Async block"
else
  puts "IO#timeout= did NOT work on File in Async block"
end

Gives me:

IO#timeout= worked on STDIN
IO#timeout= worked on UNIXSocket
IO#timeout= did NOT work on File
IO#timeout= did NOT work on File in Async block

EDIT: It works for IO.fd_for(some_readiness_fd) inside an Async block, but not outside one. For File it doesn't work at all. Is it not supposed to?

[ioquatix]

I suppose timeouts should be considered advisory and/or best effort. Like, a safety net.

However, not working for File is probably to be expected, but I wonder if we can improve it. For sure, when running within Async, on the URing backend, it should be possible to make it work.