From: anselm <anselm@...>
Date: 2007-03-22T20:35:05+09:00
Subject: Re: Catching thread exceptions (Net::IMAP timeout)

On Mar 21, 9:03 pm, Brian Candler <B.Cand...@pobox.com> wrote:
> On Thu, Mar 22, 2007 at 02:55:12AM +0900, anselm wrote:
> > I have a question : is it possible to catch exceptions that are raised
> > on a thread by another thread ? Say if you have two threads, A and B
> > and thread A does
>
> > B.raise "bug"
>
> > Is there a way for thread B to catch and process that exception, and
> > resume it's execution where it was at  ?
>
> Well, one option is for B to start a new thread C, where it does all its
> work. The original thread B hangs around in an infinite loop just catching
> and processing exceptions.

Yes, this is pretty good thank you ! Maybe in my particular case I
could do it the other way round : start the imap thread from a new
thread wich will then just wait for the exception. This should then re-
raise exceptions that are not the timeout back on the main thread
(since in those cases the imap library blocks while waiting for
responses, this should not be a problem -- the exception should still
appear to come out of the imap call)

mainthread = Thread.current
imap = nil
Thread.new {
  begin
    limap = Net::IMAP.new('example.com')
    limap.login('username', 'password')
    imap = limap
    sleep 10000 while true
  rescue Exception => e
    if e.kind_of? Net::IMAP::ByeResponseError
      # deal with timeout
    else
       mainthread.raise e
    end
 end
}

# Wait for connection to be established
begin
  sleep 1 while imap.nil?
rescue Exception => e
  # Connection error
end

begin
  imap.select('', 'INBOX')
rescue Net::IMAP::Error
  # Synchronous exceptions should still be caught here
end

Thanks,
Anselm