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Feature #2250 » io-finalize.rb

pilcrow (Mike Pomraning), 10/22/2009 12:43 PM

 
#!/usr/bin/env ruby

require 'socket'
require 'iosyssocket' # Adds IO::syssocket(), IO::sysclose()

include Socket::Constants

FIN = proc { |id| puts "Finalizing an IO::for_fd() object..." }

begin
#
# 1. Simulate an extension library which uses sockets internally,
# exposing an fd to the ruby layer for for_fd()
#
[ IO.syssocket(AF_INET, SOCK_STREAM, 0) ].each do |fd|
io = IO.for_fd(fd)
ObjectSpace.define_finalizer(io, FIN)
#
# 2. here we'd probably Kernel.select( [io], ... ), etc. ...
#
IO.sysclose(fd) # 3. extension library cleans itself up
end
end

dev_null = File.new("/dev/null") # 4. We re-use the fd our library just closed

p dev_null.stat # 5. Which appears quite normal, until ...
GC.start
p dev_null.stat # 6. ... the IO::for_fd() object finalizer closes it!
# Errno::EBADF
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