Replace Timeout.timeout with Socket.tcp(..., open_timeout:)

[osyoyu]

Resolves #6.

This patch replaces the implementation of #open_timeout from Timeout.timeout from the builtin timeout in Socket.tcp, which was introduced in Ruby 3.5 (https://bugs.ruby-lang.org/issues/21347).

The builtin timeout in Socket.tcp is better in several ways. First, it does not rely on a separate Ruby Thread for monitoring Timeout (which is what the timeout library internally does). Also, it is compatible with Ractors, since it does not rely on Mutexes (which is also what the timeout library does).

This change allows the following code to work.

require 'net/http'
Ractor.new {
  uri = URI('http://example.com/')
  http = Net::HTTP.new(uri.host, uri.port)
  http.open_timeout = 1
  http.get(uri.path)
}.value

In Ruby <3.5 environments where Socket.tcp does not have the open_timeout option, I have kept the behavior unchanged. net/http will use Timeout.timeout { TCPSocket.open }.

Changes in behavior

The raised Net::OpenTimeout's message has slightly changed, and also carrys a Errno::ETIMEDOUT as its cause. I can keep the message compatible if needed.

/home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1668:in 'Net::HTTP#connect': Failed to open TCP connection to example.com:80 (Connection timed out - user specified timeout)
(Net::OpenTimeout)
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1636:in 'Net::HTTP#do_start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1625:in 'Net::HTTP#start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:2376:in 'Net::HTTP#request'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1991:in 'Net::HTTP#get'
        from nethttptest.rb:13:in '<main>'
/home/osyoyu/.rbenv/versions/master/lib/ruby/3.5.0+2/socket.rb:898:in 'block in Socket.tcp_with_fast_fallback': Connection timed out - user specified timeout (Errno::ETIMEDOUT)
        from /home/osyoyu/.rbenv/versions/master/lib/ruby/3.5.0+2/socket.rb:728:in 'Kernel#loop'
        from /home/osyoyu/.rbenv/versions/master/lib/ruby/3.5.0+2/socket.rb:728:in 'Socket.tcp_with_fast_fallback'
        from /home/osyoyu/.rbenv/versions/master/lib/ruby/3.5.0+2/socket.rb:667:in 'Socket.tcp'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1660:in 'Net::HTTP#connect'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1636:in 'Net::HTTP#do_start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1625:in 'Net::HTTP#start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:2376:in 'Net::HTTP#request'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1991:in 'Net::HTTP#get'
        from nethttptest.rb:13:in '<main>'

Previously, it looked like this.

/home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1663:in 'TCPSocket#initialize': Failed to open TCP connection to example.com:80 (execution expired) (Net::OpenTimeout)
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1663:in 'IO.open'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1663:in 'block in Net::HTTP#connect'
        from /home/osyoyu/.rbenv/versions/3.4.4/lib/ruby/3.4.0/timeout.rb:185:in 'block in Timeout.timeout'
        from /home/osyoyu/.rbenv/versions/3.4.4/lib/ruby/3.4.0/timeout.rb:192:in 'Timeout.timeout'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1662:in 'Net::HTTP#connect'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1636:in 'Net::HTTP#do_start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1625:in 'Net::HTTP#start'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:2376:in 'Net::HTTP#request'
        from /home/osyoyu/Development/rubyorg/net-http/lib/net/http.rb:1991:in 'Net::HTTP#get'
        from nethttptest.rb:13:in '<main>'

[osyoyu]

The failing test is caused by https://bugs.ruby-lang.org/issues/21512. We can wait until it gets fixed

[osyoyu]

Replaced by #224