Question

$ irb
1.9.3-p448 :001 > require 'socket'
 => true 
1.9.3-p448 :002 > TCPSocket.new('www.example.com', 111)

给出

Errno :: ETIMEDOUT：操作超时 - 连接（2）

问题：

如何定义TCPSocket.new？
如何正确捕获超时（或一般来说，套接字）异常？

Answer 1

至少从2.0开始就可以使用：

Socket.tcp("www.ruby-lang.org", 10567, connect_timeout: 5) {}

对于旧版本@falstru，答案似乎是最好的。

Answer 2

使用begin .. rescue Errno::ETIMEDOUT来捕捉超时：

require 'socket'

begin
  TCPSocket.new('www.example.com', 111)
rescue Errno::ETIMEDOUT
  p 'timeout'
end

要捕获任何套接字例外，请改用SystemCallError。

根据SystemCallError documentation：

SystemCallError是所有低级平台相关错误的基类。

当前平台上可用的错误是子类 SystemCallError并在Errno模块中定义。

TCPSocket.new不直接支持超时。

使用Socket::connect_non_blocking和IO::select设置超时。

require 'socket'

def connect(host, port, timeout = 5)

  # Convert the passed host into structures the non-blocking calls
  # can deal with
  addr = Socket.getaddrinfo(host, nil)
  sockaddr = Socket.pack_sockaddr_in(port, addr[0][4])

  Socket.new(Socket.const_get(addr[0][0]), Socket::SOCK_STREAM, 0).tap do |socket|
    socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)

    begin
      # Initiate the socket connection in the background. If it doesn't fail 
      # immediatelyit will raise an IO::WaitWritable (Errno::EINPROGRESS) 
      # indicating the connection is in progress.
      socket.connect_nonblock(sockaddr)

    rescue IO::WaitWritable
      # IO.select will block until the socket is writable or the timeout
      # is exceeded - whichever comes first.
      if IO.select(nil, [socket], nil, timeout)
        begin
          # Verify there is now a good connection
          socket.connect_nonblock(sockaddr)
        rescue Errno::EISCONN
          # Good news everybody, the socket is connected!
        rescue
          # An unexpected exception was raised - the connection is no good.
          socket.close
          raise
        end
      else
        # IO.select returns nil when the socket is not ready before timeout 
        # seconds have elapsed
        socket.close
        raise "Connection timeout"
      end
    end
  end
end

connect('www.example.com', 111, 2)

以上代码来自“Setting a Socket Connection Timeout in Ruby”。

Answer 3

如果您希望避免使用the pitfalls of Timeout，但希望避免必须处理自己的*_nonblock + select实施方式，则可以使用the tcp_timeout gem

tcp_timeout gem monkey-patches TCPSocket＃connect，＃read和#write，以便它们使用非阻塞I / O并具有您可以启用的超时。

Answer 4

您可以使用ruby的Timeout模块进行超时：

reqiure 'socket'
reqiure 'timeout'

begin 
   Timeout.timeout(10) do
      begin
         TCPSocket.new('www.example.com', 111)
      rescue Errno::ENETUNREACH
         retry # or do something on network timeout
      end
   end
rescue Timeout::Error
   puts "timed out"
   # do something on timeout
end

你将在10秒后得到：

# timed out
# => nil

如何定义Ruby TCPSocket超时？

4 个答案: