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recvfrom_nonblock(...) public

Receives up to maxlen bytes from socket using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor. flags is zero or more of the MSG_ options. The first element of the results, mesg, is the data received. The second element, sender_sockaddr, contains protocol-specific information on the sender.

When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns an empty string as data. The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.

Parameters

  • maxlen - the number of bytes to receive from the socket
  • flags - zero or more of the MSG_ options

Example

     # In one file, start this first
     require 'socket'
     include Socket::Constants
     socket = Socket.new(AF_INET, SOCK_STREAM, 0)
     sockaddr = Socket.sockaddr_in(2200, 'localhost')
     socket.bind(sockaddr)
     socket.listen(5)
     client, client_sockaddr = socket.accept
     begin
       pair = client.recvfrom_nonblock(20)
     rescue Errno::EAGAIN
       IO.select([client])
       retry
     end
     data = pair[0].chomp
     puts "I only received 20 bytes '#{data}'"
     sleep 1
     socket.close

     # In another file, start this second
     require 'socket'
     include Socket::Constants
     socket = Socket.new(AF_INET, SOCK_STREAM, 0)
     sockaddr = Socket.sockaddr_in(2200, 'localhost')
     socket.connect(sockaddr)
     socket.puts "Watch this get cut short!"
     socket.close

Refer to Socket#recvfrom for the exceptions that may be thrown if the call to recvfrom_nonblock fails.

Socket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure, including Errno::EAGAIN.

See

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