1.1 Networking

Felix provides builtin support for asynchronous socket I/O. This is supported by platform dependent event notification services, using the best of select, poll, epoll, kqueue, Solaris I/O completion ports and Windows I/O completion ports. A single pre-emptive thread monitors the events and does all data transfers on behalf of the client fibres. The client fibres block, but the thread running them does not. The subsystem performing the event management is called demux and that performing the data transfers and fibre scheduling is called faio.

  
  // Get library resources
  
  include "std/io/iostream";
  include "std/io/socket";
  open IOStream;
  open Socket;
  open IOStream::TerminalIOByteStream[Socket::socket_t];
  
  // announce the program
  print "NETWORKING_01: MAINLINE: flx tcp stream test\n";
  
  // make a listening socket for our server
  var listener: socket_t;
  var port = 0;  // you choose
  mk_listener(&listener, &port, 1);
  println$ "NETWORKING_01: MAINLINE 01: Got port: " + port.str; 
  println$ "NETWORKING_01: MAINLINE 02: listener created on socket " + str listener;
  
  print "NETWORKING_01: MAINLINE 03: spawning server\n";
  spawn_fthread
  {
    var s: socket_t;
    println$ "NETWORKING_01: SERVER 01: listening on socket " + str listener;
    accept(listener, &s);
    println$ "NETWORKING_01: SERVER 02: Server accepted connection on socket " + str s;
    ioclose(listener);  // not needed anymore
  
    var eof = false;
    println$ "NETWORKING_01: SERVER 03: Attempting write";
    write_string(s, "NETWORKING_01: SERVER to CLIENT: server says hi\n", &eof);     // newline important here
    println$ "NETWORKING_01: SERVER 04: write complete";
  
    var st: string;
    println$ "NETWORKING_01: SERVER 05: Attempting read";
    get_line(s, &st);
    println$ "NETWORKING_01: SERVER 06: read complete";
  
    println$ "NETWORKING_01: SERVER 07: server got " + st.str;
    ioclose(s);
    println$ "NETWORKING_01: SERVER 08: closed socket " + str s;
  };
  
  print "NETWORKING_01: MAINLINE 04: spawning client\n";
  spawn_fthread
  {
    var eof = false;
    var c: socket_t;
    var err = 0;
    println$ "NETWORKING_01: CLIENT 01: trying to connected to server";
    connect(&c, C_hack::cast[+char]c"127.0.0.1", port, &err); // connect to localhost
    if err == 0 do
      println$ "NETWORKING_01: CLIENT 02: connected to server on socket is " + str c;
      var st: string;
  
      println "NETWORKING_01: CLIENT 03: Attempting read";
      get_line(c, &st);
      println$ "NETWORKING_01: CLIENT 04: read complete";
  
      println$ "NETWORKING_01: CLIENT 05: connector got "+ st.str;
  
      println$ "NETWORKING_01: CLIENT 06: Attempting write";
      write_string(c, "CLIENT to SERVER: thanks\n", &eof);         // newline important
      println$ "NETWORKING_01: CLIENT 07: write complete";
  
      ioclose(c);  
      println$ "NETWORKING_1: CLIENT 08: closed socket " + str c;
    else
     println$ "NETWORKING_01: CLIENT ERR: Connect error " + err.str;
    done
  };
  
  println$ "NETWORKING_01: MAINLINE 05: waiting for job to complete";