while-connected

Invoke a function given that the socket is connected

Installation

npm install while-connected

Example

var whileConnected = require('while-connected');
 
...
 
tcpServer.on('connection', function(socket){
  socket.id = ...;
  trackConnection(socket, 5000);
})
 
// Every milliseconds update a database field
// regarding this sockets connection status.
function trackConnection(socket, interval_ms){
  var key = 'connections:'+ conn.id;
  // Make the key's ttl slightly longer than our loop
  // to minimize false positives.
  var key_ttl = (interval_ms/1000) + 2;
 
  whileConnected(socket, ms, function(again){
    // Refresh a database key re this socket's
    // connection that expires in 7 seconds.
    db.setex(key, key_ttl, true, function(){
      if (err) return console.error(err);
      again();
    });
  });
}

API

whileConnected(socket, debounce_ms, handler(again()))

whileConnected :: Socket a, Int b, (( -> void) -> *) -> void

• socket –– An instance of or inherited from net.Socket.

• debounce_ms –– The maximum loop speed. See handler for more info.

• handler ––

  Run some desired logic while the socket is connected.

  handler receives again function. Invoke again to re-run handler.

  1. whileConnected is invoked
  • if socket is connected: handler(again) (goto 2)
  1. debounce_ms countdown begins, once done goto 3
  2. if again() occured: handler(again) (goto 2)
  • otherwise, when next again() does occur: handler(again) (goto 2)

  Multiple again()s in a single "loop" is a noop.

  Immediately upon socket disconnection, handler(again) never occurs again. Loop effectively stops if it is running, again is a noop, etc.