Add XON/XOFF and eparate write from processing

Part of xtermjs#425

demo/app.js

@@ -60,6 +60,9 @@ app.ws('/terminals/:pid', function (ws, req) {
 
  term.on('data', function(data) {
  try {
+ // XOFF - stop pty pipe
+ // XON will be triggered by emulator before processing data chunk
+ term.write('\x13');
  ws.send(data);
  } catch (ex) {
  // The WebSocket is not open, ignore

src/xterm.js

@@ -202,6 +202,11 @@ function Terminal(options) {
  this.prefix = '';
  this.postfix = '';
 
+ // user input states
+ this.writeBuffer = [];
+ this.writeInProgress = false;
+ this.user_xoff = false; // user pressed XOFF
+
  // leftover surrogate high from previous write invocation
  this.surrogate_high = '';
 
@@ -1341,8 +1346,27 @@ Terminal.prototype.scrollToBottom = function() {
  * @param {string} text The text to write to the terminal.
  */
 Terminal.prototype.write = function(data) {
+ this.writeBuffer.push(data);
+ if (!this.writeInProgress) {
+ // Kick off a write which will write all data in sequence recursively
+ this.writeInProgress = true;
+ // Kick off an async innerWrite so more writes can come in while processing data
+ setTimeout(() => this.innerWrite(this.writeBuffer.shift()));
+ }
+}
+
+Terminal.prototype.innerWrite = function(data) {
  var l = data.length, i = 0, j, cs, ch, code, low, ch_width, row;
 
+ // TODO: Need to have another buffer where data is held where write can grab lines from
+ // When this hits a certain threshold it should send this.write('\x13')
+
+ // XON - about to process data, thus we can get more
+ // dont lift XOFF if user pressed it
+ if (!this.user_xoff) {
+ this.send('\x11');
+ }
+
  this.refreshStart = this.y;
  this.refreshEnd = this.y;
 
@@ -2380,6 +2404,12 @@ Terminal.prototype.write = function(data) {
 
  this.updateRange(this.y);
  this.refresh(this.refreshStart, this.refreshEnd);
+
+ if (this.writeBuffer.length > 0) {
+ this.innerWrite(this.writeBuffer.shift());
+ } else {
+ this.writeInProgress = false;
+ }
 };
 
 /**
@@ -2423,6 +2453,12 @@ Terminal.prototype.keyDown = function(ev) {
  var self = this;
  var result = this.evaluateKeyEscapeSequence(ev);
 
+ if (result.key === '\x13') { // XOFF
+ this.user_xoff = true;
+ } else if (result.key === '\x11') { // XON
+ this.user_xoff = false;
+ }
+
  if (result.scrollDisp) {
  this.scrollDisp(result.scrollDisp);
  return this.cancel(ev, true);
@@ -2728,6 +2764,7 @@ Terminal.prototype.evaluateKeyEscapeSequence = function(ev) {
  }
  break;
  }
+
  return result;
 };