markRestarted method

void markRestarted()

Puts the session back to how it looked before its first line, because a new process is about to write into it.

The pane is emptied, and that is the decision rather than an accident of implementation. The output explaining why a service died is worth keeping right up to the moment someone asks for the service back — and the key that asks for it back is the point at which they have said they are done with it. Carrying it over would mean a pane where a stack trace from the dead process sits above the boot of the live one with nothing but a rule between them, and every question about it ("is this still broken?") is answered by scrolling past history the reader did not ask to keep.

This is the third and last thing that empties a pane, and the three are deliberately kept apart:

• the child writing kClearScreen while it redraws — a kRedrawDivider rule, and the history stays;
• c — clear, the settled lines go, the unterminated tails stay;
• s on a dead service — here, where everything goes.

Unlike clear, each stream's unterminated pending is dropped too. That tail belongs to a process that no longer exists, and holding it would splice the dead child's half-written line onto the front of the new child's first chunk.

_exitCode going back to null is what makes the session listen again: _note ignores every frame once a session knows it has exited, so a restarted service would otherwise sit on starting forever however much it printed.

baseUrl is deliberately kept, for the reason a reload keeps it: the port does not move, the new child re-announces and overwrites it in a moment, and in the gap the old address is the best answer there is.

Implementation

void markRestarted() {
  _settled.clear();

  for (final stream in [_stdout, _stderr]) {
    stream
      ..pending = ''
      ..transient = null;
  }

  // For [clear]'s reason: an anchor into a buffer that no longer exists draws
  // a blank pane, which reads as the restart having failed.
  _scrollTop = null;

  _exitCode = null;
  _state = ServiceState.starting;

  notifyListeners();
}