flush method
See IOSink.flush
from dart:io
.
Because this base class doesn't do any buffering of its own, flush always completes immediately.
Subclasses that do buffer events should override flush to complete once
all events are delivered. They should also call super.flush()
at the
beginning of the method to throw a StateError if the sink is currently
adding a stream.
Implementation
Future<void> flush() {
if (_addingStream) throw StateError('StreamSink is bound to a stream');
if (_closed) return Future.value();
_addingStream = true;
return onFlush().whenComplete(() {
_addingStream = false;
});
}