close method
void
close()
Undeclares the subscriber and releases native resources.
Safe to call multiple times -- subsequent calls are no-ops.
Implementation
void close() {
if (_closed) return;
_closed = true;
bindings.zd_subscriber_drop(_ptr.cast());
// closeAndDrain, not a bare port close: a retained handle that arrived and
// was never delivered has no other owner, so this is its only release.
_channel.closeAndDrain();
calloc.free(_ptr);
}